Abstract
Doxazosin and terazosin are alpha1-adrenergic blockers that are commonly used for the treatment of benign prostatic hyperplasia (BPH). Doxazosin or terazosin can both be given once daily because of their relatively long elimination half-lives (approximately 22 hours for doxazosin, and 9 to 12 hours for terazosin). Common adverse effects of these two drugs include orthostatic hypotension and syncope, especially with the first dose or initial therapy. Based on cost and equivalent efficacy between the two alpha1 blockers, terazosin was selected as the formulary agent for a long-acting alpha1-adrenergic blocker in the Cheyenne Veterans Administrative Medical Center (Cheyenne VAMC). The study was conducted with 12 patients with symptomatic BPH to evaluate the appropriate doses of terazosin when patients taking doxazosin are switched for the treatment of BPH. The results indicated that the two alpha1 blockers provided similar control of BPH symptoms. The mean differences of symptom scores obtained after the two treatment regimens (doxazosin vs terazosin) were not significant (mean ± S.D. 11.17 ± 7.93 vs 9.67 ± 7.48, 95% confidence interval [CI] of the mean difference −1.18 ± 4.18; P = 0.243). No dosage titration was needed at the time of initial switching from doxazosin to terazosin. Additionally, it appears that terazosin doses of 1, 2, 5, 7, and 10 mg can be used initially when doxazosin (at corresponding doses of 1, 2, 4, 6, and 8 mg, respectively) is converted to terazosin for the management of BPH.
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