Postinor, tablets 0,75 mg 2 pcs

Pharmacotherapeutic group: Medication for emergency contraception.
ATX code: G03AD01

Pharmacodynamics
Levonorgestrel is a synthetic progestagen with contraceptive action. It is used as an emergency contraceptive due to its pronounced gestagenic and anti-estrogenic effects. The main mechanism of action is inhibition and/or delay of ovulation as a result of suppression of peak luteinizing hormone. With the recommended dosing regimen, levonorgestrel suppresses ovulation and fertilization if sexual intercourse occurs in the pre-ovulatory phase, when the possibility of fertilization is greatest. Levonorgestrel is not effective if implantation of a fertilized egg has already occurred.

Efficacy: According to a previous clinical study, two doses of levonorgestrel 0.75 mg at 12-hour intervals prevented pregnancy in 85% of cases. Its efficacy decreases with time after sexual intercourse (95% if taken within 24 hours, 85% between 24 and 48 hours, and 58% between 48 and 72 hours).
The results of another clinical study showed that 2 0.75 mg tablets of levonorgestrel taken simultaneously (within 72 hours of unprotected intercourse) prevented pregnancy in 84% of cases.
There is limited data, requiring further confirmation, on the effect of excess body weight/high body mass index (BMI) on contraceptive efficacy. Two clinical trials (CIs) have shown decreased efficacy of levonorgestrel and increased pregnancy rates in women with BMI ≥30 kg/m2 compared with women with normal BMI (5.19% and 0.96%, respectively). However, no decrease in the contraceptive efficacy of levonorgestrel was demonstrated in other trials (pregnancy rates were 1.17% in women with
obesity and 0.99% in women with normal BMI).
With the recommended dosing regimen, levonorgestrel has no significant effect on clotting factors, lipid, and carbohydrate metabolism.
Adolescent girls under 18 years of age
In a prospective observational study, it was shown that of 305 cases of levonorgestrel as an emergency contraceptive, seven cases resulted in pregnancy. Thus, the overall failure rate was 2.3%.
The failure rate in adolescent girls younger than 18 years (2.6% or 4/153) was comparable to the failure rate in women 18 years and older (2.0% or 3/152).

Pharmacokinetics

Assimilation
Levonorgestrel is rapidly and almost completely absorbed when taken orally. After taking levonorgestrel at a dose of 1.5 mg, the maximum plasma concentration (Cmax) is 18.5 ng/ml and is reached after 2 hours. After reaching the maximum values, the concentration of levonorgestrel decreases. Absolute bioavailability is 100%.

Distribution
Levonorgestrel binds to plasma albumin and sex hormone-binding globulin (hGBS). Only 1.5% of the total dose is in free form; 65% is bound to hGH. Levonorgestrel penetrates into breast milk.

Metabolism
Metabolism of levonorgestrel corresponds to that of sex hormones. Levonorgestrel is hydroxylated in the liver and metabolites are excreted as conjugated glucuronides. Pharmacologically active metabolites of levonorgestrel are unknown.

Elimation
Excreted exclusively as metabolites, approximately equally by the kidneys and through the intestine. The elimination half-life (T1/2) is about 26 hours.

Pharmacokinetics in special groups of patients
In adolescent girls under 18 years

Studies of levonorgestrel pharmacokinetics were performed only in adult volunteers.

Patients with renal or hepatic impairment
Pharmacokinetics of levonorgestrel has not been studied in patients with hepatic or renal impairment.

Patients with obesity
A pharmacokinetics study showed that levonorgestrel concentrations were significantly reduced in obese women (BMI ≥30 kg/m²) (approximately 50% reduction in Cmax and AUC0-24 was observed) compared with those in women with normal BMI (< 25 kg/m²).
Another study also reported a reduction in levonorgestrel Cmax of approximately 50% in obese women compared with normal BMI women, while plasma concentrations of levonorgestrel after a 3 mg dose in obese women were comparable to plasma concentrations of levonorgestrel in women with normal BMI after a 1.5 mg dose. The clinical significance of these data is unclear.

Indications

Emergency (post-coital) contraception (after unprotected intercourse or unreliability of the contraceptive method used).

Active ingredient

Composition

How to take, the dosage

Ingestion.

The drug can be used at any time of the menstrual cycle. In case of irregular menstrual cycle it is necessary to exclude pregnancy in advance.

To obtain a stronger contraceptive effect, 2 pills of Postinor® should be taken as soon as possible, preferably within the first 12 hours (but not later than 72 hours after unprotected intercourse). If vomiting occurs within 3 hours after taking the pills, two more Postinor® pills should be taken.

After taking Postinor®, non-hormonal contraceptive methods (condom, spermicide + cervical cap, diaphragm or contraceptive sponge) should be used until the next menstruation. The use of levonorgestrel is not a contraindication for continuation of planned hormonal contraception. The use of the drug for repeated unprotected intercourse within the same menstrual cycle is not recommended because of the increased risk of acyclic bleeding/bloody discharge.

The use of the drug in special clinical groups/i>

Children and adolescents under 16 years

The use of Postinor® is contraindicated before the age of 16 years (due to limited data on the safety and effectiveness of levonorgestrel in this age group).

Patients with renal impairment

There are no data on the use of levonorgestrel in patients with renal impairment.

Patients with hepatic impairment

There are no data on the use of levonorgestrel in patients with hepatic impairment. Its use in patients with severe hepatic impairment is contraindicated.

Interaction

Special Instructions

Synopsis

Contraindications

Side effects

Overdose

Pregnancy use

Similarities