P27 UNILATERAL GYNECOMASTIA INDUCED BY 1 mg ORAL FINASTERIDE. REPORT OF 3 CASES

¹Ferrando J, ¹Grimalt R, ¹Alsina M, ¹Bulla F, ²Manasievska E. Depts. of Dermatology. ¹Hospital Clínic. University of Barcelona. Spain. ²Centro Medicinal Kumanovo. University of Skopje. Macedonia.

Since 1998 1 mg oral finasteride (Propecia^TM) has been widely used for treament of male androgenic alopecia (MAGA). Side effects have been described in less than 2% of cases (transitory impotence, libido decrease or ejaculation disorder) and they did not imply treatment discontinuation. Five clinical trials submitted by Merck to the FDA refer those data, but only quoted a “breast enlargement and sensitivity, occasionally reported”. We had the opportunity to observe painful unilateral gynecomastia in three males under 1 mg oral finasteride regimen.

Three males aged 18 to 29 with grades II to IV of the Hamilton/Norwood classification developed unilateral gynecomastia after 2 to 6 months on treatment with 1 mg oral finasteride (one case with Proscar^TM, 1/5 of tablet per day, two cases with Propecia^TM). In two cases the diagnosis was confirmed by mamography and in the third case by aspiration-biopsy. In all cases gynecomastia disappeared between 2 to 6 months after the treatment was discontinued.

Five mg oral finasteride (Proscar^TM) used for treatment of benign prostatic hypertrophy can produce gynecomastia, so it would not be rare to find that effect with Propecia^TM. Gynecomastia is mainly caused by alterations of estrogen/androgen ratio. Finasteride decreases circulating dihydrotestosterone levels, increasing serum estradiol, so it could produce gynecomastia.Gynecomastia produced by Propecia^TM is transient and disapears if the treatment is discontinued.