Effects of branded versus generic terazosin hydrochloride in adults with benign prostatic hyperplasia: a randomized, open-label, crossover study in Taiwan.

BACKGROUND

Terazosin is an alpha1-selective adrenoceptor blocking agent that has been reported in many clinical trials to be an effective choice for the treatment of benign prostatic hyperplasia (BPH). To improve cost-effectiveness, the development of an effective and well-tolerated generic formulation is needed.

OBJECTIVE

The aim of this study was to compare the efficacy and tolerability of branded versus generic terazosin hydrochloride in adult patients with symptomatic BPH in Taiwan.

METHODS

This randomized, open-label, 2-sequence, 2-period crossover study was conducted at the Urological Clinic, National Cheng Kung University Medical Center, Taman, Taiwan. Men newly diagnosed with symptomatic BPH who had not previously received treatment for BPH were recruited between August 2002 and April 2006. Patients were randomly assigned to 1 of 2 treatment sequences. Group A received generic terazosin during period 1 (6 weeks) and branded terazosin in period 2 (6 weeks); group B received the branded drug during period 1 and the generic during period 2. The 2 study periods were separated by a 1-week washout period. All treatments were given by mouth once daily (bedtime) at an initial dosage of 2 mg/d for the first 2 weeks. At the week-2 study visit in each treatment period, the dosage could be increased to 4 mg/d or decreased to 1 mg/d based on each patient's response and experience of adverse effects (AEs), based on the opinion of the investigator. Efficacy variables included the total score on the International Prostate Symptom Scale (IPSS), a 7-item instrument used to assess objective lower urinary tract symptoms, including quality of life. IPSS was measured at baseline and weeks 2 and 6 of each treatment period, and maximal and mean uroflow rates, measured at baseline and week 6. Tolerability was assessed at each time point using physical examination, including vital signs; laboratory analysis; and spontaneous reporting.

RESULTS

Fifty-three patients were randomized; 43 were included in the efficacy analysis (mean [SD] age, group A, 64.5 [7.7] years and group B, 62.9 [8.2] years; mean [SD] weight, group A, 66.4 [7.2] kg and group B, 67.1 [8.9] kg; all patients were Taiwanese). At 2 and 6 weeks, no significant between-product differences were found in mean (SD) decreases from baseline in IPSS total score (generic, 2.46 [0.84] and 2.46 [1.00], respectively; branded, 1.56 [0.60] and 2.87 [0.71]). At week 6, the between-product difference in mean increase from baseline in maximal uroflow rate was nonsignificant (generic, 2.36 [0.90] mL/s; branded, 2.03 [0.62] mL/s). A total of 86 treatment-emergent AEs were reported (45 with the generic drug; 41 with the branded drug), all of which were considered by the investigator as nonserious except for 1 case of acute epididymitis, which occurred with the generic drug. The most common AEs reported with the generic and branded formulations were dizziness (7/48 [14.6%] and 10/50 [20.0%], respectively) and peripheral edema (1/48 [2.1%] and 3/50 [6.0%]). No significant differences in the prevalences of AEs were found between the 2 treatments.

CONCLUSION

In this group of Taiwanese patients with symptomatic BPH, the efficacy and tolerability of generic terazosin were similar to those of branded terazosin.