Review Question - QID 220760

Substance Intoxication and Withdrawal Cocaine Mechanism QID: 220760 (M2.OMB.4890)

QID 220760 (Type "220760" in App Search)

A 32-year-old man presents to the emergency department with a 1 hour history of chest pain. He was at a party when he started having the symptoms. He has not had care from a physician since he graduated from college. In the interim, he has been largely unemployed and admits that he has recently been homeless. The patient admits to alcohol and marijuana use but denies illicit drug use. His temperature is 98.7°F (37°C), blood pressure is 157/99 mmHg, pulse is 73/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam reveals an anxious and agitated man with dilated pupils and a perforated nasal septum. An ECG is obtained with the results shown in Figure A. Which of the following describes the mechanism of action of the agent most likely responsible for this patient's presentation?

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Activating the acetylcholine receptor

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Antagonizing the NMDA receptor

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Blocking reuptake of dopamine and norepinephrine

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Inhibiting breakdown of biogenic amines

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Inhibiting the GABA receptor

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This patient, who presents with a perforated nasal septum, hypertension, pupil dilation, and ST-elevation myocardial infarction, most likely has taken cocaine. This drug acts by blocking the reuptake of biogenic amines such as dopamine, norepinephrine, and serotonin.

Cocaine is a stimulant drug that functions by blocking the reuptake of biogenic amines such as dopamine, norepinephrine, and serotonin. Possible symptoms of acute cocaine intoxication include hallucinations, paranoia, angina, and sudden cardiac death. Patients will have hypertension as well as pupillary dilation. Since cocaine is commonly snorted, signs of occlusion of vascular beds in the nose may be seen on exam, including septal perforation. Cocaine use is a common cause of ST-elevation myocardial infarctions in young people because of its adrenergic effects on the heart, combined with its vaso-occlusive effects.

Hollander and Hoffman review the evidence regarding the diagnosis and treatment of cocaine-induced myocardial infarctions. They discuss how this drug can lead to vaso-occlusive events in young patients. They recommend following these patients to ensure they do not have recurrent episodes.

Figure/Illustration A is an ECG that demonstrates ST-segment elevations (black circles). These findings are consistent with a vaso-oclusive event due to the use of cocaine.

Incorrect Answers:
Answer 1: Nicotine is an example of an acetylcholine receptor agonist. Nicotine intoxication may present with restlessness, insomnia, anxiety, and arrhythmias. Patients can present with the sequelae of smoking, such as poor healing and black teeth.

Answer 2: Well-known NMDA receptor antagonists include phencyclidine (PCP) and ketamine. PCP intoxication may present with belligerence, psychosis, psychomotor agitation, and vertical and horizontal nystagmus.

Answer 4: Monoamine oxidase inhibitors inhibit monoamine oxidase family enzymes, which usually break down amines like norepinephrine, dopamine, and serotonin. Monoamine oxidase inhibitor toxicity is generally caused by a reaction with foods containing tyramine, which leads to hypertension, tachycardia, seizures, and hyperthermia.

Answer 5: Flumazenil is a GABA antagonist. This medication is a drug used to treat benzodiazepine overdose. It can trigger seizures in patients who are chronically on benzodiazepines, so it should be used with caution.

Bullet Summary:
Cocaine acts by blocking the reuptake of biogenic amines such as dopamine, norepinephrine, and serotonin.