Discussion: In a randomized, placebo-controlled, crossover trial. The effects of rifampin on the pharma. Cokinetics of tamoxifen were studied in 10 healthy males. Each subject received either 600 mg rifampin or placebo once daily for 5 days. On day6, tamoxifen 80 mg was taken. Pretreatment with rifampin reduced the peak plasma levels of tamoxifen 56 % (from 145 to 64 ng / ml) and increased plasma levels of its active N-demethyltamoxifen metabolite 46 % (from 41 to 60 ng /ml). in addition, rifampin administration decreased the area under the plasma concentration-time curve of tamoxifen 86 %, and the elimination half-life 42 % (from 118 to 68 hours).

Indications: see under Dose and notes above

Cautions: occasional cystic ovarian swellings in premenopausal women, occasional hypercalcaemia if bony metastases; increased risk of thromboembolic events when used with cytotoxics; breast-feeding (Appendix 5); endometrial changes.

Important: see below; porpyuria.

Interaction: Appendix 1 (tamoxifene) ENDOMETRIAL CHANGE. Increased endometrial changes, including hyperplasia, polyps, and cancer reported; prompt investigation required if abnormal vaginal bleeding including menstrual irregularities, vaginal discharge, and pelvic pain or pressure in those receiving (or who have received) tamoxifen.

Contra-Indications: Pregnacy (exclude before commencing and advise non-hormonal contraception if appropriate-Appendix 4)

Adverse Effects: Fluhing, amenorrhoea, oligomenorrhoea, vaginal discharge, vaginal bleeding, bone pain, nausea, cough, oedema, fatigue, ovarian, cyst, depression, hypercalcemia, increased risk of thromboemobolism, thrombocytopenia, disturbed liver function tests.

Uses
• Treats advanced breast cancer.
• Can help prevent breast cancer in those at risk.

HOW TO TAKE ?
Tablets-Swallow with liquid. If you can't swallow whole, crumble tablet and take with liquid or food. Instructions to take on empty stomach mean 1 hour before or 2 hours after eating. Ebteric-coated tablets-Swallow whole.

WHEN TO TAKE ?
Follow doctor's instructions.

IF YOU FORGET A DOSE ?
Skip the missed dose and return to regular schedule. Don't double dose.

WHAT DRUG DOES ?
Blocks uptake of estradiol and inhibits growth of cancer cells.

TIME LAPSE BEFORE DRUG WORKS
4 to 10 weeks.
With bone metastases-several months.

WARNINGS & PRECAUTIONS

BEFORE YOU START, CONSULT YOUR DOCTOR
• If you have cataracts.
• If you have blood disorders.
• If you have high cholesterol.

PREGANCY Consult doctor.

BREAST-FEEDING Effect not documented. Consult your doctor.

INFANTS & CHILDREN Not intended for use in children.

SKIN & SUNLIGHT No problems expected.