Which medications in the drug class Alpha2-agonists, Central-acting are used in the treatment of Hypertension?

Updated: Feb 22, 2019
  • Author: Matthew R Alexander, MD, PhD; Chief Editor: Eric H Yang, MD  more...
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Answer

Alpha2-agonists, Central-acting

Centrally acting alpha2-agonists stimulate presynaptic alpha2-adrenergic receptors in the brain stem, which reduces sympathetic nervous activity.

Methyldopa

Methyldopa stimulates central alpha-adrenergic receptors by a false transmitter, exerting a direct effect on peripheral sympathetic nerves. Decreases in blood pressure are greatest when the patient is standing but are also significant when the patient is supine. Postural hypotension has been reported in patients receiving methyldopa. Methyldopa is not associated with a rebound effect, as with clonidine.

Clonidine (Catapres)

Clonidine stimulates alpha2-adrenoreceptors in the brain stem, activating an inhibitory neuron, which in turn results in reduced sympathetic outflow. These effects result in a decrease in peripheral resistance, renal vascular resistance, blood pressure, and heart rate. Clonidine can be used alone or in combination with other antihypertensives. Clonidine is associated with a rebound effect, especially at higher doses or with more severe hypertension.

Guanfacine (Tenex)

Guanfacine is an orally active antihypertensive agent whose principal mechanism of action appears to be stimulation of central alpha-2 adrenergic receptors. By stimulating these receptors, guanfacine reduces sympathetic nerve impulses from the vasomotor center to the heart and blood vessels. This results in a decrease in peripheral vascular resistance and a reduction in heart rate. Guanfacine may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.


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