Cremophor EL pharmacokinetics in a phase I study of paclitaxel (Taxol (R))and carboplatin in non-small cell lung cancer patients

The purpose of our study was to investigate the pharmacokinetics of Cremoph or EL following administration of escalating doses of Taxol(R) (paclitaxel dissolved in Cremophor EL/ethanol) to non-small cell lung cancer (NSCLC) pa tients. Patients with NSCLC stage IIIb or IV without prior chemotherapy tre atment were eligible for treatment with paclitaxel and carboplatin in a dos e-finding phase I study. The starting dose of paclitaxel was 100 mg/m(2) an d doses were escalated with steps of 25 mg/m(2), which is equal to a starti ng dose of Cremophor EL of 8.3 ml/m(2) with dose increments of 2.1 ml/m(2). Carboplatin dosages were 300, 350 or 400 mg/m(2). Pharmacokinetic sampling was performed during the first and the second course, and the samples were analyzed using a validated high-performance liquid chromatographic assay. A total of 39 patients were included in this pharmacokinetic part of the st udy. The doses of paclitaxel were escalated up to 250 mg/m(2) (20.8 ml/m(2) Cremophor EL). Pharmacokinetic analyses revealed a low elimination-rate of Cremophor EL (CI=37.8-134 ml/h/m(2); t(1/2)=34.4-61.5 h) and a volume of d istribution similar to the volume of the central blood compartment (V-SS=4. 96-7.85 I). In addition, a dose-independent clearance of Cremophor EL was f ound indicating linear kinetics. Dose adjustment using the body surface are a, however, resulted in a non-linear increase in systemic exposure. The use of body surface area in calculations of Cremophor EL should therefore be r e-evaluated. [(C) 2000 Lippincott Williams & Wilkins].