Comparative Pharmacology
Head-to-head clinical analysis: ENOVID E versus TRI NORINYL 21 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ENOVID E versus TRI NORINYL 21 DAY.
ENOVID-E vs TRI-NORINYL 21-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination estrogen-progestin contraceptive. Suppresses gonadotropin release, inhibits ovulation, increases cervical mucus viscosity, and alters endometrial morphology.
Combination oral contraceptive containing ethinyl estradiol and norethindrone. Ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects, increases viscosity of cervical mucus, alters endometrial morphology, and inhibits ovulation.
5 mg orally once daily for 20 days starting on day 5 of menstrual cycle
One tablet (35 mcg ethinyl estradiol, 0.5 mg norethindrone for 7 days, 1 mg norethindrone for 9 days, 0.5 mg norethindrone for 5 days) orally once daily for 21 days, then 7 days off. Start on first day of menstrual period or first Sunday after onset.
None Documented
None Documented
Norethynodrel: 5-10 hours; mestranol: 2-5 hours (metabolized to ethinyl estradiol, half-life 10-20 hours). Steady-state reached in 5-7 days.
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-23 hours. Steady-state reached within 5-7 days; clinical relevance for missed dose timing and resumption of ovulation.
Renal (50-60% as metabolites, <1% unchanged); fecal (40-50%)
Renal: ~50-60% (as metabolites); Fecal: ~30-40% (via bile); unchanged drug <1%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive