Alpha Adrenergic Agents Flashcards
what do sympatholytic drugs inhibit?
they inhibit the effect of sympathetic pathway of the ANS
what do sympathomimetic drugs do?
they mimic/duplicate the sympathetic effects
what are the 2 mechanisms of sympatholytic agents?
- block the adrenergic rectpors
- reduce the release of norepinephrine from neurons
what MOA do alpha blockers use more?
the firsst mechanism (block the sympathetic adrenergic receptors)
what MOA does a2 agonists use more?
second mechanism (reduce norepinepherine)
where are a1 receptors found?
smooth muscles of the arterioles, the GI tract, urinary sphincters, urethra, prostate gland, and pupillae muscle of the eye
what does agonist of a1 receptor binding cause within the body?
- vasoconstriction
- increased systemic vascular resistance
- increased BP
- urinary retention
- mydriasis
where are a2 receptors found in the body?
the brain (specifically on the presynaptic sympathetic nerves)
what happens when a2 receptors are activated
decreased release of norepinepherine from the neuron (reduce CNS activation)
what is the effect within the body of activating a2 receptors?
- vasodilation
- sedation
what is a pheochromoytoma
a rare neuroendocrine, catecholamine producing tumor found in the adrenal medulla
what symptoms can a pheochromocytoma cause
- hypertensive crisis
- flushing
- tachycardia
what two drug classes are the most common agents for initial management of pheochromocytoma?
phenoxybenzamine and phentolamine
non-selective alpha receptor antagonists
what is unique about phenoxybenzamine
irreversible antagonist resulting in longer/pronounce effects
when is a2 agonists useful?
management of HTN and CNS disorders
