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Many Americans use complementary and alternative medicine (CAM) to prevent or alleviate common illnesses, and these medicines are commonly used by individuals with cancer.These medicines or botanicals share the same metabolic and transport proteins, including cytochrome P450 enzymes (CYP), glucuronosyltransferases (UGTs), and P-glycoprotein (Pgp), with over-the-counter and prescription medicines increasing the likelihood of drug-botanical interactions.This review provides a brief description of the different proteins, such as CYPs, UGTs, and Pgp.The potential effects of drug-botanical interactions on the pharmacokinetics and pharmacodynamics of the drug or botanical and a summary of the more common models used to study drug metabolism are described.The remaining portion of this review summarizes the data extracted from several laboratory, animal, and clinical studies that describe the metabolism, transport, and potential interactions of 8 selected botanicals. The 8 botanicals include black cohosh, Echinacea, garlic, Gingko biloba, green tea, kava, milk thistle, and St John's wort; these botanicals are among some of the more common botanicals taken by individuals with cancer.These examples are included to demonstrate how to interpret the different studies and how to use these data to predict the likelihood of a clinically significant drug-botanical interaction. [ABSTRACT FROM AUTHOR]

Background: Encephalopathy occurs in 10-40% of patients treated with high-dose ifosfamide. Proposed risk factors for encephalopathy include hepatic or renal dysfunction, brain metastases, electrolyte imbalances and drug-drug interactions.Objective: The purpose of this retrospective cohort study and literature review was to estimate the prevalence of encephalopathy, identify characteristics associated with encephalopathy and evaluate the effectiveness of methylthioninium chloride (methylene blue) in its prevention.Study Design and Methods: A total of 19 patients received high-dose ifosfamide for soft tissue sarcoma during a 4-year period at our medical centre. Eight patients developed encephalopathy based on adverse drug event (ADE) reports submitted by a clinical pharmacist. These reports incorporate the Naranjo probability scale, which is used to assess the likelihood that a change in clinical status is the result of an ADE rather than the result of other factors, such as progression of disease. The demographics, concurrent medication therapy, co-existing illnesses and laboratory parameters were documented from the medical records. We also conducted a review of the literature by searching MEDLINE (1996-October 2007).Main Outcome and Results: A total of 19 patients received high-dose ifosfamide; eight patients experienced encephalopathy (group I, 42%) and 11 patients did not experience encephalopathy (group II, 58%). More women than men developed encephalopathy (group I, 87.5% vs group II, 27.3%). Serum albumin (group I, 3.1 +/- 0.3 vs group II, 3.6 +/- 0.3 g/dL), haemoglobin (10.5 +/- 1.5 vs 12.4 +/- 1.7 g/dL) and total bilirubin (0.5 +/- 0.2 vs 0.8 +/- 0.3 mg/dL) levels were substantially lower in patients with encephalopathy, whereas the ratio of actual bodyweight to the ideal bodyweight (1.4 +/- 0.3 vs 1.1 +/- 0.2) was substantially higher in these patients. Five (62.5%) patients received a subsequent cycle of high-dose ifosfamide; all of these patients received methylthioninium chloride to minimize the risk of encephalopathy. All of these patients developed encephalopathy. Other reports have found that hypoalbuminaemia is associated with encephalopathy and that methylthioninium chloride does not prevent ifosfamide-induced encephalopathy.Conclusions: In summary, female sex, low total bilirubin, albumin and haemoglobin levels, and obesity appear to be associated with ifosfamide-induced encephalopathy. Methylthioninium chloride did not appear to prevent encephalopathy with subsequent doses of high-dose ifosfamide. [ABSTRACT FROM AUTHOR]

Tyrosine kinase inhibitors (TKI) have improved the outcome and life expectancy of patients with chronic myeloid leukemia (CML). Patients are diagnosed with CML at younger ages, and patients treated for CML may become pregnant or choose to breastfeed. The information available to date on the safety of TKIs during pregnancy and lactation and the optimal management of these patients is largely anecdotal, based on personal or small-group experience, and heterogeneous. A panel of interested parties was convened by U.S. Food and Drug Administration to analyze the current data and discuss possible solutions. Possible solutions include prospective data collection, in clinical trials and in routine clinical practice, a more uniform and specific data collection, and greater coordination among involved entities. As patients with cancer are living longer, frequently receiving therapies for extended periods of time (or for life), data on appropriate management of patients through different reproductive phases of life are needed. It is thus time to change our approach for how to study treatment of cancer (including CML) during pregnancy or breastfeeding to develop evidence-based guidelines for safe and effective patient care., (©2024 American Association for Cancer Research.)

Optimized dosages provide a secure foundation for the development of well-tolerated and effective oncology drugs. Project Optimus, an initiative within the Oncology Center of Excellence, strives to reform the dosage optimization and dosage selection paradigm in oncology. This initiative stems from the availability of targeted drugs and from the demand for more tolerable dosages from patients, caregivers, and advocates. Reforming dosage optimization for oncology drugs requires a paradigm shift from the one employed for cytotoxic chemotherapy to one that understands and considers the unique attributes of targeted therapy, immunotherapy, and cellular therapy. Limited characterization of dosage during drug development may result in (1) patients not staying on a therapy long-term due to poor tolerability, (2) failure to establish positive benefit-risk in clinical trials for regulatory approval (3) withdrawal of drugs from the market (4) removal of indications of drugs from the market. Timely access to drugs is important for all patients with cancer, so it is vital to iteratively analyze all nonclinical and clinically relevant data at each stage of development and leverage quantitative approaches, innovative trial designs, and regulatory support to arrive at dosages with favorable benefit-risk. This review highlights the key challenges and opportunities to embracing this new paradigm and realizing the full potential of new oncology therapies., (Published 2024. This article is a U.S. Government work and is in the public domain in the USA.)

The discovery and development of anticancer drugs for pediatric patients have historically languished when compared to both past and recent activity in drug development for adult patients, notably the dramatic spike of targeted and immune-oncology therapies. The reasons for this difference are multifactorial. Recent changes in the regulatory landscape surrounding pediatric cancer drug development and the understanding that some pediatric cancers are driven by genetic perturbations that also drive disparate adult cancers afford new opportunities. The unique cancer-initiating events and dependencies of many pediatric cancers, however, require additional pediatric-specific strategies. Research efforts to unravel the underlying biology of pediatric cancers, innovative clinical trial designs, model-informed drug development, extrapolation from adult data, addressing the unique considerations in pediatric patients, and use of pediatric appropriate formulations, should all be considered for efficient development and dosage optimization of anticancer drugs for pediatric patients., (Published by Cold Spring Harbor Laboratory Press.)

