Comparative Pharmacology
Head-to-head clinical analysis: AFIRMELLE versus LOESTRIN FE 1 20.
Peer-Reviewed Evidence
Head-to-head clinical analysis: AFIRMELLE versus LOESTRIN FE 1 20.
AFIRMELLE vs LOESTRIN FE 1/20
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.
Combination oral contraceptive consisting of ethinyl estradiol and norethindrone acetate. Inhibits gonadotropin secretion (FSH, LH) via negative feedback on the hypothalamic-pituitary-ovarian axis, suppressing ovulation. Increases cervical mucus viscosity and alters endometrial structure, impeding sperm penetration and 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 (norethindrone acetate 1 mg and ethinyl estradiol 20 mcg) orally once daily for 21 consecutive days, followed by one ferrous fumarate tablet (75 mg) orally once daily for 7 days.
None Documented
None Documented
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Norethindrone: 6-9 hours (terminal). Ethinyl estradiol: 13-27 hours (terminal, mean 16 hours). Steady-state reached within 5-7 days.
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Norethindrone: 50-60% renal (as metabolites), 20-30% fecal. Ethinyl estradiol: 40-50% renal (as glucuronide conjugates), 30-40% fecal (as sulfate conjugates).
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive