Simultaneous determination of the camptothecin analogue CPT-11 and its active metabolite SN-38 by high-performance liquid chromatography: application to plasma pharmacokinetic studies in cancer patients.
CPT-11 (I; 7-ethyl-10-[4-(1-piperidino)-1- piperidino]carbonyloxycamptothecin) is a new anticancer agent currently under clinical development. A sensitive high-performance liquid chromatographic assay suitable for the simultaneous determination of I and its active metabolite SN-38 (II) in human plasma, and their preliminary clinical pharmacokinetics, are described. Plasma samples were processed using a solid-phase (C18) extraction step allowing mean recoveries of I, II and the internal standard camptothecin (III) of 84, 99 and 72%, respectively. The extracts were chromatographed on a C18 reversed-phase column with a mobile phase composed of acetonitrile, phosphate buffer and heptanesulphonic acid, with fluorescence detection. The calibration graphs were linear over a wide range of concentrations (1 ng/ml-10 micrograms/ml), and the lower limit of determination was 1 ng/ml for both I and II. The method showed good precision: the within-day relative standard deviation (R.S.D.) (5-1000 ng/ml) was 13.0% (range 4.9-19.4%) for I and 12.8% (6.7-19.1%) for II; the between-day R.S.D. (5-10,000 ng/ml was 7.9% (5.4-17.5%) for I and 9.7% (3.5-15.1%) for II. Using this assay, plasma pharmacokinetics of both I and II were simultaneously determined in three patients receiving 100 mg/m2 I as a 30-min intravenous infusion. The mean peak plasma concentration of I at the end of the intravenous infusion was 2400 +/- 285 ng/ml (mean +/- standard error of the mean). Plasma decay was triphasic with half-lives alpha, beta and gamma of 5.4 +/- 1.8 min, 2.5 +/- 0.5 h and 20.2 +/- 4.6 h, respectively. The volume of distribution at steady state was 105 +/- 15 l/m2, and the total body clearance was 12.5 +/- 1.9 l/h.m2. The maximum concentrations of the active metabolite II reached 36 +/- 11 ng/ml.
Barilero
I
I
Laboratoire de Pharmacologie Clinique (URA 147 CNRS, U 140 INSERM), Institut Gustave-Roussy, Villejuif, France.
Gandia
D
D
Armand
J P
JP
Mathieu-Boué
A
A
Ré
M
M
Gouyette
A
A
Chabot
G G
GG
D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007262:Infusions, Intravenous; D000077146:Irinotecan; D013997:Time Factors
D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002166:Camptothecin