Aims 1)To characterize the population pharmacokinetics of apomine in healthy males and in male and female patients with solid tumours and 2) to understand more fully the influence of induction and between-and within-subject variability on exposure to drug using Monte Carlo simulation. MethodsApomine was administered once-or twice-daily with or without food in single and multiple oral doses of 30-2100 mg to healthy males ( n = 19) and patients with solid tumours ( n = 19). The data were divided into model development and validation sets. Models were developed using standard population methods. These were the identification of an appropriate base model, calculation of the empirical Bayes estimates of the primary pharmacokinetic parameters, covariate screening, forward stepwise addition of covariates using the likelihood ratio test as a model selection criteria, and backwards elimination to obtain the final model. To study the influence of data from individual subjects, the model development dataset was subjected to the delete-1 jack-knife and the final model was fitted to each jack-knifed dataset. Principal components analysis of the jack-knifed matrix of model parameters identified two influential subjects who were removed from the dataset, and the final model contained data from the remaining subjects. Model validation was examined using goodness of fit statistics and relative error measures using independent datasets from cancer patients. The model provided a reasonable approximation to the pharmacokinetic measurements in the validation datasets. Computer simulations were undertaken to understand further the pharmacokinetics of apomine in otherwise healthy females, a population not yet studied. ResultsApomine pharmacokinetics were complex and consistent with a two-compar tment model with a lag-time. Apparent oral clearance at baseline and apparent volume of distribution at steady-state were larger in healthy males than in cancer patients (41 ml h -1 and 14.1 l vs 10 ml h -1 and 8.9 l, respectively, for a 75 kg person). Clearance was time-variant showing a maximal increase with full induction of 320 ml h -1 , independent of patient type. The time to reach 50% maximal induction was about 2 days. The fraction of drug absorbed was relatively constant at doses less than 100-200 mg once daily but decreased at higher doses. Food also decreased relative bioavailability by 36%. Patient characteristics had no effect on apomine pharmacokinetics except for weight, which was proportional to the volume of the central compartment. Between-subject variability (68% for clearance, 30% for central volume, and 141% for peripheral volume) was moderate to large and independent of patient type. Inter-occasion variability was small (18% for both clearance and central volume). Residual variability was modelled with an additive and propor tional error model. Cancer Population pharmacokinetics of APOMINE™ Br J Clin Pharmacol 58 :2 143 patients had slightly higher plasma concentrations than healthy males but this difference was probably n...
Metastatic melanoma continues to be a very difficult disease to treat. Options are limited and often have very little impact on the course of the disease. The objective of the current study was to evaluate the efficacy and safety of continuously administered Apomine (SR-45023A), a novel bisphosphonate, in patients with previously treated metastatic malignant melanoma. Adult patients with previously treated metastatic melanoma received Apomine 100 mg orally, twice daily (total dose 200 mg per day) continuously for 28 days (defined as a cycle). Treatment was continued until disease progression or unacceptable toxicity. A total of 42 patients received at least one dose of Apomine. Stable disease was achieved in 2 patients (5%). No complete or partial responses were observed. Progression free survival of at least 16 weeks was observed in 6 patients (14%). The median overall survival was 6.1 months (95% CI, 4.9-9.4 months). Time to treatment failure was 1.7 months (95% CI, 1.6-1.8 months) with Apomine therapy. By cycle 2, Apomine concentrations reached steady-state. Apomine was well tolerated with only 37% of patients experiencing any drug-related event. Abdominal pain was the most frequent adverse event occurring in 26% of patients. In conclusion, Apomine, at the current dose studied, failed to produce a 30% progression free survival rate at 16 weeks considered to be a meaningful benefit for further development.
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