Effect of terazosin hydrochloride in airways of patients with bronchial asthma

<B>Introduction</b>: This study aimed to determine the potential effect of terazosin hydrochloride on bronchodilatation and compare it with the agonist effect of salbutamol in patients with asthma and bronchial hyperreactivity.<br /> <B>Material and methods</b>: Twelve patients with the diagnosis of asthma and increased bronchial hyperreactivity were enrolled in an open label cohort study. We registered the functional pulmonary parameters by body plethysmography, including airway resistance, intrathoracic gas volume and specific resistance in each clinical subject. Terazosin hydrochloride was orally administered in the dosage of 1 mg and 2 mg tablets. <br /> <B>Results</b>: The results of this study performed in patients with bronchial asthma and hyperreactivity showed that the blockade of specific α₁-adrenergic receptors with terazosin hydrochloride (1 mg and 2 mg, oral tablets) did not change significantly (p > 0.1) bronchomotor tone of the tracheobronchial system compared with the group of patients treated with salbutamol (specific agonist of β₂-adrenergic receptors). The arterial blood pressure decreased slightly, but not significantly, after use of 1 mg and 2 mg tablets of terazosin hydrochloride.<br /> <B>Conclusions</b>: The results of the study show that the activity of specific α₁-adrenoreceptors in tracheobronchial smooth muscle tone is not the primary mechanism for bronchorelaxation in patients with increased bronchial reactivity. The antagonism of α₁-adrenoreceptors has a minor impact on the tracheobronchial tone compared with the agonist effect of β₂-adrenergic drugs, which cause a significant decrease in specific resistance of airways.