Yasmin’s contraceptive effect arises from synergistic actions of its components:

1. Ovulation Suppression: Ethinylestradiol suppresses follicle-stimulating hormone (FSH), inhibiting follicular development, while drospirenone blocks the luteinizing hormone (LH) surge, preventing ovulation (Lippincott Textbook of Pharmacology).
2. Cervical Mucus Thickening: Drospirenone alters cervical mucus, impeding sperm penetration.
3. Endometrial Changes: Progestin thins the endometrial lining, reducing implantation potential (Lange Basic & Clinical Pharmacology).

Drospirenone, a spironolactone analogue, also exhibits anti-androgenic (reducing acne) and anti-mineralocorticoid effects (mitigating fluid retention), broadening its therapeutic applications.

1. Contraception: Primary use, with >99% efficacy when taken correctly (BNF).
2. Acne Management: Approved for moderate acne in women seeking contraception, leveraging drospirenone’s anti-androgenic activity.
3. Premenstrual Dysphoric Disorder (PMDD): Alleviates emotional and physical symptoms via hormonal stabilization (Lippincott).

• Standard Regimen: One tablet (0.03 mg ethinylestradiol + 3 mg drospirenone) daily for 21 days, followed by a 7-day placebo/break. Restart on day 8, even if bleeding occurs (BNF).
• Initiation: Start on menstrual cycle day 1 or the first Sunday after onset. Backup contraception is advised for the first 7 days.
• Missed Dose: Follow BNF guidelines: If <24 hours late, take immediately; if >24 hours, additional contraception is required.

• Common: Nausea, headache, breast tenderness, breakthrough bleeding.
• Serious:
  • Venous Thromboembolism (VTE): Risk elevated compared to levonorgestrel-containing pills (BNF).
  • Hyperkalemia: Due to drospirenone’s mineralocorticoid antagonism; monitor in high-risk patients (Lange).
  • Hepatic Issues: Rare hepatocellular carcinoma or benign adenomas.

• Absolute Contraindications: History of VTE, cardiovascular disease, migraine with aura, estrogen-sensitive cancers, severe liver disease, or undiagnosed vaginal bleeding (BNF).
• Relative Precautions: Hypertension, diabetes, obesity, or renal impairment (drospirenone is contraindicated in adrenal insufficiency or severe renal dysfunction).
• Monitoring: Check potassium levels in patients on potassium-sparing drugs or with renal impairment (Lippincott).

• Efficacy Reduction: Enzyme inducers (e.g., rifampicin, carbamazepine, St. John’s Wort) accelerate metabolism, risking contraceptive failure (BNF).
• Hyperkalemia Risk: Concomitant use with ACE inhibitors, ARBs, NSAIDs, or potassium-sparing diuretics necessitates monitoring (Lange).
• Hormonal Interactions: Broad-spectrum antibiotics (e.g., rifampicin) may reduce efficacy; consider backup methods.

• Active Ingredients: Ethinylestradiol (alternatively spelled ethinyl estradiol) and drospirenone.
• Brands: Marketed as Yasmin; generics may be labeled as ethinylestradiol/drospirenone.