Comparative Pharmacology
Head-to-head clinical analysis: DEMULEN 1 35 21 versus LYBREL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DEMULEN 1 35 21 versus LYBREL.
DEMULEN 1/35-21 vs LYBREL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol (estrogen) and ethynodiol diacetate (progestin). Inhibits gonadotropin secretion (FSH, LH) via negative feedback on hypothalamic-pituitary axis, suppressing ovulation. Additionally, thickens cervical mucus and alters endometrial receptivity.
Combination of levonorgestrel and ethinyl estradiol: suppression of gonadotropins (FSH and LH) via negative feedback, inhibiting ovulation; thickening of cervical mucus to impede sperm penetration; alteration of endometrium to reduce implantation likelihood.
One tablet orally once daily for 21 days, followed by 7 days off. Each tablet contains 1 mg ethynodiol diacetate and 35 mcg ethinyl estradiol.
One tablet (levonorgestrel 0.1 mg/ethinyl estradiol 0.02 mg) orally once daily for 21 days, followed by 7 placebo tablets for 28-day cycle.
None Documented
None Documented
Ethinyl estradiol: 13±3 hours (terminal); norethindrone: 8±3 hours. Steady-state achieved after ~5 days.
Terminal elimination half-life: 27 ± 8 hours; requires ~5 days to reach steady-state; clinical significance: missed doses lead to rapid loss of contraceptive efficacy.
Renal (primarily as glucuronide and sulfate conjugates): ~60%; fecal: ~40%
Renal: 50-60% as metabolites, ~20% as parent drug; fecal: 30-40%; biliary: 10-20%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive