Medical Treatment of Benign Prostate Hyperplasia
2008
Benign prostate hyperplasia (BPH) is a common clinical condition of men due to process of aging. Histiologic prostate enlargement can be identified in 40% of men from age 50 to 60 years and in about 90% at age 85. Half of men with histiologic nodular hyperplasia will develop clinical prostate enlargement and only 30% to 40% of men with clinical prostate enlargement will manifest lower urinary tract symptoms (LUTS). Watchful waiting is an appropriate management for men who are asymptomatic or have mild to moderate LUTS without influence to their quality of life. Pharmacologic therapy is indicated when men are bothered by the LUTS suggestive of BPH. Without proper treatment, symptomatic BPH may cause bladder outlet obstruction and result in reduced uroflow rate, increase post-voiding residual and urinary retention. Risk factors for the development of urinary retention include larger prostate volume, reduced peak uroflow rate, moderate to severe lower urinary tract symptoms, older age and increased levels of prostate-specific antigen (PSA). Reduction of the sympathetic tone within the lower urinary tract by α1 adrenergic receptor antagonists and inhibition of the prostate growth by 5-alpha reductase (5-AR) inhibitors have become the main strategy in medical management of BPH. The selectivity for α1A and α1D subtypes over α1B subtype is both pharmacologically and clinically important for uroselectivity in order to reduce vasodilatory adverse events from these α1 adrenergic receptor antagonists. Four common α1 blockers including pharmacologically non-uroselective α1 antagonists (alfuzosin, doxazosin, terazosin) and one uroselective α1 antagonist (tamsulosin) are used for the treatment of LUTS suggestive of BPH. All four α1 blockers have comparable efficacy in improving LUTS and uroflow rate. The major differences among these 4 drugs are pharmacokinetic and tolerability profiles. Common side effects associated with these α1 blockers include asthenia, drowsiness, dizziness, headache, syncope, somnolence, retrograde ejaculation and orthostatic hypotension. Both 5-AR inhibitors including finasteride and dutasteride are effectively in improving LUTS, reducing prostate volume and decreasing the long-term outcomes of acute urinary retention and BPH-related surgeries. Common side effects from 5-AR inhibitors include erectile dysfunction, loss of libido, ejaculation disorders and gynecomastia. Men with moderate to severe LUTS suggestive of BPH and larger prostate volume (>30cm^3), who have poor response to α1 blocker or 5-AR monotherapy are beneficial from long-term combination use of both drugs. Additional antimuscarinic to α1 blocker may be a reasonable therapeutic option to relieve irritative symptoms for men with poor response to α1 blocker monotherapy.
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