Doxazosin, a new alpha-1-antagonist drug, controls hypertension without causing airways obstruction in asthma and COPD.

The treatment of systemic hypertension in patients with coexisting chronic airflow limitation is difficult. Even a 'cardioselective' beta-blocker potentially can increase airflow limitation. However it is very unlikely that alpha 1 blockers can bronchoconstrict. We have therefore evaluated the efficacy and safety of doxazosin, a new orally active selective alpha 1 blocker, in patients with systemic hypertension with concomitant airflow limitation. We studied 21 patients (11M, 10F) whose diastolic blood pressure was 95-114 mmHg and FEV1 22-73% of predicted. In the 19 patients who completed the study the dose of doxazosin to achieve satisfactory control of the systemic hypertension lay between 1 and 16 mg (mean 6 +/- 3.6 mg). This doxazosin dosage reduced the diastolic blood pressure on average from 103 to 91 mmHg (P = 0.0001). However this produced no significant changes in peak expiratory flow rate (PEFR) over the days of the study (P greater than 0.05). The mean variations in PEFR both 'day to day' (P less than 0.001) and 'within day' (P less than 0.002) were reduced during doxazosin therapy, and FEV1 rose on average from 1.6 to 1.7 (P less than 0.05). We conclude that doxazosin is an effective oral antihypertensive drug, which does not exacerbate pre-existing airflow limitation.