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Notes: Abstract Background: Vinorelbine and Doxil (liposomal doxorubicin) are active chemotherapeutic agents in metastatic breast cancer. A phase I study was designed to evaluate combination therapy. Patients and methods: Thirty women with metastatic breast cancer were enrolled. Dose-limiting toxicity was determined through a dose escalation scheme, and defined for the first treatment cycle, only. Pharmacokinetic studies were performed during the first cycle of treatment. Results: In the first cohort of Doxil 30 mg/m2 day 1 and vinorelbine 25 mg/m2 days 1 and 8, patients experienced severe neutropenia. Vinorelbine administration was changed thereafter to days 1 and 15 of each cycle. Dose limiting toxicity was observed at Doxil 50 mg/m2 and vinorelbine 25 mg/m2. Doxil 40 mg/m2 and vinorelbine 30 mg/m2 was defined as the maximally tolerated dose. Few toxicities (principally neutropenia) were seen at this dose level, with the notable absence of significant nausea, vomiting, or alopecia. Though 63% of patients had received prior anthracycline-based chemotherapy, only one patient developed grade 2 cardiac toxicity. Pharmacokinetic studies revealed prolonged exposure to high doxorubicin concentrations for several days following Doxil administration. Conclusions: Combination chemotherapy with Doxil and vinorelbine affords treatment with two active drugs in women with metastatic breast cancer, and appears to have a favorable toxicity profile. A schedule of Doxil 40 mg/m2 day 1 and vinorelbine 30 mg/m2 days 1 and 15 given every 28 days is recommended for phase II studies.

Notes: Abstract Background:This study was performed to evaluate thepharmacokinetics, bioequivalence, and feasibility of a combined oralformulation of 5-flurouracil (5-FU) and eniluracil (Glaxo Wellcome Inc.,Research Triangle Park, North Carolina), an inactivator of dihydropyrimidinedehydrogenase (DPD). The rationale for developing a combined eniluracil/5-FUformulation oral dosing form is to simplify treatment with these agents, whichhas been performed using separate dosing forms, and decrease the probabilityof severe toxicity and/or suboptimal therapeutic results caused byinadvertently high or conversely insufficient 5-FU dosing. Patients and methods:The trial was a randomized, three-waycrossover bioequivalence study of three oral dosing forms of eniluracil/5-FUtablets in adults with solid malignancies. Each period consisted of two daysof treatment and a five- to seven-day washout phase. Eniluracil at a dose of20 mg, which results in maximal DPD inactivation, was administered twice dailyon the first day and in the evening on the second day of each of the threetreatments. On the morning of the second day, all patients received a totaleniluracil dose of 20 mg orally and a total 5-FU dose of 2 mg orally as eitherseparate tablets (treatment A) or combined eniluracil/5-FU tablets in twodifferent strengths (2 tablets of eniluracil/5-FU at a strength (mg/mg) of10/1 (treatment B) or 8 tablets at a strength of 2.5/0.25 (treatment C)). Thepharmacokinetics of plasma 5-FU, eniluracil, and uracil, and the urinaryexcretion of eniluracil, 5-FU, uracil, and α-fluoro-β-alanine (FBAL),were studied. To determine the bioequivalence of the combined eniluracil/5-FUdosing forms compared to the separate tablets, an analysis of variance onpharmacokinetic parameters reflecting eniluracil and 5-FU exposure wasperformed. Results:Thirty-nine patients with advanced solid malignancies hadcomplete pharmacokinetic studies performed during treatments A, B, and C. Thepharmacokinetics of eniluracil and 5-FU were similar among the three types oftreatment. Both strengths of the combined eniluracil/5-FU dosing form and theseparate dosing forms were bioequivalent. Mean values for terminal half-life,systemic clearance, and apparent volume of distribution for oral 5-FU duringtreatments A/B/C were 5.5/5.6/5.6 hours, 6.6/6.6/6.5 liters/hour, and50.7/51.5/50.0 liters, respectively. The intersubject coefficient of variationfor pharmacokinetic variables reflecting 5-FU exposure and clearance intreatments ranged from 23% to 33%. The urinary excretion ofunchanged 5-FU over 24 hours following treatments A, B, and C averaged52.2%, 56.1%, and 50.8% of the administered dose of 5-FU,respectively. Parameters reflecting DPD inhibition, including plasma uraciland urinary FBAL excretion following treatments A, B, and C were similar.Toxicity was generally mild and similar following all three types oftreatments. Conclusions:The pharmacokinetics of 5-FU and eniluracil weresimilar and met bioequivalence criteria following treatment with the separateoral formulations of 5-FU and eniluracil and two strengths of the combinedformulation. The availability of a combined eniluracil/5-FU oral dosing formwill likely simplify dosing and decrease the probability of severe toxicityor suboptimal therapeutic results caused by an inadvertent 5-FU overdose orinsufficient 5-FU dosing in the case of separate oral formulations, therebyenhancing the overall feasibility and therapeutic index of oral 5-FU therapy.