special subjects
Cocaine
Pathophysiology ofCocaineIntoxication
Cocaine, an alkaloid present in the leaves of the coca plant, enhancesnorepinephrine,dopamine, and serotonin activity in the central and peripheral nervous systems by blocking the reuptake of biogenic amines. Enhancement ofdopamineactivity is the likely cause of the drug’s intended effects and thus of the reinforcement that contributes to developing abuse and dependence. Norepinephrineactivity accounts for the sympathomimetic effects: tachycardia, hypertension, mydriasis, diaphoresis, and hyperthermia. Cocainealso blocks sodium channels, accounting for its action as a local anesthetic and arrhythmogenic.Cocainecauses vasoconstriction and thus can affect almost any organ. Myocardial infarction, cerebral ischemia and hemorrhage, aortic dissection, intestinal ischemia, and renal ischemia are possible sequelae. Onset ofcocaine’s effects depends on mode of use: IV injection and smoking: Immediate onset, peak effect after about 3 to 5 minutes, and duration of about 15 to 20 minutes Intranasal use: Onset after about 3 to 5 minutes, peak effect at 20 to 30 minutes, and duration of about 45 to 90 minutes Oral use: Onset after about 10 minutes, peak effect at about 60 minutes, and duration of about 90 minutes Becausecocaineis such a short-acting drug, heavy users may inject it or smoke it repeatedly every 10 to 15 minutes. Cocaine can adversely affect the 