Drugs of Abuse and Alcohols
Sympathomimetics and club drugs
Cocaine and amphetamines cause hypertension, tachycardia, diaphoresis, mydriasis, agitation, hyperthermia, seizures, and acute coronary syndrome. Give benzodiazepines first; for cocaine-associated ACS use nitroglycerin, calcium-channel blockers, and phentolamine, and avoid unopposed beta-blockade. Sodium bicarbonate treats QRS widening from cocaine's sodium-channel blockade. MDMA adds hyponatremia (SIADH plus free-water intake) and serotonin syndrome. GHB produces abrupt sedation and a withdrawal syndrome requiring high-dose benzodiazepines.
Opioids
Miosis, respiratory depression, and CNS depression form the classic triad. Titrate naloxone to respiration, remembering its shorter half-life relative to methadone and fentanyl analogs, so infusion or extended observation is required. Body packers with suspected cocaine packets need surgical consultation for obstruction; do not give laxatives to a symptomatic packer.
Alcohols
Ethanol: zero-order metabolism (~15–20 mg/dL/hour), osmolar gap early, hypoglycemia in children; treat with dextrose and thiamine. Methanol: osmolar gap then anion-gap acidosis from formic acid, visual loss, putaminal necrosis; fomepizole, folinic acid, and hemodialysis. Ethylene glycol: oxalate crystals, hypocalcemia, renal failure, anion-gap acidosis, osmolar gap; fomepizole, pyridoxine, thiamine, dialysis. Isopropanol: hemorrhagic gastritis, acetone, ketosis without significant acidosis; supportive care.
Traps
The osmolar gap normalizes late in methanol or ethylene glycol poisoning once metabolism is complete - a normal gap does not exclude the diagnosis. Ethanol can substitute for fomepizole when unavailable. Never delay treatment awaiting methanol or ethylene glycol levels.
Worked example
Visual snow, anion-gap acidosis, and an osmolar gap after drinking homemade spirits: give fomepizole immediately, start folinic acid, and arrange hemodialysis based on pH and level.