Comparative Pharmacology
Head-to-head clinical analysis: IMPLANON versus SEASONALE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: IMPLANON versus SEASONALE.
IMPLANON vs SEASONALE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Etonogestrel, a progestin, binds to progesterone and androgen receptors, suppressing gonadotropin release (FSH, LH) and preventing ovulation. It also increases cervical mucus viscosity, impeding sperm penetration, and alters endometrial morphology.
Seasonale is a combination oral contraceptive containing ethinyl estradiol and levonorgestrel. It suppresses gonadotropin release, inhibiting ovulation, and alters cervical mucus to reduce sperm penetration and endometrial lining to reduce implantation.
Insert 1 rod (68 mg etonogestrel) subdermally in the inner upper arm; replacement every 3 years.
One tablet (0.03 mg ethinyl estradiol and 0.15 mg levonorgestrel) orally once daily for 84 consecutive days, followed by 7 days of placebo.
None Documented
None Documented
Terminal elimination half-life is approximately 25-30 hours; significant interindividual variability
Ethinyl estradiol: terminal half-life 13-27 hours (mean 17 hours); levonorgestrel: terminal half-life 11-45 hours (mean 25 hours). Clinical context: Supports once-daily dosing; steady-state achieved within 5-10 days.
Metabolites primarily excreted in urine (approximately 50%) and feces (30-35%)
Renal excretion of metabolites (approximately 50-60% as glucuronide and sulfate conjugates of ethinyl estradiol and levonorgestrel) and fecal elimination (approximately 40-50%).
Category C
Category C
Contraceptive
Contraceptive, Combination Hormonal