0071643192.pdf

PSYCHOBEHAVIORAL DISORDERS

EFFECTS OF SELECTED PSYCHOTROPIC MEDICATIONS

A 55-year-old woman with a history of depression treated with phenelzine

presents to the ED after drinking Chianti wine at dinner. What is the hallmark

symptom of the tyramine reaction?

Severe occipital or temporal headache.

Monoamine Oxidase Inhibitor (MAOI) Toxicity

Monoamine oxidase (MAO) is a major enzyme in the metabolism of nor-
epinephrine, dopamine, and serotonin. MAO also decreases the availability of
absorbed dietary biogenic amines (tyramine) in the body via hepatic and
intestinal metabolism (see Table 16.9).

TABLE 16.9. MAOI Toxicity

TOXICITY ONSET SYMPTOMS/EXAM DIFFERENTIAL TREATMENT

MAOI Can be Agitation, mydriasis, Symphatomimetic ■Activated charcoal/ gastric lavage

overdose delayed rigidity, hyperthermia, or PCP intoxication, for overdose

up to coma, hyperreflexia, alcohol or sedative ■Supportive care

24 hr nystagmus, seizures, withdrawal, CVA, ■Phentolamine and nitroprusside

tachycardia, hypertension; ICH, meningitis, for severe hypertension.

can cause hypotension encephalitis, ■Nifedipine or prazosin for moderate

and bradycardia if severe serotonin syndrome, hypertension.

neuroleptic malignant ■Lidocaine for ventricular arrhythmias

syndrome, heat ■Avoid β-blockers and Ca channel

stroke, acute blockers (unopposed αreceptor

coronary stimulation, can also worsen

syndrome (ACS), hypotension and bradycardia).

pheochromocytoma, ■IV fluids for rhabdomyolysis

thyroid storm, ■Dantrolene for life-threatening

malignant hyperthermia.

hyperthermia. ■Benzodiazepines for agitation

■Observe for 4—6 hr, admit for those

with persistent symptoms.

Tyramine 15—90 min Rapid onset of severe occipital/ Same as for MAOI Same as for MAOI overdose

reaction after temporal headache, overdose

ingestion hypertension, diaphoresis,

mydriasis, neck stiffness,

neuromuscular excitation,

palpitations, chest pain.

MAOI Minutes to MAOI have interactions Same as for MAOI Same as for MAOI overdose

drug hours with multiple drugs, namely, overdose

interaction Meperidine, dextromethorphan,

tramadol, and SSRI can

precipitateserotonin syndrome

Complications of MAOI toxicity,

although rare, include

intracranial hemorrhage and

myocardial infarction. Do a

head CT for persistent, severe

headache or focal neurological

findings, and an ECG on all

patients with chest pain!