SALICYLATE POISONING

Overview

Contained in aspirin, sodium salicylate, methyl salicylate, oil of wintergreen
Found in analgesic products (also in keratolytics and heat rubs)
Chronic toxicity frequently missed diagnosis (up to 50%)
Mortality/Morbidity - particularly high if untreated
Appropriate treatment involves good supportive care, adequate re-hydration with urinary alkalisation and potassium replacement

	ACUTE TOXICITY	CHRONIC TOXICITY
Epidemiology	Accidental ingestion in children Suicide attempts in adults	Accidental in the elderly with rheumatological conditions (decreased renal function, large Vd, decreased protein, often dehydrated, poor nutrition)
Chronology	may be preceded by relatively asymptomatic period	often gradual and insidious (ingestion over > 12 hrs)
Symptoms	Initial Anorexia, nausea and vomiting Tinnitus and decreased hearing (early) Hyperpnea/respiratory alkalosis Hyperglycaemia Later Metabolic acidosis Hyperthermia	Memory loss/mental status changes - lethargy, disorientation, and hallucinations
Differential Diagnosis	Theophylline/Caffeine toxicity Acute iron poisoning Reye’s syndrome Diabetic ketoacidosis Sepsis Meningitis	Acute myocardial infarction Encephalitis Stroke Ketoacidosis.
Salicylate levels	>40 mg/dL or 2.3 mmol/L is toxic	Correlates poorly with clinical effects
Treatment	Treat if symptomatic or > 150mg/kg or > 40mg/dL	Treat on symptoms
Mortality	1%	25%

COMPLICATIONS

Dehydration (may be severe in chronic toxicity)
Hypo-natraemia
Hypo-kalaemia
Hypo-calcaemia/Seizures/Tetany
Seizures, Cerebral oedema, Coma, and Death
Coagulopathy
Pylorospasm, decreased gastro intestinal motility (acute)
Gastric erosions, Iron deficiency anaemia (in chronic)
ARDS (chronic severe toxicity)
Renal tubular damage (rare)
Haemolysis (rare)

HYPERSENSITIVITY

Bronchospasm, hypotension
Rhinitis, Nasal polyps (chronic)

ASSESSMENT

Confirm ingestion

Ferric chloride test - Add few drops of 10% ferric chloride1 ml to patient's urine (brown purple = salicylate)

Estimate severity

Type, Amount, Time of ingestion, Chronicity

Acute toxicity likely with > 150 mg/kg (4ml of oil wintergreen)

Large overdose has prolonged peak effect

Serum levels/Ingested Dose

Dose (mg/kg)

Serum Level (mg/dL)

Estimated Severity

Clinical Features

<150

<40
Minimal GIT intolerance, bleeding
Hypersensitivity
Acute gout

150-300

40-110
Mild-to-moderate Tinnitus, deafness, vertigo
Nausea & vomiting, dehydration
Fever
Hyperventilation
Respiratory alkalosis/Metabolic acidosis

300-500

110-160
Serious Circulatory collapse
Coma
Coagulopathy

>500

>160
Potentially lethal cerebral oedema

Complicating issues

Co-ingestants (inhibits respiratory compensation of metabolic acidosis)

Complicating medical conditions (chronic renal failure => early dialysis)

Pregnancy (fetus at risk)

See Treatment of salicylate poisoning

See Basic Pharmacology of Salicylates

See Toxicology of Salicylates

Dose (mg/kg)	Serum Level (mg/dL)	Estimated Severity	Clinical Features
<150	<40	Minimal	GIT intolerance, bleeding Hypersensitivity Acute gout
150-300	40-110	Mild-to-moderate	Tinnitus, deafness, vertigo Nausea & vomiting, dehydration Fever Hyperventilation Respiratory alkalosis/Metabolic acidosis
300-500	110-160	Serious	Circulatory collapse Coma Coagulopathy
>500	>160	Potentially lethal	cerebral oedema