In methyl alcohol poisoning there is CNS depression, cardiac depression and optic nerve atrophy. These effects are produced due to –
**Core Concept**
Methanol poisoning is a toxic condition caused by the ingestion of methanol, a volatile, colorless, and flammable liquid. The toxic effects of methanol are primarily due to its metabolites, formaldehyde and formic acid, which are produced through the action of alcohol dehydrogenase.
**Why the Correct Answer is Right**
The correct answer involves the metabolism of methanol to its toxic metabolites. Methanol is first converted to formaldehyde by alcohol dehydrogenase, and then formaldehyde is converted to formic acid by aldehyde dehydrogenase. Formic acid is responsible for the toxic effects of methanol, including CNS depression, cardiac depression, and optic nerve atrophy. The optic nerve is particularly susceptible to formic acid toxicity, leading to visual disturbances and potentially permanent blindness.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a plausible mechanism for methanol toxicity. While other alcohols may have different metabolic pathways, methanol's toxicity is well-documented to be due to its conversion to formic acid.
* **Option B:** This option is incorrect because the toxic effects of methanol are not primarily due to its local anesthetic properties. While methanol may have some local anesthetic effects, its systemic toxicity is much more significant and is due to the formation of formic acid.
* **Option C:** This option is incorrect because the toxic effects of methanol are not primarily due to its central nervous system (CNS) depressant effects. While methanol does cause CNS depression, this is a secondary effect of the formation of formic acid, rather than a primary mechanism of toxicity.
**Clinical Pearl / High-Yield Fact**
It is essential to note that fomepizole, an alcohol dehydrogenase inhibitor, can be used as an antidote for methanol poisoning. Fomepizole prevents the conversion of methanol to formaldehyde and formic acid, thereby reducing the toxic effects of methanol.
**Correct Answer:** C. Formic acid is responsible for the toxic effects of methanol, including CNS depression, cardiac depression, and optic nerve atrophy.