P450 inducers = increase metabolism of drugs metabolised by cytochrome P450 and thus decrease drug effect
- Carbamazepine
- Phenytoin
- Rifampicin
- Phenobarbital
- Tobacco
- Chronic alcohol
- St Johns Wort
P450 inhibitors = decrease metabolism of drugs metabolised by cytochrome P450 and thus increase drug effect
- Cardiac
- Amiodarone
- Verapamil
- Quinidine
- Antibiotics
- Ciprofloxacin
- Erythromycin
- Metronidazole
- Trimethoprim
- Isoniazid
- Antifungals
- Fluconazole
- Terbafine
- HIV antivirals
- Antacids
- Cimetidine
- Omeprazole
- Psychiatric drugs
- TCA
- SSRIs especially fluoxetine
- Haloperidol
- Others
- Methadone
- Grapefruit juice
Drugs metabolised by cytochrome P450 include:
- Cardiac
- Beta blockers
- Angiotensin II blockers
- Statins
- Psychiatric drugs
- TCA
- SSRI
- antipsychotics
- Analgesics
- Tramadol
- Codeine
- Ibuprofen
- Antiepileptics
- Other
- Sildenafil
- Warfarin
- Donepezil
- PPIs
- Glipizide
- Theophylline
Small print gem: the name cytochrome P450 comes from the fact the enzymes are inside the cell (cyto) and contain a haem pigment (chrome P) that absorbs light at a wavelength of 450nm when exposed to carbon monoxide
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