An LC/MS/MS method for the quantitation of MTIC (5-(3- N-methyltriazen-1-yl)-imidazole-4-carboxamide), a bioconversion product of temozolomide, in rat and dog plasma

• Published in: Journal of pharmaceutical and biomedical analysis Vol. 19; no. 5; pp. 659 - 668
• Main Authors: Chowdhury, S.K., Laudicina, D., Blumenkrantz, N., Wirth, M., Alton, K.B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-1999; Elsevier Science
• Subjects: Analysis; Animals; Antineoplastic Agents, Alkylating - blood; Biological and medical sciences; Calibration; Chromatography, High Pressure Liquid; Dacarbazine - analogs & derivatives; Dacarbazine - blood; Dogs; Female; General pharmacology; Male; Mass Spectrometry; Medical sciences; MS/MS; MTIC; Pharmacology. Drug treatments; Quality Control; Rats; Reproducibility of Results; Temozolomide; MS/MS; MTIC; Temozolomide; Antineoplastic agent; Validation; Fissipedia; Carnivora; Rat; Metabolite; Spraying; Rodentia; Oral administration; HPLC chromatography; Metabolism; Electrospray; Blood plasma; Vertebrata; Mammalia; Electric field; Animal; Mass spectrometry MS/MS; Carboxamide; Dog; Quantitative analysis
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/S0731-7085(98)00198-8

A sensitive and selective HPLC/electrospray ionization tandem mass spectrometric (LC/ESI/MS/MS) method for the quantitative determination of MTIC (5-(3-
N-methyltriazen-1-yl)-imidazole-4-carboxamide), a pharmacologically active hydrolysis product of temozolomide, was developed and validated over a linear range from 10 to 400 ng ml
−1 in dog plasma and from 10 to 500 ng ml
−1 in rat plasma. This HPLC method utilized small plasma volumes (70 μl), rapid sample processing, and isocratic elusion conditions to achieve sensitive and selective MS/MS detection. Samples were processed and analyzed one at a time every 4.5 min in order to compensate for the inherent instability of MTIC. Both MTIC and the internal standard DTIC [5-(3,3′-
N,
N′-dimethyltriazen-1-yl)-imidazole-4-carboxamide] were quantitated in the positive ion, selected reaction monitoring (SRM) mode. The lower limit of quantitation (LLOQ) was 10 ng ml
−1 in the plasma from both species. Inter-assay accuracy and precision of all calibration standards and quality control (QC) samples were within ±11 and 12%, respectively, with the exception of the LLOQ in rat plasma (17%). The validated method was used to determine the time dependent plasma concentration of MTIC in rats and dogs following a single oral dose of temozolomide. The standard curve and the quality control data indicate that the method performed acceptably throughout the sample analysis period.