Three policemen, with difficulty, drag an agitated and very combative young man into an emergency room. Once there, he is restrained because he reacts with rage and tries to hit anyone who approaches him. When it is finally safe to approach him, the resident on call notices that the patient has very prominent veical nystagmus. Sholy thereafter, the patient has a generalized seizure. Which of the following substances of abuse is the most likely to produce this presentation?

**Core Concept**
Cocaine is a powerful central nervous system stimulant that can cause a range of severe psychiatric and physical symptoms, especially with chronic or high-dose use. The presentation of violent behavior, followed by nystagmus and seizures, is characteristic of cocaine-induced toxicity.

**Why the Correct Answer is Right**
Cocaine is a potent dopamine and norepinephrine reuptake inhibitor, leading to excessive levels of these neurotransmitters in the brain. This can cause intense euphoria, agitation, and aggression, as seen in the patient's presentation. The subsequent development of nystagmus and seizures is likely due to cocaine's effects on the brain's reward and motor control centers, as well as its ability to disrupt normal neuronal function. The prominent vertical nystagmus, in particular, is a classic sign of cocaine-induced toxicity.

**Why Each Wrong Option is Incorrect**
**Option A:** Amphetamine can also cause agitation and aggression, but it is less likely to produce the specific combination of nystagmus and seizures seen in this case.
**Option B:** PCP (phencyclidine) can cause psychosis, agitation, and aggression, but it is not typically associated with nystagmus or seizures.
**Option D:** Meperidine is an opioid analgesic and is not typically associated with the presentation described.

**Clinical Pearl / High-Yield Fact**
Cocaine-induced toxicity can be unpredictable and rapidly progress to severe symptoms, making prompt recognition and treatment essential. In cases of suspected cocaine-induced seizures, benzodiazepines and sodium bicarbonate may be used to manage seizures and correct acidosis.

**✓ Correct Answer: C. Cocaine**

✓ Correct Answer: C. Cocaine