Levonorgestrel is a preparation used for emergency contraception. It is also a synthetic progestogen, actively used as an active component of hormonal contraceptives.
Indications for use
Mechanism of action
This preparation causes structural changes in the endometrium and suppresses ovulation, as a result of which a fertilized egg cannot be implanted normally. Also, the hormone affects the viscosity of the cervical mucus slowing the progress of the spermatozoa.
A single intake of 0.75 mg of the drug ensures the maximum concentration of the substance in the blood after 1-2 hours. The synthetic hormone has a high degree of binding to plasma proteins – about 55% (albumin and globulin).
The metabolism of the drug occurs in the liver tissues, resulting in the formation of pharmacologically inactive metabolites. The half-life is approximately 1 day. The medicine is withdrawn in the form of inactive metabolites with urine and insignificantly – with fecal masses.
Mode of application and dosage
Oral administration. Synthetic hormone is taken in the form of tablets for 96 hours after unprotected sexual intercourse. The average Levonorgestrel dose ranges from 0.75 to 1.5 mg of the drug. The substance should be used at once. It is not recommended to take pills for emergency contraception more than once every 4-6 months.
The drug is contraindicated:
- individual intolerance;
- pregnant women or suggested pregnancy;
- patients with severe liver or bile passages’ diseases;
- adolescent age;
- breastfeeding period.
Other side effects include:
- recurrent or acute inflammatory diseases of the pelvic organs;
- endometritis after childbirth;
- infection of the genitourinary tract;
- septic abortion carried out during the last 3 months;
- dysplasia or malignant tumors of the cervical or uterine cavity;
- tumors that depend on progestogen including breast cancer;
- uterine bleeding of unknown etiology;
- uterus’ abnormalities, acquired or congenital;
- liver tumor or other severe hepatic disorders.
During the clinical trials, the following side effects after Levonorgestrel application were identified:
- pain in the lower abdomen;
- menstrual bleeding of a different character;
- malfunctions in the menstrual cycle;
- swelling and tenderness in the mammary glands;
Other side effects may be comprised of:
- irritability, bad mood;
- emotional lability;
- rashes on the skin;
- eczema and itching;
- vaginal spotting;
- benign neoplasms of the ovaries (cysts);
- weight gain;
- decreased sexual desire;
Levonorgestrel, when combined with rifampicin, primidone, phenytoin and barbiturates, has a less contraceptive effect due to the acceleration of the steroid processes in the organism.
A combined use of ampicillin, chloramphenicol, phenoxymethylpenicillin, Sulfamethoxypyridazine, nitrofurantoin, neomycin may increase breakthrough bleeding. It happens because of the inhibition of enterohepatic circulation of sex steroids due to changes in the intestinal flora.
This birth control drug reduces the effectiveness of anticoagulants, anticonvulsant, hypoglycemic and antihypertensive agents intended for an oral administration.
Levonorgestrel and pregnancy
The drug is contraindicated in pregnant women. The substance may penetrate in large quantities into breast milk, so it is recommended to arrest breastfeeding.