Gynecomastia is defined as a benign enlargement of the male mammary glands, resulting in palpable subalveolar tissue.[1
] Gynecomastia results from conditions that cause an imbalance of estrogenic and androgenic effects on the breast, resulting in an increased or unopposed estrogen action on the breast tissue. Approximately 4–10% cases of gynecomastia are due to drugs.[2
] Mechanisms by which drugs cause gynecomastia include inhibition of androgen synthesis and/or metabolism (ketoconazole), antagonism at androgen receptor (flutamide, finastride), direct action at estrogen receptors by estrogen-like drugs (estrogen vaginal cream, clomiphine) and displacement of estrogen from sex hormone-binding globulin (thereby increasing the free estrogen level, e.g. spironolactone). Some drugs can directly damage the testis and may cause gynecomastia (busulfan, vincristine).
Digoxin is a cardiac glycoside used for the treatment of congestive heart failure due to its positive inotropic effect by inhibiting Na+
ATPase enzyme on myocardial cells. In addition, it is also used in patients with atrial fibrillation to control the ventricular rate. The adverse effects of digoxin are both cardiac and extracardiac. Gynecomastia is one of the well-known extracardiac side-effects. Furosemide, a loop diuretic, also indicated in congestive heart failure, is also reported to cause gynecomastia.[3
] Hence, chances of gynecomastia could be enhanced if these two drugs are coadministered. To our knowledge, there is no report of this adverse effect when both are prescribed concurrently. Here, we report a case of gynecomastia suspected to have resulted from the coadministation of digoxin and furosemide.