Isopropyl alcohol is a clear, colorless liquid with a bitter taste used widely as a solvent, an antiseptic, and a disinfectant. It is commonly available in the home as a 70% solution (rubbing alcohol), and may be ingested by alcoholics as a cheap ethanol substitute. Unlike methanol and ethylene glycol, isopropyl alcohol is not metabolized to highly toxic organic acids and therefore does not produce a profound anion gap acidosis.

1. Isopropyl alcohol is a potent depressant of the CNS. 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.
2. Very large doses of isopropyl alcohol may cause hypotension secondary to vasodilation and possibly myocardial depression.
3. Isopropyl alcohol is irritating to the GI tract and commonly causes gastritis.
4. Chronic inhalation of isopropyl alcohol can cause respiratory tract irritation. Chronic exposure has also been associated with elevated hepatic transaminases, dementia, cerebellar dysfunction, and myopathy.
5. Pregnancy. Isopropyl alcohol crosses the placenta and is associated with decreased birth weight in animals.
6. Pharmacokinetics. Isopropyl alcohol is rapidly absorbed with peak levels 30 minutes after ingestion. It can also be absorbed dermally and by inhalation. It has a volume of distribution approximating body water (0.6 L/kg), and is metabolized by alcohol dehydrogenase to acetone (half-life 2.5-8 hours). Up to 20% is excreted unchanged in the urine.

Isopropyl alcohol is approximately two to threefold more potent than ethanol.

1. 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 CNS depressants are ingested. Fatalities have occurred after adult ingestion of 240 mL, but patients with ingestions of up to 1 L have recovered with supportive care.
2. Inhalation. The odor of isopropyl alcohol can be detected at an air level of 40-200 ppm. The OSHA Permissible Exposure Limit (PEL) 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 2,000 ppm. Toxicity has been reported in children after isopropyl alcohol sponge baths, probably as a result of inhalation rather than skin absorption.

Intoxication mimics drunkenness from ethanol with slurred speech, ataxia, and stupor followed by coma, hypotension, and respiratory arrest in large ingestions.

1. Because of the gastric-irritant properties of isopropyl alcohol, abdominal pain and vomiting are common, and hematemesis may occur.
2. Metabolic acidosis may occur but is usually mild. The osmol gap is usually elevated. The serum creatinine may be falsely elevated owing to interference with certain laboratory methods (specifically the Jaffe method).
3. 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. Acetone is metabolized through several organic acid intermediates, which may explain the occasional report of anion gap metabolic acidosis after acute isopropyl alcohol poisoning.

Usually is based on a history of ingestion and the presence of an elevated osmol gap, the absence of severe acidosis, and the characteristic smell of isopropyl alcohol or its metabolite, acetone. Ketonemia and ketonuria may be present within 1-3 hours of ingestion.

1. Specific levels. Serum isopropyl alcohol and acetone levels are usually available from commercial toxicology laboratories. The serum level may also be estimated by calculating the osmol gap (see Table I-22). Isopropyl alcohol levels higher than 150 mg/dL usually cause coma, but patients with levels up to 560 mg/dL have survived with supportive care and dialysis. Serum acetone concentrations may also be elevated.
2. Other useful laboratory studies include electrolytes, glucose, BUN, creatinine (may be falsely elevated), serum osmolality and osmol gap, and blood gases or pulse oximetry, and urinalysis for ketones.

1. Emergency and supportive measures
   1. Maintain an open airway and assist ventilation if necessary. Administer supplemental oxygen if needed.
   2. Treat coma, hypotension, and hypoglycemia (p 37) if they occur.
   3. Admit and observe symptomatic patients for at least 6-12 hours.
2. Specific drugs and antidotes. There is no specific antidote. Fomepizole or ethanol therapy is not indicated because isopropyl alcohol does not produce toxic organic acid metabolites.
3. Decontamination. Because isopropyl alcohol is absorbed rapidly after ingestion, gastric-emptying procedures are not likely to be useful if the ingestion is small (a swallow or two) or if more than 30 minutes has passed. For a large, recent ingestion, consider performing aspiration of gastric contents with a small, flexible tube.
4. Enhanced elimination
   1. Hemodialysis effectively removes isopropyl alcohol and acetone but is rarely indicated because most patients can be managed with supportive care alone. Dialysis should be considered when levels are extremely high (eg, >400-500 mg/dL), if hypotension does not respond to fluids and vasopressors, and in acute renal failure.
   2. Hemoperfusion, repeat-dose charcoal, and forced diuresis are not effective.