Comparative Pharmacology
Head-to-head clinical analysis: AFIRMELLE versus NORINYL 1 50 21 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: AFIRMELLE versus NORINYL 1 50 21 DAY.
AFIRMELLE vs NORINYL 1+50 21-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial receptivity.
Norinyl 1+50 21-Day contains norethindrone (a progestin) and mestranol (an estrogen). Mestranol is converted to ethinyl estradiol, which provides negative feedback on gonadotropin release, inhibiting ovulation. Norethindrone suppresses gonadotropins and alters cervical mucus and endometrial lining to prevent implantation.
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
One tablet (1 mg norethindrone + 0.05 mg mestranol) orally once daily for 21 days, followed by 7 placebo tablets. Start on day 1 of menstrual cycle or first Sunday after onset.
None Documented
None Documented
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Norethindrone: 5-8 hours; Ethinyl estradiol: 7-15 hours; steady-state reached within 5-7 days
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Renal (40% as metabolites), fecal (50% as metabolites), <1% unchanged
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive