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April 22, 2015
Finasteride for Hair Loss Trials Fail to Address
Sexual Dysfunction Chicago—How should pharmacists respond when questioned about the safety of finasteride for treatment of hair loss in men? New research suggests that is a good question without a conclusive answer. The study, published recently in JAMA Dermatology, finds that, based on published reports of clinical trials, there is insufficient information to adequately establish the safety of the drug used for that condition. The first meta-analysis of the quality of safety reporting in clinical trials of finasteride for treatment of male hair loss was led by researchers at Northwestern University’s Feinberg School of Medicine. Noting that finasteride blocks 5-alpha reductase in the scalp and male reproductive organs, inhibiting the conversion of the male hormone testosterone to its more potent form, 5-alpha dihydrotestosterone (5-alpha DHT), background information in the article notes that men who take finasteride demonstrate a 70% reduction in the amount of 5-alpha DHT in their blood. Yet, according to the authors, none of the 34 published clinical trial reports provide adequate information about the severity, frequency, or reversibility of sexual adverse effects. Adequate quality of adverse event reporting was defined as using an explicit toxicity scale to grade adverse event severity and reported numbers and/or rates of occurrence for each specific type of adverse event per study arm. Specifically, the researchers said the trials fail to answer questions about the risk of sexual dysfunction with finasteride, how severe that might be and whether stopping the drug will restore sexual function. Originally developed to treat prostatic hyperplasia in older men, finasteride for hair loss is being used in men who typically are young and take much less of the drug—about one-fifth the dose used for prostatic hyperplasia. The analysis found that, of 5,704 men in the Northwestern Medicine clinical data repository who were treated for male pattern baldness with finasteride, only 31% would meet inclusion criteria for the trials referenced in the manufacturer's “Full Prescribing Information.” The authors point out that some men with hair loss who are taking finasteride have diabetes mellitus, high blood pressure, or are taking other drugs such as diuretics or antidepressants that also increase the risk of sexual dysfunction. In addition, duration of drug safety evaluation was limited to 1 year or less for 26 of 34 trials, although 33% of men in the Northwestern clinical data repository took finasteride for more than a year. “People who take or prescribe the drug assume it's safe, but there is insufficient information to make that judgment,” said lead author Steven Belknap, MD, research assistant professor of dermatology and general internal medicine at Northwestern. “Our findings raise several questions,” Belknap suggested. “Why do the published reports of these 34 clinical trials not provide adequate information about the severity and frequency of sexual toxicity? Was this information obtained but then not included in published articles? Or, were these clinical trials performed in a way that simply didn't capture this essential information? And most importantly, is the risk to benefit ratio of finasteride acceptable?” The study is a report from the Feinberg School’s RADAR (Research on Adverse Drug Events and Reports) project. The authors emphasize that the “opportunity to identify and characterize drug toxicity may be lost when investigators do not use validated, effective methods for detecting adverse events, grading their severity, and evaluating causality. Remarkably, the sole study that used validated methods to assess depression in men found a strong association between finasteride exposure and depression, while only one of the remaining 33 trials reports “mood disorder” as an adverse event and determined this to be not significant. “Clinicians depend on clinical trial reports as the definitive source of information on drug toxicity,” they add. “One might reasonably expect that 34 studies and 2 meta-analyses would be adequate to establish the rate of finasteride adverse effects in AGA, yet this does not seem to be the case.” |
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