On March 16, 2023, the FDA approved dabrafenib in combination with trametinib (Tafinlar, Mekinist; Novartis Pharmaceuticals Corporation) for the treatment of pediatric patients with low-grade glioma (LGG) with a BRAFV600E mutation who require systemic therapy. FDA also approved oral formulations of both drugs suitable for patients who cannot swallow pills. This approval was based on the LGG cohort from study CDRB436G2201 (NCT02684058), a multicenter, open-label trial in which pediatric patients with LGG with a BRAFV600E mutation were randomly assigned 2:1 to dabrafenib plus trametinib (D+T) or carboplatin plus vincristine (C+V). The overall response rate (ORR) by independent review based on Response Assessment in Neuro-oncology LGG (2017) criteria was assessed in 110 patients randomly assigned to D+T (n = 73) or C+V (n = 37). ORR was 47% [95% confidence interval (CI), 35-59] in the D+T arm and 11% (95% CI, 3.0-25) in the C+V arm. Duration of response (DOR) was 23.7 months (95% CI, 14.5-NE) in the D+T arm and not estimable (95% CI, 6.6- NE) in the C+V arm. Progression-free survival (PFS) was 20.1 months (95% CI: 12.8, NE) and 7.4 months (95% CI, 3.6- 11.8) [HR, 0.31 (95% CI, 0.17-0.55); P < 0.001] in the D+T and C+V arms, respectively. The most common (>20%) adverse reactions were pyrexia, rash, headache, vomiting, musculoskeletal pain, fatigue, diarrhea, dry skin, nausea, hemorrhage, abdominal pain, and dermatitis acneiform. This represents the first FDA approval of a systemic therapy for the first-line treatment of pediatric patients with LGG with a BRAFV600E mutation., (©2023 American Association for Cancer Research.)

On April 10, 2020, the FDA approved selumetinib (KOSELUGO, AstraZeneca) for the treatment of pediatric patients 2 years of age and older with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. Approval was based on demonstration of a durable overall response rate per Response Evaluation in Neurofibromatosis and Schwannomatosis criteria and supported by observed clinical improvements in plexiform neurofibroma-related symptoms and functional impairments in 50 pediatric patients with inoperable plexiform neurofibromas in a single-arm, multicenter trial. The overall reponse rate per NCI investigator assessment was 66% (95% confidence interval, 51-79) with at least 12 months of follow-up. The median duration of response was not reached, and 82% of responding patients experienced duration of response ≥12 months. Clinical outcome assessment endpoints provided supportive efficacy data. Risks of selumetinib are consistent with MAPK (MEK) inhibitor class effects, including ocular, cardiac, musculoskeletal, gastrointestinal, and dermatologic toxicities. Safety was assessed across a pooled database of 74 pediatric patients with plexiform neurofibromas and supported by adult and pediatric selumetinib clinical trial data in cancer indications. The benefit-risk assessment for selumetinib in patients with inoperable plexiform neurofibromas was considered favorable., (©2021 American Association for Cancer Research.)

The FDA conducts independent reviews of scientific data obtained with investigational drug products to ensure that they are safe and effective. As a result of this process, FDA-approved product labeling is generated that is considered one of the most trusted sources of information for use of an approved drug. But FDA approval is only the beginning of the life cycle of a new drug; the first oncology drugs now have more than 7 decades of clinical experience in the postmarketing setting. Due, in part, to lack of incentives, some companies may not seek inclusion of new data, other than new safety information, in FDA-approved product labeling. Ensuring that product labeling provides adequate directions for use is important for all drugs, including older therapies that may form the backbone of many standard combination regimens for pediatric and adult cancers. Project Renewal is an FDA Oncology Center of Excellence pilot program that leverages expertise from the clinical and scientific oncology communities to review published literature and generate a drug-specific product report summarizing data that may support updates to FDA-approved product labeling. This article provides a broad overview of Project Renewal's collaborative pilot process for identifying and assessing literature supporting potential labeling updates, while engaging the oncology community to increase awareness of FDA's evidentiary standards and deliberative processes used when considering the addition of new indications and dosing regimens to product labeling., (©2020 American Association for Cancer Research.)

On August 3, 2017, the FDA granted regular approval to Vyxeos (also known as CPX-351; Jazz Pharmaceuticals), a liposomal formulation of daunorubicin and cytarabine in a fixed combination, for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia (t-AML) or acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC). Approval was based on data from Study CLTR0310-301, a randomized, multicenter, open-label, active-controlled trial comparing Vyxeos with a standard combination of daunorubicin and cytarabine ("7+3") in 309 patients 60-75 years of age with newly diagnosed t-AML or AML-MRC. Because of elemental copper concerns with the Vyxeos formulation, patients with Wilson disease were excluded from the study. Vyxeos demonstrated an improvement in overall survival (HR 0.69; 95% confidence interval, 0.52-0.90; P = 0.005) with an estimated median overall survival of 9.6 months compared with 5.9 months for the "7+3" control arm. The toxicity profile of Vyxeos was similar to that seen with standard "7+3" with the exception of more prolonged neutropenia and thrombocytopenia on the Vyxeos arm. Because the pharmacology of Vyxeos differs from that of other formulations of daunorubicin and cytarabine, labeling includes a warning against interchanging formulations during treatment. This is the first FDA-approved treatment specifically for patients with t-AML or AML-MRC., (©2018 American Association for Cancer Research.)

On August 30, 2017, the U.S. Food and Drug Administration approved Actemra (tocilizumab, Genentech, Inc., South San Francisco, CA) for the treatment of severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) in adults and in pediatric patients 2 years of age and older. The approval was based on a retrospective analysis of data for patients who developed CRS after treatment with CTL019 and KTE-C19 on prospective clinical trials. Evaluable patients had been treated with intravenous tocilizumab 8 mg/kg (12 mg/kg for patients <30 kg) for severe or life-threatening CRS; only the first episode of CRS was included in the analysis. The efficacy population for the CTL019 cohort included 24 male and 21 female patients (total 45 patients) of median age 12 years. The median time from the start of CRS to the first dose of tocilizumab was 4 days (range, 0-18 days). Patients were considered responders if CRS resolved within 14 days of the first dose of tocilizumab, if no more than 2 doses of tocilizumab were needed, and if no drugs other than tocilizumab and corticosteroids were used for treatment. Thirty-one patients (69%; 95% confidence interval, 53%-82%) achieved a response as defined. In an independent cohort of 15 patients with KTE-C19-induced CRS, 53% responded. Further study is needed to determine the optimal dose of tocilizumab and to confirm the safety of its use for treatment of patients with CAR T cell-induced CRS., Implications for Practice: Severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) requires urgent treatment to prevent fatal outcomes. In two independent cohorts, the majority of patients with severe or life-threatening CAR T cell-induced CRS responded to treatment with one or two doses of tocilizumab in addition to advanced supportive care. More research is needed to determine the optimal dose and schedule of tocilizumab for treatment of CAR T cell-induced CRS., Competing Interests: Disclosures of potential conflicts of interest may be found at the end of this article., (Published 2018. This article is a U.S. Government work and is in the public domain in the USA.)

