Drug interactions of paclitaxel metabolism in human liver microsomes.

The human liver metabolism of paclitaxel (Taxol), an anticancer drug, leads to three metabolites: 6alpha-hydroxypaclitaxel, 3'-p-hydroxypaclitaxel and 6alpha,3'-p-dihydroxypaclitaxel. The inter-individual variability of paclitaxel metabolism was investigated first in vitro using 22 human liver microsomes. Three metabolites have been detected by HPLC.

Individual dosing of carboplatin based on drug monitoring in children receiving high-dose chemotherapy.

Individual dosing of carboplatin based on drug monitoring was performed within a multi-centric phase I study based on high AUC-levels in children. Twelve patients (aged 3-17 years old) have been included: 3, 5, and 4 patients at the overall target ultrafilterable carboplatin AUC of 20, 25, or 30 mg/ml x min, respectively. Carboplatin was administered as a daily 60-min infusion, repeated on five consecutive days.

Phase I and pharmacokinetic study of escalating dose of docetaxel administered with granulocyte colony-stimulating factor support in adult advanced solid tumors.

Purpose: The purpose of our study was to assess the feasibility, toxicity, and pharmacokinetics of an escalating dose of docetaxel when administered with granulocyte colony-stimulating factor (G-CSF) support every 3 weeks.

Experimental Design: Patients with advanced solid malignancies were treated with escalating doses of docetaxel as a 1-h infusion every 3 weeks, supported by s.c.

Impact of the oxaliplatin-5 fluorouracil-folinic acid combination on respective intracellular determinants of drug activity.

The combination of 5-fluorouracil-folinic acid and oxaliplatin has led to a significant improvement of chemotherapy efficacy in advanced pretreated colorectal cancer. The objective of the present study was, considering the oxaplatin-5-fluorouracil-folinic acid combination, to examine the impact of one given drug on the cellular determinants of cytotoxic activity of the other drug. These cellular factors were analysed on the human colon cancer cell line WiDr in clinically relevant conditions of drug exposure ('De Gramont' schedule) with oxaliplatin-folinic acid during 2 h followed by 5-fluorouracil 48 h.

Rapid high-performance liquid chromatographic determination of docetaxel (Taxotere) in plasma using liquid-liquid extraction.

A new rapid and sensitive high-performance liquid chromatographic method for analysis of docetaxel (Taxotere) in human plasma was developed and validated. After adding an internal standard (paclitaxel, Taxol), plasma was extracted following a simple liquid-liquid extraction with diethyl ether. Extraction efficiency averaged 95% for docetaxel.

Phase I trial and pharmacological study of a 3-hour paclitaxel infusion in children with refractory solid tumours: a SFOP study.

The maximum tolerated dose of paclitaxel administered by 24-hour continuous infusion in children is known. Short infusion might offer equivalent antitumour efficacy and reduced haematological toxicity, without increasing the allergic risk. Our aims were to determine the maximum tolerated dose and the pharmacokinetics of paclitaxel in children when administered in 3-h infusion every 3 weeks.

Monitoring of the intracellular activation of 5-fluorouracil to deoxyribonucleotides in HT29 human colon cell line: application to modulation of metabolism and cytotoxicity study.

An HPLC method was developed for in vitro detection and monitoring of intracellular metabolites of [3H]-5-fluorouracil (FUra). Results showed a preferential activation of FUra to ribonucleoside and ribonucleotide derivatives (FURd, FUMP, FUDP and FUTP) in the human colorectal HT29 cell line. We screened various agents so as to determine if they could act as modulators of metabolism and/or toxicity of FUra by reversing the activation pathway of FUra from ribo- to deoxyribonucleotides, thus enhancing FdUMP formation.

Enhanced antitumor activity of 5-fluorouracil in combination with 2'-deoxyinosine in human colorectal cell lines and human colon tumor xenografts.

We investigated the effects of 2'-deoxyinosine (d-Ino), a modulator yielding thymidine phosphorylase activity, on cellular pharmacology of 5-fluorouracil (FUra) in various human colorectal cell lines and its antitumoral activity when combined with FUra in human xenografts. Associating d-Ino with FUra increased by 38 up to 700 times the sensitivity of HT29 and FUra-resistant SW620 lines, respectively, but not of CaCO2 cells, although high levels of intracellular FdUMP and subsequent higher thymidylate synthase inhibition were observed. Cell death studies confirmed the ability of d-Ino to enhance both early and late apoptosis induced by FUra in HT29 and SW620 but not in CaCo2.

Pharmacokinetics of intrapleural cisplatin for the treatment of malignant pleural effusions.

