Efficacy and tolerability of drugs for treatment of benign prostatic hyperplasia.

It has long been recognised that neural factors are of considerable importance in lower urinary tract function. Whilst reduction in the bulk of the human prostate is feasible, experience on this therapeutic approach proved to be disappointing. Existing trial data with the agent finasteride are reviewed. A number of formulations derived from plant extracts have been advocated but their mechanism of action remain largely obscure and there is a dearth of placebo controlled information to support their efficacy. Experience over the last 10 years has demonstrated efficacy with the use of alpha adrenoceptor blockade in the management of BPH. Alpha adrenoceptor antagonists relax the prostatic smooth muscle by interrupting the sympathetic pathway at the receptor level. Recent developments in this field include the recognition that there are alpha I adrenoceptor subtypes. The functional adrenoceptor in the human prostate is predominantly the alpha IA - subtype. Of the alpha 1-adrenoceptor antagonists only tamsulosin discriminates between the alpha 1-adrenoceptor subtypes. Alpha 1-blockers should be used in first-line medical therapy for BPH and 5-alpha-reductase inhibitors reserved for those patients in whom alpha-blocker therapy fails. Alpha I-blockers such as doxazosin, tamsulosin, terazosin, alfuzosin are effective in the treatment of BPH both in younger and in older men. The drugs are well tolerated. The majority of side effects were classified as minor and mild. The most common complaints, as with other alpha-blockers, are dizziness, fatigue and headache, and these are often transient. In contrast, finasteride can lead to impotence, reduced libido. gynaecomastia or ejaculatory disorders. Men with small prostates may not be suitable candidates for finasteride therapy.