Tamsulosin and gynecomastia: data from the Italian spontaneous reporting system

Background: Gynecomastia is caused by drugs in 10–25%of all cases.[1] It is defined histologically as a benign proliferation of the glandular tissue of the male breast and clinically by the presence of a rubbery or firm mass extending concentrically from the nipple(s). There are evidences of gynecomastia due to 5a-Reductase inhibitors as finasteride and dutasteride but there aren’t available studies about gynecomastia associated with tamsulosin use in literature. To date, gynecomastia is not reported in the Summary Product Information (SPC) of the drug. Aim of this study is to evaluate the cases of gynecomastia tamsulosininduced in the Italian spontaneous reporting database (Rete Nazionale di FarmacoVigilanza - RNF). Methods: Adverse reaction are coded in the RNF using both MedDRA and WHO-ART. Cases of gynecomastia has been defined as reports associated to WHO-ART Preferred terms Gynaecomastia, Breast enlargement, Breast pain male, Breast pain and Breast discomfort. Results: Up to December 2011 about 132 800 reports are present in the RNF, excluding vaccines and reports from the literature. In the whole database 247 reports have been associated to tamsulosin, whereas in 699 reports tamsulosin has been reported as concomitant drug. Eight cases of gynecomastia associated to tamsulosin have been reported: two of these have also dutasteride as concomitant drug. Other 10 reports with gynecomastia have tamsulosin as concomitant drug. Eight of these have been associated to another 5a-reductase inhibitor (dutasteride or finasteride). Time of onset showed a great variability from 1 day to 4 years since the start of therapy. Among cases with tamsulosin as the only suspected drug, no information on laboratory analyses was available. A positive dechallenge has been reported in two cases. In the WHO database (Vigibase) 78 reports of gynecomastia in which tamsulosin is indicated as suspected/concomitant drug are present. These reports have been submitted by eleven different countries and tamsulosin is the only drug suspected in fifty of them. Conclusion: A high number of cases of gynecomastia in reports with tamsulosin are present in the RNF. Most of these reports have tamsulosin as concomitant drug or have also other 5a-reductase inhibitor leading to a difficult causality assessment. However, in six cases tamsulosin is the only reported drug suggesting an association to gynecomastia also for this drug. The combination tamsulosin-gynecomastia should probably be highlighted in product information.