5-alpha-reductase inhibitors finasteride

Testosterone-5-alpha reductase inhibitors (finasteride, dutasteride)... 

A systematic review and meta-analysis of randomized trials of S. repens in men with benign prostatic hyperplasia showed that saw palmetto extracts improve urinary symptoms and flow measures to a greater extent than placebo, and similar improvements in urinary symptoms and flow measures to the 5-alpha-reductase inhibitor finasteride with fewer adverse effects (6). 

The client diagnosed with mild benign prostatic hypertrophy (BPH) is prescribed the 5-alpha-reductase inhibitor finasteride (Proscar) to relieve symptoms of urinary frequency. Which intervention should the clinic nurse implement ... 

Geriatric Considerations - Summary Alpha-adrenergic blockers are modestly effective alone, and in combination with 5-alpha reductase inhibitors (e,g, finasteride) in the treatment of urinary obstructive symptoms related to benign prostatic hyperplasia. Alfuzosin is a "uroselective" alpha-blockerwhich appears to cause less orthostatic hypotension than nonselective alpha-blockers such as terazosin, prazosin, and doxazosin. 

The benefit of combining an alpha-adrenoceptor antagonist with a 5-alpha-reductase inhibitor has been assessed in men with benign prostatic hyperplasia (23). Modified-release alfuzosin was more effective than finasteride, with no additional benefit in combining the drugs. The adverse effects of alpha-blockade were postural hypotension, hypotension, headache, dizziness, and malaise the adverse effects of finasteride were ejaculatory disorders and impotence. 

Steiner JF. Finasteride a 5 alpha-reductase inhibitor. Clin Pharm 1993 12(l) 15-23. 

Reddy GK. Finasteride, a selective 5-alpha-reductase inhibitor, in the prevention and treatment of human prostate cancer. Clin Prostate Cancer 2004 2(4) 206-8. 

Gormley GJ, Stoner E, Rittmaster RS, Gregg H, Thompson DL, Lasseter KC, Vlasses PH, Stein EA. Effects of finasteride (MK-906), a 5 alpha-reductase inhibitor, on circulating androgens in male volunteers. J Clin Endocrinol Metab 1990 70(4) 1136-41. 

A recent study by Bach, Schmitt, and Ebeling compared three prescriptive medications with a standardized saw palmetto extract. The drugs worked by two different mechanisms. Finasteride is a synthetic 5-alpha-reductase inhibitor, and the other two drugs, terazosin and alfuzosin, are alpha-1 blockers. In all important parameters, the saw palmetto was a comparable treatment with far fewer side effects. It decreased residual urine volume, reduced irritation, and increased urinary flow 80 percent of patients rated their improved quality of life as good to very good. 

P. O. Gisleskog, D. Hermann, M. Hammarlund-Udenaes, and M. O. Karlsson, A model for the turnover of dihydrotestosterone in the presence of the irreversible 5 alpha-reductase inhibitors Gil98745 and finasteride. Clin Pharmacol Ther 64 636-647 (1998). M. Pirmohamed and B. K. Park, in Elandbook of Drug Metabolism, T.F. Woolf (Ed.). Marcel Dekker, New York, 1999, pp. 443 76. 

Finasteride (Proscar), a 5-alpha-reductase inhibitor, and digoxin (Lanoxin), a cardiac glycoside. 

The use of finasteride and other 5-alpha reductase inhibitors in benign prostatic hyperplasia has been associated with adverse sexual outcomes, including dysfunction of erection or ejaculation and... 

The investigators found that the described 10 SNP variants of SRD5A2 differ in their biologic effects, not only in how much they affect levels of DHT, but also in their response to finasteride, a competitive inhibitor of 2,5-alpha reductase. Finasteride (Proscar) is marketed for the treatment of BPH and is under investigation for the chemoprevention of prostate cancer. The investigators found a 200-fold range in activity of the enzymes encoded by these gene variants and as much as a 60-fold difference in the ability of finasteride to inhibit the enzyme s activity. 

Finasteride is a selective inhibitor of 5-alpha-reductase. It thereby reduces prostatic concentrations of dihydrotestosterone and so reduces prostatic size (6,7,8). It is therefore used to treat benign prostatic hyperplasia (9,10,11,12) and in the prevention and treatment of prostate cancer (13). It is poorly effective in patients with prostatic obstruction and small prostate glands (14), but in patients with glands larger than 40 ml it produces significant symptomatic improvement. 

Answer B. Finasteride blocks the formation of dihydrotestosterone by inhibiting 5-alpha reductase and may be useful in both male pattern baldness and benign prostatic hyperplasia. It is quite possible that drugs acting to block androgen receptors, or to cause suppression of FSH, may also be useful in these conditions. Aromatase inhibitors tend to cause increased levels of androgens, with excessive masculinization as a side effect. 

---