Drugs of Abuse, Withdrawal Syndromes, and Addiction
Intoxication patterns
Sympathomimetics (cocaine, methamphetamine) produce hypertension, tachycardia, diaphoresis, agitation, and seizures; treatment is benzodiazepines, cooling, and sodium bicarbonate for wide-complex rhythms. MDMA adds serotonergic features and, critically, hyponatremia from free-water intake plus SIADH, which can cause seizures and cerebral edema - treat symptomatic hyponatremia with hypertonic saline, not fluid restriction alone. Hallucinogens cause perceptual distortion with preserved orientation; cannabinoids cause conjunctival injection and tachycardia, while synthetic cannabinoids and cathinones produce unpredictable agitation and cardiotoxicity.
Withdrawal syndromes
The withdrawal syndrome is generally the mirror image of intoxication, and timing reflects the drug's half-life.
- Alcohol: tremor and autonomic hyperactivity at 6–24 h, seizures at 12–48 h, delirium tremens at 48–96 h. Benzodiazepines are first-line; give thiamine with glucose; phenytoin does not treat withdrawal seizures.
- Benzodiazepines: onset depends on half-life (days for long-acting agents); taper slowly.
- Opioids: lacrimation, rhinorrhea, yawning, piloerection, diarrhea, mydriasis; unpleasant but rarely lethal. Clonidine or buprenorphine.
- GHB: abrupt autonomic and psychiatric withdrawal requiring high-dose benzodiazepines.
Traps
Confusing serotonin syndrome, neuroleptic malignant syndrome, and anticholinergic toxicity; assuming a negative urine screen excludes use; attributing seizures to withdrawal when hypoglycemia or meningitis is the cause; and using antipsychotics as first-line sedation in stimulant toxicity.
Rule of thumb: match the withdrawal timeline to the drug's elimination half-life - the shorter the half-life, the earlier and more intense the syndrome.