^I don't know if everything in that thread is actually true. For example, the statement:
AlphaOdure said:
Since Cimetidine is eliminated and metabolized by the same enzyme that metabolizes opioids, i usually wait for the methadone to realize its effect first; then take the booster to hinder my body in metabolizing it quickly.
Cimetidine does occupy the CYD enzymes that metabolize opioids (and other drugs)
I don't think that is correct. I don't think antacids potentiate by keeping the enzymes busy metabolizing the antacid. And the enzymes that activate a particular drug are not the same ones that deactivate it, so it is not necessary to wait until the effects of the opioid are already at their peak before taking the enzyme inhibitor. In addition, that poster was talking about methadone, and with methadone the methadone itself is responsible for most of its effects, only with "pro-drugs" does the drug need to be metabolized into an active metabolite (and even in those cases, as I said, the enzymes are different). With oxycodone, like methadone, the oxycodone itself is responsible for most of its effects. A potentiator is just going to decrease the drug being deactivated by being metabolized to inactive metabolites. What antacids do is inhibit the enzyme that deactivates certain drugs, so that there is less of that enzyme in your liver and therefore not as much of the drug gets removed from your system as quickly.
The poster also meant to say CYP enzymes, not CYD. Cimetidine is a known inhibitor of many enzymes of the cytochrome CYP (also known as P450) enzyme system, (specifically CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4). This inhibition forms the basis of the numerous drug interactions that occur between cimetidine and other drugs. Cimetidine is known to potentiate the effects of several opioids which are metabolized by CYP, which can lead to heightened plasma levels of these drugs.
So the above is how antacids can affect the drugs after they have been absorbed from the digestive tract. But in addition, like Johnsonville alluded to, antacids can also affect the absorption of certain drugs. They do this by changing the acidity of the stomach. Depending on the drug, this can either increase or decrease the rate of absorption. For example, absorption of NSAIDs is increased. I'll see if I can find any info on how it affects the absorption of oxycodone and other opioids - my assumption (and subjective experience) would be that making the stomach less acidic speeds up the absorption.
token