Za Pharmacy
Drugs, Supplies and Delivery
Gynera (Ethinylestradiol/Gestodene)
Gynera is a combined oral contraceptive (COC) pill containing ethinylestradiol (20 µg, a synthetic estrogen) and gestodene (75 µg, a third-generation synthetic progestin). Widely prescribed for contraception, it is recognized for its efficacy and tolerability. This article examines its pharmacology, clinical applications, and safety profile, referencing authoritative sources including the BNF, Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology.
Gynera prevents pregnancy through three primary mechanisms:
- Ovulation Suppression: Ethinylestradiol inhibits follicle-stimulating hormone (FSH), halting follicular maturation, while gestodene blocks the luteinizing hormone (LH) surge, preventing ovulation (Lippincott).
- Cervical Mucus Alteration: Gestodene thickens cervical mucus, creating a barrier to sperm entry.
- Endometrial Thinning: Progestin action reduces endometrial receptivity, impairing implantation (Lange).
Gestodene, a potent third-generation progestin, exhibits high affinity for progesterone receptors with minimal androgenic activity, reducing side effects like acne compared to older progestins.
- Contraception: Primary indication, with >99% efficacy when used correctly (BNF).
- Menstrual Cycle Regulation: Stabilizes cycles and reduces dysmenorrhea (painful periods) and menorrhagia (heavy bleeding) (Lippincott).
- Standard Regimen: One tablet (20 µg ethinylestradiol + 75 µg gestodene) daily for 21 days, followed by a 7-day hormone-free interval. Restart on day 8, regardless of bleeding (BNF).
- Initiation: Begin on day 1 of menstruation or the first Sunday thereafter. Use backup contraception (e.g., condoms) for the first 7 days.
- Missed Dose: If delayed <12 hours, take immediately. If >12 hours, follow BNF guidelines: Take missed pill ASAP, continue the pack, and use backup contraception for 7 days.
- Common: Nausea, headache, breast tenderness, breakthrough bleeding, mood changes.
- Serious:
- Venous Thromboembolism (VTE): Higher risk compared to second-generation progestins (e.g., levonorgestrel) (BNF).
- Cardiovascular Events: Increased risk in smokers >35 years or those with hypertension.
- Hepatic Effects: Rare hepatotoxicity, gallstones, or benign liver tumors (Lange).
- Absolute Contraindications: History of VTE, arterial thrombosis, estrogen-dependent cancers, severe liver disease, undiagnosed vaginal bleeding, or migraine with aura (BNF).
- Relative Precautions: Obesity, diabetes, hypertension, or familial hyperlipidemia.
- Monitoring: Regular blood pressure checks and screening for VTE risk factors (e.g., family history).
- Reduced Efficacy: Enzyme-inducing drugs (e.g., rifampicin, carbamazepine, St. John’s Wort) accelerate metabolism of ethinylestradiol, necessitating alternative contraception (BNF).
- Antibiotics: Limited evidence for interaction with broad-spectrum antibiotics (e.g., amoxicillin), but backup contraception is advised.
- Other Interactions: Avoid concurrent use with hepatotoxic drugs (e.g., acetaminophen overdose) or cyclosporine (gestodene may increase plasma levels) (Lippincott).
- Active Ingredients: Ethinylestradiol (20 µg) and gestodene (75 µg).
Brands: Marketed as Gynera; generics may be labeled as ethinylestradiol/gestodene
