Levonorgestrel Zentiva (Levonorgestrel)

Levonorgestrel acts on the hormonal regulation pathway to provide contraceptive and menstrual benefits across several clinical scenarios, including emergency and routine use.

• Emergency contraception: prevents pregnancy when taken within a defined time after unprotected sexual intercourse.
• Progestin‑only hormonal contraception: provides daily suppression of ovulation for ongoing birth control in women of reproductive age.
• Management of menstrual disorders: reduces heavy menstrual bleeding and helps regulate cycle length in affected individuals.
• Progestin‑only birth control: offers a convenient daily oral option for women seeking a hormone‑only contraceptive method.

• Levonorgestrel is a synthetic progestogen that binds to progesterone receptors in the hypothalamus and pituitary, inhibiting the luteinizing hormone surge and thereby suppressing ovulation. It also induces cervical mucus changes that impede sperm penetration and alters the endometrial lining, making it less suitable for implantation. These combined actions create a hormonal environment that prevents fertilization and implantation. The effect is dose‑dependent and reversible upon discontinuation.

Levonorgestrel may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Nausea: mild stomach upset that may occur within hours of taking the tablet.
• Headache: transient tension‑type headaches that usually resolve without treatment.
• Breast tenderness: temporary discomfort or swelling of the breasts during the cycle.
• Irregular bleeding: spotting or changes in menstrual flow, including lighter or heavier periods.

Serious or Rare Side Effects

• Thromboembolic events: formation of blood clots in veins or arteries, potentially life‑threatening.
• Severe allergic reaction: rash, swelling, or difficulty breathing that requires immediate medical attention.
• Hepatic dysfunction: abnormal liver enzyme elevations indicating possible liver stress.
• Ectopic pregnancy: implantation of a fertilized egg outside the uterus if pregnancy occurs despite use.

When prescribing Levonorgestrel, clinicians should consider several precautionary measures to ensure safe use.

• Contraindications: avoid in women with known hypersensitivity to levonorgestrel or other progestins.
• Cardiovascular risk: assess for history of thromboembolic disease before use.
• Liver function: monitor in patients with existing hepatic impairment.
• Pregnancy status: confirm non‑pregnant status prior to emergency dosing.
• Drug interactions: review concomitant medications that may reduce efficacy.
• Store at ambient temperature: keep tablets below 25°C in the original packaging, protected from moisture and light.

Levonorgestrel can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Enzyme inducers: rifampicin, carbamazepine, phenytoin may markedly reduce contraceptive efficacy.
• Antifungal agents: griseofulvin can lower hormone levels, compromising protection.

Moderate Interactions (Monitor Closely)

• Antiretrovirals: efavirenz may decrease effectiveness; monitor and consider backup contraception.
• Anticonvulsants: topiramate at high doses may reduce efficacy.
• St. John’s wort: herbal supplement that can diminish hormone levels.
• Hormonal therapies: combined estrogen‑containing products may increase risk of thrombotic events.