title: Bioavailability of norethindrone and menstrual pattern after insertion of norethindrone acetate implants in rhesus monkeys.
abstract: Subdermal silastic implants releasing norethindrone acetate were inserted in five rhesus monkeys for a period of seven months. The serum norethindrone (NET) levels were estimated from blood samples collected fortnightly. There was an initial high level of NET followed by fluctuating levels of NET in 4 out of five monkeys. The serum NET values showed individual variation between time periods as well as between monkeys. The analysis of menstrual cycles showed initial amenorrhoea up to day 120-140 in four out of five monkeys. Only one monkey showed vaginal bleeding pattern comparable to normal menstrual cycles; this monkey had serum NET levels less than 10 ng/ml. The pharmacokinetic and pharmacodynamic parameters were similar to those reported in the human female.
authors.affiliation: Department of Reproductive Biology, All India Institute of Medical Sciences, New Delhi.
authors.forename: P
authors.initials: P
authors.lastname: Jha
authors.forename: K
authors.initials: K
authors.lastname: Murugesan
authors.forename: A
authors.initials: A
authors.lastname: Farooq
mesh_terms: D000568:Amenorrhea / Q000139:chemically induced; D000818:Animals; D001682:Biological Availability; D004343:Drug Implants; D005260:Female; D008253:Macaca mulatta; D008598:Menstruation / Q000187:drug effects*; D009640:Norethindrone / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics*; D000077563:Norethindrone Acetate; D011863:Radioimmunoassay
chemical_list: D004343:Drug Implants; D000077563:Norethindrone Acetate; D009640:Norethindrone