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Objectives: To evaluate acceptability, safety, and continuation rates of centchroman following abortion., Study Design: Prospective, observational study. Following spontaneous/induced abortion, women were offered centchroman, 30-mg tablet twice weekly for first 3 months, then once weekly with 1 year of follow-up., Results: Of 120 women who opted for centchroman, continuation rate was 91% at 12 months. There was one case of user failure and one method failure and 26% had infrequent cycles., Conclusions: Centchroman is safe, effective, has good acceptance, and continuation rate post abortion with infrequent menstrual cycles as the main limiting factor for its continuation., Implications: Centchroman, available in Government scheme for contraception, has good acceptance and continuation rate post abortion. Its inclusion in contraceptive choices offered for postabortion contraception can go a long way in spacing of pregnancies, decreasing repeated unintended pregnancies, unsafe abortions, maternal morbidity, and mortality., Competing Interests: Conflicts of interest statement The authors have no conflicts of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Tumor angiogenesis is primarily regulated by vascular endothelial growth factor and its receptor (VEGF-VEGFR) communication, which is involved in cancer cell growth, progression, and metastasis. Diindolylmethane (DIM), a dietary bioactive from cruciferous vegetables, has been extensively studied in preclinical models for breast cancer prevention and treatment. Nevertheless, the possible role of DIM in the angiogenesis and metastasis regulations in triple-negative breast cancer (TNBC) remains elusive. Here, we investigated the potential anti-angiogenic and anti-metastatic role of DIM in combination with centchroman (CC). We observed that the oral administration of the DIM and CC combination suppressed primary tumor growth and tumor-associated vascularization in 4T1 tumors. Further, the DIM and CC combination exhibited a strong inhibitory effect on VEGF-induced angiogenesis in matrigel plugs. The mechanistic study demonstrated that DIM and CC could effectively downregulate VEGFA expression in tumor tissue and strongly interact with VEGFR2 to block its kinase activity. Interestingly, the DIM and CC combination also suppressed the lung metastasis of the highly metastatic 4T1 tumors through the downregulation of FAK/MMP9/2 signaling and reversal of epithelial-to-mesenchymal transition (EMT). Overall, these findings suggest that DIM-based nutraceuticals and functional foods can be developed as adjuvant therapy for treating TNBC.

Overexpression of drug efflux transporters is commonly associated with multidrug-resistance in cancer therapy. Here for the first time, we investigated the ability of diindolylmethane (DIM), a dietary bioactive rich in cruciferous vegetables, in enhancing the efficacy of Centchroman (CC) by modulating the drug efflux transporters in human breast cancer cells. CC is a selective estrogen receptor modulator, having promising therapeutic efficacy against breast cancer. The combination of DIM and CC synergistically inhibited cell proliferation and induced apoptosis in breast cancer cells. This novel combination has also hindered the stemness of human breast cancer cells. Molecular docking analysis revealed that DIM had shown a strong binding affinity with the substrate-binding sites of ABCB1 (P-gp) and ABCC1 (MRP1) drug-efflux transporters. DIM has increased the intracellular accumulation of Hoechst and Calcein, the substrates of P-gp and MRP1, respectively, in breast cancer cells. Further, DIM stimulates P-gp ATPase activity, which indicates that DIM binds at the substrate-binding domain of P-gp, and thereby inhibits its efflux activity. Intriguingly, DIM enhanced the intracellular concentration of CC by inhibiting the P-gp and MRP1 expression as well as activity. The intracellular retaining of CC has increased its efficacy against breast cancer. Overall, DIM, a dietary bioactive, enhances the anticancer efficiency of CC through modulation of drug efflux ABC-transporters in breast cancer cells. Therefore, DIM-based nutraceuticals and functional foods can be developed as adjuvant therapy against human breast cancer., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest, (Copyright © 2021. Published by Elsevier Inc.)

