TYK150
Postoperative hypotension following pheochromocytoma resection may be refractory to α-agonists in patients who have been treated with phenoxybenzamine because:
a) Phenoxybenzamine has a prolonged half-life
b) Renal clearance of phenoxybenzamine is significantly reduced in these patients
c) Adrenoreceptor blockade is permanent and new receptors must be generated
d) Residual catecholamines compete with α-agonists at the nerve terminals
e) Volatile agents induce receptor destruction in the presence of phenoxybenzamine
Answer
Answer c.
Phenoxybenzamine is an irreversible, noncompetitive blocker of α- adrenoreceptors. Thus, effects outlast the pharmacokinetic half-life. Postoperative hypotension may be refractory to α-agonists until new receptors are generated.
Notes
- This question originally printed in the Pediatric Anesthesiology Review Topics kindle book series, and appears courtesy of Naerthwyn Press, LLC.
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