Centchroman is a non-steroidal, non-hormonal, selective estrogen receptor modulator (SERM) developed in India by the Central Drug Research Institute (CDRI). It is a unique oral contraceptive and therapeutic agent for menstrual disorders, acting as a post-coital contraceptive with a once-weekly dosage regimen. It is known for its high efficacy, good tolerability, and lack of significant metabolic side effects common to hormonal contraceptives.
Adult: **Contraception:** 30 mg orally twice a week for the first 12 weeks, then once a week. **Dysfunctional Uterine Bleeding:** 30 mg twice a week. The dose and duration are adjusted based on response, typically for 12 weeks.
Note: To be taken orally with or without food, preferably on fixed days of the week (e.g., Mondays and Thursdays for the initial phase). For contraceptive use, the first dose should be taken within 3 days of unprotected coitus. For DUB, therapy is usually initiated on the first day of the menstrual cycle.
Centchroman acts as a selective estrogen receptor modulator (SERM). It competitively binds to estrogen receptors in target organs, exerting both estrogenic and anti-estrogenic effects depending on the tissue. In the endometrium and breast, it acts primarily as an anti-estrogen, inhibiting estrogen-mediated proliferation. In the bone, it may have an estrogen-agonist effect.
Pregnancy: **Category X.** Contraindicated. It is a post-coital contraceptive/anti-implantation agent. Must be excluded before initiation.
Driving: May cause dizziness; patients should be cautioned about driving or operating machinery if affected.
| Rifampicin | Induces CYP3A4, may decrease Centchroman plasma levels, reducing efficacy. | Major |
| Ketoconazole, Itraconazole | Inhibits CYP3A4, may increase Centchroman plasma levels, increasing risk of side effects. | Moderate |
| Phenytoin, Carbamazepine | Enzyme inducers, may reduce Centchroman efficacy. | Moderate |
| Warfarin | Potential interaction due to protein binding displacement; may alter INR. Monitor closely. | Moderate |