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

Abstract

The purpose of our study was to investigate the pharmacokinetics of Cremophor EL following administration of escalating doses of Taxol (paclitaxel dissolved in Cremophor EL/ethanol) to non-small cell lung cancer (NSCLC) patients. Patients with NSCLC stage IIIb or IV without prior chemotherapy treatment were eligible for treatment with paclitaxel and carboplatin in a dose-finding phase I study. The starting dose of paclitaxel was 100 mg/m2 and doses were escalated with steps of 25 mg/m2, which is equal to a starting dose of Cremophor EL of 8.3 ml/m2 with dose increments of 2.1 ml/m2. Carboplatin dosages were 300, 350 or 400 mg/m2. 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 study. The doses of paclitaxel were escalated up to 250 mg/m2 (20.8 ml/m2 Cremophor EL). Pharmacokinetic analyses revealed a low elimination-rate of Cremophor EL (CI=37.8-134 ml/h/m2; t 1/2=34.4-61.5 h) and a volume of distribution similar to the volume of the central blood compartment (Vss=4.96-7.85 l). In addition, a dose-independent clearance of Cremophor EL was found indicating linear kinetics. Dose adjustment using the body surface area, however, resulted in a non-linear increase in systemic exposure. The use of body surface area in calculations of Cremophor EL should therefore be re-evaluated.

<i>In Vitro</i> Effects of Paclitaxel and Cremophor EL on Human Riboflavin Transporter SLC52A2

“…Recently, supportive therapy has been established for myelosuppression, but neurotoxicity remains the main reason to decrease the total cumulative dose administered, which may affect the therapeutic outcome. 14) It has also been reported that neurotoxicity is induced by CrEL alone. 13) This study showed that CrEL dose-dependently inhibited uptake of riboflavin by HEK293 cells transfected with the SLC52A2 riboflavin transporter (Fig.…”

“…After intravenous administration, paclitaxel results in peak serum concentrations of 2.5-10.7 nM, and the associated CrEL peak serum concentration is reportedly in the range of 0.2-0.8% (v/v). 15,16) Windebank et al showed 0.01-1% concentration of CrEL inhibited neurite outgrowth of dorsal root ganglion cells in vitro. 17) Therefore 0.05-5% of CrEL was used in our experiments.…”