Comparative Pharmacology
Head-to-head clinical analysis: PLAN B versus PREVEN EMERGENCY CONTRACEPTIVE KIT.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PLAN B versus PREVEN EMERGENCY CONTRACEPTIVE KIT.
PLAN B vs PREVEN EMERGENCY CONTRACEPTIVE KIT
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Levonorgestrel, a progestin, prevents pregnancy primarily by inhibiting ovulation and altering cervical mucus to impede sperm penetration. It may also inhibit implantation.
The levonorgestrel component is a progestin that inhibits ovulation and fertilization by altering the cervical mucus and endometrial lining, preventing implantation. The ethinyl estradiol component suppresses gonadotropin release, inhibits ovulation, and alters the endometrium.
One 1.5 mg tablet (levonorgestrel) orally as a single dose, taken as soon as possible within 72 hours of unprotected intercourse.
The kit contains levonorgestrel 0.75 mg tablets. The regimen is two tablets: one tablet taken orally as soon as possible within 72 hours of unprotected intercourse, followed by a second tablet taken orally 12 hours later.
None Documented
None Documented
Terminal elimination half-life: 24-30 hours. Clinical context: The prolonged half-life supports single-dose regimen for emergency contraception; may be affected by obesity (shorter half-life in obese women).
26 hours (range 17-35 hours; clinical: no significant accumulation with single dose).
Renal (approximately 50% as unchanged drug and metabolites); fecal (approximately 40% as metabolites); less than 1% biliary.
Primarily renal (50-60% as metabolites, <1% unchanged) and fecal (30-40% as metabolites).
Category C
Category C
Emergency Contraceptive
Emergency Contraceptive