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Caspase-3 is known as the key executioner caspase, activated in both the intrinsic and extrinsic apoptotic pathway, and an effector far downstream in the apoptotic cascade. Procaspase-activating compound-1 (PAC-1) and 1541 were launched as direct activators of procaspase-3 to caspase-3, and anticipated to be promising therapeutic agents for the treatment of cancer. PAC-1 has recently been evaluated in a phase I preclinical trial. However, little is known about the effect of these substances in cells. Activation of caspase-3 in whole cells may be more complicated than thought, as it is likely that this key protease is tightly regulated both in development and apoptosis. In this study, we investigated the effect of epidermal growth factor (EGF) on PAC-1-induced caspase-3 activity and cell death. We show that EGF can block caspase-3 activity generated by PAC-1, and protect both PC12 cells and primary cerebellar granule neurons against PAC-1-induced death. Similar results were obtained with 1541. Both substances reduced cellular p-ERK levels. Crosstalk between caspase-3 and growth factor signaling pathways may present a challenge for the use of such caspase-3-activating substances in cancer therapy, since aberrant growth factor signaling is frequently seen in malignant cells. This study adds important knowledge about cellular effects of procaspase-3 activators like PAC-1 and 1541. Effects mediated by these substances may also contribute to the understanding of caspase signaling in cells.

Famotidine is an effective new H2 receptor antagonist. Famotidine is a specific, long acting H2 receptor antagonist. It is indicated for the treatment of duodenal ulcer, gastric ulcer, GERD and Zollinger-Ellison Syndrome. Since its introduction for the treatment of acid related disorders in 1985, an estimated 18.8 million patients worldwide have been treated with famotidine. In this study 40 mg famotidine tablets were formulated and coated with two different coating materials i.e. HPMC and opadry white, to check the effect of these coating materials on the bioavailability of famotidine tablets. In vitro techniques like disintegration test and dissolution test were used to evaluate famotidine tablets. Disintegration test was performed on both the formulations. Mean disintegration time for formulation 1 was found to be 5 minutes and mean disintegration time for formulation 2 was 3 minutes. The results of dissolution after 120 minutes for formulation 1 showed release up to 100.01% and the formulation 2 was released up to 100.05%. For in vivo evaluation these two formulations were administered to eight normal human subjects with one week washout period. Blood samples were collected and plasma was obtained and analysized by HPLC. Pharmacokinetic parameters of formulation 1 were Cmax 0.97±0.47 μg/ml, tmax was 1.68±0.37 hours, AUC 3.97±1.61 μg.h/ml, AUMC 13.35±5.97 μg.h2/ml, MRT 2.27±0.55 hours, Ke 0.394±0.052, T1/2 1.97 ±0.38 hours, Vd 5.78±4.45 L/Kg, Vss 1.92±0.68 L/Kg, Cl 2.08±0.08 ml/h/Kg and for formulation 2 these values were 1.64±1.02 μg/ml, 1.5±0.46 hours, 10.07±0.21 μg.h/ml, 11.06±0.64 μg.h2/ml, 2.38±0.99 hours, 0.394±0.07, 1.97±0.69 hours, 6.309±2.72 L/Kg, 1.61±0.118 L/Kg, 1.76±0.037 ml/h/Kg respectively. Statistical analysis was performed and it was found that the formulation 2 which was coated with opadry white was more bioavailable than formulation 1 which was coated with HPMC. It was also concluded that coating materials affect the bioavailability of Famotidine tablets. Özet Famotidin yeni, etkili, spesifik ve uzun etkili bir H2 reseptör antagonistidir. Zollinger-Ellison Sendromu, GERD, gastrik ülser ve duedonal ülser tedavisinde kullanilmaktadir. 1985 yilinda asitlerle ilgili rahatsizliklarin tedavisi için tanitildigindan beri Dünya’da tahminen 18.8 milyon hasta famotidin ile tedavi edilmistir. Bu çalismada, kaplama materyallerinin famotidin tabletlerinin biyoyararliligi üzerine olan etkilerinin arastirilmasi amaciyla, 40 mg lik famotidin tabletleri HPMC ve opadry white gibi 2 farkli kaplama materyalleri ile kaplanmis ve formule edilmistir. Famotidin tabletlerinin degerlendirilmesinde dagilma ve dissolusyon gibi in-vitro teknikler kullanilmistir. Dagilma testi her iki formulasyona da uygulanmistir. Birinci formulasyon için dagilma süresi 5 dakika, ikinci formulasyon için ise 3 dakika bulunmustur. Birinci formulasyon için 120 dakika sonrasindaki dissolusyon degeri % 100.01, ikinci formulasyon için ise % 100.05 olarak bulunmustur. In-vivo degerlendirme için bu iki formulasyon 6normal insana bir haftalik temizlenme (washout) süreleri dikkate alinarak verilmistir. Bu kisilerin kan ve plazma örnekleri HPLC de analiz edilmistir. Birinci formulasyonun farmakokinetik parametreleri sirasiyla; Cmax: 0.97±0.47 μg/ml, tmax: 1.68±0.37 saat, AUC: 3.97±1.61 μg.h/ml, AUMC: 13.35±5.97 μg.h2/ml, MRT: 2.27±0.55 saat, Ke: 0.394±0.052, T1/2: 1.97±0.38 saat, Vd: 5.78±4.45 L/Kg, Vss: 1.92±0.68 L/Kg, Cl: 2.08±0.08 ml/h/Kg olarak tespit edilmistir. Ikinci formulasyon için ise ayni parametreler sirasiyla; Cmax: 1.64±1.02 μg/ml, tmax: 1.5±0.46 saat, AUC: 10.07±0.21 μg.h/ml, AUMC: 11.06±0.64 μg.h2/ml, MRT: 2.38±0.99 saat, Ke: 0.394±0.07, T1/2: 1.97±0.69 saat, Vd: 6.309±2.72 L/Kg, Vss: 1.61±0.118 L/Kg, Cl: 1.76±0.037 ml/h/Kg seklinde tespit edilmistir. Uygulanan istatistiksel analizlere göre opadry white ile kaplanmis olan ikinci formulasyonun, HPMC ile kaplanmis olan birinci formulasyona göre biyoyararliliginin daha iyi oldugu anlasilmistir. Ayrica, kaplama materyallerinin famotidin tabletlerinin biyoyararliligini etkiledigi sonucuna varilmistir.

