Pulmicort Drug Interactions

Turbuhaler: No clinically relevant interactions with other agents for asthma are known.
Ketoconazole 200 mg once daily increased the plasma concentrations of oral budesonide (3 mg in a single dose) on average six-fold when administered concomitantly. When ketoconazole was administered 12 hours after budesonide, the concentration was increased on average three-fold. Information about this interaction is lacking for inhaled budesonide, but markedly increased plasma levels are also expected in such cases. Since there is an absence of data to permit dosage recommendations, the combination should be avoided.
If this is not possible, the time interval between administration of ketoconazole and budesonide should be as long as possible. A reduction of the budesonide dose must also be considered. Other potent inhibitors of CYP3A4, i.e. itraconazole also cause a marked increase in the plasma levels of budesonide.
Respules: The metabolism of budesonide is primarily mediated by CYP3A, a subfamily of cytochrome P450. Inhibitors of this enzyme e.g. ketoconazole and itraconazole, can therefore increase systemic exposure to budesonide. This is of limited clinical importance for short-term (1-2 weeks) treatment with CYP3A inhibitors, but should be taken into consideration during long-term treatment.