Case report: delirium due to a diltiazem-fentanyl CYP3A4 drug interaction.
BACKGROUND
Fentanyl and diltiazem are frequently used medications. Diltiazem inhibits cytochrome P450 3A4 isoenzymes. This can suppress fentanyl metabolism.


METHODS
We present a case of delirium after coadministration of fentanyl and diltiazem.


CONCLUSIONS
Cautious use is warranted while concomitantly administering fentanyl and diltiazem as this can potentiate fentanyl toxicity. Other 3A4 inhibitors include ketoconazole, erythromycin, nefazodone, ritonavir, delavirdine, aprepitant and imatinib. Psychosomatic medicine psychiatrists, pain and palliative care physicians and cardiologists in particular should be aware of this interaction.
Department of Psychiatry and Behavioral Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA. levint@mskcc.org
Tomer T
TT
Levin
Mohamed Hussien
MH
Bakr
Tanya
T
Nikolova
D000279:Administration, Cutaneous; D000369:Aged, 80 and over; D000701:Analgesics, Opioid / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000009:adverse effects* / Q000627:therapeutic use; D051544:Cytochrome P-450 CYP3A; D065692:Cytochrome P-450 CYP3A Inhibitors; D003693:Delirium / Q000097:blood / Q000139:chemically induced*; D004110:Diltiazem / Q000009:adverse effects* / Q000627:therapeutic use; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005283:Fentanyl / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000627:therapeutic use; D006801:Humans; D008297:Male; D010098:Oxycodone / Q000009:adverse effects / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy*; D013617:Tachycardia, Supraventricular / Q000097:blood / Q000188:drug therapy*
D000701:Analgesics, Opioid; D002121:Calcium Channel Blockers; D065692:Cytochrome P-450 CYP3A Inhibitors; D010098:Oxycodone; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D004110:Diltiazem; D005283:Fentanyl