Aims: We have previously reported that Centchroman (CC), an oral contraceptive drug, inhibits breast cancer progression and metastasis. In this study, we investigated whether CC inhibits local invasion of tumor cells and/or their metastatic colonization with detailed underlying mechanisms., Main Methods: The effect of CC on the experimental metastasis and spontaneous metastasis was demonstrated by using tail-vein and orthotopic 4T1-syngeneic mouse tumor models, respectively. The anti-angiogenic potential of CC was evaluated using well established in vitro and in vivo models. The role of RAC1/PAK1/β-catenin signaling axis in the metastasis was investigated and validated using siRNA-mediated knockdown of PAK1 as well as by pharmacological PAK1-inhibitor., Key Findings: The oral administration of CC significantly suppressed the formation of metastatic lung nodules in the 4T1-syngeneic orthotopic as well as experimental metastatic models. More importantly, CC treatment suppressed the tube formation and migration capacities of human umbilical vein endothelial cells (HUVEC) and inhibited pre-existing vasculature as well as the formation of neovasculature. The suppression of migration and invasion capacities of metastatic breast cancer cells upon CC treatment was associated with the inhibition of small GTPases (Rac1 and Cdc42) concomitant with the downregulation of PAK1 and downstream β-catenin signaling. In addition, CC upregulated the expression of miR-145, which is known to target PAK1., Significance: This study warrants the repurposing of CC as a potential therapeutic agent against metastatic breast cancer., Competing Interests: Declaration of competing interest The authors declare no potential conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Aims: Recently, strategies of cancer treatment using combination of agents with distinct molecular mechanism(s) of action are considered more promising due to its high efficacy and reduced systemic toxicity. The study is aimed to improve the efficacy of selective estrogen receptor modulator, Centchroman (CC) by combination with the phytoestrogen Genistein (GN)., Methods: Cytotoxicity was evaluated by Sulforhodamine B assay. Cell cycle analysis was done through flow cytometry. Further, Apoptosis was analyzed using Annexin V/PI staining, tunel assay and electron microscopic examination and verified using western blot analysis. In order to validate the in vitro results, in vivo analysis was performed using 4T1-syngeneic mouse model., Key Findings: In this study, we report that the dietary isoflavone genistein (GN) synergistically improved antineoplasticity of CC in breast cancer by arresting cells at G2/M phase culminating in ROS dependent apoptosis. The combination of CC plus GN caused dysregulation of Bax and Bcl-2 ratio inducing mitochondrial dysfunction, activation of Caspase-3/7, -9 and PARP cleavage. Further, combination significantly suppresses phosphorylation of PI3K/Akt/NF-κB, enhancing apoptosis. Additionally, combination markedly reduced tumor growth compared to CC and GN alone in mouse 4T1 breast tumor model., Significance: Together, these studies suggest that GN represents a potential adjunct molecule whose role in CC induced apoptosis deserves attention., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To systematically identify and map the available evidence on effectiveness, side effects, pharmacokinetics and mechanism of action of centchroman as a contraceptive pill., Introduction: Centchroman was introduced in the Indian national family planning programme in 2016 as a once-a-week short-term contraceptive pill/oral contraceptive. At present there are no WHO recommendations on this method of contraception. We examined the available evidence through a scoping review., Methods: A search was conducted inclusive to the years 1970-2019 on electronic databases, grey literature sources and reference lists of included studies to identify studies. The five stages of Arksey and O'Malley's scoping review framework were applied in undertaking this scoping review., Results: The review identified 33 studies conducted between 1976 and 2017. Two studies reported mechanism of action of centchroman. Pharmacokinetics was reported by five studies among non-breastfeeding women and four studies among breastfeeding women. Eight studies reported on effectiveness ranging from 93% to 100%. Pregnancies due to user failure ranged from 2.6% to 10.2%. Although side effects were reported in 13 studies, the incidence varied greatly between the studies. Continuous bleeding and prolonged cycles >45 days were the most commonly reported side effects. All studies conducted had a small sample size and the duration of follow-up of women was 12 months or less. Fifty-five per cent of studies were by the developers of the pill (Central Drug Research Institute) and results of the phase IV clinical trial were unavailable., Conclusions: The scoping review shows that studies with robust designs and conducted in international context are lacking. Insufficient evidence exists on centchroman use as a postcoital contraceptive pill. The broad uncertainty in range of side effects and effectiveness in the studies implies insufficient evidence to make global recommendations on centchroman that is currently licensed as a contraceptive in India., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Despite advancements in the prognosis and management of breast cancer, it remains a major cause of mortality in women worldwide. Centchroman (CC), an oral contraceptive has been found to exhibit anti-cancer potential against a wide range of cancer including breast cancer., Purpose: The present study is intended to evaluate the ability of soy isoflavone Daidzein (DZ) in enhancing the efficacy of CC in Human Breast Cancer Cells (HBCCs)., Methods/study Design: Sulforhodamine B assay was employed to determine the cytotoxicity induced by 10 µM CC & 50 µM DZ separately and together in MCF-7/MDA MB-231 HBCCs and non-tumorigenic Human Mammary Epithelial Cells (HMECs) MCF-10A as a control. Combination Index (CI) analysis was executed using CompuSyn software. Further, apoptosis was assessed using Annexin V/PI, AO/PI staining and tunel assay. Cell cycle, reactive oxygen species generation and mitochondrial membrane potential alteration was determined using flow cytometry. Western blot analysis was performed to check the expression of respective proteins., Results: The results suggest that the combination exerts elevated toxicity as compared to control and each drug per se without affecting HMECs MCF-10A. This therefore implies cancer cell specific action of CC plus DZ administered together. Additionally, combination index analysis suggests synergistic action of CC and DZ combination in HBCCs. Cell cycle analysis, Annexin V/PI staining, tunel assay and western blot analysis confirms the induction of apoptosis by combination in HBCCs. Interestingly, western blot analysis also revealed that the combination down-regulated the expression of proteins involved in cell survival i.e. PI3K, Akt and mTOR, suggesting inhibition of cell survival pathway., Conclusion: The results overall demonstrate that CC plus DZ has higher anticancer efficacy as compared to either drug alone. Hence, the combination of CC plus DZ may offer a novel strategy for the management of breast cancer., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Centchroman (CC) or Ormeloxifene has been shown to induce apoptosis and cell cycle arrest in various types of cancer cells. This has, however, not been addressed for endometrial cancer cells where its (CC) mechanism of action remains unclear. This study focuses on the basis of antineoplasticity of CC by blocking the targets involved in the cell cycle, survival and apoptosis in endometrial cancer cells. Ishikawa Human Endometrial Cancer Cells were cultured under estrogen deprived medium, exposed to CC and analyzed for proliferation and apoptosis. Additionally, we also analyzed oxidative stress induced by CC. Cell viability studies confirmed the IC 50 of CC in Ishikawa cells to be 20 µM after 48 h treatment. CC arrests the cells in G0/G1 phase through cyclin D1 and cyclin E mediated pathways. Phosphatidylserine externalization, nuclear morphology changes, DNA fragmentation, PARP cleavage, and alteration of Bcl-2 family protein expression clearly suggest ongoing apoptosis in the CC treated cells. Activation of caspase 3 & 9, up-regulation of AIF and inhibition of apoptosis by z-VAD-fmk clearly explains the participation of the intrinsic pathway of programmed cell death. Further, the increase of ROS, loss of MMP, inhibition of antioxidant (MnSOD, Cu/Zn-SOD and GST) and inhibition of apoptosis with L-NAC suggests CC induced oxidative stress leading to apoptosis via mitochondria mediated pathway. Therefore, CC could be a potential therapeutic agent for the treatment of Endometrial Cancer adjunct to its utility as a contraceptive and an anti-breast cancer agent.

Centchroman (CC), a female oral contraceptive, has been shown to possess breast anti-cancer activities. Recently, we have shown CC-mediated antimetastatic effect through reversal of epithelial-to-mesenchymal transition (EMT) in breast cancer. The loss of tumor suppressor genes (TSGs) has been shown to promote EMT in breast cancer. Therefore, in the present study, we investigated the effect of CC-treatment on the expression of tumor-related genes including both tumor suppressor- and tumor promoter genes in breast cancer. CC treatment resulted in G 0 /G 1 phase cell cycle arrest in human breast cancer MDA-MB-231, SK-BR-3, and ZR-75-1 cells with the concomitant induction of TSGs such as p21 WAF1/CIP1 , p16 INK4a , and p27 Kip1 . In addition, CC treatment also resulted in the downregulation of tumor promoter gene, human telomerase reverse transcriptase (hTERT). The induction of TSGs and downregulation of hTERT was found to be correlated with decreased expression levels of histone deacetylases (HDACs) and DNA methyltransferases (DNMTs). Further, mechanistic studies revealed CC-induced global DNA demethylation and alterations in the enrichment of chromatin modification markers at the promoters of p21 and hTERT. These in vitro results were corroborated with in vivo findings in 4T1-syngeneic mouse model, where CC-treatment resulted in tumor growth reduction accompanied with the induction of TSGs and alterations in the expression levels of HDACs, DNMT1, and histone modification markers. Overall, our findings suggest that CC-treatment induces the expression of TSGs and downregulates hTERT through histone modifications and DNA methylation changes. Therefore, CC could be further developed into a promising drug candidate against breast cancer. © 2015 Wiley Periodicals, Inc., (© 2015 Wiley Periodicals, Inc.)

Objective: To investigate the effect of xy2004, a centchroman derivative, on the proliferation of MCF-7 cells and the mechanisms., Methods: The effects of xy2004 on MCF-7 cell proliferation and apoptosis were evaluated with MTT assay and flow cytometry, respectively. The expressions of the apoptosis-related proteins were examined with Western blotting. Competitive estrogen-receptor binding assay was used to investigate the affinity of xy2004 to estrogen receptors (ER)., Results: xy2004 induced proliferation of MCF-7 cells at low concentrations but inhibited cell proliferation at high concentrations. The application of tamoxifen inhibited xy2004-induced proliferation of MCF-7 cells. The relative binding affinity of xy9906 to ERα and ERβ, presented as the IC50 value, was 7.38 × 10⁻³ mol/L and 4.12 × 10⁻⁷ mol/L, respectively. Treatment of MCF-7 cells with high-concentration xy2004 reduced the cellular expression of Bcl-2 protein and increased Bax protein expression., Conclusion: At low concentrations, xy2004 directly stimulates the proliferation of MCF -7 cells through ligand-receptor binding, and at high concentrations, it inhibits the cell proliferation by regulating the expression levels of the apoptosis-related proteins.

