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标题：Metabolic Formation of Dimethylamine and Methylamine from Basic Drugs Containing N-Methyl Group : A Newly Established Chromatographic Assay and Its Application to the Determination of Deaminase Activity
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作者：Hideyuki YAMADA ; Takeshi SHIMIZUDANI ; Megumu HATSUMURA 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：1993
卷号：16
期号：9
页码：847-851
DOI：10.1248/bpb.16.847
出版社：The Pharmaceutical Society of Japan
摘要：A new method of assaying deaminase activity was established in which methylamine and/or dimethylamine formed from drugs containing N, N-dimethyl or N-methyl group were derivatized with phenylisothiocyanate to phenylthiourea derivatives. After purification with Sep-PAK C₁₈ cartridge, the derivatives were separated by a reversed phase high-performance liquid chromatography monitored by ultraviolet absorption. The recoveries and determination limits of methylamine and dimethylamine were over 55% and about 0.4 nmol/ml of incubation mixture, respectively. The method was used to measure the deaminase activities of liver microsomes of rats, rabbits and guinea pigs for 11 drugs. Of the compounds tested, diphenhydramine and diltiazem are deaminated with microsomes from all the above animal species; rat and rabbit liver microsomes also well deaminated promethazine. Most other drugs such as chlorpromazine, promazine, imipramine, amitriptyline and tetracaine were found to be poor substrates. In general, dimethylamine but not methylamine was the predominant metabolite formed from drugs containing N, N-dimethylamino group. The results also suggested that the deamination of these compounds takes place mainly via a one step mechanism, thus implying that the sequential reaction consisting of N-demethylation and elimination of ammonia is of minor importance. The relation between in vitro deaminase activity and the extent of the in vivo deamination for drugs is discussed.
关键词：deaminase activity;alkylamine;methylamine;dimethylamine;phenylisothiocyanate;cytochrome P450