Comparative Pharmacology
Head-to-head clinical analysis: MICROGESTIN FE 1 20 versus PIRMELLA 1 35.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MICROGESTIN FE 1 20 versus PIRMELLA 1 35.
MICROGESTIN FE 1/20 vs PIRMELLA 1/35
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol (estrogen) and norethindrone acetate (progestin). Suppresses gonadotropins via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; increases cervical mucus viscosity and alters endometrial lining.
Combination of norethindrone (progestin) and ethinyl estradiol (estrogen) that suppresses gonadotropin secretion via negative feedback on the hypothalamic-pituitary-ovarian axis, inhibiting ovulation. Additionally, causes cervical mucus thickening and endometrial atrophy, reducing sperm penetration and implantation.
One tablet orally once daily, containing norethindrone acetate 1 mg and ethinyl estradiol 20 mcg, taken at the same time each day for 21 days followed by 7 days of placebo (iron tablets) or continuous cycling per prescribing information.
One tablet orally once daily for 21 days, followed by 7 placebo tablets during the withdrawal bleed.
None Documented
None Documented
Norethindrone: 5-14 hours (mean 8 hours); Ethinyl estradiol: 12-24 hours (mean 18 hours); Steady-state in 5-7 days
Terminal half-life 24–30 hours for ethinyl estradiol; 13–18 hours for norethindrone. Steady state reached after 7–10 days.
Renal: ~50-60% as metabolites; Fecal: ~30-40% as metabolites; Biliary: minor; <1% unchanged
Renal 60–80% as metabolites (glucuronide conjugates), biliary/fecal 10–20%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive