A 27-year-old, previously healthy man suddenly collapses at a party where both legal and illicit drugs are being used. En route to the hospital, he requires resuscitation with defibrillation to establish a normal cardiac rhythm. On physical examination, his temperature is 40deg C; respirations, 30/ min; heart rate, 110/min; and blood pressure, 175/90 mm Hg. He has dilated pupils, a perforated nasal septum, and a prominent callus on the right thumb. CT scan of the head shows an acute right frontal lobe hemorrhage. Which of the following substances is most likely responsible for these findings?

Cocaine is a powerful vasoconstrictor and has various vascular effects, including ischemic injury to the nasal septum following the route of administration, which is inhalation in this case. Many complications result from the cardiovascular effects, which include arterial vasoconstriction with ischemic injury to the heart, arrhythmias, and central nervous system (CNS) hemorrhages. Hyperthermia is another complication with "excited delirium" in some cases of cocaine intoxication. The callus is caused by flicking a lighter for use of a crack cocaine pipe. Amphetamines are CNS stimulants. Barbiturates are CNS depressants. Acute ethanolism may lead to CNS depression, but it does not have serious immediate cardiac effects. Opiates can depress CNS and respiratory function, and heroin may produce acute pulmonary edema. Marijuana (with active agent delta-9-tetrahydrocannabinol) has no serious acute toxicities. Phencyclidine (PCP) produces acute toxicity that mimics psychosis.