Polyphenols as "sensitizers" together with cytotoxic drugs as "inducers" cooperate to trigger apoptosis in various cancer cells. Hence, their combination having similar mode of mechanism may be a novel approach to enhance the efficacy of inducers. Additionally, this will also enable to achieve the physiological concentrations facilitating significant increase in the activity at concentrations which the compound can individually provide. Here we propose that polyphenols (Resveratrol (RES) and Curcumin (CUR)) pre-treatment may sensitize MCF-7/MDA MB-231 (Human Breast Cancer Cells, HBCCs) to Centchroman (CC, antineoplastic agent). 6 h pre-treated cells with 10 µM RES/CUR and 100 µM RES/30 µM CUR doses, followed by 10 µM CC for 18 h were investigated for Ser-167 ER-phosphorylation, cell cycle arrest, redox homeostasis, stress activated protein kinase (SAPKs: JNK and p38 MAPK) pathways and downstream apoptosis effectors. Low dose RES/CUR enhances the CC action through ROS mediated JNK/p38 as well as mitochondrial pathway in MCF-7 cells. However, RES/CUR sensitization enhanced apoptosis in p53 mutant MDA MB-231 cells without/with involvement of ROS mediated JNK/p38 adjunct to Caspase-9. Contrarily, through high dose sensitization in CC treated cells, the parameters remained unaltered as in polyphenols alone. We conclude that differential sensitization of HBCCs with low dose polyphenol augments apoptotic efficacy of CC. This may offer a novel approach to achieve enhanced action of CC with concomitant reduction of side effects enabling improved management of hormone-dependent breast cancer.

Centchroman (CC; 67/20; INN: Ormeloxifene) is a non-steroidal antiestrogen extensively used as a female contraceptive in India. In the present study, we report the anti-proliferative effect of CC in head and neck squamous cell carcinoma (HNSCC) cells. CC inhibited cell proliferation in a dose dependent manner at 24 h of treatment. Further studies showed that CC treatment induced apoptosis, inhibited Akt/mTOR and signal transducers and activators of transcription protein 3 (STAT3) signaling, altered proteins associated with cell cycle regulation and DNA damage and inhibited colony forming efficiency of HNSCC cells. In addition, CC displayed anti-proliferative activity against a variety of non-HNSCC cell lines of diverse origin. The ability of CC to serve as a dual-inhibitor of Akt/mTOR and STAT3 signaling warrants further studies into its role as a therapeutic strategy against HNSCC., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Aims: Centchroman (CC) has been established as a potent antineoplastic agent in MCF-7 (ER+ve) and MDA MB-231 (ER-ve) Human Breast Cancer Cells (HBCCs) previously by us. To elucidate its antineoplastic action, we investigated the factors involved in cell-cycle progression and apoptosis., Main Methods: Tamoxifen (TAM), a widely used antiestrogen was employed as a positive control. Role of Cycloheximide (CHX), Actinomycin-D (Act-D) and caspases were explored using specific inhibitors. Involvement of cell-cycle and apoptosis related factors were explored using western blotting and immunoprecipitation., Key Findings: Metabolic inhibitors viz. CHX, Act-D and pan-Caspase inhibitor, Z-VAD-FMK attenuated CC-induced apoptosis. The upregulation of both p21(Waf1/Cip1) and p27(Kip1) along with p21-CDK6 (Cyclin Dependent Kinase 6) and p21-PCNA (Proliferating Cell Nuclear Antigen) interaction suggests their role in CC-induced cell-cycle arrest. The downregulation of Cyclin-D(1) and -E levels further confirms the antiestrogenic profile of CC. Unlike MDA MB-231, in MCF-7 cells, CC upregulates the level of phospho-p53 (Ser-15) and FasL, suggesting the involvement of extrinsic pathway. CC altered the intracytosolic balance of members of Bcl-2 family along with the cleavage of Poly (ADP-ribose) polymerase (PARP), Bcl-X(L), Bid and AIF (Apoptosis Inducing Factor). The evaluation of Mitogen Activated Protein Kinases (MAPKs) using specific inhibitors and Western blotting confirms CC-induced the upregulation of phospho-c-Jun and phospho-p38. Additionally elevated SOD (Superoxide Dismutase) and unaltered CAT (Catalase) expression further suggest the involvement of oxidative stress., Significance: These results confirm that the antineoplasticity of CC in MCF-7 and MDA MB-231 cells involves the extrinsic and intrinsic pathways of apoptosis along with oxidative stress., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Studies with Centchroman (CC) as a candidate anti-breast cancer agent are into phase III multicentric clinical trial in stage III/IV breast cancer. We have previously demonstrated its anti-neoplastic activity in Estrogen Receptor positive (ER+ve) MCF-7 Human Breast Cancer Cells (HBCCs). We now present the basis for anti-neoplastic activity of CC, mediated through apoptosis in both ER+ve/-ve MCF-7 and MDA MB-231 HBCCs respectively, compared to Tamoxifen (TAM) as a positive control. All the experiments were performed with 48 h estrogen-deprived cells exposed to CC/TAM for the subsequent 48 h. Cytotoxic potential of CC was assessed through SRB assay. Cell-cycle analysis, Time-dependent cytotoxicity, Reactive Oxygen Species (ROS) and Mitochondrial Membrane Permeability were investigated by Flow Cytometry. Early-stage apoptosis was detected by Annexin-PI staining. Caspases were assayed colorimetrically whereas nuclear derangements were assessed morphologically through PI staining and finally by DNA fragmentation analysis. Cell viability studies confirmed the IC50 of CC in MCF-7 and MDA MB-231 cells to be 10 and 20 microM (P < 0.001) respectively, suggesting enhanced susceptibility of the former cell type to CC. FACS data reveals CC mediated G0/G1 arrest (P < 0.01) along with the presence of prominent sub-G0/G1 peak (P < 0.001) in both the cell types suggesting ongoing apoptosis. Phosphatidylserine externalization, mitochondrial events, caspase evaluation and nuclear morphology changes reveal initiation/progression of caspase-dependent apoptosis even at a dose of 1 microM which eventually leads to DNA fragmentation in both the cell types. Results demonstrate that CC induces caspase-dependent apoptosis in MCF-7 and MDA MB-231 cells irrespective of ER status similar to TAM in terms of anti-neoplastic activity.

Background: Centchroman, a nonsteroidal oral contraceptive, was evaluated for its hitherto unstudied effect on cardiovascular system, thyroid function and tissue lipid peroxidation in rats., Study Design: Wistar sperm-positive female rats were treated with Centchroman (1.5 mg/kg per day, po) for 10 days and the alterations in serum concentration of thyroid hormones [triiodothyronine (T(3)) and thyroxine (T(4))], insulin, glucose, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), triglycerides (TG), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phospahatase (ALP) activity, hepatic type-1 iodothyronine 5'-monodeiodinase (5'D) enzyme activity and hepatic, renal, cardiac and serum lipid peroxidation (LPO) were studied. Simultaneously, alterations in endogenous antioxidants [superoxide dismutase (SOD); catalase (CAT) and reduced glutathione (GSH)], relative risk ratio (RR), atherogenic index (AI) and daily rate of food and water consumption were also investigated as supportive parameters., Results: Centchroman administration resulted in the complete inhibition of pregnancy. It increased serum T(4) marginally and HDL-C levels, hepatic SOD, CAT and GSH; cardiac SOD and GSH and renal SOD and CAT activity significantly. However, it reduced LPO in all tissues; concentrations of other serum lipids; AI; RR and activity of ALP., Conclusions: As Centchroman administration did not alter the concentrations of most active thyroid hormone, T(3), serum insulin and glucose, it appears that the drug has no side effect on thyroid function and glucose metabolism. Rather, it possesses cardiovascular and anti-peroxidative benefits.

