Isopropyl alcohol is used widely as a solvent, an antiseptic, and a disinfectant and is commonly available in the home as a 70% solution (rubbing alcohol). It is often ingested by alcoholics as a cheap substitute for liquor. Unlike the other common alcohol substitutes methanol and ethylene glycol, isopropyl alcohol is not metabolized to highly toxic organic acids and therefore does not produce a profound anion gap acidosis. Hospitals sometimes color isopropyl alcohol with blue dye to distinguish it from other clear liquids; this has led abusers to refer to it as “blue heaven.”
Mechanism of toxicity
Isopropyl alcohol is a potent depressant of the CNS, and intoxication by ingestion or inhalation may result in coma and respiratory arrest. It is metabolized to acetone (dimethyl ketone), which may contribute to and prolong CNS depression.
Very large doses of isopropyl alcohol may cause hypotension secondary to vasodilation and possibly myocardial depression.
Isopropyl alcohol is irritating to the GI tract and commonly causes gastritis.
Pharmacokinetics. Isopropyl alcohol is well absorbed within 2 hours and quickly distributes into body water (volume of distribution, 0.6 L/kg). It is metabolized (half-life, 3–7 hours) by alcohol dehydrogenase to acetone.
Toxic dose. Isopropyl alcohol is an approximately two- to threefold more potent CNS depressant than ethanol.
Ingestion. The toxic oral dose is about 0.5–1 mL/kg of rubbing alcohol (70% isopropyl alcohol) but varies depending on individual tolerance and whether any other depressants were ingested. Fatalities have occurred after adult ingestion of 240 mL, but patients with ingestions of up to 1 L have recovered with supportive care.
Inhalation. The odor of isopropyl alcohol can be detected at an air level of 40–200 ppm. The recommended workplace limit (ACGIH TLV-TWA) is 400 ppm (983 mg/m3) as an 8-hour time-weighted average. The air level considered immediately dangerous to life or health (IDLH) is 2000 ppm. Toxicity has been reported in children after isopropyl alcohol sponge baths, probably as a result of inhalation rather than skin absorption.
Clinical presentation. Intoxication mimics drunkenness from ethanol, with slurred speech, ataxia, and stupor followed in large ingestions by coma, hypotension, and respiratory arrest.
Because of the gastric-irritant properties of isopropyl alcohol, abdominal pain and vomiting are common, and hematemesis occasionally occurs.
Metabolic acidosis may occur but is usually mild. The osmole gap is usually elevated (See Serum osmolality and osmole gap). The serum creatinine may be falsely elevated (eg, 2–3 mg/dL) owing to interference with the laboratory method.
Isopropyl alcohol is metabolized to acetone, which contributes to CNS depression and gives a distinct odor to the breath (in contrast, methanol and ethylene glycol and their toxic metabolites are odorless). Acetone is also found in nail polish remover and is used widely as a solvent in industry and chemical laboratories.
Diagnosis usually is based on a history of ingestion and the presence of an elevated osmole gap, the absence of severe acidosis, and the characteristic smell of isopropyl alcohol or its metabolite, acetone. Ketonemia and ...