Finasteride Cardiovascular Impact Long-Term: What the Evidence Actually Shows

What the Proscar label reports for blood pressure

The MTOPS table, from a 4- to 6-year BPH trial of 3,047 men, reports drug-related hypotension in 1.2% of men on finasteride 5 mg alone versus 0.7% on placebo, and postural hypotension in 9.1% versus 8.0% [2]. The same rows read 3.4% and 16.7% on the alpha-blocker doxazosin alone, and 1.5% and 17.8% for the combination [2]. The label notes that MTOPS was not specifically designed to make statistical comparisons between groups for reported adverse experiences, and that direct comparisons with earlier single-agent studies may not be appropriate because of differences in patients, dosage and study design [2].

What the long-term trials measured

PCPT randomised 18,882 men aged 55 or older to finasteride 5 mg or placebo for seven years, with prostate cancer prevalence as the primary endpoint; cancer was detected in 18.4% of men on finasteride versus 24.4% on placebo, a 24.8% relative reduction (95% CI 18.6 to 30.6) [3]. PLESS randomised 3,040 men aged 45 to 78 for four years, with urinary symptom scores and treatment failure as its efficacy measures [2].

Hormones and heart medicines

Finasteride inhibits type II 5-alpha reductase, the isozyme responsible for about two-thirds of circulating DHT, with roughly 100-fold selectivity over type I; a 1 mg tablet suppresses serum DHT by about 65% within 24 hours [1]. Mean testosterone and estradiol rise by approximately 15% but stay within the physiologic range, and finasteride has no affinity for the androgen receptor [1]. The label states that no drug interactions of clinical importance have been identified and that finasteride does not appear to affect the cytochrome P450 system; antipyrine, digoxin, propranolol, theophylline and warfarin were tested without clinically meaningful interactions [1]. The label adds that, although specific interaction studies were not performed, doses of 1 mg or more were used in clinical studies with ACE inhibitors, beta blockers, calcium-channel blockers, cardiac nitrates, diuretics and HMG-CoA reductase inhibitors without evidence of clinically significant adverse interactions [1].

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