Alfentanil, drug interactions

Kharasch ED, Russell M, Mautz D, et al. The role of cytochrome P450 3A4 in alfentanil clearance. Implications for interindividual variability in disposition and perioperative drug interactions. Anesthesiology 1997 87 36-50. 

In one study alfentanil was particularly likely to cause hemodynamic instability and myocardial ischemia however, drug interactions or the dosage regimen may have been responsible (4). 

The glucuronide metabolite of AZT was isolated from rat and human liver microsomal incubations (177), and the formation of a toxic metabolite of AZT was demonstrated in rat hepatocytes and liver microsomes (177). The metabolism of tamoxifen was examined in human liver homogenate and human Hep G2 cell line preparations by LC/API/MS (178). Several metabolites were detected in the human liver homogenate extracts, namely, N-didesmethyltamoxifen, a-hydroxy-tamoxifen, 4-hydroxytamoxifen, N-desmethyltamoxifen, and tamoxifen N-oxide. All of these metabolites, except the N-didesmethyltamoxifen, were observed in the samples after incubating tamoxifen with the human Hep G2 cell line. In-vitro studies have also used MS to examine potential drug-drug interactions. For example, (179) demonstrated that the a2-agonist, dexmedetomidine, inhibited metabolism of the anesthetic alfentanil, whereas clonidine had no effect. 

Ibrahim AE, Feldman J, Karim A, Kharasch ED. Simultaneous assessment of drug interactions with low- and high-extraction opioids. Application to parecoxib effects on the pharmacokinetics and pharmacodynamics of fentanyl and alfentanil. Anesthesiology (2003) 98,853-61. 

The interaction of alfentanil with fluconazole and voriconazole appears to be established and clinically important. In vitro data indicate that ketoco-nazole and itraconazole may interact in a similar wayAlfentanil should be given with care to those who have recently received these drugs, and it may be necessary to use a lower alfentanil dose. Be alert for evidence of prolonged alfentanil effeets and respiratory depression. 

Combining midazolam and alfentanil or fentanyl for the induction of anaesthesia reduces the dose required of both the benzodiazepine and the opioid, when compared with either drug alone.The interaction is synergistic. ... 

---