Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Rifamycin antibiotics may speed up how quickly your liver processes posaconazole. Posaconazole may slow down how quickly your liver processes rifabutin.
What might happen:
The amount of posaconazole in your blood may decrease and it may not work as well. If you are taking rifabutin, the amount of rifabutin in your blood may increase and cause toxic side effects.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together or if you have recently taken any rifamycin antibiotic. Your doctor may want to adjust the dose of your antifungal medicine while you are taking your antibiotic and for a few weeks after you finish it or your doctor may want to change your medicine. Your doctor may also want to check the number of cells in your blood.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Noxafil (posaconazole) UK summary of product characteristics. Schering-Plough Ltd. February 2, 2006.
2.Noxafil (posaconazole) US prescribing information. Merck & Co. Inc March, 2014.