Pharmacokinetics of Nitroimidazoles

Abstract

In this paper I want to try and show how a knowledge of the metabolism and pharmacokinetics of a compound helps us to understand the reasons why it may or may not satisfy the criteria desired of a particular drug. How we want a drug to behave depends on the use we have in mind for it. For example, in Fig. 1, are shown the plasma profiles for two nitroimidazole drugs which are used for the treatment of Trichomonas vaginalis. In this indication it is important to maintain plasma levels above the minimum inhibitory concentration (MIC) for as long a time as possible. It can be seen from the Figure that this level will be maintained longer when the compound with the longer elimination half-life, the time taken for the plasma concentration to drop to half its value, is administered. There is also the advantage that the peak levels are approximately equal for both compounds so the therapeutic ratio for ornidazole should be better than for metronidazole.