Mercilon (Desogestrel, Ethinylestradiol)

Mercilon, a combined oral contraceptive, acts on the hormonal regulation of the menstrual cycle to provide reliable birth control.

• Prevention of pregnancy: offers effective contraception when taken daily as directed.
• Regulation of menstrual cycle: helps achieve more predictable bleeding patterns and reduces menstrual irregularities.
• Management of dysmenorrhea: may lessen menstrual pain associated with ovulatory cycles.

• Desogestrel is a progestogenic agent that binds to progesterone receptors, inhibiting the mid‑cycle surge of luteinising hormone and follicle‑stimulating hormone, thereby preventing ovulation. Ethinylestradiol provides estrogenic activity that stabilises the endometrium and enhances negative feedback on the hypothalamic‑pituitary axis. Together they also thicken cervical mucus, creating a barrier to sperm penetration and altering the endometrial lining to reduce the chance of implantation.

Oral contraceptives may cause a range of adverse reactions, which are generally classified by frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset, especially during the first cycles.
• Breast tenderness: temporary swelling or discomfort in the breasts.
• Headache: occasional tension‑type or migraine‑like headaches.
• Spotting or breakthrough bleeding: irregular light bleeding between periods.
• Mood changes: mild fluctuations in emotional state.
• Weight fluctuation: slight increase or decrease in body weight.

Serious or Rare Side Effects

• Venous thromboembolism: blood clots in deep veins, potentially leading to pulmonary embolism.
• Arterial thrombosis: clot formation affecting arteries, which can cause stroke or heart attack.
• Hypertension: significant rise in blood pressure requiring medical attention.
• Liver disorders: jaundice or hepatic dysfunction.
• Severe allergic reactions: rash, swelling, or anaphylaxis.
• Visual disturbances: sudden changes in vision or eye pain.

Before prescribing Mercilon, clinicians should evaluate patient history and consider specific safety measures.

• Contraindications: avoid in women with known thromboembolic disorders, estrogen‑dependent tumors, active liver disease, or confirmed pregnancy.
• Smoking: contraindicated for patients over 35 who smoke due to increased cardiovascular risk.
• Cardiovascular risk: assess history of hypertension, diabetes, or hyperlipidaemia before initiation.
• Drug interactions: review concomitant medications that may affect hormone levels or clotting risk.
• Monitoring: schedule regular blood pressure checks and evaluate for signs of thrombosis during treatment.
• Store at ambient temperature: keep tablets below 25 °C in the original packaging, protected from moisture and direct sunlight.

Mercilon can interact with other medicines, altering its effectiveness or increasing adverse event risk.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampicin, carbamazepine, phenytoin): may markedly reduce contraceptive efficacy.
• Anticoagulants (e.g., warfarin): combined use can increase the risk of thrombotic events.
• Certain antiretrovirals (e.g., protease inhibitors): may alter hormone metabolism leading to unpredictable protection.

Moderate Interactions (Monitor Closely)

• Selective serotonin reuptake inhibitors (SSRIs): may enhance mood‑related side effects.
• Antihypertensive agents: hormonal changes can affect blood pressure control, requiring dose adjustments.
• Herbal supplements containing St. John’s wort: may decrease contraceptive effectiveness.