>>6852344 (PB)
METHANOL TOXICITY
https://en.m.wikipedia.org/wiki/Methanol_toxicity
Methanol toxicity is poisoning from methanol.[1] Symptoms may include a decreased level of consciousness, poor coordination, vomiting, abdominal pain, and a specific smell on the breath.[1][2] Decreased vision may start as early as twelve hours after exposure.[2] Long term outcomes may include blindness and kidney failure.[1] Toxicity and death may occur even after drinking a small amount.[1]
Symptoms
The initial symptoms of methanol intoxication include central nervous system depression, headache, dizziness, nausea, lack of coordination, and confusion. Sufficiently large doses cause unconsciousness and death. The initial symptoms of methanol exposure are usually less severe than the symptoms from the ingestion of a similar quantity of ethanol.[5] Once the initial symptoms have passed, a second set of symptoms arises, from 10 to as many as 30 hours after the initial exposure, that may include blurring or complete loss of vision, acidosis, and putaminal hemorrhages, an uncommon but serious complication.[6][7] These symptoms result from the accumulation of toxic levels of formate in the blood, and may progress to death by respiratory failure. Physical examination may show tachypnea, and ophthalmologic examination may show dilated pupils with hyperemia of the optic disc and retinal edema.
Methanol has a high toxicity in humans
Methanol has a high toxicity in humans. As little as 10 mL of pure methanol when drunk is metabolized into formic acid, which can cause permanent blindness by destruction of the optic nerve. 15 mL is potentially fatal.[1] Although the median lethal dose is typically 100 mL (3.4 fl oz) (i.e. 1–2 mL/kg body weight of pure methanol[8]). Reference dose for methanol is 2 mg/kg/day.[9]
Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase (ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining.[10] Formate is toxic because it inhibits mitochondrial cytochrome c oxidase, causing hypoxia at the cellular level, and metabolic acidosis, among a variety of other metabolic disturbances.[11]
Treatment
Ethanol, the active ingredient in alcoholic beverages, acts as a competitive inhibitor by more effectively binding and saturating the alcohol dehydrogenase enzyme in the liver, thus blocking the binding of methanol. Methanol is excreted by the kidneys without being converted into the very toxic metabolites formaldehyde and formic acid. Alcohol dehydrogenase instead enzymatically converts ethanol to acetaldehyde, a much less toxic organic molecule.[6][14] Additional treatment may include sodium bicarbonate for metabolic acidosis, and hemodialysis or hemodiafiltration to remove methanol and formate from the blood.[6] Folinic acid or folic acid is also administered to enhance the metabolism of formate.[6]