Metabolism and pharmacokinetics of a novel Src kinase inhibitor TG100435 ([7-(2,6-dichloro-phenyl)-5-methyl-benzo[1,2,4]triazin-3-yl]-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-amine) and its active N-oxide metabolite TG100855 ([7-(2,6-dichloro-phenyl)-5-methylbenzo[1,2,4]triazin-3-yl]-{4-[2-(1-oxy-pyrrolidin-1-yl)-ethoxy]-phenyl}-amine).

TG100435 ([7-(2,6-dichloro-phenyl)-5-methyl-benzo[1,2,4]triazin-3-yl]-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-amine) is a novel multitargeted, orally active protein tyrosine kinase inhibitor. The inhibition constants (K(i)) of TG100435 against Src, Lyn, Abl, Yes, Lck, and EphB4 range from 13 to 64 nM. TG100435 has systemic clearance values of 20.1, 12.7, and 14.5 ml/min/kg and oral bioavailability of 74%, 23%, and 11% in mouse, rat, and dog, respectively. Four oxidation metabolites of TG100435 have been found in human, dog, and rat in vitro and in vivo. The ethylpyrrolidine N-oxide of TG100435 is the predominant metabolite (TG100855; [7-(2,6-dichloro-phenyl)-5-methyl-benzo[1,2,4]triazin-3-yl]-{4-[2-(1-oxy-pyrrolidin-1-yl)-ethoxy]-phenyl}-amine) in human, dog, and rat. TG100855 is 2 to 9 times more potent than the parent compound. Flavin-containing monooxygenases are the primary enzymes mediating the biotransformation. Significant conversion of TG100435 to TG100855 has been observed in rat and dog after oral administration. Systemic exposure of TG100855 is 1.1- and 2.1-fold greater than that of TG100435 in rat and dog after oral dosing of TG100435. Since TG100435 is predominantly converted to the more potent N-oxide metabolite across species in vivo and in vitro, the overall tyrosine kinase inhibition in animal models may be substantially increased after oral administration of TG100435.

Monitoring of occupational exposure to methylene chloride: sampling protocol and stability of urine samples.

A sampling protocol for biomonitoring of the volatile solvent methylene chloride (MeCl(2)) by analysis of urine from exposed workers was established. Storage temperature, sample volume in headspace vial (HSV), and time to sealing HSV on determination of MeCl(2) in urine were evaluated. MeCl(2) was analyzed by a solid-phase microextraction technique combined with gas chromatography. Volume of urine in HSV has no effect on MeCl(2) analysis. Delays of 30 and 60 min from collection of urine until sealing the HSV caused 14.47 +/- 6.98% and 26.17 +/- 9.57% decreases from baseline concentration, respectively. MeCl(2) concentration in spiked urine samples stored in sealed HSVs decreased on day 2 and then remained stable for 2 weeks. Refrigeration did not improve recovery although it seems to be associated with less variability. MeCl(2) in urine samples of seven exposed workers was in the range of 0.02-0.06 mg/L. Sampling of MeCl(2)-containing urine should include collection of urine in closed plastic bottles, transfer to HSV within 15 min, sealing and clamping of HSV within 15 s, and storage of HSV in refrigeration until analysis, but no longer than 2 weeks. Standard samples should be prepared on the day of test sample collection and handled under the same conditions.

A simple approximation for busulfan dose adjustment in adult patients undergoing bone marrow transplantation.

Busulfan is an alkylating agent used in preparative regimens before bone marrow transplantation (BMT). Busulfan concentrations in plasma, expressed as the area under the concentration-time curve (AUC), were reported to correlate with treatment outcome. Because busulfan is administered in 16 doses of 1 mg/kg every 6 hours for 4 days, the opportunities to "correct" the dose as a consequence of the measured AUC are limited to the 16-dosage protocol. In the present research busulfan pharmacokinetics were prospectively evaluated in 27 adult patients treated according to the above protocol by measuring the first, second, and fifth dose AUC. The pharmacokinetic analysis was based on a noncompartment model for extravascular absorption, but calculations according to a 1-compartment model gave similar results. A simple mathematical approximation allowed prediction of the AUC of the second dose from that of the first and the busulfan concentration at trough. Fifteen patients had the dose adjusted at the fourth dose to obtain an AUC within the "therapeutic window" of 950-1500 microM-min. This procedure was then validated by the measurement of the fifth dose AUC. It appears that this simple pocket calculator method allows a rapid evaluation of the need and the extent of dose adjustment and proved to be a valuable tool to improve busulfan administration in pre BMT treatment.