Epigenetic modifications play a critical role in the development of pediatric and adult cancers, contributing to the cumulative changes observed as normal cells undergo malignant transformation. These modifications have been studied to develop epigenome-targeted therapies and new diagnostic tools. The U.S. Food and Drug Administration has approved four epigenome-targeted anticancer drugs. Two are drugs that inhibit DNA methyltransferases: azacitidine and decitabine, and two are drugs that inhibit histone deacetylases: vorinostat and romidepsin. These initial successes demonstrate the potential effectiveness of epigenome-targeted therapies as monotherapy in hematologic malignancies, but newer studies are focused on combination therapy in many cancers. Epigenetic modifications have also been used to evaluate potential biomarkers to diagnose patients with cancer, identify patient populations likely to respond to specific anticancer therapies, and select reasonable dosages for investigational anticancer drugs, as observed with other newer targeted anticancer drugs. Although much has been learned about the relationship between the epigenome and cancer, many questions remain unanswered at this time. The next step is to continue to translate emerging epigenetic knowledge into anticancer drug development. In this review, we discuss the role of epigenetic modifications in the development of cancer and anticancer drug resistance, and we describe the progress and challenges associated with developing epigenome-targeted anticancer drugs and diagnostic tools that identify epigenetic modifications., (Published 2014. This article is a U.S. Government work and is in the public domain in the USA.)

The 2012 American College of Clinical Pharmacy (ACCP) Certification Affairs Committee was charged with developing guidelines for the desired professional development pathways for clinical pharmacists. This document summarizes recommendations for postgraduate education and training for graduates of U.S. schools and colleges of pharmacy and describes the preferred pathways for achieving, demonstrating, and maintaining competence as clinical pharmacists. After initial licensure within the state or jurisdiction in which the pharmacist intends to practice, completion of an accredited PGY1 pharmacy residency is recommended to further develop the knowledge and skills needed to optimize medication therapy outcomes. An accredited PGY2 pharmacy residency should be completed if a pharmacist wishes to seek employment in a specific therapeutic area or practice setting, if such a residency exists. Clinical pharmacists intending to conduct advanced research that is competitive for federal funding are encouraged to complete a fellowship or graduate education. Initial certification by the Board of Pharmacy Specialties (BPS) or other appropriate sponsoring organizations should be completed in the desired primary therapeutic area or practice setting within 2 years after accepting a position within the desired specific therapeutic area or practice setting. Clinical pharmacists subsequently will need to meet the requirements to maintain pharmacist licensure and board certification. Traineeships, practice-based activities, and certificate programs can be used to obtain additional knowledge and skills that support professional growth. Pharmacists are strongly encouraged to adopt a lifelong, systematic process for professional development and work with ACCP and other professional organizations to facilitate the development and implementation of innovative strategies to assess core practice competencies., (© 2013 Pharmacotherapy Publications, Inc.)

Background: The Centers for Medicare and Medicaid Services (CMS) issued a national coverage determination (NCD) in July 2007, which imposed restrictions on the reimbursement of ESAs for Medicare and Medicaid beneficiaries. Since a majority of our patients are Medicare or Medicaid beneficiaries, we changed our clinical practice regarding the use of erythropoiesis stimulating agents (ESAs) to coincide with the NCD's reimbursement restriction., Objective: To evaluate the number of transfusions in patients diagnosed with chemotherapy-induced anemia (CIA) receiving ESAs before and after the clinical practice was changed at the University of Illinois Medical Center (UIMC)., Methods: The medical records of all adult patients diagnosed with a nonmyeloid malignancy and CIA who received an ESA between July 2006 and June 2008 at the UIMC were evaluated. The patients were divided into two groups: patients in receipt of ESAs BEFORE (group 1) and AFTER (group 2). The number of transfusions, the response rates to chemotherapy and ESAs therapy, and overall survival were compared., Results: Medical records for 110 patients were reviewed. More transfusions were given to patients AFTER we implemented the change in clinical practice (BEFORE 18 transfusions vs. AFTER 52 transfusions, p = 0.004). More patients responded to ESA therapy AFTER we implemented the change (67% vs. 83%, p = NS). The treatment response to chemotherapy and overall survival were similar between the two groups., Conclusion: The primary goal of reducing the number of transfusions in patients with CIA by administering ESAs cannot be met when clinical practice coincides with the NCD.

Identifying sources of variability in the response to cancer chemotherapy requires knowledge of all variables, including concomitant medications, that can alter the metabolism and pharmacokinetics of chemotherapy. This study investigated the accuracy of the lists of concomitant medications in the charts of cancer patients. Information collated from a questionnaire, patient interview, and the patient's medical chart was used to obtain validated medication lists. Patients took an average of 4.8 prescription drugs, 1.6 nonprescription drugs, and 1.6 other remedies within the 3 days prior to chemotherapy. Of the concomitant drugs actually taken, the medical records did not report 24% of prescription drugs, 84% of nonprescription drugs, and 83% of other remedies. Electronic medical records (EMRs) were more complete than paper charts, but even these omitted >75% of nonprescription drugs and other remedies. Potential drug interactions were noted in this study. This study documents the extent and complexity of the concomitant drugs taken by patients undergoing chemotherapy and the deficiencies in recording this information in medical charts.

Membrane transporters play a role in determining the absorption, distribution, metabolism and excretion of small molecule anticancer drugs and mediating chemosensitivity and resistance of tumor cells to these drugs. Our understanding of the influence of these transporters on the pharmacokinetics, clinical effectiveness and tolerability has considerably increased in the last decade. Therefore, determining the interaction of membrane transporters with small molecule anticancer drugs can facilitate the development of effective and safe treatments. We reviewed the interaction of the small molecule anticancer drugs approved in the last decade with the more common membranes transporters, such as ABCB1, ABCG2, and OATP. The drugs were divided into three categories: targeted therapies, cytotoxic agents and hormonal therapies. The literature appears to focus on the interaction of the targeted therapies compared to the remaining two categories. Furthermore, most data stemmed from nonclinical studies with only a few clinical examples where transporters corresponded with systemic exposure or clinical effectiveness or tolerability. More nonclinical and clinical studies are needed to improve the ability to use the findings from these nonclinical studies to predict clinical outcomes, but the literature appears to be rapidly expanding as our understanding of these transporters groups. Therefore, determining the interaction of membrane transporters with small molecule anticancer drugs can be facilitate the development of effective and safe treatment.

