title: Acute and chronic haemodynamic effects of doxazosin in hypertension at rest and during exercise.
abstract: The acute and chronic haemodynamic effects of doxazosin were studied in 14 patients (10 males, four females) with essential hypertension, at rest supine and sitting and during 100 W bicycling exercise. Blood pressure (BP) was recorded intra-arterially in the brachial artery, cardiac output (CO) was measured by Cardiogreen and heart rate (HR) by ECG. One hour after injection of doxazosin 0.5-1.0 mg i.v., mean arterial pressure (MAP) was reduced by 8% at rest supine, 12% at rest sitting and 10% at 100 W (all changes statistically significant), associated with a reduction in total peripheral resistance index (TPRI) of 5% at rest supine, 9% at rest sitting (P less than 0.01) and 14% at 100 W (P less than 0.001). HR was slightly increased (5%, NS) and cardiac index (CI) was unchanged during rest and slightly increased during exercise (4%, P less than 0.05). Patients were then given doxazosin capsules (2-16 mg once daily), aiming at a casual BP of less than or equal to 140/90 mmHg without side-effects. Central haemodynamics were restudied after 1 year. After 1 year of doxazosin treatment, MAP was reduced by 13% at rest supine, 16% at rest sitting and 17% at 100 W (all P-values less than 0.001). TPRI was reduced by 19% at rest supine, 20% at rest sitting and 18% at 100 W (all changes statistically significant). CI was increased by 8% at rest supine (P less than 0.05) but was unchanged sitting and at 100 W. It is concluded that doxazosin lowers BP through a reduction in TPRI acutely as well as chronically, without reductions in CO. BP control was maintained over 1 year without side-effects. Thus, doxazosin normalizes central haemodynamics in patients with mild to moderate essential hypertension, both at rest and during exercise.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D017292:Doxazosin; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D011224:Prazosin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D000959:Antihypertensive Agents; D017292:Doxazosin; D011224:Prazosin