We determined the toxicity and pharmacokinetics of high-dose intrapleural cisplatin (CDDP) as a treatment of malignant pleural effusions (MPE). Fourteen patients with MPE were enrolled in this study. After complete drainage of the fluid, a catheter was inserted into the pleural cavity during a thoracoscopy.

Interspecies variability and drug interactions of clozapine metabolism by microsomes.

Cytochrome P450 expression in liver is influenced by several factors, including species, sex and strain. We compared metabolism formation of clozapine in different species (rat, mouse, guinea-pig, dog, monkey and man) so as to choose between species to further validate interaction studies. Liver microsomes of male and female Sprague-Dawley rats, hairless rats, OF1 mice, Balb C mice and Dunkin-Hartley albino guinea-pigs, male beagle dogs, male cynomolgus monkeys and man were used to investigate in vitro metabolism of clozapine.

Pharmacokinetic-pharmacodynamic relationships between pirarubicin exposure and hematotoxicity: clinical application using only one blood sample.

The objective of the present study was to evaluate the relationship between the pharmacokinetic parameters of pirarubicin and of its metabolite doxorubicin measured in plasma and whole blood, and the hematologic toxicity of this drug, in order to evaluate the predictability of changes in white blood cells (WBC) by single measurement of drug concentrations. This pharmacokinetic-pharmacodynamic relationship was studied in a total of 45 patients with different tumor types treated by combined chemotherapy containing pirarubicin, administered as short infusion (10+/-2 min) at doses ranging from 50 to 90 mg. In 45 courses performed in 24 patients, we established the relationship between the half-product of pirarubicin level in whole blood at the end of the infusion and the duration of this infusion, which represents an estimate of the area under the time x concentration curve (AUC(PIRA,wb,ei) = C(PIRA,wb,ei) x duration of infusion/2), the age of the patients and the relative fall in WBC counts.

Bayesian calculation of methotrexate clearance after low dose intramuscular administration in patients with rheumatoid arthritis.

Objective: To determine a pharmacokinetic procedure (Bayesian method) for estimation of methotrexate (MTX) clearance, using only 2 blood samples, in outpatients with rheumatoid arthritis treated with low dose intramuscular (i.m.) MTX.

Assay of paclitaxel (Taxol) in plasma and urine by high-performance liquid chromatography.

A new, rapid and sensitive high-performance liquid chromatographic method for the analysis of paclitaxel (Taxol) in human plasma and urine was developed and validated. After addition of an internal standard, paclitaxel was extracted from plasma or urine by a liquid-liquid extraction using diethyl ether. Extraction efficiency averaged 90%.

Effects of tobacco smoke on the gene expression of the Cyp1a, Cyp2b, Cyp2e, and Cyp3a subfamilies in mouse liver and lung: relation to single strand breaks of DNA.

Cigarette smoking is a worldwide health problem and is the greatest risk factor for lung cancer. By activating procarcinogens, hepatic and extrahepatic cytochromes P450 can participate in lung carcinogenesis. Tobacco smoke contains numerous cytochrome P450 inducers, substrates, and inhibitors.

A Bayesian dosing method for carboplatin given by continuous infusion for 120 h.

Carboplatin (CBDCA), an analogue of cisplatin, exhibits reduced toxicity but wide interpatient variability of its pharmacokinetic parameters. Individualization of the CBDCA dose is therefore necessary. Although various formulas have been developed for this purpose, major side effects have been reported on CBDCA administration by short-term infusion (0.

Simultaneous determination of all-trans-, 13-cis-, 9-cis-retinoic acid and their 4-oxo-metabolites in plasma by high-performance liquid chromatography.

A gradient reversed-phase high-performance liquid chromatographic technique is described for the easy separation and quantification of some retinoids; all-trans-retinoic acid, 13-cis-retinoic acid, 9-cis-retinoic acid and their corresponding 4-oxometabolites, in plasma. The method involved a diethyl ether-ethyl acetate (50:50, v/v) mixture extraction at pH 7 with acitretin and 13-cis-acitretin as internal standards. A Nova-Pak C18 steel cartridge column was used.

Effects of different exposure times to tobacco smoke intoxication on carboxyhemoglobin and hepatic enzymate activities in mice.

The aim of this work was to determine the effects of different exposure times to smoke on carboxyhemoglobin (HbCO) and hepatic enzymate activities in order to adapt a tobacco smoke intoxication model in mice. Mice were exposed to tobacco smoke for various durations of either 2 (group S2), 4 (group S4), 8 (group S8), or 31 days (group S31) using the Hamburg II machine. Controls (nonexposed animals) were used under the same experimental conditions.

