A new observational study supports a link between long-term dutasteride treatment and sexual side effects, including worsening erectile dysfunction (ED) and reduced testosterone levels. Use of the 5-alpha reductase inhibitor (5-ARI) was also associated with several parameters of metabolic dysfunction, including increased glucose and hemoglobin A1c and lipid abnormalities.

The findings suggest that long-term dutasteride may harm men’s overall health, corresponding author Abdulmaged M. Traish, MBA, PhD, of Boston University School of Medicine told Renal & Urology News. “The increase in blood glucose and A1C may predispose men to diabetes and the increase in lipids may predispose them to NAFLD [non-alcoholic fatty liver disease]. Most importantly, this agent worsens sexual function and reduces quality of life.”

Using a registry from a single urology office, Dr Traish and colleagues compared data from 230 men (aged 47 to 68) taking dutasteride (0.5 mg/day) and 230 men (aged 52 to 72 years) taking the alpha blocker tamsulosin (0.4 mg) for lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH). Dutasteride significantly improved LUTS over 36 to 42 months, according to results published in Hormones Molecular Biology and Clinical Investigations. It reduced prostate volume, International Prostate Symptom Score, and PSA. However, the 5-ARI also was associated with increased blood glucose, hemoglobin A1c, triglycerides, and low-density lipoprotein levels over the long term. In addition, dutasteride appeared to increase liver transaminase activity and Aging Male Symptom score, which indicates inflammation and reduced quality of life.

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The team also found reduced testosterone levels and worsening ED as assessed by the International Index of Erectile Function questionnaire. Investigators observed no such relationships in the tamsulosin group.

“We have to re-think more seriously about the metabolic adverse effects of drugs that inhibit 5-alpha reductases and their negative impact on men’s health” Dr Traish said. “We strongly recommend that physicians discuss with their patients these potential serious adverse effects of long-term dutasteride therapy prior to instituting this form of treatment.”

Some patients were taking phosphodiesterase type 5 inhibitors and statins at baseline, which may have influenced the ED and cholesterol results.

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1. Traish A, Haider KS, Doros G, Haider A. Long-term dutasteride therapy in men with benign prostatic hyperplasia alters glucose and lipid profiles and increases severity of erectile dysfunction. Horm Mol Biol Clin Investig 2017; published online ahead of print.

2. Popular prostate drug linked to serious side effects. Boston University Medical Center; June 22, 2017. [news release]