title: Advantages and disadvantages of alpha 2-adrenoceptor agonists for systemic hypertension.
abstract: Alpha 2-receptor agonists are effective antihypertensive drugs that reduce sympathetic activity by both central and peripheral mechanisms. Plasma noradrenaline and renin concentrations are reduced. Hemodynamic disturbances are minor with a near-normal cardiovascular response to standing, exercise and volume depletion. The main problems are due to central adverse effects, particularly sedation, and a syndrome of sympathetic overactivity on sudden withdrawal. These problems can be minimized by using lower doses, while therapy with a useful antihypertensive drug is maintained. Clonidine and its analogs have a low toxicity and very few contraindications. They remain a useful part of the therapeutic armamentarium in hypertension.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D003000:Clonidine / Q000627:therapeutic use; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D013375:Substance Withdrawal Syndrome / Q000209:etiology
chemical_list: D000318:Adrenergic beta-Agonists; D000959:Antihypertensive Agents; D003000:Clonidine