Ephedrine Mixed Tachyphylaxis — FRCA Primary MCQ
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Correct answer: B — It has mixed direct and indirect sympathomimetic actions with tachyphylaxis due to depletion of noradrenaline stores
Ephedrine has mixed direct (alpha and beta agonism) and indirect (noradrenaline release from presynaptic terminals) sympathomimetic actions. It increases HR / BP / and CO. Tachyphylaxis occurs with repeated doses due to depletion of presynaptic noradrenaline stores. It crosses the BBB causing CNS stimulation.
Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care