Its use is advised against in people on strong CYP3A4 inhibitors such as clarithromycin, chloramphenicol, ketoconazole, ritonavir and nefazodone due to its reliance on CYP3A4 for metabolism. Likewise it is a CYP3A4, CYP2D6 and CYP2C9 inhibitor and hence concurrent treatment with substrates of any of these enzymes may increase plasma concentrations of said drugs. Since<unk>  is mainly metabolised via the liver enzyme CYP3A4, substances influencing the activity of this enzyme change the plasma concentration of the drug. An example of a drug that increases<unk>  activity and therefore side effects by blocking CYP3A4 is ketoconazole. The same could be true of itraconazole, clarithromycin, grapefruit juice, among others. Conversely, CYP3A4 inductors like rifampicin and St John's Wort reduce the drug's activity, risking therapy failure.<unk>  also acts as an inhibitor of CYP3A4, 2C9 and 2D6, increasing the plasma concentrations of a number of other drugs like simvastatin, ciclosporin, pimozide, warfarin, metoprolol, and possibly paracetamol. The drug also reduces plasma levels of levothyroxin via an unknown mechanism. As with other<unk> munosuppressants, application of live vaccines is contraindicated because the microorganisms in the vaccine could multiply and infect the patient. Inactivated and toxoid vaccines do not hold this risk, but may not be effective under<unk>  therapy.
Imatinib
Neratinib
Dasatinib
Ponatinib
Afatinib
Tucatinib
Lapatinib
Fostamatinib