The clinical efficacy and tolerability of doxazosin standard and gastrointestinal therapeutic system for benign prostatic hyperplasia


John Fitzpatrick, University College Dublin, Mater Misericordiae Hospital, Dublin, Ireland.


The therapeutic goal of treating benign prostatic hyperplasia (BPH) through early detection and effective therapy is to relieve the symptoms, improve patients’ quality of life, decrease postvoid residual urine volume, and prevent the associated morbidity when the condition remains untreated. á1-Adrenoreceptor antagonists, e.g. doxazosin, terazosin, tamsulosin and alfuzosin, relax the bladder outlet to improve urinary flow, by reducing prostatic smooth muscle tone through the blockade of sympathetic adrenergic receptors. Doxazosin gastrointestinal therapeutic system (GITS) is a controlled-release formulation developed to enhance the pharmacokinetic profile of the drug while simultaneously minimizing possible adverse effects and reducing the need for dose titration. While both doxazosin standard and GITS are indicated for hypertension, they are also useful in the pharmacologically or naturally normotensive patient with BPH. In a cross-over trial comparing doxazosin GITS and tamsulosin, doxazosin gave a significantly greater improvement from baseline in symptoms. Results from recent trials (e.g. Medical Therapy of Prostatic Symptoms, MTOPS) showed that doxazosin was significantly more effective than the 5á-reductase inhibitor finasteride in relieving lower urinary tract symptoms, irrespective of prostate volume. The MTOPS trial showed clearly that over the long term, the combination of doxazosin and finasteride was more effective than either agent alone in significantly improving symptoms and reducing the clinical progression of BPH. Both doxazosin standard and GITS are well-tolerated, long-term therapies that are equally effective in younger and older men, and not associated with causing sexual dysfunction.