Effect of terfenadine on urination

Area of Science:

• Pharmacology
• Urology

Background:

• Anticholinergic effects of antihistamines can worsen urinary difficulties in men with benign prostatic hypertrophy (BPH).
• Newer antihistamines with reduced anticholinergic properties may offer an alternative for allergy relief without impacting voiding.

Purpose of the Study:

• To investigate the effect of terfenadine on voiding characteristics in normal male volunteers and patients with benign prostatic hypertrophy.
• To assess whether terfenadine, a newer antihistamine, exacerbates lower urinary tract symptoms.

Main Methods:

• A randomized, double-blind, placebo-controlled, crossover study was conducted in two phases.
• Phase I involved eight normal male volunteers; Phase II included 11 patients with documented benign prostatic hypertrophy.
• Subjects received terfenadine or placebo for 1 week, followed by a 1-week washout and crossover. Efficacy was assessed via skin testing, and voiding was evaluated using uroflowmetry and symptom assessment.

Main Results:

• Terfenadine effectively suppressed histamine skin test responses in both phases, confirming its antihistaminic efficacy.
• No significant changes in peak urinary flow rate were observed with terfenadine compared to placebo in either normal volunteers or BPH patients.
• Urinary symptom scores remained unchanged throughout the study for all participants.

Conclusions:

• Terfenadine, at the commonly recommended dosage, does not significantly alter voiding characteristics.
• The findings suggest that terfenadine is a safe option for patients with benign prostatic hypertrophy experiencing allergies and seeking relief from urinary difficulties.