Metabolic acidosis and visual damage occurs in poisoning due to:
Ans: A (Methanol) Ref: The Essentials of Forensic Medicine and Toxicology by KS Naravan Reddy. 29th edition. 2010. Pg: 521Explanation:Methyl alchohol (Methanol) PoisoningMethanol has a high toxicity in humans.The median lethal dose is typically 100 mLMethanol is toxic by two mechanisms.- Methanolcan be fatal due to its CNS depressant properties in the same manner as ethanol poisoning.- In a process of toxication. it is metabolized to formic acid (which is present as the formate ion) via formaldehyde in a process initiated by the enzyme alcohol dehydrogenase in the liver.Methanol is converted to formaldehyde via alcohol dehydrogenase <ADH> and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase (ALDH).Formate is toxic because it inhibits mitochondrial cytochrome c oxidase, causing the symptoms of hypoxia at the cellular level, and metabolic acidosis.Methanol poisoning can be treated with the antidotes ethanol or fomepizoleBoth drugs act to reduce the action of alcohol dehydrogenase on methanol by means of competitive inhibition, so it is excreted by the kidneys rather than being transformed into toxic metabolites.Further treatment may include giving sodium bicarbonate for metabolic acidosis, and hemodialysis or hemodiafiltration can be used to remove methanol and formate from the blood.Folinic acid or folic acid is also administered to enhance the metabolism of formate.The initial symptoms of methanol intoxication include:Central nervous system depressionHeadacheDizzinessNausealack of coordinationConfusionUnconsciousness and death (with large doses)Death due to respiratory failure.Physical examination may show TachypneaOphthalmologic examination may show dilated pupils with hyperemia of the optic disc and retinal edema.
Methanol
Ethanol
Cocaine
Opium
Alcohol and Alcoholism