Hydrocodone and homatropine and Rifampin interaction
Hydrocodone and homatropine and Rifampin: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Hydrocodone and homatropine (Hydrocodone Bitartrate and Homatropine Methylbromide) label · effective 2026-05-07
In addition, discontinuation of a concomitantly used cytochrome P450 3A4 inducer may result in an increase in hydrocodone plasma concentration.
Concomitant use with CYP3A4 inhibitors (or discontinuation of CYP3A4 inducers) can result in a fatal overdose of hydrocodone.
Avoid the use of hydrocodone bitartrate and homatropine methylbromide in patients who are taking CYP3A4 inducers.
Similarly, discontinuation of a CYP3A4 inducer, such as rifampin, carbamazepine, and phenytoin, in hydrocodone bitartrate and homatropine methylbromide-treated patients may increase hydrocodone plasma concentrations and prolong opioid adverse reactions.
Concomitant use of hydrocodone bitartrate and homatropine methylbromide with CYP3A4 inducers or discontinuation of a CYP3A4 inhibitor could decrease hydrocodone plasma concentrations, decrease opioid efficacy or, possibly, lead to a withdrawal syndrome in a patient who had developed physical dependence to hydrocodone.
From the Rifampin label · effective 2026-05-05
Decrease AUC by 56% Narcotic Analgesics Oxycodone Decrease AUC by 86% Morphine Decrease exposure Progestin Antagonist Mifepristone Prevention or Management: Refer to the posttreatment assessment in the mifepristone prescribing information to verify that treatment has been successful.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.