Comparative Pharmacology
Head-to-head clinical analysis: NORPLANT versus NORPLANT SYSTEM IN PLASTIC CONTAINER.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORPLANT versus NORPLANT SYSTEM IN PLASTIC CONTAINER.
NORPLANT vs NORPLANT SYSTEM IN PLASTIC CONTAINER
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Progestin (levonorgestrel) suppresses gonadotropin secretion, inhibiting ovulation, thickening cervical mucus, and altering endometrial lining to prevent implantation.
Levonorgestrel is a synthetic progestogen that inhibits ovulation, thickens cervical mucus to impede sperm penetration, and alters endometrial receptivity to implantation.
6 subdermal capsules (36 mg levonorgestrel total) implanted subdermally in the inner aspect of the upper arm, effective for up to 5 years.
Subdermal implantation of 6 capsules (each containing 36 mg levonorgestrel) in the upper arm, providing contraception for up to 5 years.
None Documented
None Documented
Terminal elimination half-life: approximately 24.4 hours (range 16-30 hours) for levonorgestrel. After removal of implants, levonorgestrel levels decline with a half-life of 18-20 hours, but contraceptive effect persists for 1-2 cycles due to tissue reservoir.
Terminal elimination half-life: 16-18 hours after single dose; during steady-state (implant), effective half-life is extended to 2-3 weeks due to continued release from the implant.
Renal: 40-50% (as metabolites), Fecal: 40-50% (as metabolites). Biliary excretion contributes to fecal elimination. Less than 1% excreted unchanged.
Renal (40-60% as metabolites), Fecal (25-35% as metabolites), Biliary (minor). Levonorgestrel is extensively metabolized; <5% excreted unchanged.
Category C
Category C
Contraceptive Implant
Contraceptive Implant