Pharmaceuticals: which of the following is a drug used in oral contraceptive formulations (as an estrogen component)?

Introduction:
Combined oral contraceptives typically contain an estrogen and a progestin. Recognizing common active ingredients is important for pharmacy, medicine, and biotechnology students.

Given Data / Assumptions:

• Mestranol is a synthetic estrogen (a prodrug of ethinyl estradiol).
• Other listed compounds have unrelated indications.
• Question asks specifically for a contraceptive drug.

Concept / Approach:
Estrogen components (e.g., mestranol, ethinyl estradiol) are combined with progestins (e.g., norethindrone, levonorgestrel) to suppress ovulation and alter the endometrium/cervical mucus. Antibiotics (penicillin), analgesic/liniment component (methyl salicylate), and antibacterial sulfonamide (sulphadiazine) are not used as contraceptives.

Step-by-Step Solution:
Identify estrogenic agent: mestranol.Exclude antibiotics/analgesics: not contraceptives.Select mestranol as correct contraceptive component.

Verification / Alternative check:
Drug compendia list mestranol–norethindrone as a historical combination; modern products often use ethinyl estradiol instead of mestranol but the classification remains valid.

Why Other Options Are Wrong:

• Penicillin: antimicrobial, no contraceptive effect.
• Methyl salicylate: topical counterirritant.
• Sulphadiazine: antibacterial sulfonamide.

Common Pitfalls:
Assuming any hormone-like name is a contraceptive; only specific estrogens/progestins are used for this indication.

Final Answer:
Mestranol