Induction:

Phenytoin with erythromycin (K Bachman et al, Single dose phenytoin clearance during erythromycin treatment. Res Commun Chem Pathol Pharmacol, 46:207, 1984) This report underscores the fact that the induction process takes some time; therefore single dose therapy seems to be permissible!)

Cimetidine with fluconazole (surprise! Although one would predict an interesting interaction because of the cyp enzymology since they are both potent inhibitors of Cyp2C9, the predominant interaction is because of absorption! RA Blum et al, Increased gastric pH and the bioavailability of fluconazole and ketoconazole. Ann Intern Med, 114:755, 1991)