Aims: The aim of the study was to determine the effects of oral clotrimazole troches on the pharmacokinetics of oral and intravenous midazolam in the plasma., Methods: We conducted a randomized, open-label, four-way crossover study in 10 healthy volunteers. Each volunteer received oral midazolam 2 mg or intravenous midazolam 0.025 mg kg(-1) with and without oral clotrimazole troches 10 mg taken three times daily for 5 days. Each study period was separated by 14 days. Serial blood samples were collected up to 24 h after oral midazolam and 6 h after intravenous midazolam. Plasma concentrations for midazolam and its metabolite 1-hydroxymidazolam were measured and fitted to a noncompartmental model to estimate the pharmacokinetic parameters., Results: Ten healthy volunteers aged 21-26 years provided written informed consent and were enrolled into the study. Clotrimazole decreased the apparent oral clearance of midazolam from 57 +/- 13 l h(-1)[95% confidence interval 48, 66] to 36 +/- 9.8 l h(-1) (95% confidence interval 29, 43) (P= 0.003). These changes were accompanied by a decrease in the area under the concentration-time curve (mean difference 22 microg h(-1) l(-1), P= 0.001) and bioavailability (mean difference 0.21, P= NS). There were no significant differences in the systemic clearance of midazolam with or without clotrimazole troches., Conclusions: Oral clotrimazole troches decreased the apparent oral clearance of midazolam; no significant differences in the systemic clearance of midazolam were found.

Purpose: We conducted a prospective, open-label study in 54 adult subjects with sickle cell disease to determine the relationship between morphine concentrations, cytochrome P450 (CYP) 2D6 genotype, and clinical outcomes., Methods: A blood sample was obtained for genotyping and serial blood samples were drawn to measure codeine and its metabolites in the plasma before and after oral codeine sulfate 30 mg. Codeine and its metabolites were measured by liquid chromatography-tandem mass spectrometry (LC-MS). CYP2D6 genetic testing included four single nucleotide polymorphisms (SNP) indicative of three variant alleles: *17 (1023T); *29 (1659A, 3183A); and *41 (2988A) alleles., Results: Thirty subjects (group I) had a mean (standard deviation) maximal morphine concentration of 2.0 (1.0) ng/ml. Morphine was not measurable in the remaining 24 subjects (group II). Nine (30%) subjects in group I and 11 (46%) subjects in group II carried a variant *17, *29, or *41 allele (p = 0.23); one (3%) subject in group I and 5 (21%) subjects in group II were homozygous for *17 or *29 allele (p = 0.07). Emergency room visits (group I 1.5 +/- 1.8 vs. group II 2.1 +/- 4.3, p = NS) did not differ based on metabolic status, but more hospital admissions (0.9 +/- 1.4 vs. 2.2 +/- 4.1, p = 0.05) were documented in patients with no measurable morphine concentrations., Conclusions: We conclude that Blacks with sickle cell disease without measurable plasma morphine levels after a single dose of codeine were not more likely to be a carrier of a single variant allele commonly associated with reduced CYP2D6 metabolic capacity; however, homozygosity for a variant CYP2D6 allele may result in reduced metabolic capacity. Furthermore, it appears that subjects without measurable morphine concentrations were more likely to be admitted to the hospital for an acute pain crisis.

Background: We observed that paclitaxel altered the pharmacokinetic properties of gemcitabine in patients with non-small cell lung cancer (NSCLC) and limited the accumulation of gemcitabine and its metabolites in various primary and immortalized human cells. Therefore, we classified the drug-drug interaction and the effects of paclitaxel on deoxycytidine kinase (dCK) and cytidine deaminase (CDA) in three NSCLC cell lines. These enzymes are responsible for the metabolism of gemcitabine to its deaminated metabolite dFdU (80% of the parent drug) and the phosphorylated metabolites dFdCMP, dFdCDP and dFdCTP. These metabolites appear to relate to sensitivity and tolerability of gemcitabine based on previous animal and laboratory studies., Methods: Three immortalized human cells representative of the most common histological subtypes identified in patients with advanced NSCLC were exposed to the individual drugs or combinations to complete a multiple drug effect analysis. These same cell lines were exposed to vehicle-control or paclitaxel and the mRNA levels, protein expression and specific activity of dCK and CDA were compared. Comparisons were made using a two-tailed paired t-test or analysis of variance with a P value of < 0.05 considered significant., Results: The multiple drug effect analysis indicated synergy for H460, H520 and H838 cells independent of sequence. As anticipated, paclitaxel-gemcitabine increased the number of G2/M cells, whereas gemcitabine-paclitaxel increased the number of G0/G1 or S cells. Paclitaxel significantly decreased dCK and CDA mRNA levels in H460 and H520 cells (40% to 60%, P < 0.05) and lowered dCK protein (24% to 56%, P < 0.05) without affecting CDA protein. However, paclitaxel increased both dCK (10% to 50%) and CDA (75% to 153%) activity (P < 0.05). Paclitaxel caused substantial declines in the accumulation of the deaminated and phosphorylated metabolites in H520 cells (P < 0.05); the metabolites were not measurable in the remaining two cell lines. The ratio of dCK to CDA mRNA levels corresponded to the combination index (CI) estimated for sequential paclitaxel-gemcitabine., Conclusion: In summary, paclitaxel altered the mRNA levels and specific activity of dCK and CDA and these effects could be dependent on histological subtype. More cell and animal studies are needed to further characterize the relationship between mRNA levels and the overall drug-drug interaction and the potential to use histological subtype as a predictive factor in the selection of an appropriate anticancer drug regimen.

Purpose: The adverse events associated with bevacizumab therapy are characterized, and the underlying pathophysiology, risk factors, frequency, and management of these events are described., Summary: The adverse events associated with bevacizumab include hypertension, proteinuria, thromboembolism, impaired wound healing, bleeding, perforation, reversible leukoencephalopathy syndrome, skin rash, and infusion-related hypersensitivity reactions. Patients should be monitored for these events throughout the course of bevacizumab therapy. Hypertension is by far the most common adverse event associated with bevacizumab. Blood pressure should be routinely monitored, and hypertension should be medically managed with antihypertensive drugs as deemed appropriate during bevacizumab therapy. Patients should be monitored for proteinuria every three to four weeks, and bevacizumab should be discontinued with persistent proteinuria of >2+. Thromboembolic events, impaired wound healing, bowel and nasal septum perforation, and bleeding share similar pathophysiology. Thromboembolic events should be managed in accordance with guidelines established by the American College of Chest Physicians, and bevacizumab should be discontinued for new life-threatening venous or arterial thromboembolism. To minimize the risk of bleeding or impaired wound healing, bevacizumab should be started at least four weeks after surgery or discontinued for at least six to eight weeks before elective surgery. The management of other adverse events is more anecdotal, with relatively few reports of their occurrence with bevacizumab., Conclusion: Many of the potential serious complications of bevacizumab can be averted by close monitoring of patient-specific variables, which should be measured at baseline and then at predetermined intervals throughout the course of therapy to maximize patient safety.

