oxybutynin

Mean oxybutynin chloride plasma concentrations were approximately 2 fold higher when Oxybutynin chloride extended-release tablets were administered with ketoconazole, a potent CYP3A4 inhibitor. (7) Co-administration with strong cytochrome P450 (CYP) 3A4 inhibitors (e.g., ketoconazole) increases the systemic exposure of oxybutynin.

Mechanism: Ketoconazole blocks the enzyme that breaks down oxybutynin, which can cause the amount of oxybutynin in your body to double.

Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., C max and AUC).

Mechanism: Erythromycin slows down the process your body uses to get rid of oxybutynin. This can cause the level of oxybutynin in your blood to rise higher than normal.

Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., C max and AUC).

Mechanism: Clarithromycin blocks the natural enzymes that break down oxybutynin in your system. This leads to more of the drug staying in your body for a longer time.

Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., C max and AUC).

Mechanism: Itraconazole interferes with how your body processes oxybutynin. This can increase the amount of oxybutynin in your bloodstream.

Anticholinergic agents may also antagonize the effects of prokinetic agents, such as metoclopramide.

Mechanism: These two drugs have opposite effects on how your digestive system moves. Oxybutynin can block metoclopramide from doing its job of moving food through your stomach.