Centrally Acting Alpha2 Adrenergic Agonist Therapy

Centrally acting alpha2 adrenergic agonists are medications that are primarily used to treat hypertension. There are 3 centrally acting alpha2 adrenergic agonists: clonidine, methyldopa, and guanfacine.

Okay, so normally, neurons in the brainstem carry signals to the spinal cord, where they release the neurotransmitter norepinephrine, which stimulates the sympathetic nervous system, or SNS. This triggers actions like an increase in heart rate and blood pressure, and vasoconstriction.

Now, alpha2 adrenergic agonists, like clonidine, work by selectively stimulating alpha2 receptors in the brainstem which then activate inhibitory neurons that oppose the SNS. This results in reduced sympathetic outflow to the heart and blood vessels, promoting vasodilation, decreased heart rate, decreased blood pressure, as well as decreased cardiac output.

Alright, common side effects of clonidine can include CNS depression, bradycardia, and hypotension. Xerostomia, also known as dry mouth, is common but this usually decreases after 2 to 4 weeks of therapy. And rarely, nausea, taste changes, anorexia, loss of appetite, and even heart failure can occur.