Centchroman (Ormeloxifene) is a nonsteroidal selective estrogen receptor modulator that is used as once a week oral contraceptive agent. The effect of centchroman on the immune system was evaluated by using different experimental models such as carbon clearance test, cyclophosphamide induced neutropenia, neutrophil adhesion test, effect on serum immunoglobulins, mice lethality test and indirect haemagglutination test. The first three models namely carbon clearance test, cyclophosphamide induced neutropenia and neutrophil adhesion test were used to study cell mediated immunity while the latter three models were used to see the effect on humoral immunity. Centchroman was administered orally at a dose of 5 mg/kg and levamisole (2.5 mg/kg/ p.o) was used as standard drug. Centchroman significantly increased the levels of serum immunoglobulins and also prevented the mortality induced by bovine Pasteurella multocida in mice. It also increased significantly the circulating antibody litre in indirect haemagglunation test. However, it did not show any significant effect on phagocytic index in carbon clearance assay and nor did influence the adhesion of neutrophils in the neutrophil adhesion test. Centchroman was also not effective in preventing the cyclophosphamde induced neutropenia. Hence, it was concluded that centchroman increases humoral immunity with no significant effect on cell mediated immunity.

Introduction: Centchroman (international nonproprietary name: ormeloxifene) is a nonsteroidal selective estrogen receptor modulator, oral contraceptive, anticancer and antiosteoporotic agent that is intended for long-term use by women. In view of the vast clinical applications and interactions of steroidal oral contraceptives with commonly used therapeutic agents, the interaction potential of certain concomitantly administered therapeutic agents was investigated in terms of postcoital contraceptive efficacy (pharmacological) and the pharmacokinetic profile of centchroman in female Sprague-Dawley rats. The coadministered drugs used in the study were ciprofloxacin, cefixime, amoxicillin, metronidazole, amlodipine, atenolol, theophylline, metformin, pioglitazone and glibenclamide., Materials and Methods: The pharmacological activity of centchroman was evaluated in sperm-positive female rats at 1.5 mg/kg, with or without coadministered drugs. Rats were sacrificed on Day 10 postcoitus, and autopsy was performed to check for the presence or absence of implantations. The estrogenic and antiestrogenic activities of centchroman were evaluated in immature ovariectomized rats. Pharmacokinetic interaction was studied in normal female rats with or without coadministered drugs. Serum samples were taken over 120 h and analyzed using a validated high-performance liquid chromatography method to generate the pharmacokinetic profile of centchroman. Pharmacokinetic parameters were estimated using noncompartmental analysis, and the results were compared., Results: In pharmacological interaction studies, centchroman alone showed a 100% success rate when given alone or in the presence of coadministered drugs. The only exception was amoxicillin coadministration, with 66% rats in the group showing resorbed implantations. Further investigation with amoxicillin in ovariectomized immature rats indicates no alteration in the estrogenic and antiestrogenic profiles of centchroman. In pharmacokinetic interaction studies, most of the therapeutic agents affected the rate and extent of absorption of centchroman. In other pharmacokinetic parameters, clearance (CL) remained unchanged; however, there was decrease in bioavailability (F) and volume of distribution (V(d)) in some situations., Conclusions: The results indicate that there is no direct link between the altered pharmacokinetics of centchroman and the failure of pharmacological effect. The pharmacological interaction with amoxicillin could not be explained on the basis of alteration in the estrogenic and antiestrogenic activities of centchroman, indicating that different mechanisms are involved. The findings, however, suggest that amoxicillin coadministration may result in pharmacological interaction with centchroman and that caution should be taken in clinical practice.

Studies were undertaken to evaluate the influence of estrogen antagonist-cum anti-implantation agent, ormeloxifene, on 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity and estrogen action in rat uterus during preimplantation period and to examine its ability to induce progesterone receptor (PR) in immature rat model. A group of female rats received orally a contraceptive dose of 1.25 mg/kg of ormeloxifene on Day 1 postcoitum (pc). Rats were sacrificed on Days 3, 4 and 5 pc, and uterine tissues were processed for enzymatic, estrogen receptor and estradiol (E(2)) estimations. Immature ovariectomized rats received ormeloxifene, subcutaneously for 3 days at various doses in the absence or presence of estradiol, and uterine PR levels were measured using (3)H-R5020 as radioligand. Results revealed that ormeloxifene treatment caused a marked increase in enzyme activity of 17beta-HSD on Days 3, 4 and 5 pc as compared to respective controls. Further, total uterine estrogen receptors as estimated by exchange assay showed a noticeable decrease on Days 4 (35%) and 5 (>80%) pc in ormeloxifene-treated groups. The results correlated well with a decrease in tissue E(2) levels. In immature rats, ormeloxifene caused a dose-dependent increase in cytosolic PR levels; ormeloxifene given along with E(2) (0.1 mug) for 3 days caused a significant reduction in concentration of PRs at 10 mug and higher doses. Ormeloxifene also induced (3)H-progesterone (P) uptake by immature rat uterus. However, in the presence of E(2), it significantly reduced (3)H-P uptake. The in vitro competitive binding experiments did not reveal any displacement of (3)H-R5020 either by ormeloxifene or by its hydroxy derivative from PR. The results suggest that in addition to its competitive antagonism at estrogen receptor level, ormeloxifene enhances the inactivation of intracellular E(2) to estrone, a biologically less active form, thus declining estrogen receptor pool. Moreover, it causes indirect anti-progestational effects in the uterus by virtue of its anti-estrogenic profile rather than by blocking the PRs.

Among the 10 commonly used therapeutic agents investigated, concurrent oral administration of tetracycline (140 mg/kg) twice daily on Days 1-5 post-coitum (pc) interfered with the post-coital anti-implantation activity and almost completely abolished estrogen antagonistic activity of the single anti-implantation (1.5 mg/kg, orally) dose of dl-ormeloxifene administered on Day 1 pc, resulting in the occurrence of resorbed implantations in 50% of the females. However, no such interaction was evident when tetracycline was administered intramuscularly or when ormeloxifene was administered at twice its anti-implantation dose. There was no effect of ormeloxifene and/or tetracycline treatment on serum estradiol and progesterone levels, and all animals presented apparently normal corpora lutea. Ormeloxifene administered per se inhibited aminopyrine-N-demethylase (AD), glucose-6-phosphate dehydrogenase (G-6-PDH) and glutathione-S-transferase (GST) in the liver on the day of maximal endometrial receptivity, which was prevented by tetracycline co-administration. Aniline hydroxylase and AD were not detected in small intestine or uterus in vehicle control or any of the treatment groups. There was, however, no effect of ormeloxifene plus tetracycline treatment on serum total alkaline phosphatase activity. Findings suggest that interference with anti-implantation action of ormeloxifene by tetracycline might be due primarily to the almost complete abolition of its estrogen antagonistic activity at the uterine level, effected by decreased bioavailability of ormeloxifene and/or its active metabolite(s) by altered enterohepatic recirculation because of the effect on gut microflora. This might alternatively be related to an increased rate of its metabolism and elimination from the system via prevention of ormeloxifene-induced inhibition of hepatic AD, G-6-PDH, and GST, which, by effecting a decreased rate of metabolism, might be responsible for prolonged (approximately 120 h) duration of estrogen antagonistic/anti-implantation action of ormeloxifene in this species.

