Effects of alpha1-blockers on urodynamic parameters of bladder outlet obstruction in patients with lower urinary tract symptoms suggestive of benign prostatic enlargement: a review

α1-adrenergic receptors blockers (ABs) are recommended as first-line medical therapy in men with Lower Urinary Tract Symptoms suggestive of Benign Prostatic Enlargement (LUTS/BPE). Available ABs include: terazosin, doxazosin, tamsulosin, naftopidil, alfuzosin and silodosin. These agents have different profiles of selectivity for α1-adrenergic receptors subtypes. All these agents are efficacious in improving both storage and voiding LUTS. In recent years the efficacy of ABs in improving urodynamic parameters of bladder outlet obstruction (BOO) has been questioned. We reviewed literature evidences about the effects of available ABs on invasive urodynamic parameters of BOO in men with LUTS/BPE. The impact of ABs therapy on urodynamic parameters indicative of BOO has been evaluated for all currently approved drugs. Available data demonstrate improvements in terms of both free uroflowmetry and pressure-flow parameters. While the impact of ABs on maximum urinary flow is clinically modest, the improvement of detrusor pressure at maximum urinary flow is more robust. Only few studies exist that directly compare the urodynamic effects of a small number of ABs. According to these studies there are no differences among ABs in terms of urodynamic efficacy. Indirect comparison of ABs suggests greater effectiveness of silodosin in terms of detrusor pressure at maximum urinary flow reduction. Studies that stratified populations based upon the degree of obstruction at baseline demonstrated greater urodynamic changes in patients with baseline BOO with respect to the unobstructed patients. Globally, the quality of studies available is low and there is considerable heterogeneity among studies.