Levonorgestrel Cristers (Levonorgestrel)

Levonorgestrel acts on the reproductive hormonal pathway to prevent unwanted pregnancy.

• Emergency contraception: prevents pregnancy after unprotected intercourse when taken within the recommended time window.
• Regular contraception: used as a progestogen‑only method to prevent pregnancy in women of reproductive age.
• Cycle management: may be employed to delay or regulate menstrual bleeding in specific clinical situations.

• Levonorgestrel binds to progesterone receptors in the hypothalamus and pituitary, suppressing the luteinizing hormone surge and thereby preventing ovulation. It also thickens cervical mucus to impede sperm penetration and induces endometrial changes that reduce the likelihood of implantation.

Levonorgestrel may cause a range of adverse reactions.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Headache: transient tension‑type headaches.
• Breast tenderness: mild discomfort in the breast tissue.
• Menstrual changes: spotting, irregular bleeding, or delayed periods.
• Abdominal pain: cramping or lower‑abdomen discomfort.
• Fatigue: feeling unusually tired.

Serious or Rare Side Effects

• Thromboembolic events: deep‑vein thrombosis or pulmonary embolism.
• Severe allergic reaction: anaphylaxis with rash, swelling, or breathing difficulty.
• Hepatic dysfunction: jaundice or abnormal liver enzymes.
• Ectopic pregnancy: implantation outside the uterus if pregnancy occurs.
• Persistent high blood pressure: sudden increase in blood pressure readings.

Before using Levonorgestrel Cristers, consider the following precautions.

• Assess contraindications: ensure the patient has no known hypersensitivity to levonorgestrel.
• Review medical history: avoid use in individuals with active thromboembolic disease or severe liver impairment.
• Evaluate drug interactions: consider concurrent enzyme‑inducing medications that may reduce efficacy.
• Pregnancy testing: not indicated for women who are already pregnant.
• Breastfeeding discussion: weigh potential risks and benefits with a healthcare professional.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture and light.

Levonorgestrel may interact with several medicines, requiring attention to avoid reduced effectiveness or increased toxicity.

Major Interactions (Avoid)

• Rifampicin: induces metabolism and may lower levonorgestrel levels.
• Anticonvulsants (e.g., phenytoin, carbamazepine): reduce hormonal efficacy.
• St. John's Wort: may decrease plasma concentrations.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (e.g., ketoconazole): can increase levonorgestrel exposure.
• Protease inhibitor antiretrovirals: may alter drug metabolism.
• Phytoestrogen‑containing herbal supplements: potential impact on contraceptive effectiveness.