Microval (Levonorgestrel)

Levonorgestrel acts as a hormonal contraceptive by modulating the progestogenic pathway to prevent pregnancy.

• Emergency contraception: prevents pregnancy when taken shortly after unprotected intercourse.
• Prevention of pregnancy: provides ongoing contraceptive protection when used as directed.
• Hormonal contraceptive therapy: part of progestin‑only regimens for birth control.

• Levonorgestrel binds to progesterone receptors in the hypothalamus and pituitary, suppressing the luteinizing hormone surge required for ovulation. It also thickens cervical mucus, reducing sperm penetration, and alters the endometrial lining to make it less receptive to implantation, thereby inhibiting fertilization and preventing implantation of a fertilized egg.

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

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Headache: transient cranial pain.
• Breast tenderness: discomfort or swelling of the breasts.
• Irregular bleeding: spotting or changes in menstrual flow.
• Fatigue: feeling unusually tired.
• Mood changes: irritability or emotional fluctuations.

Serious or Rare Side Effects

• Thromboembolic events: blood clots in veins or arteries.
• Severe allergic reaction: rash, swelling, or anaphylaxis.
• Liver dysfunction: jaundice or abnormal liver enzymes.
• Ectopic pregnancy: implantation outside the uterus if fertilization occurs.
• Persistent abdominal pain: may indicate a serious complication.

When prescribing levonorgestrel, clinicians should consider several safety precautions.

• Contraindication in pregnancy: avoid use if the patient is known to be pregnant.
• Liver disease caution: use with care in patients with severe hepatic impairment.
• Hypersensitivity: do not administer to individuals with known allergy to levonorgestrel or excipients.
• Thromboembolic risk: assess history of clotting disorders before use.
• Limit duration: follow recommended treatment length and avoid repeated emergency dosing.
• Store at room temperature: keep in original packaging, protect from moisture and heat.

Levonorgestrel can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Rifampin: induces metabolism, reducing contraceptive effectiveness.
• Anticonvulsants (phenytoin, carbamazepine, phenobarbital): increase hepatic clearance, lowering drug levels.
• St. John’s wort: herbal inducer that may diminish contraceptive protection.

Moderate Interactions (Monitor Closely)

• Antifungal agents (ketoconazole, itraconazole): may increase levonorgestrel concentrations.
• Certain antibiotics (rifabutin, griseofulvin): can modestly reduce efficacy.
• HIV protease inhibitors (ritonavir): may alter hormone levels.
• Hormonal therapies (combined oral contraceptives): assess additive hormonal effects.