From the Guidelines
Terazosin is an effective treatment option for promoting urination in men with benign prostatic hyperplasia (BPH), as it relaxes the muscles in the prostate and bladder neck, making it easier to urinate. According to the American Urological Association (AUA) guideline on management of BPH 1, terazosin is one of the alpha-blocker medications that are appropriate treatment options for patients with lower urinary tract symptoms (LUTS) secondary to BPH. The guideline states that alpha-blocker therapy is based on the hypothesis that clinical BPH is partly caused by alpha1-adrenergic-mediated contraction of prostatic smooth muscle, resulting in bladder outlet obstruction. Terazosin works by blocking alpha-1 adrenergic receptors, which causes smooth muscle relaxation in the prostate and bladder neck, reducing resistance to urine flow without affecting the muscle's ability to contract.
The typical starting dose of terazosin is 1 mg at bedtime, which may be gradually increased to 5-10 mg daily based on response 1. Improvement in urinary symptoms usually occurs within 2-4 weeks of starting treatment. Side effects may include dizziness, lightheadedness, and low blood pressure, especially when standing up quickly. The first dose should be taken at bedtime to minimize these effects. The AUA guideline also notes that the combination of an alpha-adrenergic receptor blocker and a 5 alpha-reductase inhibitor (combination therapy) is an appropriate and effective treatment for patients with LUTS associated with demonstrable prostatic enlargement 1. However, the safety of specific combinations other than finasteride plus doxazosin, terazosin, and alfuzosin has not been assessed.
Some key points to consider when using terazosin to promote urination include:
- The medication should be taken at bedtime to minimize side effects
- The dose may need to be gradually increased to achieve optimal results
- Improvement in urinary symptoms usually occurs within 2-4 weeks of starting treatment
- Side effects may include dizziness, lightheadedness, and low blood pressure
- The combination of terazosin with a 5 alpha-reductase inhibitor may be considered for patients with LUTS associated with demonstrable prostatic enlargement.
From the FDA Drug Label
The reduction in symptoms and improvement in urine flow rates following administration of terazosin is related to relaxation of smooth muscle produced by blockade of alpha-l adrenoceptors in the bladder neck and prostate Because there are relatively few alpha-l adrenoceptors in the bladder body, terazosin is able to reduce the bladder outlet obstruction without affecting bladder contractility. Results from these studies indicated that terazosin statistically significantly improved symptoms and peak urine flow rates over placebo Analysis of the effect of terazosin on individual urinary symptoms demonstrated that compared to placebo, terazosin significantly improved the symptoms of hesitancy, intermittency, impairment in size and force of urinary stream, sensation of incomplete emptying, terminal dribbling, daytime frequency and nocturia
Terazosin helps promote urination by reducing bladder outlet obstruction and improving peak urine flow rates without affecting bladder contractility, as shown in three placebo-controlled studies 2, 2, and 2.
- Key benefits:
- Relaxation of smooth muscle in the bladder neck and prostate
- Improvement in peak urine flow rates
- Reduction in symptoms of hesitancy, intermittency, and incomplete emptying
- Mechanism of action: Blockade of alpha-1 adrenoceptors in the bladder neck and prostate.
From the Research
Effectiveness of Terazosin in Promoting Urination
- Terazosin has been shown to improve peak urinary flow rate in patients with benign prostatic hyperplasia (BPH) 3, 4, 5, 6, 7.
- Studies have demonstrated that terazosin increases peak urinary flow rate by an average of 2-2.6 ml/s compared to baseline or placebo 3, 5.
- Terazosin has also been found to reduce residual urine volume and improve obstructive and irritative symptom scores in patients with BPH 3, 4, 5.
Mechanism of Action
- Terazosin selectively antagonizes alpha 1-adrenoceptor-mediated contraction of the prostate, prostatic capsule, proximal urethra, and bladder base, reducing urethral pressure and bladder outlet resistance 4.
- This mechanism of action helps to improve urine flow and reduce urinary symptoms associated with BPH.
Comparison to Other Treatments
- Terazosin has been compared to other treatments for BPH, including finasteride and transurethral resection of the prostate (TURP) 6, 7.
- Studies have shown that terazosin is more effective than finasteride in improving symptom scores and peak urinary flow rate, and has a similar effectiveness to other alpha-blockers 6, 7.
- Terazosin has also been found to be a cost-effective treatment option for BPH, with similar total direct treatment costs to placebo and lower costs than TURP 6.