Butalbital, acetaminophen, caffeine, and codeine and Rifampin interaction

Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex.

Use of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with Butalbital, Acetaminophen, Caffeine, and Codeine Phosphate Capsules requires careful consideration of the effects on codeine, and the active metabolite, morphine [see Warnings and Precautions ( 5.7 )] .

• The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex.

Risks of Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex.

…3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir) or discontinuation of a cytochrome P450 3A4 inducer such as rifampin, carbamazepine, and phenytoin, may result in an increase in codeine plasma concentrations with subsequently greater metabolism by cytochrome…

Quinine Prevention or Management : Avoid concomitant use Decrease AUC by 75%-85% Telithromycin Decrease AUC by 86% Theophylline Decrease exposure by 20%-40% Effect of Other Drugs on Rifampin Concomitant antacid administration may reduce the absorption of rifampin.

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.