Objectives: This randomised, double-blind, placebo-controlled, 8-week exploratory study was designed to assess the effect of the new formulation of tamsulosin (oral controlled absorption system: OCAS) on nocturia, the hours of undisturbed sleep and quality of life in patients with LUTS/BPH. Methods: After a two-week single-blind, placebo run-in period, older men (greater than or equal to45 years) with lower urinary tract symptoms (LUTS: total International Prostate Symptom Score (I-PSS) greater than or equal to13) suggestive of benign prostatic hyperplasia (BPH: maximum flow rate 4-12 ml/s) and greater than or equal to2 nocturnal voids per night were randomised to 8 weeks of treatment with placebo or tamsulosin OCAS 0.4 mg once daily in a 1:1 ratio. The primary efficacy variable was the mean change from baseline to endpoint in mean hours of undisturbed sleep, defined as the time from falling asleep to the first awakening to void. Nocturnal voids, I-PSS nocturia sub-score and quality of life were also assessed. The relationship between improvement of nocturia and hours of undisturbed sleep, nocturia and quality of life, and hours of undisturbed sleep and quality of life were investigated. Tolerability was mainly assessed by documenting adverse events (AEs) reported by the patient. Results: A total of 117 patients were randomised to placebo (N = 56) and tamsulosin OCAS 0.4 mg (N = 6 1). The mean increase in Hours of Undisturbed Sleep (HUS) from baseline was 60 minutes for placebo and 82 minutes for tamsulosin OCAS (p = 0.198). The mean decrease in number of nocturnal voids from baseline was 0.7 for placebo and 1.1 for tamsulosin OCAS (p = 0.099). The mean reduction in total I-PSS score was statistically significant different with 8.0 points for tamsulosin OCAS and 5.6 points for placebo (p = 0.0099). The decrease in I-PSS nocturia score for tamsulosin OCAS was 1.0 points and for placebo 0.7 points, this difference was stastically significant (p = 0.028). The improvement of QoL was statistically significant different between tamsulosin OCAS and placebo with a reduction in score of 2.0 and 1.3 respectively (p = 0.0087). A reduction in the number of nocturnal voids correlated with an increase in hours of undisturbed sleep (Spearman coefficient -0.63) and a reduction of I-PSS nocturia correlated with an improvement in the I-PSS QoL (Spearman coefficient 0.64). The two most frequently reported AEs were dizziness (3.3% in the tamsulosin OCAS group and 0% in placebo group) and nasopharingitis (0% in the tamsulosin OCAS group and 3.6% in placebo group). No cases of orthostatic hypotension were reported. A total of 18 treatment-emergent adverse events were reported, 8 in the tamsulosin OCAS group and 10 in the placebo group. No patients were withdrawn due to AEs. Conclusions: Tamsulosin OCAS 0.4 mg is efficacious in the treatment of nocturia in LUTS/BPH. An improvement in nocturia. increase of the hours of undisturbed sleep and improvement in the I-PSS QoL were observed. This exploratory stud), confirms the relationship between the treatment of one of the most bothersome symptoms of LUTS/BPH with tarnsulosin OCAS 0.4 mg and an improvement in the hours of undisturbed sleep and QoL. (C) 2004 Elsevier B.V. All rights reserved.