Pharmacokinetics of orally administered norethisterone enanthate in rabbit, monkey, and women.
Norethisterone enanthate (NET-En), an established intramuscular long-acting contraceptive agent, has previously been shown to be effective in inhibiting fertility in two rodent species even 4 days after oral ingestion. Pharmacokinetics of NET and NET-En were studied after oral and intramuscular doses in two animal species and a few women. The results suggest that the NET-En was absorbed within a day in all the species after oral dose. The estimates of relative bioavailability ranged from 13 to 51% in rabbits, monkeys, and women. The elimination half-life was 5-10 days. The presence of the active component, NET, in the circulation over the experimental period of 15 days suggests that NET-En could be useful as a long-acting oral pill. The suppression of progesterone levels during the luteal phase of menstrual cycle in women also supports this finding.
Ravinder
P
P
National Institute of Nutrition, Indian Council of Medical Research, Hyderabad, India.
Shatrugna
V
V
Nair
K M
KM
Sivakumar
B
B
D000284:Administration, Oral; D000818:Animals; D003280:Contraceptives, Oral, Synthetic / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008253:Macaca mulatta; D009640:Norethindrone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D011817:Rabbits; D013997:Time Factors
D003280:Contraceptives, Oral, Synthetic; D003692:Delayed-Action Preparations; C024319:norethindrone enanthate; D009640:Norethindrone