Background: The optimal rasburicase dose for adult patients has not been determined., Objective: To retrospectively examine use of rasburicase in our centre and to evaluate the effect of a single dose of rasburicase on urate and serum creatinine levels in our adult patients., Method: A retrospective chart review was conducted of all adult patients who received rasburicase for treatment of tumour lysis syndrome-associated hyperuricaemia at our academic, urban medical centre from July 2002 to October 2006., Result: Twenty-one patients received rasburicase with an average first dose of 0.15 +/- 0.03 mg/kg. The drug dosing was calculated based on the patients' ideal body weight (IBW) or adjusted body weight (aBW) for those who were more than 30% above their IBW. Patients experienced a mean serum urate reduction of 89.7 +/- 9.0% from the baseline through the first 24 h after a single rasburicase dose (11.4 +/- 4.5 mg/dL vs. 1.4 +/- 1.4 mg/dL, respectively, P < 0.001). The urate levels remained within normal limits (<8 mg/dL) in all the patients for 48 h after a single dose of rasburicase. The major limitation of our study is that in 18 of 21 patients we lacked adequate documentation to ascertain that the blood samples sent for urate analysis after drug administration were handled according to the manufacturer's recommendations. However, in this small group of patients, we observed that the effect of rasburicase on serum urate was similar to the total study population. The effect was sustained for 48 h after a single dose. Serum creatinine levels at 24-72 h after the single rasburicase dose were not significantly different from baseline (1.8 mg/dL vs. 2.3 mg/dL, respectively, P = 0.14)., Conclusion: Rasburicase is an effective treatment for patients with hyperuricaemia and may aid in the prevention of hyperuricaemia-associated nephrotoxicity. From our experience, a single dose of 0.15 mg/kg (IBW or aBW) of rasburicase appears to effectively decrease and maintain urate levels within normal limits for 48 h.

Background: Serum creatinine (SCr)-based formulas are used to estimate glomerular filtration rate (GFR) when calculating a dosage for carboplatin using the Calvert equation, but these formulas often underestimate measured GFR. The Modified Diet in Renal Disease (MDRD) equation appears to be a more accurate estimate of GFR in patients with chronic kidney disease, but this equation has not been studied extensively in patients with cancer., Objective: To determine the absolute difference between the dose of carboplatin administered (traditional SCr-based formulas used to estimate GFR) and the dose calculated using the MDRD equation to estimate GFR and compare the frequencies of thrombocytopenia, neutropenia, and dosage modifications between subjects in whom the difference in dose was 20% or more (divergent) or less than 20% (nondivergent)., Methods: A retrospective analysis was conducted using data from patients who received carboplatin. Inclusion criteria were receipt of at least 2 doses of carboplatin, either as monotherapy or combination therapy, and documentation of desired area under the concentration-time curve (AUC). Patients were excluded if the baseline values needed to estimate GFR using the MDRD equation were not available. The absolute difference between the dose of carboplatin administered and that calculated using the MDRD equation was determined and, from this comparison, the subjects were divided into 2 groups (divergent vs nondivergent)., Results: The medical records of 186 adults who received more than 2 doses of carboplatin were included in the analysis. The doses were divergent in 89 (48%) patients. The mean target AUC values were 5.3 mg/mL/min and 5.1 mg/mL/min in the divergent and nondivergent groups, respectively, and most patients received cytotoxic regimens with a relatively low risk of febrile neutropenia. The frequencies of neutropenia, thrombocytopenia, and dosage modifications were similar between the 2 groups. Use of the MDRD equation to calculate the carboplatin dosage did not appear to result in a change in the frequency of myelosuppression or the need for dose modifications compared with traditional SCr-based formulas., Conclusions: The traditional SCr-based formulas for the calculation of carboplatin dosage should be used to estimate carboplatin dose until more data become available regarding the use of the MDRD equation in this population.

Background: We sought to determine whether cyclooxygenase-1 (PTGS1) genotype is associated with the ability of aspirin to inhibit platelet aggregation in patients at risk for stroke., Methods: Blood and urine samples were collected from 60 subjects, including 28 African Americans, who were taking aspirin for primary or secondary stroke prevention. Samples were analyzed for the PTGS1 A-707G, PTGS1 P17L, and glycoprotein IIIa (ITGB3)P1(A1/A2) genotypes, ex-vivo platelet aggregation, serum cholesterol, plasma salicylate levels, and urinary 11-dehydrothromboxane B(2) (11-dhTxB(2)) concentrations. The association between PTGS1 A-707G and P17L genotypes and aspirin response, as assessed by ex vivo studies and 11-dhTxB(2) concentrations, was evaluated by statistical testing and nonlinear mapping., Results: Salicylate concentrations, ITGB3 genotype distribution and 11-dhTxB(2) concentrations were similar among PTGS1 genotype groups. More subjects with the PTGS1 17PP versus PL genotype had incomplete ex-vivo inhibition of platelet aggregation by aspirin (57 vs. 20%; p = 0.04). Fifty-nine percent of subjects homozygous for both the PTGS -707A and 17P alleles, but none with both the PTGS1 -707G and 17L alleles had incomplete inhibition with aspirin; p = 0.04. Similarly, nonlinear mapping showed a direct relationship between the PTGS1 17P allele and decreased aspirin response. When analyzed separately by ethnicity, the association with the P17L genotype and aspirin response persisted in African Americans, but not Caucasians., Conclusions: Our data suggest that the PTGS1 P17L genotype contributes to response to aspirin as assessed by ex-vivo platelet aggregation. Our data further suggest that the association between PTGS1 genotype and aspirin response might vary by ethnicity.

Cytochrome P450 2C9 (CYP2C9) expression is regulated by multiple nuclear receptors including the constitutive androstane receptor (CAR) and pregnane X receptor (PXR). We compared coregulation of CYP2C9 with CYP2B6 and CYP3A4, prototypical target genes for human CAR and PXR using human hepatocyte cultures treated for three days with the PXR activators clotrimazole, rifampin, and ritonavir; the CAR/PXR activator phenobarbital (PB); and the CAR-selective agonists CITCO, (6-(4-chlorophenyl)imidazo[2,1-beta][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime) and phenytoin. Clotrimazole, rifampin, ritonavir, phenytoin, and phenobarbital induced CYP2C9 consistent with previous findings for CYP3A4. We observed EC(50) values of 519 microM (phenobarbital), 11 microM (phenytoin), and 0.75 microM (rifampin), similar to those for CYP3A4 induction. Avasimibe, a potent PXR activator, produced nearly identical concentration-dependent CYP2C9 and CYP3A4 activity profiles and EC(50) values. In 17 donors, rifampin increased mean basal CYP2C9 activity from 59 +/- 43 to 143 +/- 68 pmol/mg protein/min; fold induction ranged from 1.4- to 6.4-fold. Enzyme activity and mRNA measurements after rifampin, CITCO and PB treatment demonstrated potency and efficacy consistent with CYP2C9 regulation being analogous to CYP3A4 rather than CYP2B6. We demonstrate that hepatic CYP2C9 is differentially regulated by agonists of CAR and PXR, and despite sharing common regulatory mechanisms with CYP3A4 and CYP2B6; this enzyme exhibits an induction profile more closely aligned with that of CYP3A4., ((c) 2009 Wiley Periodicals, Inc.)