High inducibility of mouse renal CYP2E1 gene by tobacco smoke and its possible effect on DNA single strand breaks.

Several studies have shown in humans an association between renal carcinoma and cigarette smoking. Cigarette smoke contains numerous cytochrome P450 inducers and substrates. In the present study we investigated the effect of cigarette smoke on the regulation of murine cytochrome P450 expression in kidney and its possible role in the induction of single strand breaks in DNA.

[Individual dose adjustment of high-dose methotrexate in clinical practice].

Since its discovery in 1948 the clinical applications of methotrexate have widened; and in order to overcome resistances to methotrexate, the concept of high-dose methotrexate has been proposed. The use of rescue by folinic acid, as well as rapid dosage of MTX coupled with pharmacokinetic studies, have permitted us to administer an optimum dose of drug, with maximum therapeutic effects, but with reduced toxicity. Individual adaptation of posology, calculated using the test dose or according to population pharmacokinetic with a Bayesian method of parameter estimation (which allows us to adjust the dose of high-dose methotrexate during its infusion) permits control of inter and intra-individual variations of this drug.

Dosage adjustment of high-dose methotrexate using Bayesian estimation: a comparative study of two different concentrations at the end of 8-h infusions.

Bayesian estimation (BE) of pharmacokinetic parameters enables the clinician to adjust the dosage of high-dose methotrexate (HDMTX) to correct the inter- and intraindividual variation of concentrations that are responsible for severe toxicity. In this study of 672 HDMTX infusions, we validated an approach that consisted of reaching as nearly as possible a theoretical concentration of 5.10(-4) M or 10(-3) M at the end of an 8-h infusion by adjusting, when necessary, the dosage at the 6th h.

Glucuronidation of propofol in microsomal fractions from various tissues and species including humans: effect of different drugs.

This in vitro study was conducted to evaluate propofol glucuronidation and the effect of concomitantly administered drugs in various species. Propofol glucuronidation was studied in microsomal fractions from rat, rabbit, and human livers. Extrahepatic metabolism was investigated using lung and kidney microsomes.

Comparative effects of antifungal agents on zidovudine glucuronidation by human liver microsomes.

Zidovudine (ZDV) is extensively metabolised by the liver to an inactive glucuronide (GZDV). Since ZDV is often administered with antimycotic drugs, we studied the effect of six systemic antifungal agents on the in vitro glucuronidation of ZDV by human liver microsomes. 5-fluorocytosine and itraconazole had no inhibitory effect whereas amphotericine B, ketoconazole, miconazole and fluconazole inhibited in vitro GZDV formation (Ki values were 0.

Lack of correlation between pharmacokinetics and efficacy of low dose methotrexate in patients with rheumatoid arthritis.

Objective: To determine if the variability in the efficacy of methotrexate (MTX) in rheumatoid arthritis (RA) is correlated with its pharmacokinetics.

Methods: MTX pharmacokinetics was evaluated in 46 patients with RA starting a weekly intramuscular low dose MTX treatment. The patients were divided into 32 responders and 14 nonresponders to MTX according to the clinical response in the 6 months after the pharmacokinetic study.

Pharmacokinetics and metabolism of pirarubicin in humans: correlation with pharmacodynamics.

The pharmacokinetic monitoring of anthracycline-containing regimens is warranted because of the important toxicity of these drugs and because pharmacokinetic-pharmacodynamic relationships have been clearly established. We studied the pharmacokinetics of the new anthracycline pirarubicin in 80 courses of treatment performed in 27 patients, using a limited sampling protocol we had previously validated. We observed (for 47 of these courses) a significant correlation between the leucocyte cell kill and the pirarubicin area under the time x concentration curve, but the most significant correlation was obtained using the plasma concentration of doxorubicin, a metabolite of pirarubicin, at the end of the infusion.

Effect of cigarette smoke on hepatic and pulmonary cytochromes P450 in mouse: evidence for CYP2E1 induction in lung.

Pulmonary and liver microsomes of male NMRI mice were used to study the inductive effect of cigarette smoke on various cytochrome P450 isoforms implicated in precarcinogen and premutagen bioactivation. The enzymatic activities catalyzed by CYP1A1, CYP2B, CYP2C, CYP2D, CYP2E1 and CYP3A were induced in liver microsomes. Immunoquantification of lung and liver CYP1A1, 2E1 and 3A demonstrated that 1) CYP1A1 was induced in lung and liver, 2) CYP3A subfamily was induced in liver and not detected in lung, 3) CYP2E1 was slightly induced in liver whereas its pulmonary expression was more largely increased (6.