Pharmacokinetics of levonorgestrel in Indian women.

A low dose combination pill containing levonorgestrel 150 micrograms and ethynylestradiol 50 micrograms was administered orally to 13 women. Based on their anthropometric index they were classed as well-nourished (Group A) or undernourished (Group B). Plasma levels of levonorgestrel at various intervals after dosing were analysed by a specific radioimmunoassay and its pharmacokinetic parameters were computed. Peak plasma levels in both groups occurred within 2 h and the absorption half-lives were also similar. The decline in plasma levonorgestrel showed a tri-exponential decline in all Group A women, whereas it was biphasic in most of Group B. The pi t1/2 was lower in Group A women and the alpha-phase was found to be negligible in Group B. A significant positive correlation between elimination half-life (beta t1/2) and some of the anthropometric indices suggests a possible role of nutritional status in the metabolic handling of levonorgestrel.