Drugs that Interact with Codeine
Codeine which is an 'Opiate' like Morphine, Oxycodone, Hydrocodone (Vicodin) has the potential to interact with Quinidine and Cimetidine medications. If you are unsure about the interaction of Codeine with your current medication it is a good idea to consult with your pharmacist or read the information sheet that comes with the medication. In such cases Codeine and other narcotic analgesics will be described as Opiates, that description will apply to all these narcotic analgesics, very usually the interaction will result in the decrease of the effect of Codeine as a pain relief agent.

One example is the interaction with Quinidine, in that case a mild interaction results in Codeine becoming ineffective for pain relief and an alternative pain relief agent is advised. Quinidine is used as a Cytochrome enzyme inhibitor, as an Antiarrhythmic.

In the case of Cimetidine a strong interaction does happen but primarily with Vicodin and DihydroCodeine type narcotics, it is not documented with Codeine but the interaction with the other opiates causes strong Central Nervous System CNS depression. DihydroCodeine interactions with Cimetidine has been known to produce toxins. Cimetidine like Quinidine is used as a Cytochrome Enzyme inhibitor, H2 Receptor Antagonist. It should be noted that Cimetidine is known to interact with many other medications.

Finally it should be noted that Opiates can act as antagonists when combined with other medications such as antipsychotics, alchohol is also known to act as an antagonist when combined with antipsychotics. As always the best way to find out if your medication will interact with Codeine as an antagonist is to check your medication info sheet for Opiate interactions.