DL-Centchroman (67/20; INN: Ormeloxifene) synthesized at the Central Drug Research Institute, Lucknow, is a nonsteroidal once-a-week oral contraceptive. It was introduced in Delhi in July, 1991, marketed in India in 1992 as Saheli and Choice-7 (Hindustan Latex Ltd., Thiruvananthapuram) and Centron (Torrent Pharmaceuticals India Ltd., Ahmedabad), and included in the National Family Welfare Programme in 1995.5 According to post-marketing surveillance, approximately 100,000 women were using this pill and approximately 1100,000 menstrual cycles were covered until 1996. It is a unique need-oriented contraceptive being effective when taken immediately after coitus or routinely as a weekly pill and has the advantage of less frequent administration. Its contraceptive action is quickly reversible. It has long terminal serum halflife of 168 hr in women and exhibits duration of anti-implantation/estrogen antagonistic action of 120 hr, despite a short (24.1 hr) serum halflife, in the rat. In lactating women, it is excreted in milk in quantities considered unlikely to cause any deleterious effect on suckling babies. In phase II and III multicentric trials as a contraceptive, children born of method-and-user failure pregnancies showed normal milestones, without any congenital anomaly. Reports of its promising action in the management of certain hormone-related clinical disorders are available. It has an excellent therapeutic index and is considered safe for chronic administration., (Copyright 2001 John Wiley & Sons, Inc.)

The antimutagenic effects of the two enantiomers of centchroman, a nonsteroidal oral contraceptive, were evaluated and compared with tamoxifen, a known breast cancer drug. Anticlastogenic assays in subacute in vivo studies in Swiss albino mice were used. They revealed that both d-centchroman and I-centchroman reduced the chromosome aberrations produced by dimethylbenz(a)anthracene and cyclophosphamide, when compared with the group treated only with the former mutagen. Tamoxifen also reduced the chromosome aberrations produced by the two mutagens. Overall the results showed that l-centchroman alone was more effective in reducing cyclophosphamide-induced aberrations than d-centchroman, and for toxicity reasons may be an alternative to tamoxifen in breast cancer therapy.

Centchroman (CC), a non-steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients. The potent anti-oestrogenic activity, negligible side-effects and anti-breast cancer activity of CC prompted us to evaluate the antimutagenic effects of this compound in a bacterial mutagenicity assay and CHO/HPRT and AS52/GPT mutation assays in vitro and in vivo in female Swiss albino mice as measured by both sister chromatid exchange (SCE) and chromosome aberrations (CA) against three known positive mutagen compounds, dimethylbenz[a]anthracene (DMBA), cyclophosphamide (CP) and mitomycin C (MMC). Antimutagenicity assays in Salmonella strains TA97a, TA100, TA98 and TA102 were carried out against commonly used known positive mutagens, sodium azide, 4-nitro-o-phenylenediamine, cumine hydroperoxide, 2-aminofluorene and danthron. A significantly reduced number of bacterial histidine revertant colonies was observed in the plates treated with 0.1, 1, 5 and 10 microg/plate CC and a positive compound when compared with bacterial plates treated with the respective positive compound alone. Ethyl methanesulfonate (EMS), a commonly used positive mutagen for CHO/HPRT and AS52/GPT gene mutation assays, was used for antimutagenicity assay in these cells. CC exhibited protective effects against the mutagenicity of EMS in these two mammalian cell mutation assays, CHO/HPRT and AS52/GPT. In the in vivo studies, pretreatment with CC reduced DMBA-induced SCE and CA and CP- and MMC-induced CA when compared with the group treated only with the positive compounds. These results indicate that CC can reduce the mutagenic effects of known genotoxic compounds.

Centchroman (CC), a non steroidal oral contraceptive and a candidate drug for breast cancer, has been reported to exhibit partial to complete remission of lesions in 40.5% of breast cancer patients. Recently, we have reported the antimutagenic effects of CC in multiple mutational assays. The potent antioestrogenic activity, negligible side effects, anti-breast cancer activity and antimutagenic effects of CC prompted us to evaluate the anticlastogenic effects of CC and two of its enantiomers. i.e. D-centchroman (DC) and L-centchroman (LC) in the acute in vivo studies in female Swiss albino mice as measured by chromosome aberrations (CA) and sister chromatid exchange (SCE) assays against two known positive mutagen compounds, i.e. dimethylbenz[a]anthracene (DMBA) and cyclophosphamide (CP). The results of anti-mutagenicity assays of CC and its enantiomers have been compared to the known breast cancer drug tamoxifen (TM). CC and LC reduced both DMBA and CP induced CA when compared with the group treated with only DMBA and CP. DC did not reduce the DMBA-induced CA when compared with the DMBA-treated group alone. It reduces only the CP induced CA. TM also reduces both DMBA and CP induced CA when compared with group received only DMBA or CP. SCE were carried out only for LC. A weak but significant decrease in SCE was observed in both LC plus DMBA- and LC plus CP-treated groups when compared with respective positive controls alone. Thus the overall results indicate that both CC and LC are more effective in reducing the genotoxic effects of DMBA and CP than DC.

Centchroman (CC)--a contraceptive and a candidate drug for breast cancer has been developed by the Central Drug Research Institute. It has been successfully marketed as a contraceptive for last several years. CC has also been reported to exhibit partial to complete remission of lesions in 40.5% breast cancer patients. Recently, we have reported the antimutagenic effects of CC in Ames Salmonella assay and in vivo and in vitro mammalian cells in multiple mutational assay. The potent antimutagenic activity of CC and its anti-breast cancer activity prompted us to evaluate the antimutagenic effects of its enantiomers, i.e., D-centchroman (DC) and L-centchroman (LC) in the Ames Salmonella strains TA97a, TA98, TA100 and TA102 against known bacterial mutagens. Attempts have also been made to compare the results of antimutagenicity assays of CC and its enantiomers with the known breast cancer drug tamoxifen (TM). The main objective was to identify the best suitable form of CC having antimutagenic effects with anticancer profile similar to TM, would replace the latter for toxicity reasons. When mutagenicity assays were carried out with these compounds as expected like CC, none of these enantiomers or TM showed any mutagenic effects in these Salmonella strains. In the antimutagenicity assay a significantly reduced number of bacterial histidine revertant colonies were observed when positive compounds were co-incubated with certain concentrations of LC compared with bacterial plates treated with respective positive compound. This was observed in some concentrations in all the four strains in both plate incorporation and preincubation tests. The protective effects of LC in preincubation tests were slightly more than in plate incorporation tests. Both the DC and TM showed protective effects only in certain concentrations in some strains in either plate or preincubation tests. Thus the above results indicate that LC showed more protective effects in Salmonella strains TA97a, TA98, TA100 and TA102 than either DC or TM.

To assess the alleged estrogenic and antiestrogenic profile of centchroman, a phenotypical response was studied in native uterine cells or migrant blood cells in adult ovariectomized rats under the influence of estradiol-dipropionate (EDP) and centchroman (CC) given per se and together. Histologic observations were divided arbitrarily into the following regions: luminal epithelium, superficial and deep stroma, and the two layers of muscularis. Glandular cell proliferation, mitoses, and vascularity were examined additionally. It was found that CC per se stimulated luminal epithelial cell height and glandular cell proliferation better than EDP. Leukocytic infiltration and vascularity were also more pronounced in the uteri of CC-treated rats. Furthermore, except for a slight reduction in glandular cell size and edematous condition of circular muscle layer, the changes remained unaffected after conjoint treatment of CC and EDP. The observations revealed that some of the nongenomic responses, elicited by the rat uterus after CC treatment, seem to be unrelated to the hormonal attributes of the molecule.

