CHAPTER SUMMARY FROM THE PHARMACOTHERAPY HANDBOOK
Although symptomatic benign prostatic hyperplasia (BPH) is rare in men younger than 50 years, it is common in men 60 years and older. Prostate growth is androgen-dependent. Symptoms commonly result from both static and dynamic factors.
BPH symptoms may be exacerbated by medications, including antihistamines, phenothiazines, tricyclic antidepressants, and anticholinergic agents. In these cases, discontinuing the causative agent can relieve symptoms.
For patients with mild disease who are asymptomatic or have mildly bothersome symptoms and no complications of BPH disease, watchful waiting is indicated. Watchful waiting includes behavior modification, lifestyle modification, discontinuation of medications that contribute to voiding symptoms, and return visits to the physician at 6- or 12-month intervals for assessment of worsening symptoms or signs of bladder outlet obstruction.
If symptoms progress to a moderate or severe level, drug therapy or surgery is indicated. α1-Adrenergic antagonists quickly relieve voiding symptoms, but do not prevent disease progression. 5α-Reductase inhibitors delay symptom progression and reduce the incidence of BPH-related complications in patients with prostates of at least 30 to 40 g, but may not reduce voiding symptoms for 3 to 6 months.
All α1-adrenergic antagonists are equally effective in relieving BPH symptoms. Older second-generation immediate-release formulations of α1-adrenergic antagonists (eg, terazosin, doxazosin) can cause adverse cardiovascular effects, mainly first-dose syncope, orthostatic hypotension, and dizziness. For patients who cannot tolerate these hypotensive adverse effects, the third-generation, pharmacologically uroselective agents α1A-adrenergic antagonists (eg, tamsulosin, silodosin) or an extended-release formulation of alfuzosin, a second-generation, functionally uroselective agent, are good alternatives.
5α-Reductase inhibitors are useful primarily for patients with large prostates greater than 30 to 40 g who wish to avoid surgery and cannot tolerate the side effects of α1-adrenergic antagonists. 5α-Reductase inhibitors have a slow onset of action, taking up to 6 months to exert maximal clinical effects, which is a disadvantage of their use, especially when used as single drug therapy for BPH. In addition, decreased libido, erectile dysfunction, and ejaculation disorders are common adverse effects, which may be troublesome problems in sexually active patients.
Phosphodiesterase inhibitors can be used in patients with moderate to severe BPH and erectile dysfunction. They improve irritative voiding symptoms, but do not produce significant increases in urinary flow rate or reductions in postvoid residual (PVR) urine volume. Hence, a phosphodiesterase inhibitor is considered less effective than an α-adrenergic antagonist for BPH. A phosphodiesterase inhibitor may be used alone; however, symptom improvement and an increase in peak urinary flow rate has been demonstrated when the phosphodiesterase inhibitor is used along with an α-adrenergic antagonist or a 5α-reductase inhibitor.
Anticholinergic agents are indicated in patients with moderate to severe lower urinary tract symptoms (LUTS) with a predominance of irritative voiding symptoms. In this case, the drugs are commonly added ...
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