5-alpha-reductase inhibitors (RIs) (eg, finasteride and dutasteride) are less likely to cause hypotension than alpha-1-adrenergic antagonists (AAs) (eg, tamsulosin, doxazocin, terazocin, and alfuzocin), the other major class of drugs commonly used for treatment of signs and symptoms of benign prostatic hypertrophy (BPH).
A Cochrane systematic review found that finasteride, an RI, has a lower risk of postural hypotension compared to doxazosin, an AA. 1 In fact, there’s no solid evidence that RIs exacerbate hypotension on their own. 2,3 Unfortunately, RIs take longer to achieve benefit because they work by reducing prostate size over time, while AAs work much faster by reducing prostate smooth muscle tone.4 So, while it’s reasonable to choose an RI over an AA in our patient with soft pressures, it’s also reasonable to expect it won’t work quite as well during his hospital stay and you may still be forced to choose an AA.
Among AAs, tamsulosin is the least likely to be associated with hypotension when compared to others in the same class (eg, doxazocin and terazocin) which are also sometimes used for treatment of hypertension. Thus, tamsulosin may be the best choice for patients at risk of hypotension.5 However, even tamsulosin is not totally safe in this regard, especially in the first 4 weeks after starting or re-starting treatment when its risk of hospital admission for hypotension is about double that of RIs.6
Bonus pearl: Did you know that prazocin was the first promising selective AA investigated for BPH but likely because of its availability in generic form and the general notion at the time that medical therapy of BPH would not be widely accepted by urologists, larger randomized-controlled trials were never pursued!7
- Tacklind J, Fink HA, MacDonald R, et al. Finasteride for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews, 2010 Oct 6. https://www.ncbi.nlm.nih.gov/pubmed/20927745
- Finasteride prescribing information: https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020180s037lbl.pdf
- Dutasteride prescribing information: https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/021319s014lbl.pdf
- Rigatti P, Brausi M, Scarpa RM, et al. A comparison of the efficacy and tolerability of tamsulosin and finasteride in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia. Prostate Cancer and Prostatic Diseases 2003; 6:315–323. https://www.ncbi.nlm.nih.gov/pubmed/14663474
- Tewari A and Narayan P. Alpha-adrenergic blocking drugs in the management of benign prostatic hyperplasia: interactions with antihypertensive therapy. Urology 1999 Mar;53:14-20. https://www.ncbi.nlm.nih.gov/pubmed/10094096
- Bird ST, Delaney JAC, Brophy JM, et al. Tamsulosin treatment for benign prostatic hyperplasia and risk of severe hypotension in men aged 40-85 years in the United States: risk window analyses using between and within patient methodology. BMJ 2013; 347 :f6320. https://www.ncbi.nlm.nih.gov/pubmed/24192967
- Lepor H. Alpha blockers for the treatment of benign prostatic hyperplasia. Rev Urol 2007;9:181-90. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2213889/
Contributed by Nick Bodnar, Harvard medical student, Boston, MA.
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