The period of maximal endometrial sensitivity in the rat was characterized by high alkaline phosphatase activity in uterine luminal and glandular epithelium and endometrial stroma. The activity in endometrial stroma increased following decidualization. Pinopod development on the endometrial surface was first observed during the presensitivity period. Their number increased, apparently more so on the antimesometrial rather than the mesometrial segment of the uterus, on the day of maximal sensitivity. Inhibition in endometrial sensitivity by single anti-implantation (1.25 mg/kg, po) dose of centchroman on day 1 post-coitum (p.c.), although it did not affect alkaline phosphatase activity on days 2 and 3 p.c., caused complete inhibition in its activity in uterine luminal and glandular epithelium and pinopod development on days 4 and 5-coinciding, respectively, with time of entry of preimplantation embryos into the uterus and period of maximal endometrial sensitivity in this species. Significant decrease in enzyme activity was also evident in the entire endometrial stroma and myometrium, except blood capillaries, on these days. In comparison, prevention of entry of native embryos into the uterus by placing a ligature at the utero-tubal junction had no effect on pinopod development, but caused marked decrease in enzyme activity in luminal and glandular epithelium only during the immediate postimplantation period. The uterine lumen on the day of maximal sensitivity in centchroman-treated rats appeared highly distended and was lined with tall columnar epithelium, in comparison to low cuboidal epithelium in controls. The findings demonstrate: (a) a correlation between uterine luminal epithelial alkaline phosphatase activity and endometrial sensitivity; (b) complete inhibition in enzyme activity in luminal and glandular epithelium following centchroman treatment might be related to altered permeability characteristics of epithelial cells, which together with the absence of pinopods and highly distended uterine lumen on the day of maximal sensitivity, suggest inhibition of endocytosis/pinocytosis of luminal fluid, luminal closure, apposition of blastocyst trophoblast to luminal epithelium, and secretory activity of glandular epithelium; (c) pinopod development on the endometrial surface was independent of presence of viable blastocysts in utero; and (d) complete absence of pinopods suggests lack of endometrial sensitivity, but their presence might not necessarily indicate a sensitized endometrium in the rat.

Recent studies have indicated that estrogen has a stimulatory influence on the male reproductive tract. Evidence includes the presence of measurable levels of estrogen in the circulation, retention of exogenous estrogen, and presence of estrogen receptors in the male accessory sex organs during prepubertal life. In the present study, estrogen antagonists (CDRI-85/287 and centchroman) have been used to examine this concept by antagonising estrogen action at critical stages in the life in rat. Centchroman or 85/287 administration to 14 day old rats for 7 days did not alter gonadal or accessory organ weight. In contrast, in 21 day old castrated rats, treatment with either compound from day 28-35 of life stimulated an increase in all organ weights. When administered to normal rats during the critical phase of transition, i.e. days 30-60 of life, both testis and accessory organs showed an increase in weight. In contrast castrated rats treated with estrogen alone or in combination with 85/287 from days 37-45 of life and sacrificed on day 46 did not show any change, but 85/287 per se markedly reduced the weight of accessory organs. In adult castrated rats, the potency of DHT as a promoter of growth was potentiated by estradiol. Compound 85/287 negated the estradiol-induced increase. Glycerylphosphorylcholine (GPC) and sialic acid levels showed about 100% increase, with both high and low doses of 85/287 (treated from 30-60 days of life), However, centchroman (CDRI-67/20) was less potent in this regard. The effect of estrogen antagonists in relation to epididymal physiology during different phases of life in the rat is discussed.

We studied effects of calmodulin antagonists on osteoclastic activity and calmodulin-dependent HCl transport. The results were compared to effects on the calmodulin-dependent phosphodiesterase and antagonist-calmodulin binding affinity. Avian osteoclast degradation of labeled bone was inhibited approximately 40% by trifluoperazine or tamoxifen with half-maximal effects at 1-3 microM. Four benzopyrans structurally resembling tamoxifen were compared: d-centchroman inhibited resorption 30%, with half-maximal effect at approximately 100 nM, cischroman and CDRI 85/287 gave 15-20% inhibition, and l-centchroman was ineffective. No benzopyran inhibited cell attachment or protein synthesis below 10 microM. However, ATP-dependent membrane vesicle acridine transport showed that H(+)-ATPase activity was abolished by all compounds with 50% effects at 0.25-1 microM. All compounds also inhibited calmodulin-dependent cyclic nucleotide phosphodiesterase at micromolar calcium. Relative potency varied with assay type, but d- and l-centchroman, surprisingly, inhibited both H(+)-ATPase and phosphodiesterase activity at similar concentrations. However, d- and l-centchroman effects in either assay diverged at nanomolar calcium. Of benzopyrans tested, only the d-centchroman effects were calcium-dependent. Interaction of compounds with calmodulin at similar concentrations were confirmed by displacement of labeled calmodulin from immobilized trifluoperazine. Thus, the compounds tested all interact with calmodulin directly to varying degrees, and the observed osteoclast inhibition is consistent with calmodulin-mediated effects. However, calmodulin antagonist activity varies between specific reactions, and free calcium regulates specificity of some interactions. Effects on whole cells probably also reflect other properties, including transport into cells.

Antiestrogens affect spermatozoa through their action on Leydig and Sertoli cells. Direct effect of antiestrogens namely tamoxifen and centchroman in concentration of 1, 2.5, 5, 10 and 20 micrograms/ml in incubation medium was determined on motility and penetration ability of human spermatozoa. Motility (%) was invariably reduced after 15, 30 and 60 min. of incubation. Addition of 17 beta-estradiol to medium with antagonist caused inhibition of motility in dose related manner. The distance travelled by spermatozoa treated with tamoxifen or centchroman in media was reduced by 30% and addition of estradiol along with antiestrogen reduced it to 50% compared to that of untreated spermatozoa.

Effect of antiestrogen ormeloxifene on progesterone-induced development of giant mitochondria in uterine glandular epithelial cells in ovariectomized adult Sprague-Dawley rats was investigated. Antiestrogen tamoxifen and antiprogestin onapristone were used for comparison. Well-formed giant mitochondria were observed in uterine glandular epithelial cells in rats treated with progesterone (20 mg/kg, subcutaneous [SC] per se for three consecutive days. In rats primed with estradiol-17 beta (0.5 micrograms/day, s.c.) on days-2 and -1 before progesterone treatment, there was, in addition, a marked increase and distension of smooth endoplasmic reticulum (SER) and Golgi complex, in comparison to extensive rough endoplasmic reticulum (RER) and polyribosomes in progesterone per se treated rats. Cytological picture in rats receiving single (1.25 mg/kg, day 1, p.o.) or multiple (0.25 mg/kg, days 1-3, p.o.) anti-implantation doses of ormeloxifene showed marked reduction in glandular epithelial cell height, luminal surface microvilli, RER, polyribosomes and cytoplasm:nucleus ratio, straightening of intercellular membranes, and interdigitation of basement membrane. Mitochondria were of normal size and nuclei were heterochromatic. Inhibition in the case of tamoxifen (0.1 mg/kg, days 1-3, p.o.) appeared partial and rare giant mitochondria with degenerating cristae and outer membranes were apparent. Onapristone (10 mg/kg, day 1, s.c.), in addition to inhibiting development of giant mitochondria, caused extensive vacuolization and distension of intercellular membranes in glandular epithelial cells.

