Terazosin hydrochloride is used alone or in combination with other classes of antihypertensive agents for the management of hypertension. Terazosin's efficacy in hypertensive patients appears to be similar to that of other α1-adrenergic blocking agents, thiazide diuretics, β-adrenergic blocking agents, angiotensin-converting enzyme (ACE) inhibitors, and calcium-channel blocking agents. However, in one randomized, double-blind clinical study (the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial; [ALLHAT]), doxazosin, an α1-blocker, was shown to be less effective in lowering mean systolic blood pressure (by about 2-3 mm Hg) than chlorthalidone, a thiazide-like diuretic. In order to achieve target blood pressure in hypertensive patients, use of doxazosin required additional hypotensive therapy more frequently than chlorthalidone. In addition, interim analysis (median follow-up: 3.3 years) of this study indicates that use of doxazosin in high-risk (at least 2 risk factors for coronary heart disease) hypertensive patients 55 years of age and older was associated with a higher risk of stroke and incidence of combined cardiovascular disease events (including twice the risk of congestive heart failure) than use of chlorthalidone. Study investigators concluded that such increased risk of congestive heart failure could not have been caused by the relatively small difference in the mean target systolic blood pressure observed in patients receiving doxazosin compared with those receiving chlorthalidone. Therefore, based on these findings, the trial's Data Safety and Monitoring Board recommended that the α-blocker treatment arm be terminated prematurely. The remaining antihypertensive arms (e.g., calcium-channel blockers, ACE inhibitors, diuretics) and lipid-lowering (pravastatin vs usual care) components of the study subsequently were completed and reported.
Because of established clinical benefits (e.g., reductions in overall mortality and in adverse cardiovascular, cerebrovascular, and renal outcomes), ACE inhibitors, angiotensin II receptor antagonists, calcium-channel blockers, and thiazide diuretics generally are considered the preferred drugs for the initial management of hypertension in adults. Although in the past α1-blockers such as terazosin were recommended as one of several classes of first-line antihypertensive therapy or as initial therapy in selected hypertensive patients (e.g., those with symptomatic prostatic hyperplasia), current antihypertensive and urology guidelines no longer recommend α1-blockers as preferred first-line therapy for any patients with hypertension, principally because of negative findings observed in ALLHAT. However, α1-blockers are effective antihypertensive drugs and many experts still consider their use appropriate for the management of resistant hypertension as a component of combination therapy. Therapy with an α1-blocker is most effective when used in combination with a diuretic. Although some experts state that an α1-blocker may be a useful component of antihypertensive treatment regimens in older men with coexisting benign prostatic hyperplasia (BPH), the American Urology Association (AUA) states that monotherapy with these drugs is not optimal in hypertensive patients with lower urinary tract symptoms (LUTS) or BPH and that such conditions should be managed separately .
The beneficial effects of α1-blockers on blood glucose and lipid concentrations may mitigate some of the adverse metabolic effects of diuretics, and α1-blockers may offer some advantage in patients with underlying lipoprotein disorders (e.g., hypercholesterolemia) or in those with lipoprotein abnormalities induced by other antihypertensive agents (e.g., thiazide diuretics). The possibility that geriatric patients may be more susceptible than younger patients to the postural hypotensive effects of α1-blockers should be considered in the selection of therapy. Blood pressure response to α1-blockers appears to be comparable in white and black patients.
Benign Prostatic Hyperplasia
Terazosin hydrochloride is used to reduce urinary obstruction and relieve associated manifestations in patients with symptomatic benign prostatic hyperplasia (BPH, benign prostatic hypertrophy). For patients who can tolerate the potential cardiovascular and other effects of α1-adrenergic blockade, the drug can effectively relieve mild to moderate obstructive manifestations (e.g., hesitancy, terminal dribbling of urine, interrupted stream, impaired size and force of stream, sensation of incomplete bladder emptying or straining) and urinary flow rates in a substantial proportion of patients and may be a useful alternative to surgery, particularly in those who are awaiting or are unwilling to undergo surgical correction of the hyperplasia (e.g., via transurethral resection of the prostate [TURP]) or who are not candidates for such surgery.
Therapy with α1-blockers appears to be less effective in relieving irritative (e.g., nocturia, daytime frequency, urgency, dysuria) than obstructive symptomatology. In addition, therapy with the drugs generally can be expected to produce less subjective and objective improvement than prostatectomy, and periodic monitoring (e.g., performance of digital rectal examinations, serum creatinine determinations, serum prostate specific antigen [PSA] assays) is indicated in these patients to detect and manage other potential complications of or conditions associated with BPH (e.g., obstructive uropathy, prostatic carcinoma). While symptomatic improvement has been maintained for at least up to 2 years of terazosin therapy in some patients, the long-term effects of the drug on the need for surgery and on the frequency of developing BPH-associated complications such as acute urinary obstruction remain to be established.
Combination therapy with an α1-blocker and 5α-reductase inhibitor (e.g., finasteride) has been more effective than therapy with either drug alone in preventing long-term BPH symptom progression; combined therapy also can reduce the risks of long-term acute urinary retention and the need for invasive therapy compared with α-blocker monotherapy.
Because many of the signs and symptoms of BPH can occur with carcinoma of the prostate and with certain genitourinary conditions, including prostatitis and neurologic disorders, the possibility of such conditions, particularly this carcinoma, should be ruled out in any patient for whom terazosin therapy for presumed hyperplasia is being considered.