ALFUZOSIN - A REVIEW OF ITS PHARMACODYNAMIC AND PHARMACOKINETIC PROPERTIES, AND THERAPEUTIC POTENTIAL IN BENIGN PROSTATIC HYPERPLASIA

Alfuzosin, a new quinazoline derivative, acts as a selective and competitive antagonist of alpha1-adrenoceptor-mediated contraction of prostatic, prostatic capsule, bladder base and proximal urethral smooth muscle, thereby reducing the tone of these structures. Consequently, urethral pressure and resistance, bladder outlet resistance, bladder instability and symptoms associated with benign prostatic hyperplasia are reduced. A limited range of clinical studies have shown oral alfuzosin to be more effective than placebo (in studies of less-than-or-equal-to 6 months' duration), to have sustained effects on long term administration (less-than-or-equal-to 30 months), and to be comparable with the alpha1-adrenoceptor antagonist prazosin, in the symptomatic treatment of benign prostatic hyperplasia. This is reflected in increases in urinary flow rate and decreases in symptom score and residual urinary volume. The most marked improvements occur in patients with severe pretreatment urinary flow abnormalities. Furthermore, preliminary results suggest a beneficial effect of alfuzosin on quality of life in patients with benign prostatic hyperplasia. The overall incidence of adverse effects appears similar to that with placebo, and the incidence of vasodilatory-related adverse effects appears lower than that with prazosin. The relative selectivity of alfuzosin for alpha1-adrenoceptors in the genitourinary tract compared with receptors in the vasculature is a potential advantage over other alpha-adrenoceptor antagonists, including prazosin, as the symptoms of benign prostatic hyperplasia may be reduced by alfuzosin at doses that have minimal vasodilatory effects, thereby minimising postural hypotension and syncope. However, vasodilatory-related adverse effects are the most common adverse effects that occur with alfuzosin, and dose and first-dose hypotensive relationships, especially in the elderly, cannot be excluded at this stage in the clinical use of alfuzosin. The full potential of alfuzosin in the symptomatic treatment of benign prostatic hyperplasia will be clarified by further long term comparative studies (with large patient numbers) against placebo and other al-adrenoceptor antagonists. Nevertheless, oral alfuzosin 7.5 to 10 mg/day in divided doses appears to be a promising first-line agent for symptomatic treatment of noncomplicated mild to moderate benign prostatic hyperplasia in patients with a high dynamic component to their obstruction. In addition, alfuzosin offers an alternative to prostatectomy (the current 'gold standard) in patients who require surgery but are unfit for this treatment, and in patients requiring symptomatic relief while awaiting surgery.