[Intra-individual comparison of the long term effect of Non-Ovlon on caffeine pharmacokinetics]

The effect of the oral contraceptive, Non-Ovlon, on the pharmacokinetics of the model substance, caffeine, was studied in an intraindividual comparison in the course of seven months, i.e. four and two weeks before as well as 0.5, one, three and six months after the women had begun to take the contraceptive. The study commenced in twelve women of which, after seven months, only five were involved. The measuring compartment chosen was saliva so as to minimize strain on the volunteers by this noninvasive approach. Non-Ovlon delayed the caffeine elimination of 4.0 +/- 1.7 hr to 9.0 +/- 4.5 hr and 11.0 +/- 10.4 hr at the end of the first and third intake cycle, respectively. Markedly successive decreases in clearance and an increase in AUC levels were seen in addition to longer half-lives. Interindividual variations were considerable, a finding that might be relevant to the therapy by other, similarly interacting, drugs. There were no differences observed between the initial phase and the median phase of normal menstrual cycle. In one smoker, the caffeine elimination was highly accelerated compared to the average, throughout the period of investigation.