Fentanyl drug interactions

Labroo, R. B., Paine, M. F., Thummel, K. E., Kharasch, E. D., Fentanyl metabolism by human hepatic and intestinal cytochrome P4503A4. Implications for interindividual variability in disposition, efficacy and drug interactions, Drug Metab. Disp. 1997, 25, 1072-1080. 

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. 

Drug interactions since fentanyl is metabolized mainly via the human cytochrome P450 3A4 isoenzyme system (CYP3A4) possible interactions may occur when fentanyl buccal tablet or fentanyl oralet is given along with medications that affect CYP3A4 activity. 

Horton R, Barber C. Opioid-induced respiratory depression resulting from transdermal fentanyl-clarithromycin drug interaction in a patient with advanced COPD. / Pain Symptom Manage 2009 37 ... 

Drug-drug interactions Paroxetine Serotonin syndrome in a 49-year-old woman after cardiac surgery was linked to an interaction of paroxetine 40 mg/day with perioperative fentanyl 5 micrograms/kg [74 ]. 

Drug-drug interactions A 72-year-old female using fentanyl patches at 87 ng/h daily for pain from metastatic breast cancer was started on clarithromycin 500 mg twice daily as part of treatment for a new pleural effusion. The day after initiation of clarithromycin, the patient became confused, somnolent and ultimately experienced respiratory failure that resolved after administration of naloxone [34 ]. This and other case series demonstrate that coadministration of drugs that are inhibitors of CYP3A4 can prolong the effects of fentanyl. 

T. T. Levin, M. H. Bakr and T. Nikolova, Case report delirium due to diltiazem-fentanyl CYP3A4 drug interaction, Gen. Hasp. Psychiatry,... 

Drugs that may affect amiodarone include hydantoins, cholestyramine, fluoroquinolones, rifamycins, ritonavir, and cimetidine. Drugs that may be affected by amiodarone include anticoagulants, beta-blockers, calcium channel blockers, cyclosporine, dextromethorphan, digoxin, disopyramide, fentanyl, flecainide, hydantoins, lidocaine, methotrexate, procainamide, quinidine, and theophylline. Drug/Lab test interactions Amiodarone alters the results of thyroid function tests, causing an increase in serum T4 and serum reverse T3 levels and a decline in... 

As with any narcotic, fentanyl is addictive. Because it interacts with the mu receptor, which has an effect on addiction, it is highly addictive. Fentanyl users also build a tolerance to the drug s effects, thus needing more of the drug to reach the same euphoric experiences. Building up a tolerance to the drug can be harmful to the user. As the user continues to consume more and more of the drug to achieve the same effects, an overdose becomes likely. 

Drugs metabolized by CYP that interact with cimetidine include, but are not limited to, the following lidocaine, quinidine, midazolam, triazolam, nifedipine, verapamil, and fentanyl (4). In each instance, inhibition of CYP by cimetidine results in reduced metabolic clearance and increases in serum concentrations of the other drug, which can lead to the expected toxicity and adverse experiences characteristic of the other drug. 

Fentanyl and its analogs are drugs of abuse. Overdose and dependence may lead to respiratory complications and death.58 Adverse effects can be treated with drugs such as naloxone, atropine, and neuromuscular blockers. In general, interactions are similar to those of opioid analgesics. 

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. ... 

The terminal half-life of fentanyl 100 mierograms/kg was reported to be more than doubled, from 155 to 340 minutes, by pretreatment with cimetidine (10 mg/kg the night before and 5 mg/kg 90 minutes before the fentanyl dose). This increase in half-life probably oeeurs beeause cimetidine inhibits the metabolism of fentanyl by the liver, thereby delaying its elear-ance from the body. The clinical importance of this interaction has not been assessed, but if both drugs are used concurrently, be alert for increased and prolonged fentanyl etfects. 

---