Objectives: To compare cytochrome P450 activity in people with and without cancer and examine the relationship between CYP2C9 activity and serum cytokine levels., Patients and Methods: 10 subjects with cancer who were currently receiving treatment and 10 additional subjects without cancer who were matched to the subjects with cancer based on gender and race were enrolled into the study. Serial blood samples were drawn to measure tolbutamide in the plasma before and after oral tolbutamide 500 mg. Total urine excreted was collected from 0 to 12 h following the dose. Tolbutamide and its metabolites were measured in plasma and urine by HPLC. CYP2C9 genotype was determined by PCR and pyrosequencing and cytokine values were determined by ELISA., Results: The mean apparent oral clearance (cancer, 19.5 +/- 10.5 vs. non-cancer, 15.8 +/- 5.0 ml/min) and the mean urinary metabolic ratio from 0 to 12 h were similar (838 +/- 693 vs. 775 +/- 390). Neither age nor genotype statistically affected the outcomes. Mean interleukin-6 (7.2 +/- 9.4 vs. 1.5 +/- 1.3 pg/ml) and tissue necrosis factor-a (26.2 +/- 71.2 vs. 1.5 +/- 1.3 pg/ml) were 5- to 7-fold higher, respectively, in subjects with cancer. No statistically significant correlation between cytokine values and oral clearance or urinary metabolic ratio was found., Conclusions: CYP2C9 activity as measured by apparent oral clearance and urinary metabolic ratio following oral tolbutamide appear similar in people with and without cancer. Serum cytokine values appear higher in patients with cancer, although the differences did not reach statistical significance.

Purpose: To discuss the clinical issues we addressed in the development of our institutional guidelines regarding the assessment of iron stores for cancer- and treatment-related anemia and the administration of parenteral iron with erythropoiesis-stimulating agents (ESAs)., Data Source: Studies published from January 1995 to August 2007 were identified by computer searches of Medline and hand searching of bibliographies of the articles identified via the computer searches. The current clinical practice guidelines were identified by computer searches of the web sites for national professional organizations that represent health care professionals who treat patients with cancer., Results: of data analysis. Hematopoietic responses demonstrate that epoetin alfa and darbepoetin alfa provide similar outcomes for patients with chemotherapy-induced anemia (CIA); however, up to 50% of patients receiving these agents fail to adequately respond. Functional iron deficiency defined as a state of iron-restricted erythropoiesis is likely the primary contributor to the lack of response. Hematopoietic responses following ESA therapy with parenteral iron are substantially higher compared to response with no or oral iron., Conclusions: Iron stores should be assessed in all patients with cancer- or treatment-related anemia and parenteral iron should be administered to patients receiving ESA therapy to improve hematopoietic response. A unique algorithm that summarizes our institutional guidelines to assess iron stores and administer parenteral iron with ESA therapy in patients with CIA is included.

A common side effect of opioids is nausea and vomiting; however, the incidence in hospitalized patients receiving opioids for acute pain is unknown. We performed a retrospective study in adult patients with sickle cell disease admitted for an acute pain crisis during a six-month period to evaluate the incidence of nausea and vomiting and characterize the prescribing of antiemetics. Eligibility included normal hepatic and renal function. Thirty-four subjects with a total of 97 admissions were evaluated. As expected, opioids were prescribed during all admissions. Fifty percent of the subjects experienced nausea or vomiting during the study period and these same patients accounted for the majority of the admissions, 17 subjects with 71 admissions (Group I). Nausea was reported in 18 (25%) of these admissions and vomiting was reported in 24 (34%) of these admissions. The most common antiemetics prescribed were: prochlorperazine, metoclopramide, and promethazine and antiemetics were ordered during 22 (23%) separate admissions for all subjects included in the study. The clinical benefit of these medications is limited due to uneven documentation. In conclusion, many of our patients experienced nausea or vomiting with antiemetics infrequently prescribed on an as needed basis. This suggests a need for better approaches to manage nausea and vomiting in patients receiving opioids., ((c) 2007 Wiley-Liss, Inc.)

The incidence of thrombosis and bleeding is higher in patients with cancer receiving warfarin compared with low molecular weight heparins. Despite these findings, warfarin remains a commonly used treatment strategy for anticoagulation in patients with cancer secondary to several factors that limit the use of low molecular weight heparins. Determining the appropriate warfarin dose in cancer patients is challenging. The objective of our study is to compare the weekly warfarin dose in patients with and without cancer. In a retrospective analysis, the average weekly warfarin dose was compared for 63 subjects who 1) were treated for cancer while receiving warfarin (n = 21), 2) completed treatment for their cancer before starting warfarin (n = 21), and 3) received warfarin with no diagnosis of cancer (n = 21). The data were abstracted from the medical record from the date the subject started taking a stable dose of warfarin after the initial titration until the discontinuation of warfarin. No significant differences were observed in the mean weekly warfarin dose, but the dose demonstrated greater intrasubject variability for subjects in group 1 (group 1, 31 +/- 22% vs. 2, 19 +/- 11% and 3, 15 +/- 10%, P = 0.003). Subjects in group 1 also spent more time above their goal International Normalized Ratio (group 1, 30 +/- 21% vs. 2, 21 +/- 16% and 3, 15 +/- 16%, P = 0.038). The average weekly warfarin dose was similar for the three groups, but the results of this study suggest that patients with cancer receiving treatment for their cancer and anticoagulation with warfarin are more difficult to appropriately anticoagulate.

Cetuximab (Erbitux) is a recombinant, chimeric monoclonal antibody that binds with high affinity to the extracellular ligand-binding domain of human epidermal growth factor receptor. We report a case of repeated responses to cetuximab in a patient with nonresectable squamous cell skin cancer having strong human epidermal growth factor receptor expression. Nonmelanoma skin cancer is the most common cancer in the US, with more than 1 million new cases detected annually, of which 20-25% are squamous cell carcinomas. Although most primary cutaneous squamous cell carcinomas have a high clinical cure rate and are easily treated, the small subset of cancers that recur or metastasize has a poor prognosis, and accounts for approximately 2000 deaths per year. Treatment with cetuximab should be considered for human epidermal growth factor receptor expressing tumors in a palliative setting.

Few studies describe the administration of Taxol to rats; however, rats are typically used to study the toxicity of new drugs or novel formulations. A dose finding study was conducted to determine a safe dose of Taxol following intravenous administration in rats. Male Sprague-Dawley rats received a bolus of paclitaxel 5-20 mg/kg i.v. Blood was drawn before administration and at the following times after administration: 0.5, 1, 2, 3, 4, 6, 8, 12, 16, 20 and 24 h. Plasma concentrations were determined using high performance liquid chromatography. Two rats received paclitaxel 20 mg/kg and died immediately. Nine rats received paclitaxel 10 mg/kg; seven of these rats died within 12 h and two rats were killed due to moribund conditions. Ten rats received paclitaxel 5 mg/kg with no morbidity. The following pharmacokinetics for paclitaxel in the plasma were estimated: C0, 8977 ng/ml; AUC(0 --> infinity), 7477 ng*h/ml; CL(s), 668 ml/h*kg; V(ss), 1559 ml/kg; V(z) 2557 ml/kg and t(1/2), 2.6 h. It is concluded that further pharmacokinetic studies that are rationally designed to include appropriate measures of preclinical toxicity associated with paclitaxel are needed to identify formally the safest dose in rats following intravenous administration; however, these data indicate that male Sprague-Dawley rats can safely receive Taxol in a 5 mg/kg i.v. bolus., (Copyright 2006 John Wiley & Sons, Ltd.)

