It stimulates the alpha adrenal receptors in the brainstem, reduces the outflow of sympathetic nerves from the central nervous system, and reduces peripheral resistance, renal vascular resistance, heart rate, and blood pressure. It takes effect relatively quickly, and blood pressure reduction begins within 30-60 minutes after oral administration, and the maximum effect is achieved within 2-4 hours. Renal blood flow and glomerular filtration rate remain basically unchanged, and upright symptoms are mild and rare. Acute studies have shown that cardiac output is appropriately reduced (15%-20%) in the supine position, and peripheral resistance remains unchanged; cardiac output is slightly reduced when tilted at 45°, and peripheral resistance is reduced. During long-term treatment, cardiac output tends to return to control values, while peripheral resistance remains reduced.

Not yet clear

Extract from the above information

It stimulates brainstem α-adrenergic receptors, reduces sympathetic nerve impulses from the central nervous system, reduces peripheral resistance, renal vascular resistance, heart rate and blood pressure; basically maintains renal blood flow and glomerular filtration rate unchanged; reduces plasma renin activity, aldosterone and catecholamine secretion; strongly stimulates the release of growth hormone in children and adults, but long-term use does not cause a chronic increase in growth hormone.