The main ones can be remembered using "CRAP GPs spend all day on SICKFACES.COM".
These induce CYP450 activity, and thus reduce the concentration of drugs which are metabolised by this system.
Carbemazepine Rifampicin Alcohol (chronic use) Phenytoin Griseofulvin Phenobarbitone Sulphonylureas, St John's Wort, Smoking
Also topiramate.
These inhibit CYP450 enzyme activity and thus increase the concentration of drugs which are metabolised by this system.
Sodium valproate Isoniazid Cimetidine Ketoconazole Fluconazole Alcohol (acute use), Amiodarone, Allopurinol Chloramphenicol Erythromycin Sulfonamides, SSRIs Ciprofloxacin Omeprazole Metronidazole
Also grapefruit, cranberry juice, diltiazem, verapamil, clarithromycin.
Medications which commonly interact with CYP450 inhibitors and inducers are:
Warfarin
Phenytoin
Combined Oral Contraceptive Pill (COCP)
Theophylline
Corticosteroids
Tricyclic antidepressants
Statins
Lamotrigine
Midazolam