Why is mixing alcohol with drugs bad?

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Why is mixing alcohol with drugs bad?

Post by eXce11eNt » Sun Jan 13, 2008 6:36 am

Okay, I have no formal training in the field of biology, beyond the prereq's my college has had me take, but here's my theory and I was hoping someone more knowledgeable than I could tell me how far off I am.

Certain substances are metabolized by the liver, i.e., alcohol, and aspirin. Now, here's where I am delving into theory. The liver produces enzymes to metabolize (for example) alcohol. Certain enzymes are designed to metabolize certain drugs. When alcohol is being metabolized, the enzymes present in the liver are either not capable of metabolizing two different substances simultaneously, or they are not the ones designed to handle (for example) aspirin, if it is taken with a glass of vodka.

How true is this? If it is completely untrue, could someone help explain this?

What I am getting at is why is it unadvised to mix alcohol with certain drugs? AND, how could these drugs (Ibuprofen, aspirin, acetaminophen, etc.) cause liver damage (specifically, bleeding) in conjuction with alcohol? When the liver becomes inundated with large quantities of a certain substance to metabolize, does the substance join a queue and wait its turn, or does it just pass through the liver and wreak havok along the way?

I'm interested in the science behind this, so maybe I should talk to a Biology/physiology professor at my school? I just don't like being passed off with the "oh that's not my department" line, so I was hoping maybe someone knowledgeable on this topic is a poster here.

Thank you!

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Post by genovese » Sun Jan 13, 2008 8:01 am

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Post by Revenged » Sun Jan 13, 2008 2:21 pm

you misunderstand... it's to do with gastrointestinal damage (dyspepsia, nausea, gastritis, diarrhoea, gastrointestinal bleeding)...

aspirin and ibuprofen are non-steroidal antiinflammatory drugs... they are both inhibit the enzyme COX...

the reduce the levels of prostglandins, which reduces inflammation... but it inhibition of these enzymes also causes gastrointestinal damage...

this gastrointestinal damage can be avoided by using selective COX-2 inhibitors...

but this had it's own problems... e.g. the COX-2 selective inhibitor Vioxx had fatal cardiovascular events and was withdrawn from use...


alternatively, you can use paracetamol... paracetamol not anti-inflammatory but it is reduces fever and pain (as aspirin and ibuprofen do) because it only inhibits COX in the central nervous system...

alcohol is also a gastrointestinal irritant... if you binge and take aspirin or ibuprofen you dramatically increase the likelihood of getting gastrointestinal bleeding...

alcohol with NSAID or paracetmol is not a problem for the liver...

paracetamol overdose is very toxic to the liver and so is chronic alcohol intake - but don't assume they are connected...

paracetamol overdose is short term and occurs because it is metabolised to a toxic metabolite and the liver only has a limited capacity to neutralise the toxin as there is are only limited supplies of glutathione...

however, this is a completely different mechanism of action to how alcohol is metabolised by the liver... the liver can metabolise thousands of different toxins (your theory is that the liver can only metabolise only 1 toxin at a time is v v v v v v wrong)... they shouldn't interact because completely different pathways are involved... and the liver is very resistance to alcohol (it is very difficult to drink yourself to death and it can take many years of binge drinking to develop jaudice/liver cirrosis but it is relatively easy to kill yourself with a paracetamol overdose within 3 days)...

but as far as i know normal doses of paracetamol is fine with alcohol... remember that most paracetamol and aspirin are used by millions to get rid of a hangover... it is pretty safe...

however there are some drugs that interact badly with alcohol... e.g. metronidazole should never be taken with alcohol...

but drug interaction is very complicated... you really need to understand how the drugs work and even then it's complicated...

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Re: Why is mixing alcohol with drugs bad?

Post by Darby » Sun Jan 13, 2008 10:13 pm

Detoxification for most toxins takes a pathway with several contributing enzymes, which are not all available in equal amounts or work at equal efficiencies. You can overdose on acetaminophen because a liver-toxic intermediary accumulates at an enzyme bottleneck. The process is made worse if that bottleneck enzyme is also being utilized in alcohol detoxification.

But that's just an example. The chemistry of the liver (and digestion) is so complex that your question doesn't have a simple answer.

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