The goal of this study was to identify clinical characteristics and concurrent medications associated with an increased or decreased incidence of cisplatin-induced nephrotoxicity. The medical records for 62 subjects with head and neck cancer who received cisplatin 100 mg/m2 (day 1) plus fluorouracil 1000 mg/m2 (days 1-5) with or without radiation therapy were reviewed from three medical centers. The demographics, concurrent medication therapy, co-existing illnesses and clinical laboratory values were extracted from the medical records. Nephrotoxicity was defined as a minimum rise in serum creatinine of 0.5 mg/dl or above. The concurrent use of hydrochlorothiazide or multivitamins was associated with a higher incidence of nephrotoxicity after cycle 1. Use of albuterol, atenolol or hydrochlorothiazide was also associated with a higher incidence of nephrotoxicity after cycle 1 or 2. In contrast, subjects prescribed dexamethasone or ondansetron were less likely to experience nephrotoxicity. None of these medications affected treatment response. Race/ethnicity was independently correlated with the incidence of nephrotoxicity; African-American subjects were more likely to develop nephrotoxicity independent of the influence of these concurrent medications. Medications may modulate cisplatin-induced nephrotoxicity by altering the metabolic activation of cisplatin to a nephrotoxin. Genetic differences in the drug-metabolizing enzymes may contribute to the correlation with race. The results from this retrospective study provide data to support a larger prospective study to further investigate the associations between these concurrent medications and cisplatin-induced nephrotoxicity.

Background: We identified a drug-drug interaction between gemcitabine and paclitaxel in a clinical pharmacokinetic study. The purpose of the present study was to determine whether paclitaxel affected the uptake and accumulation of the parent drug gemcitabine and the formation of its metabolites after treatment of cells with gemcitabine in vitro., Materials and Methods: The human leukemia cell line CEM was treated with 15 micoM 3H-gemcitabine, with and without paclitaxel, and the accumulation of radiolabeled gemcitabine was assessed up to one minute and one hour. Peripheral blood mononuclear cells (PMN) and hepatocytes were treated with gemcitabine, with or without paclitaxel, for specified amounts of time at three concentrations of gemcitabine, and the concentrations of gemcitabine and its metabolites were measured by liquid chromatography., Results: In CEM cells, paclitaxel reduced the uptake and accumulation of gemctabine by 32% and 30%, respectively. In the hepatocytes, the mean concentrations of gemcitabine increased in the cell culture media 100%, 48% and 38% when treated with paclitaxel plus gemcitabine 5, 15 and 30 microM, respectively, compared to gemcitabine alone. The concentrations of the deaminated metabolite dFdU were significantly decreased in the cell culture media. In the PMN, the intracellular accumulation of active triphosphorylated metabolite dFdCTP was lower in cells treated with paclitaxel (up to 83%) compared to the control., Conclusion: Paclitaxel substantially reduced the uptake and accumulation of gemcitabine and the formation of its metabolites in vitro at clinically relevant concentrations.

Purpose: Gemcitabine administered at a fixed dose rate of 10 mg/m(2) per min has been reported to achieve plasma steady-state concentrations ranging from 10 to 20 microM in patients with acute leukemia. These concentrations have been shown to saturate the intracellular accumulation of the active triphosphate metabolite. We designed this pharmacokinetic study to assess the ability of a fixed dose rate of gemcitabine to achieve the desired steady-state concentration in the absence and presence of paclitaxel in patients with solid tumors., Patients and Methods: A group of 14 patients with advanced non-small-cell lung cancer received paclitaxel 110 mg/m(2) over 3 h on days 1 and 8 and gemcitabine 800 mg/m(2) over 80 min on days 1 and 8 every 21 days. Patients received gemcitabine alone on cycle (C) 1, day (D) 1. Pharmacokinetic samples were collected at 0, 15, 30, 45, 60 and 80 min during infusion and 0.25, 0.5, 1, 2, 4, 6, and 8 h after infusion on C1D1, C1D8, C2D1, C4D1 and C6D1., Results: Of 13 patients included in the pharmacokinetic analysis, 61% achieved the desired steady-state concentration (C(ss)) with gemcitabine alone (C1D1), whereas only 0 to 45% of patients achieved the desired C(ss) with paclitaxel and gemcitabine, depending on the treatment cycle. Paclitaxel significantly decreased systemic clearance (Cl(T); P=0.012) and volume of distribution (V(d); P=0.050) and significantly increased C(ss) ( P=0.009). Gemcitabine plasma pharmacokinetic parameters demonstrated great interpatient variability in the absence of paclitaxel (C(ss) 30%, Cl(T) 30%, V(d) 55%). Interpatient and intrapatient variability in gemcitabine pharmacokinetics were not observed when gemcitabine was administered in combination with paclitaxel (P>0.05)., Conclusions: Gemcitabine plasma pharmacokinetic parameters are significantly altered in the presence of paclitaxel.

The purpose of this study was to characterize the concentration-response effects of cyclophosphamide (CPA) with and without dexamethasone (DEX; 10 microM) on the expression of CYP3A4 and CYP2B6 in cultured human hepatocytes at concentrations representative of standard- and high-dose CPA therapy (25 to 750 microM). CPA produced concentration-dependent increases in CYP3A4 and CYP2B6 activity and immunoreactive protein that peaked at 250 and 125 microM, respectively, and declined thereafter. The inductive effect of CPA alone and in combination with DEX was greater in magnitude for CYP2B6 compared with CYP3A4. To further examine the inductive effect of CPA on CYP3A4, CPA (250 microM) and DEX (10 microM) alone and in combination were examined in 10 hepatocyte preparations. The combination of CPA and DEX yielded higher rates of 6beta-hydroxytestosterone formation than either agent alone. However, the effect was less than additive in human hepatocyte cultures with relatively high baseline CYP3A4 activity and additive or synergistic in human hepatocyte cultures with relatively low baseline CYP3A4 activity. Induction index was highly correlated with CYP3A4 baseline activity for both CPA (r(2) = 0.75) and CPA plus DEX (r(2) = 0.85). To investigate the potential mechanism for CPA-induced increases in CYP3A4 activity, the ability of CPA alone and in combination with DEX to activate pregnane X receptor (PXR) was explored using transient transfection assays. CPA produced a dose-dependent increase in PXR activation that was maximal at the highest CPA concentration studied (500 microM). The addition of DEX to CPA resulted in a minor increase in PXR activation compared with CPA alone. These results indicate that CPA alone and in combination with DEX differentially induces the expression of CYP3A4 and 2B in a concentration-dependent manner, which may be mediated partially through activation of PXR. The impact of these effects on the efficacy and toxicity of CPA therapy warrants further investigation.

