α₁-Adrenoceptor antagonists are useful antihypertensive agents for patients with hypertension who have hyperlipidemia, benign prostatic hyperplasia, or pheochromocytoma. The purpose of this study was to evaluate the effect of the α₁-adrenoceptor antagonist, doxazosin mesilate, on cerebral blood flow (CBF) and flow velocity in the common carotid artery in patients with hypertension and chronic cerebral infarction.
Doxazosin mesilate (1 mg/day) was orally administered for 4 to 8 weeks to 7 patients with hypertension 4 weeks after the onset of cerebral infarction. We determined blood pressure, heart rate, CBF measured with autoradiography single photon emission computed tomography (SPECT) with N-isopropyl-p-[¹²³I] iodoamphetamine (¹²³I-IMP) as a tracer, and the maximum, minimum and mean flow velocities in the common carotid arteries measured with duplex carotid ultrasonography before and 4 to 8 weeks after the beginning of treatment. Mean CBF was defined as the mean count of tracer from the 8 regions of interest (ROIs) in the frontal, parietal, occipital, and temporal cortices of the cerebral hemisphere. Values were analyzed with paired t tests.
With administration of doxazosin mesilate, systolic pressure significantly decreased from 152 ± 11 to 137 ± 7 mmHg (p<0.01), but diastolic pressure and heart rate were unchanged. Mean CBF was improved significantly from 32.0 ± 4.1 to 34.7 ± 4.1 mL/100 g brain/min (p<0.01) in the ipsilateral cerebral cortex and from 32.6 ± 6.2 to 36.2 ± 5.1 mL/100 g brain/min (p<0.05) in the contralateral cerebral cortex. The maximum, minimum, and mean flow velocities in the bilateral common carotid arteries were not changed significantly.
In the present study, the improvement of mean CBF in the ipsilateral and contralateral cerebral cortices was demonstrated in patients with hypertension and chronic cerebral infarction after the treatment with doxazosin mesilate. Doxazosin mesilate might be an effective antihypertensive agent for hypertensive chronic cerebral infarction.