A 47-year-old man with major depressive disorder started phenelzine 45 mg daily one month ago. He presents to the ED with severe occipital headache, chest pain, and diaphoresis after consuming aged cheese at dinner. Vital signs show BP 210/130 mmHg, HR 118/min, RR 20/min, temperature 37.8°C, and SpO2 98% on room air. Physical examination reveals bilateral mydriasis and profuse diaphoresis. Serum potassium is normal, and urine catecholamines are markedly elevated. ECG shows sinus tachycardia without ischemic changes. Which mechanism best explains this hypertensive crisis?
- A)Enhanced serotonin reuptake in the CNS causing systemic vasoconstriction
- B)Inhibition of acetylcholinesterase leading to parasympathetic overstimulation
- C)Direct α-adrenergic receptor stimulation by tyramine metabolites
- D)Competitive antagonism of adrenergic receptors producing reflex sympathetic activation
- E)Tyramine-induced norepinephrine release from sympathetic neurons, unopposed by normal MAO metabolismGABARITO
Explicação
MAOIs inhibit monoamine oxidase, the enzyme responsible for degrading tyramine and other trace amines. Tyramine normally enters sympathetic neurons via the tyramine transporter and is rapidly metabolized by intracellular MAO. In patients taking MAOIs, tyramine... Ver explicação completa e trilha adaptativa →