Background: Both oxaliplatin and ormaplatin undergo biotransformation to Pt(dach)Cl2 with studies suggesting a predictive relationship between systemic exposure to Pt(dach)Cl2 and the severity of the delayed sensory neuropathy associated with ormaplatin. Studies characterizing the pharmacokinetic parameters of oxaliplatin and Pt(dach)Cl2 in humans have not been reported. This study was conducted to characterize the pharmacokinetic parameters of oxaliplatin and Pt(dach)Cl2 and to determine the extent to which oxaliplatin undergoes biotransformation to Pt(dach)Cl2 in humans., Materials and Methods: Ten adult patients with metastatic colon cancer received oxaliplatin with or without fluorouracil-based chemotherapy. Blood samples were obtained during cycles 1 and 2. Total platinum, oxaliplatin and Pt(dach)Cl2 in the plasma ultrafiltrate were measured using high performance liquid chromatography and atomic absorption spectrometry. All patients underwent a thorough neurological evaluation after each cycle., Results: The median steady-state concentration (C(SS)) (interquartile range, 25% to 75%) for oxaliplatin 85 mg/m2 was 0.33 microg Pt/ml (0.28 to 0.38 microg Pt/ml). The area under the curve (AUC) was 0.79 microg Pt/ml/h (0.62 to 0.88 microg Pt/ml/h) and the elimination half-life was 0.32 h (0.27 to 0.46 h). The median C(SS) for Pt(dach)Cl2 was 0.008 microg Pt/ml (0.004 to 0.014 microg Pt/ml). The C(SS) ratio of oxaliplatin to Pt(dach)Cl2 was 31 (24 to 51). All patients reported acute cold-induced neuropathy following cycles 1 and 2. Only two patients reported delayed sensory neuropathy (grade 1)., Conclusion: The parent drug oxaliplatin is the major active platinum complex detected in plasma ultrafiltrate for at least the first few hours following oxaliplatin infusion in humans. Therefore, the plasma biotransformation products of oxaliplatin are unlikely to contribute to its efficacy or toxicity. In particular, plasma Pt(dach)Cl2 is unlikely to significantly contribute to the delayed sensory neuropathy associated with oxaliplatin, since only a limited amount (<3%) of oxaliplatin undergoes biotransformation to Pt(dach)Cl2.

The purpose of this investigation was to evaluate the role of cytochrome P450 (CYP) 3A4 in human liver microsomal bupropion (BUP) hydroxylation. Across the BUP concentration range of 0.075 to 12 mM, cDNA-expressed CYP3A4 demonstrated BUP hydroxylase activity only when incubated with concentrations > or =4 mM. When assayed at 12 mM BUP, cDNA-expressed CYP3A4 catalyzed BUP hydroxylation at a 30-fold lower rate than cDNA-expressed CYP2B6 (0.2 versus 7 pmol/min/pmol of P450). Among a panel of 16 human liver microsomes (HLMs), BUP hydroxylase activity varied 80-fold when assayed at 500 microM and did not strongly correlate with testosterone 6beta-hydroxylase activity when assayed at 250 microM testosterone (r(2) = 0.39), nor with CYP3A4 protein expression. A selective CYP3A4 inhibitor, troleandomycin (TAO), did not significantly alter rates of BUP hydroxylation when assayed in a moderate activity HLM at 10 to 2000 microM BUP, as reflected by a similarity in the kinetic parameters of BUP hydroxylation in the absence or presence of TAO. In addition, the same range of TAO concentrations (0.025-100 microM) that inhibited testosterone 6beta-hydroxylation in a concentration-dependent manner (46-81%) in pooled HLMs produced negligible inhibition (7%) of BUP hydroxylation when assayed at 500 microM BUP. These results suggest that CYP3A4 does not significantly catalyze BUP hydroxylation. Furthermore, these results complement recent data supporting selectivity of BUP hydroxylation for CYP2B6 at 500 microM BUP.

The purpose of this study was to establish bupropion (BUP) hydroxylation as a selective in vitro marker of cytochrome P450 (CYP) 2B6 catalytic activity. Among a panel of 16 human liver microsomes (HLMs), BUP hydroxylase activity varied 80-fold when assayed at 500 microM substrate and significantly correlated with CYP2B6 blotting density (r(2) = 0.99) and S-mephenytoin N-demethylase activity (r(2) = 0.98). Kinetic analysis of BUP hydroxylation was performed in a subset of seven HLMs representative of the 80-fold range in activity. Sigmoidal kinetics suggestive of allosteric activation was observed in five HLMs exhibiting low or high activity; the mean apparent K(m) for BUP hydroxylation in these HLMs (130 microM) was similar to the K(m) for cDNA-expressed CYP2B6 (156 microM). Nonsaturable, biphasic kinetics was observed in two HLMs exhibiting low activity. Among a panel of cDNA-expressed P450 isoforms, CYP2B6 and CYP2E1 demonstrated the highest rates of BUP hydroxylation at 12 mM BUP (7.0 and 2.4 pmol/min/pmol of P450, respectively). The relative contributions of CYP2B6 and CYP2E1 to BUP hydroxylation were estimated by using immunoinhibitory monoclonal antibodies (MAB) to these enzymes. MAB-2B6 produced 88% maximum inhibition of BUP hydroxylation when assayed at 12 mM BUP in a high activity HLM, whereas MAB-2E1 produced 81% maximum inhibition in a low activity HLM. However, negligible inhibition by MAB-2E1 was observed when low and high activity HLMs were assayed at 500 microM BUP. These results demonstrate selectivity of BUP hydroxylation for CYP2B6 at 500 microM BUP, thereby validating its use as a diagnostic in vitro marker of CYP2B6 catalytic activity.

The indications, pharmacokinetics, and therapeutic guidelines for available coagulation products are reviewed. Patients with hemophilia, von Willebrand's disease (VWD), or acquired inhibitors to antihemophilic factor (AHF) cannot spontaneously stop an acute hemorrhage. Coagulation products used to manage bleeding in patients with these disorders include AHF concentrates, factor IX concentrates, factor VIIa concentrate, factor IX complexes, anti-inhibitor coagulant complexes, and desmopressin acetate. Typically, these commercially available products are used to manage acute bleeding or to prevent excessive bleeding during surgery. The dosage of the coagulation products and the duration of therapy depend on many variables, including the severity of the hemorrhage, the pharmacokinetics of the coagulation products, and patient-specific factors. Product purity and viral attenuation are also important considerations in determining an appropriate dosage regimen. Recombinant versions of some coagulant factors are available and can eliminate the risk of viral transmission. A thorough understanding of each coagulation product can guide product selection, dosing, and treatment duration and can reduce the risk of viral transmission.