Clinical toxicology: part I. Diagnosis and management of common drug overdosage.

OBJECTIVE To review the diagnosis and management of drug overdosage in a two-part presentation. DATA SOURCES A review of articles reported on drug overdose and poisoning. SUMMARY OF REVIEW A patient who has taken an overdose of a common drug often presents with an alteration in neurological, cardiovascular and respiratory functions. The differential diagnosis includes, central nervous system injury and metabolic encephalopathies (e.g. hepatic failure, hyponatraemia, hypocapnia, hypoglycaemia). In general, measures to prevent absorption (e.g. emesis, gastric lavage) or increase excretion (e.g. diuresis, catharsis) of the drug, have not been shown consistently to reduce mortality associated with drug toxicity. However, in selected instances adsorbents (activated charcoal, Fuller's earth), gastric lavage and haemodialysis or continuous renal replacement therapy are useful in the management of drug overdosage and specific antidotes can be recommended for individual poisons. Nevertheless, as the major hazards of an overdose are aspiration, hypoventilation, hypoxia, hypotension and cardiac arrhythmias, the most important aspects in the management of a poisoned patient is the maintenance of the patient's airway, ventilation and circulation, while the drug is excreted. The diagnosis and management of common drug overdoses (e.g sedative, hypnotic, psychoactive, neuroleptic, anticonvulsant, sympathomimetic, analgesic and cardiac drugs) as well as the alcohols are discussed in the first part of this presentation on clinical toxicology. CONCLUSIONS In the critically ill overdosed patient, while activated charcoal, continuous renal replacement therapy and specific antidotes may be of benefit in selected cases, maintenance of the patient's airway, ventilation and circulation still remain the most important aspects of management.