Volatile Screen, plasma or serum

Alcohols represent one of the most widely abused group of substances encountered in the emergency department and toxicology laboratory.

Ethanol is the most often used and abused chemical substance. The primary route of ingestion is oral. Ethanol reaches its peak concentration 30 - 60 minutes after ingestion. Although some ethanol is absorbed while in the stomach, the principle site of absorption is the upper portion of the small intestine. Ethanol is primarily metabolized in the liver. Toxic symptoms of acute ethanol intoxication include: CNS depression, flushed skin, hypothermia, tachycardia, respiratory depression, diuresis, loss of behavior inhibitions, hypoglycemia and loss of fine motor control. 

Methanol (Wood Alcohol) is used as a solvent in a number of commercial products, as a constituent of antifreeze and window cleaning fluids and as a component of canned fuel. The CNS effects of methanol are substantially less severe than that of ethanol. Methanol is metabolized in the liver by alcohol dehydrogenase (at about 1/10th the rate of ethanol) to formaldehyde. The formaldehyde is rapidly oxidized by aldehyde dehydrogenase to formic acid. Formic acid may cause severe metabolic acidosis and optic neuropathy, resulting in blindness or death. Isopropanol (Rubbing Alcohol) is readily available to the general population as a 70 per cent solution to be used as a disinfectant. It has about twice the CNS depressant activity as ethanol, but it is less toxic than methanol. Isopropanol has a relatively short half-life of three to six hours and is rapidly metabolized in the liver by alcohol dehydrogenase to acetone. 

Acetone may be present in a patients system as the result of isopropanol ingestion (above), accidental ingestion (nail polish remover) or as a result of ketone body formation as seen in prolonged starvation or uncontrolled diabetic ketoacidosis. Acetone has CNS depressant activity similar to that of ethanol.