As a contraceptive, Levonorgestrel causes changes in the endometrium that prevent implantation of a fertilized egg. It inhibits the process of ovulation, increases the viscosity of the cervical mucus, preventing the promotion of sperm.
After ingestion, it is absorbed quickly and completely (bioavailability is 100%). The maximum plasma concentration is reached in 1-1.5 hours. It binds to plasma proteins by 97.5%. It is metabolized in the liver. The excreting half-life makes 24,4 hours. It is excreted by kidneys.
Levonorgestrel is used as an emergency contraceptive. It may be prescribed as a part of combination hormone replacement therapy.
- Breast tumors;
- Liver disease;
- Intracranial hypertension (including in the anamnesis);
- Thrombophlebitis and thromboembolism in the anamnesis;
- Undiagnosed bleeding from the genitals and urinary tract;
- Coronary heart disease;
- Individual intolerance.
Pregnancy and lactation
This drug is related to Category X in the FDA. The drug intake is contraindicated during pregnancy and lactation.
Dosage and administration
Prescribed for oral administration. The regimen: 0.75 mg for 72 hours after unprotected intercourse. Repeated administration is made after 12 hours. The drug may be taken in the dosage of 1.5 mg once within 72 hours after intercourse.
- The highest daily dose: 1.5 mg.
- The highest single dose: 1.5 mg.
- Central and peripheral nervous system: intracranial hypertension, bulbospinal paralysis, headache, emotional lability, fatigue.
- Cardiovascular system: thrombophilia.
- Digestive system: nausea, vomiting, flatulence.
- Reproductive system: metrorrhagia, amenorrhea, the formation of ovarian cysts, fibrocystic mastopathy.
- Sense organs: intolerance to contact lenses.
- Dermatological manifestations: pruritus, alopecia.
- Allergic reactions.
Strengthening of side effects, vaginal bleeding. Symptomatic treatment is conducted.
- The contraceptive effect is reduced with the use of cytochrome P450 with inducers. Preparations: amprenavir, nevirapine, lansoprazole, oxcarbazepine, topiramate, tacrolimus, barbiturates (including primidone), phenytoin, carbamazepine, tacrolimus, rifampicin
- Concurrent use with cyclosporine.
- Levonorgestrel influences the effectiveness of anticoagulants and hypoglycemic drugs.
It is not recommended to be used several times during one menstrual cycle. In patients with overweight, the contraceptive effect of the drug is reduced.