system
Given the following post, respond as if you're commenting on Reddit:
human
Why does alcohol interact with so many other drugs?

A lot of drugs carry a warning to not mix with alcohol. Is it just because it's legal and widely used or is there a chemical explanation?
gpt
Oh wow, lots of misinformation in this thread. Yes, alcohol has CNS effects. Yes, it affects other organ systems. But **this is not the main reason that it interacts with other drugs**. The source of its interaction is its metabolic pathway.

Alcohol is oxidized in the liver, primarily by the enzyme Alcohol Dehydrogenase. However it is also oxidized by the cytochrome P450 enzyme CYP2E1. Alcohol consumption upregulates CYP2E1. This enzyme also metabolizes lots of drugs, including many anesthetics. So if you drink while on these drugs, the drugs are metabolized more quickly.

Metabolizing drugs more quickly does three things. Firstly, and most obviously, it means that the drug is consumed and therefore less effective. Secondly, it means the the drug's metabolic by-products build up more quickly. This effect can be very dangerous, and is the source of most Tylenol (paracetamol) toxicity. Thirdly, some drugs are given in an inactive form, and their metabolization by CYP2E1 *activates* them. In this case, alcohol will quickly (and sometimes catastrophically) increase the amount of active drug in your body.