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The majority of women use hormonal preparations in the course of their lives, mainly for contraception. In the past, new drugs were tested in men only, due to the potential risks of foetal harm should a woman become pregnant. Yet nowadays it has become widely acceptable to develop preparations in young, healthy women, according to a guideline from the Food and Drug Administration (FDA, 1993). So with no restriction on the participation of women with childbearing potential in all phases of drug trials, we now see gender analysis which pays special attention to factors affecting pharmacokinetics, such as the role of the menstrual cycle and exogenous hormone therapy in relation to the drug, as well as the influence of the drug on oral contraceptives.
Consequently, clinical trials for contraceptives are carried out for two completely different purposes. First, in the development of contraceptive preparations for oral, transdermal, vaginal or subcutaneous application, clinical trials are performed to evaluate their efficacy (ovulation inhibition study, Pearl-Index study). Secondly, interaction studies are performed on women using contraceptives. In these cases the investigational drugs to be used for various indications are metabolised by the same hepatic enzymes as the contraceptives (and multiple other drugs). These trials aim at evaluating the mutual influence on hepatic metabolism, and a study in young, healthy women is quite suitable for this purpose.
Pro-fertility drugs are applied in the treatment of subfertile couples. Clinical trials on the efficacy of pro-fertility drugs are usually performed in the sub-fertile patient population, but in early phases of clinical development, pharmacokinetic and pharmacodynamic effects may be studied in female volunteers of reproductive age. In recent years there has been increasing attention to the development of drugs stimulating one or more aspects of sexual functioning. The effect of these drugs is generally studied in healthy pre- or postmenopausal women with or without sexual functioning disorders.
In these settings there are different aspects to be considered when designing and conducting clinical trials on female sex hormones. |