This study reports assay methodology, tissue distribution, and the basic pharmacokinetic behavior of centchroman and its 7-desmethyl metabolite [7-desmethyl centchroman (DMC)] after a single 12.5 mg/kg po dose in young female rats. Plasma, liver, lung, spleen, uterus, and adipose tissue were collected at various time intervals up to 14 days after dose. Reversed-phase HPLC, coupled with fluorescence detector, was used for simultaneous determination of centchroman and DMC in biosamples. The drug and metabolite were quantitated up to 2 and 5 ng/ml in plasma and 10 and 20 ng/g in tissues, respectively. The assay method was validated in terms of accuracy, precision, interassay, and intraassay variability, and was found to be reliable and reproducible. Peak centchroman levels in all of the tissues were found between 8-12 hr, whereas DMC peaks appeared between 8 and 24 hr, except that in liver the first peak of 1.2 micrograms/g appeared in the 1-hr sample. Tissue-to-plasma concentration ratios of centchroman were > 200 times in the lung; > 100 times in the spleen, liver, and adipose tissue; and > 40 times in the uterus at maxima in each tissue. Similarly, tissue concentrations of DMC were > 350 times in the lung, > 100 times in the liver and spleen, and > 25 times in the uterus and adipose tissue than in the plasma. High tissue-to-plasma concentration ratios of metabolites than the parent drug are indicative of its greater affinity for tissues. Terminal half-life of the centchroman and DMC in plasma were 24.1 and 36.6 hr, respectively. The mean residence time of centchroman was highest in the liver (78.4 hr), followed by the uterus (72.7 hr), adipose tissue (47.5 hr), lung (46 hr), spleen (44.1 hr), and plasma (37.7 hr). The mean residence time of DMC was also highest in the liver (133.7 hr), followed by the uterus (122 hr), adipose tissue (85.2 hr), lung (62.6 hr), spleen (62.6 hr), and plasma (48.2 hr).

There is considerable interest in identifying bone-specific estrogen-like compounds with beneficial activities on bone and the cardiovascular system, but lacking side effects on the reproductive system. Two such compounds are currently under clinical investigation -raloxifene (Lilly) and centchroman (Novo-Nordisk). There is evidence suggesting that 17 beta-estradiol can inhibit osteoclastic bone resorption although this is somewhat controversial. Therefore, we examined the effect of centchroman and raloxifene, as well as 17 beta-estradiol, in the in vitro bone slice assay, where the direct effect of compounds on osteoclast activity can be assessed. Centchroman (0.001 - 1 microM) dose-dependently inhibited osteoclastic bone resorption up to 70% at 1 microM (p = 0.007) with an IC50 = 0.1 microM, while in contrast, raloxifene had no significant effect on bone resorption over the same dose range. 17 beta-estradiol (0.0001 - 1 microM) had a modest but significant inhibitory effect on resorption (40%, p < 0.05) at 1 microM, but no effect at lower physiological/therapeutic concentrations. Centchroman (1 microM) inhibited osteoclast cytoplasmic spreading by 32%, while raloxifene and 17 beta-estradiol were without effect. These results show that centchroman at therapeutic concentrations (ED50 approximately 1 mg/kg in animal models) is a potent inhibitor of osteoclastic bone resorption in vitro, suggesting that bone-specific estrogen-like molecules may have different mechanisms of action.

Time-related estrogen antagonistic action of a single oral contraceptive (1.25 mg/kg) dose of the triphenylethylene antiestrogen centchroman was determined in ovariectomized immature rats. Tamoxifen and nafoxidine were used for comparison. A single oral administration of centchroman followed by three doses of estradiol-17 beta (1 microgram/d, s.c.) caused significant dose-dependent inhibition in estradiol-17 beta-induced increase in uterine weight and nuclear and cytosolic estrogen receptors. But the inhibition at antiimplantation dose was evident only if estradiol-17 beta treatment was initiated not later than 48 h post-antiestrogen. Alternatively, when antiestrogen treatment was followed by a single dose of estradiol-17 beta between days 2-7, a synergistic action, typical of antiestrogens possessing weak estrogen agonistic activity, was observed. In immature rats in which a condition mimicking preimplantation was produced by estradiol-17 beta (0.5 microgram/d, s.c.) priming on days -2 and -1, followed by progesterone (1 mg/d, s.c.) and an endometrial sensitizing dose (0.5 microgram/d, s.c.) of estradiol-17 beta at 1600 h on day 4, anti-implantation dose of centchroman administered on day 1, too, failed to inhibit uterine weight gain induced by sensitizing dose of estradiol-17 beta, but caused marked inhibition in endometrial sensitivity to a deciduogenic stimulus and decidualization and weight gain of traumatized uterine horn 96 h post-traumatization over non-traumatized horn was only about 150% (725% in controls). Inhibition in endometrial sensitivity and decidualization was evident when the interval between antiestrogen treatment and sensitizing estradiol was < 126 h. Pinopods were present on endometrial surface on day 5 whether or not priming and/or sensitizing doses of estradiol were administered, but decidual response was mild if either of these doses of estradiol-17 beta was deferred. Findings suggest that: (a) duration of antiestrogenic action of single anti-implantation dose of centchroman in rat was about 126 h, which in ovariectomized immature rats was evident only when a condition mimicking preimplantation was produced and the antiestrogenic response was based on inhibition in estradiol-induced endometrial sensitivity and not uterine weight gain; (b) priming as well as sensitizing estrogen were essential to get optimal decidual responses; (c) appearance of pinopods on endometrial surface may not be related to endometrial sensitivity; and (d) tamoxifen and nafoxidine appear slightly longer acting with duration of antiestrogenic action of approximately 150 h.

The present study reports the modulatory influence of oral contraceptive formulations, Ovral (0.05 mg ethinylestradiol plus 0.5 mg norgestrel per pill), Noracycline (0.05 mg ethinylestradiol plus 0.1 mg lynestrenol per pill), Pearl (0.03 mg ethinylestradiol plus 0.30 mg norgestrel) and Centchroman (30 mg), on the growth and developmental pattern of murine mammary epithelium in normal as well as ovariectomised mice. Oral treatments of ovariectomised mice for 15 days with doses D1 (1/5th of a pill) and D2 (1/10th of a pill) of Ovral, Noracycline and Pearl enhanced the diameter of the terminal end buds (TEBS) and lateral buds (LBS) significantly. The increase in the diameters of TEBS and LBS on treatment with similar doses of Centchroman were not much significant. Hence, it may be concluded from the present study that the growth and development pattern of mammary epithelium can be modulated by treatment with oral contraceptives Oral, Noracycline, Pearl and Centchroman which is indicated by the increase in the diameters of TEBS and LBS.

