Influence of gender on the pharmacokinetics and pharmacodynamics of drugs.

Historically, women, the elderly, and minorities were underrepresented in clinical drug trials. Information on possible gender-related differences in the pharmacokinetics of drugs is often lacking, although for some drugs significant differences could be demonstrated. In women, absorption, protein binding, volume of distribution, and metabolism of drugs may differ due to hormonal influences on physiological functions. Sex-related differences could be shown for phase I (cytochrome P450) as well as phase II (especially glucuronidation) reactions. Since many women world-wide take oral contraceptives, data should be provided to determine to what extent other drugs are influenced by estrogens and progestogens or to what extent the other drugs may attenuate the contraceptive efficacy. Moreover, estrogens interact with various enzymes and receptors, e.g. at the endothelial function as well as dopaminergic receptor sites, and may therefore attenuate or enhance drug effects or even drug side-effects. For a number of drugs it is well recognized, that women suffer more frequently from side-effects, however, it is often not clear, if this is due to gender differences in the pharmacokinetics or pharmacodynamics of the responsible drug. Very little is known about these gender-related differences and the possibility that women may show a different pattern of treatment response than men. As a result, drug approval authorities now require more data on the pharmacokinetics of novel drugs in women as well as a sufficient accrual of women in efficacy and outcome trials.