Table 1.

Drug combinations taken by patients attending palliative care day centres that give rise to (i) clinically important and (ii) potentially clinically important drug–drug interactions involving cytochrome P450

Category*	Drug combination	Frequency	Drug effect increased (↑) or decreased (↓)
(i) ‘important’	Omeprazole + diazepam	3	Diazepam↑
	Phenytoin + dexamethasone	2	Dexamethasone↓
(ii) ‘potentially important’	Dexamethasone + temazepam	5	Temazepam↓
	Haloperidol + oxycodone	4	Oxycodone↓
	Levomepromazine + oxycodone	3	Oxycodone↓
	Prednisolone + diazepam	3	Diazepam↓
	Dextropropoxyphene + tramadol	2	Tramadol↑
	Carbamazepine + zopiclone	1	Zopiclone↓
	Coproxamol + codeine	1	Codeine↓
	Dexamethasone + amitriptyline	1	Amitriptyline↓
	Dexamethasone + fentanyl	1	Fentanyl↓
	Dexamthasone + quinine	1	Quinine↓
	Dexamethasone + simvastatin	1	Simvastatin↓
	Dexamethasone + tacrolimus	1	Tacrolimus↓
	Dexamethasone + zopiclone	1	Zopiclone↓
	Fluoxetine + codeine	1	Codeine↓
	Haloperidol + codeine	1	Codeine↓
	Levomepromazine + haloperidol	1	Levomepromazine↑ haloperidol↑
	Levomepromazine + tamoxifen	1	Tamoxifen↓
	Prednisolone + amlodipine	1	Amlodipine↓
	Prednisolone + fentanyl	1	Fentanyl↓
	Prednisolone + trazodone	1	Trazodone↓
	Prednisolone + zopiclone	1	Zopiclone↓
	Verapamil + zopiclone	1	Zopiclone↑
	Total	39
No. (%) of patients with at least one (i) or (ii) interaction	34 (21%)

^*For definitions, see Methods.