Objective: To compare effects of various anti-estrogens on early pregnancy., Methods: Fifty regularly cycling guinea pigs were divided into five groups (five animals/group), of which three groups received 3 mg/kg body weight Nafoxidine, Centchroman, or Tamoxifen, respectively, on the 1st, 2nd, or 3rd day of pregnancy. The rest of the animals were kept as controls, and received either saline or propylene glycol. Autopsies were done on the 8th day of pregnancy in all the groups. Presence or absence of implantation sites was observed by using a stereomicroscope. Plasma levels of 17 beta-estradiol and progesterone and their receptors, as well as enzyme levels in the uterine tissue, were estimated., Results: During normal early pregnancy there was an increase in the concentration of peripheral plasma levels of steroid hormones with respect to enzyme and steroid hormone receptor levels in the uterus. Administration of anti-estrogens showed a decreased trend in all the variables studied, especially in the tamoxifen-treated animals., Conclusions: The results of the study suggest that anti-estrogens, if administered during early pregnancy, can prevent the process of ovum implantation in this species.

The duration of the anti-implantation action of a single oral post-coital dose (1.25 mg kg-1) of a triphenylethylene anti-oestrogen, centchroman, was determined in adult rats. The effects of centchroman were compared with those of tamoxifen. In rats undergoing delay, centchroman administered orally on day 7 post-coitum prevented the induction of implantation of delayed blastocysts by an implantation inducing dose (1 micrograms per rat, s.c.) of oestrone which was administered earlier than 120 h after centchroman treatment. In tamoxifen (0.2 mg kg-1, orally) pretreated rats, oestrone administered at 144 h or later induced implantation. In cyclic rats treated with centchroman at intervals of 168 h and mated with males of proven fertility, implantation was prevented only when the interval between centchroman treatment and nidatory oestrogen secretion was less than 120 h. None of the females conceived when treated regularly at intervals of 120 h during exposure to fertile males. Discontinuation of treatment resulted in the occurrence of normal implantations in rats that mated 48 h or later after the last dose of centchroman, since in these animals the interval between anti-oestrogen treatment and nidatory oestrogen secretion was greater than 120 h. These findings suggest that the duration of the anti-implantation action of a single oral antifertility dose of centchroman in rats is about 120 h. Recovery of normal blastocysts from rats treated continuously with this dose of centchroman at these intervals suggests lack of significant effect on follicular maturation, ovulation, fertilization, preimplantation development or mating behaviour.(ABSTRACT TRUNCATED AT 250 WORDS)

To study the effect of centchroman and tamoxifen on estrogen-dependent proteins of fallopian tubes of rhesus monkey, these antiestrogens were given with and without estradiol to ovariectomized monkeys. In absence of estradiol, both the compounds induced the synthesis of 130 and 95 K proteins. Concentration of 85 K protein was also increased markedly. These compounds, however, suppressed the estrogen stimulated synthesis of 130 K protein when administered with estradiol. The results show that both centchroman and tamoxifen possess estrogen agonistic as well as antagonistic properties and 130 K protein can be used as a marker protein to study estrogen action and for screening of antiestrogenic compounds in a primate model.

Centchroman was administered to rats in relation to luteal phase nidatory estrogen secreted between 21.00 on day 4 and 10.00 on day 5 of pregnancy. A single oral dose of 1.25 mg/kg before the secretion of nidatory estrogen, i.e. until 21.00 on day 4, prevented implantation in 100% of the rats without altering plasma estradiol or progesterone concentration. Administration of a dose of up to 62.5 mg/kg at 10.00 on day 5 even failed to inhibit implantation, but caused dose-dependent resorption of implantations. Resorption of all implantations at a dose of 62.5 mg/kg was associated with a decrease in circulating progesterone levels, but was only partially reversed by progesterone or progesterone + estrone supplementation. Apparently normal morulae and blastocysts recovered between days 4 and 10 from rats treated with anti-implantation doses before release of nidatory estrogen, when transferred to the uteri of control rats exhibited lower pregnancy, implantation and development rates with increasing confinement in the genital tract of treated donors. None of the embryos recovered from control or centchroman treated females implanted in the uteri of treated rats. Centchroman administration on day 1, but not on day 5, abolished endometrial receptivity to an artificial stimulus for decidualization. All term fetuses were apparently normal and their weight comparable to that of control fetuses. The study provides evidence of post-implantation fetal resorption, occurring primarily between days 10 and 19 post-coitum, in rats treated with a potent antiestrogen before or immediately after the prenidatory estrogen secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Daily oral administration of antiestrogen centchroman at 6.25, 12.5 and 25 mg/kg doses to adult female rhesus monkeys continuously for one year caused no significant effect on their total pituitary gonadotrophin content as evidenced by an almost similar extent of uterine weight gain, premature opening of vagina and cornification of vaginal epithelium in immature female mice treated with pituitary homogenates from control and centchroman treated monkeys.

The effect of three compounds (clomiphene citrate, centchroman, embelin) and plant-derived methanolic extracts (Abutilon indicum and Butea monosperma) was studied on uterotropic and uterine peroxidase activities in ovariectomized rats. It was observed that these two parameters were highly correlated in response to treatment with these test materials and also to estradiol. It was suggested that the uterine peroxidase assay could be utilized as a biochemical parameter in the screening of new antifertility agents for their estrogenic/antiestrogenic properties.

Centchroman (3, 4-trans-2, 2-dimethyl-3-phenyl-4-p-beta-pyrrolidinoethoxy-phenyl-7-methoxy-chroman) , a non-steroidal, estrogen antagonist, injected subcutaneously (2 mg/kg body wt) on days 1, 2 and 3 post-coitum in hamsters, prevented implantation in 70% of the animals. A significant decrease in the circulating levels of estradiol and progesterone was observed on day 4 post-coitum as compared to control animals following the treatment of centchroman. The activities of various lysosomal enzymes were also found diminished in the treated animals. This study shows that centchroman may act as an anti-implantation agent in hamsters indicating that estrogen plays a key role during the process of ovum implantation in this species.

Monoamine oxidase activity (MAO) was estimated in the pituitary of ovariectomized mice after a single administration of estradiol-dipropionate (0.01 mg/kg; im), progesterone (1 mg/kg; im) and centchroman (1.25 mg/kg ip). Estrogen and progesterone were found to decrease the enzymic level, as compared to control, while centchroman remarkably increased it. The significance of dissimilarity in the pituitary threshold for steroidal and nonsteroidal molecule is discussed.

Weekly oral administration of centchroman at 1 and 2.5 mg/kg doses for 3, 6 or 12 months to adult female rhesus monkeys (Macaca mulatta) significantly decreased glycogen content and activity of phosphorylase, glucokinase, lactate dehydrogenase and glucose 6-phosphate dehydrogenase enzymes in all the genital tract tissues. In general, the inhibition was dose and time dependent. No effect was, however, observed in the liver and serum.

Male rats given a single s.c. injection of 250 micrograms estradiol dipropionate on day 5 postnatal life failed to show maturational changes in the testis and the growth of accessory sex organs was reduced. Similar treatment with two non-steroidal 'estrogenic' compounds viz. Centchroman (500 micrograms) and Naphthofuran (500 micrograms) retarded the growth of the testis and accessory organs but spermatogenesis was not affected. These effects persisted through 90 days. The results of the present study suggest that the two nonsteroidal compounds being 'atypical' estrogens, their effect on hormone responsive centres of brain also is less severe as compared to that caused by classical estrogen like estradiol.

Elevation of serum luteinizing hormone levels was observed in five normal male volunteers while they were taking Centchroman. This effect resembles that of clomiphene and suggests a new biologic potential of Centchroman.