Methotrexate and 7-hydroxy-methotrexate pharmacokinetics following intravenous bolus administration and high-dose infusion of methotrexate.

The pharmacokinetics of methotrexate and 7-hydroxy-methotrexate were studied in patients undergoing very high-dose methotrexate monotherapy. The patients received, first, two methotrexate intravenous bolus test doses (50 mg/m2) one with and one without concomitant administration of folinic acid (15 mg every 6 h) in a random sequence, and, second, an 8 h infusion, individualized to achieve a peak plasma concentration of 5 X 10(-4) M methotrexate (infusion rates greater than 1000 mg/h). Methotrexate and 7-hydroxy-methotrexate concentrations were measured by specific radioimmunoassays and the data were analysed simultaneously by an integrated pharmacokinetic model.

Methotrexate test-dose protocol in the presence of 7-hydroxy-methotrexate.

Methotrexate (MTX) and 7-hydroxy-methotrexate (7-OH-MTX) plasma concentration-time curves (AUC) have been analyzed in 24 patients after different routes of MTX administration. After an i.v.

Kinetics of methotrexate and its metabolites in red blood cells.

It has been suggested that the intra-erythrocyte levels of methotrexate (MTX) and its polyglutamized derivatives could offer a method for evaluating intracellular MTX accumulation and its metabolism in children with acute lymphoblastic leukemia. We were interested in measuring the intra-erythrocyte levels of MTX in patients with solid tumors receiving high-dose MTX treatment. After a first incorporation stage occurring during infusion, MTX concentrations subsequently increased 9-12 days after the treatment as polyglutamized derivatives.

Kinetics of uptake and intracellular binding of Cyclosporine A in RAJI cells, in vitro.

Uptake characteristics of Cyclosporine A (CsA), an immunosuppressive agent widely used in organ transplantation, have been evaluated in RAJI cells, a human Burkitt lymphoma cell line which (i) does not bear T-cell markers, (ii) is insensitive to CsA after a 1 hr exposure to concentrations up to 50 micrograms/ml, and (iii) does not metabolize CsA. CsA is rapidly accumulated inside the cells until a near steady-state is achieved (within 1-3 min). This uptake is characterized by two components: one linear process saturable at low drug concentrations (lower than 1 microgram/ml) and another not saturable component even at high drug concentrations (up to 50 micrograms/ml).

Methotrexate-vindesine association in head and neck cancer: modification of methotrexate's hydroxylation in presence of vindesine.

High-dose methotrexate (HD-MTX) infusions associated with vindesine (VDS) have been used in the treatment of head and neck cancer. In a previous study, VDS was shown to increase the apparent plasma clearance of MTX. We have studied the MTX hydroxylation process in the presence of VDS.

Dosage predictions in high-dose methotrexate infusions. Part 2: Bayesian estimation of methotrexate clearance.

Population pharmacokinetics of methotrexate (MTX) was evaluated from intravenous test-dose (TD) data (n = 20 corresponding to 174 measured samples). Bayesian prediction of MTX clearance from TD experiments combining population data with measured levels (at times 0.5 and 6 h) was found to be feasible in routine situations with good performance (root mean squared error : rmse (precision) = 1.

Dosage predictions in high-dose methotrexate infusions. Part 1: Evaluation of the classic test-dose protocol.

A preliminary methotrexate (MTX) kinetic evaluation following administration of an IV bolus (test-dose) allowed individualization of high-dose infusions (HD-MTX). This approach combined with therapeutic drug monitoring was found to have good performance over a large scale of predicted steady-state levels (Css) (10(-5) to 10(-4) M over 24 to 36 h) corresponding to 17 to 650 mg/h deliveries (root mean squared error : rmse (precision) = 1.54 X 10(-5) M (21.

Methotrexate-vindesine association in leukemia: pharmacokinetic study.

Methotrexate (MTX) and vindesine (VDS) have both been found effective in the treatment of acute leukemia. With regard to their pharmacological effects at the cellular level they can reportedly interact. Administration of MTX at high dose levels has been suggested as both a curative and preventive treatment of blastic meningitis.

Methotrexate-vindesine association in the treatment of head and neck cancer influence of vindesine on methotrexate's pharmacokinetic behavior.

Determination of methotrexate (MTX) kinetics after an IV bolus (50 mg/m2) allows prediction of the steady-state plasma level of this drug during a constant infusion. This prediction allows high-dose MTX (HD-MTX) therapy without major toxicity. Patients with head and neck carcinoma received HD-MTX and vindesine (VDS) infusions concomitantly.

High-dose methotrexate: a clinical and pharmacokinetic evaluation. Treatment of advanced squamous cell carcinoma of the head and neck using a prospective mathematical model and pharmacokinetic surveillance.

Some of 66 patients with head and neck tumors were treated with high-dose methotrexate monochemotherapy. The use of a prospective mathematical model with pharmacokinetic surveillance proved to be reliable, practical, and useful. By this means chemotherapy could be individualized, with a resultant marked reduction in the frequency and severity of toxicity.