Drugs Home > Drug Interactions With Ivacaftor
More Detail on Drug Interactions With IvacaftorThe following sections explain in detail the potentially negative reactions that can occur when ivacaftor is combined with any of the drugs listed above.
Ivacaftor may increase the level of cyclosporine in the bloodstream. This should be taken into account when starting or stopping ivacaftor, or when changing the ivacaftor dosage. Your healthcare provider might want to check your cyclosporine blood levels, and may need to adjust your cyclosporine dosage accordingly.
CYP 3A4 Inducers
The liver breaks down (metabolizes) ivacaftor using enzymes known as CYP 3A4 enzymes, and some medications known as CYP 3A4 inducers speed up the activity of these enzymes. Thus, combining these drugs can increase the rate at which ivacaftor is broken down, making it less effective. It is not recommended to take a CYP 3A4 inducer while you are taking ivacaftor.
CYP 3A4 Inhibitors
The liver breaks down (metabolizes) ivacaftor using enzymes known as CYP 3A4 enzymes, and some medications known as CYP 3A4 inhibitors slow down the activity of these enzymes. Thus, taking these drugs together can decrease the rate at which ivacaftor is broken down. To account for this, a lower ivacaftor dosage is recommended for people who must take these inhibitors.
For strong CYP 3A4 inhibitors, such as clarithromycin, itraconazole, ketoconazole, posaconazole, telithromycin, or voriconazole, the recommended dosage of ivacaftor is 150 mg twice weekly. For moderate CYP 3A4 inhibitors, the dosage is ivacaftor 150 once daily.
There may be occasions where a CYP 3A4 inhibitor needs to be taken only temporarily, such as with an antibiotic. This presents a difficult dosing challenge. If possible, a different medication that does not affect ivacaftor should be chosen instead.