Ranitidine is an effective H2 receptor antagonist. Ranitidine is a specific, long acting H2 receptor antagonist. It is indicated for the treatment of duodenal ulcer, gastric ulcer, GERD and ZollingerEllison syndrome. In this study two formulations of Ranitidine 300 mg tablets were prepared and film coated. Starch and poly vinyl pyrolidone were used as binding agents to check the effect of the binding materials on the pharmacokinetic parameters of Ranitidine tablets. Different in vitro tests were used to evaluate Ranitidine tablets like disintegration test and dissolution test. Then in vivo evaluation was performed on these two formulations. Tablets were administered to eight normal human subjects comprising of two groups, each group consisted of four normal human subjects one by one in a crossover manner after one week washout period. Blood samples were collected and plasma was obtained and analyzed by HPLC. Statistical analysis was performed and the values for Cmax for formulation 1 were found to be 4.63 ± 0.47 µg/ml, and for formulation 2 it was 4.76 ± 1.02 µg/ml. The value for Tmax for formulation 1 was found to be 2.0 ± 0.37 hours, and for formulation 2 it was 1.5 ± 0.46 hours. The value for AUC for formulation 1 was found to be 18.57 ± 6.122 µg/hr/ml and for formulation 2 it was 26.43 ±22.38 µg/hr/ml. It was also concluded that different binders affect the bioavailability of the tablets and Ranitidine tablets prepared by polyvinyl pyrolidine have better bioavailability than those tablets prepared by starch as binding agent.

The lipophilic, cell-penetrating zinc chelator N,N,N',N',-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN, 1) and the zinc chelating procaspase-activating compound PAC-1 (2) both have been reported to induce apoptosis in various cell types. The relationship between apoptosis-inducing ability and zinc affinity (Kd), have been investigated with two new model compounds, ZnA-DPA (3) and ZnA-Pyr (4), and compared to that of TPEN and PAC-1. The zinc-chelating o-hydroxybenzylidene moiety in PAC-1 was replaced with a 2,2'-dipicoylamine (DPA) unit (ZnA-DPA, 3) and a 4-pyridoxyl unit (ZnA-Pyr, 4), rendering an order of zinc affinity TPEN>ZnA-Pyr>ZnA-DPA>PAC-1. The compounds were incubated with the rat pheochromocytoma cell line PC12 and cell death was measured in combination with ZnSO4, a caspase-3 inhibitor, or a ROS scavenger. The model compounds ZnA-DPA (3) and ZnA-Pyr (4) induced cell death at higher concentrations as compared to PAC-1 and TPEN, reflecting differences in lipophilicity and thereby cell-penetrating ability. Addition of ZnSO4 reduced cell death induced by ZnA-Pyr (4) more than for ZnA-DPA (3). The ability to induce cell death could be reversed for all compounds using a caspase-3-inhibitor, and most so for TPEN (1) and ZnA-Pyr (4). Reactive oxygen species (ROS), as monitored using dihydro-rhodamine (DHR), were involved in cell death induced by all compounds. These results indicate that the Zn-chelators ZnA-DPA (3) and ZnA-Pyr (4) exercise their apoptosis-inducing effect by mechanisms similar to TPEN (1) and PAC-1 (2), by chelation of zinc, caspase-3 activation, and ROS production.

Cancer cells are more sensitive to oxidative stress due to higher levels of reactive oxygen species. Therefore, the ability of anti-cancer agent combretastatin A-4 (CA-4) and triazole analogues to induce reactive oxygen species may be important for selectivity against cancer cells. The purpose of the present study was to investigate the structural requirements for reactive oxygen species production by CA-4 and the triazole analogues Ana-2, Ana-3 and Ana-4. Ana-2 and Ana-3 mimic the cis configuration in CA-4; Ana-3 lacks the phenolic hydroxyl group, while Ana-4 mimics a trans configuration. The rat pheochromocytoma cancer cell line PC12 was used as model system. CA-4 and Ana-2 were highly toxic; Ana-3 was less toxic, whereas Ana-4 was non-toxic. The probe dihydroethidium detected reactive oxygen species production from CA-4, Ana-2, and Ana-3. CA-4 and Ana-2 also induced oxidation of the reactive oxygen species probe dihydrorhodamine and activation of caspase-3. Thus, the phenolic hydroxyl group in CA-4 and Ana-2 was necessary for dihydrorhodamine oxidation, caspase-3 activation, and increased cytotoxicity.