Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 0 5 35 versus PHILITH.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 0 5 35 versus PHILITH.
CYCLAFEM 0.5/35 vs PHILITH
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing norethindrone (progestin) and ethinyl estradiol (estrogen). Inhibits gonadotropin release, suppressing ovulation. Increases cervical mucus viscosity and alters endometrium, reducing sperm penetration and implantation.
PHILITH is a combined oral contraceptive containing ethinyl estradiol and drospirenone. Ethinyl estradiol suppresses gonadotropin release, while drospirenone is a progestin with antiandrogenic and antimineralocorticoid activity, inhibiting ovulation and altering cervical mucus.
One tablet (0.5 mg norethindrone/35 mcg ethinyl estradiol) orally once daily for 21 days, followed by 7 placebo days (or no tablets) per cycle.
1 mg orally once daily
None Documented
None Documented
Terminal elimination half-life of norethindrone is 5-14 hours (mean 7.6 hours); ethinyl estradiol half-life is 7-20 hours (mean ~13 hours). Steady-state is achieved within 5-7 days.
Terminal half-life 12 hours; clinically relevant for twice-daily dosing with steady state reached after 2-3 days.
Renal excretion accounts for approximately 50-60% of the dose (as metabolites), with 30-40% excreted in feces via biliary elimination. Unchanged drug is minimal in urine.
Renal: 90% unchanged; biliary/fecal: 10% as metabolites.
Category C
Category C
Oral Contraceptive
Oral Contraceptive