Pharmacokinetics of norethindrone in Indian Women
Prasad, K.V.; Rao, B.S.; Sivakumar, B.; Prema, K.
Contraception 20(1): 77-90
1979
ISSN/ISBN: 0010-7824 PMID: 477319 DOI: 10.1016/0010-7824(79)90047-7Document Number: 442076
A correlation between nutritional levels and norethindrone pharmacokinetics was evaluated in 11 women of low socioeconomic status (SES) and 5 women of high SES. An oral dose of .35 mg of norethindrone was administered on an empty stomach in mini-pill form. Radioimmunoassay was used to measure plasma norethindrone from blood samples collected at different intervals over 24 hours. Peak norethindrone levels occurred in all women within 1-2 hours, and a semilog plot of plasma norethindrone concentration showed a biexponential decline. Peak values ranged from 7.7-12.3 ng/ml and 4.7-l4.8 ng/ml in high SES and low SES, respectively. Plasma levels of norethindrone at 12 hours were very low in low SES and could not be detected in 8 women at 25 hours. In contrast was the finding that all 5 high SES subjects had more than detectable levels of drug throughout the experimental period. Anthropometric indexes showed the low SES group with poor nutritional status had shorter half-life clearances than the relatively well-nourished high SES group. There was also a significant correlation between weight/(height) sq. times 100 index on the one hand and the time l/2-beta on the other in all women studied, thereby suggesting a role for nutritional status in the metabolic handling of norethindrone.