Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NATAZIA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NATAZIA.
CYCLAFEM 1/35 vs NATAZIA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol and norethindrone. Suppresses gonadotropin (FSH, LH) secretion via estrogen and progestin negative feedback, inhibiting ovulation. Progestin alters cervical mucus (sperm penetration) and endometrial receptivity.
Estetrol is a selective estrogen receptor modulator (SERM) with mixed agonist/antagonist activity; drospirenone is a spironolactone analog with antimineralocorticoid and antiandrogenic activity. Combined oral contraceptive inhibits ovulation and alters cervical mucus.
One tablet orally once daily. Each tablet contains 1 mg norethindrone and 0.035 mg ethinyl estradiol. Administer daily for 21 days followed by 7 days of placebo or no tablet.
Drospirenone 3 mg / ethinyl estradiol 0.03 mg orally once daily for 21 days followed by 7 days of placebo.
None Documented
None Documented
Half-life of norethindrone is 5-14 hours; ethinyl estradiol is 10-20 hours. Steady state reached after 5-7 days.
Terminal half-life approximately 30 hours for drospirenone and 24 hours for ethinyl estradiol; steady-state achieved within 8–10 days.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Fecal excretion is the primary route (approximately 68%), with renal excretion accounting for about 27% (mostly as metabolites).
Category C
Category C
Oral Contraceptive
Oral Contraceptive