VERFEN
Fentanyl citrate Injection USP 50mcg/ml
What it does
Fentanyl is a strong pain relief medication belonging to the opioid class.
Commonly used for: severe pain relief, pain after surgery, chronic pain management
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Answers come only from this medicine's registration record, BNF monograph and interaction data - not medical advice.
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Sourcing - Kenya onlyRegistration & product details
Source: Rwanda Food and Drugs Authority · fetched 2026-03-11 22:07:14 · updated 2026-09-14 02:30:15
Drug Interactions
85Pharmacodynamic Warnings
Fentanyl appears in TABLE 6: Drugs that cause bradycardia
Fentanyl appears in TABLE 11: Drugs with CNS depressant effects
Fentanyl appears in TABLE 13: Drugs that cause serotonin syndrome
Severe (9)
Fentanyl - decreases concentration
Brigatinib potentially decreases the concentration of opioids (alfentanil, fentanyl). Avoid. Also see TABLE 6 p. 1518
Fentanyl - increases exposure
Ceritinib is predicted to increase the exposure to opioids (alfentanil, fentanyl). Avoid. Theoretical → Also see TABLE 6 p. 1518
Fentanyl - decreases exposure
Lorlatinib is predicted to decrease the exposure to opioids (alfentanil, fentanyl). Avoid.
Opioids - decreases concentration
Brigatinib potentially decreases the concentration of opioids (alfentanil, fentanyl). Avoid. Also see TABLE 6 p. 1518
Opioids - increases exposure
Ceritinib is predicted to increase the exposure to opioids (alfentanil, fentanyl). Avoid. Theoretical → Also see TABLE 6 p. 1518
Opioids - increases risk of cnstoxicity
Ritonavir increases the risk of CNS toxicity when given with opioids (pethidine). Avoid.
Opioids - decreases exposure
Lorlatinib is predicted to decrease the exposure to opioids (alfentanil, fentanyl). Avoid.
Opioids - increases risk of adverse effects
Selegiline increases the risk of adverse effects when given with opioids (pethidine). Avoid. Also see TABLE 13 p. 1520
Opioids - increases exposure
Selpercatinib is predicted to increase the exposure to opioids (alfentanil, buprenorphine). Avoid.
Moderate (50)
Fentanyl - increases exposure
Dronedaroneispredictedtoincreasetheexposuretoopioids (alfentanil,buprenorphine,fentanyl,oxycodone).Monitorand adjustdose.oStudy →AlsoseeTABLE6p.1518
Fentanyl - increases concentration
Amiodarone is predicted to increase the concentration of opioids (fentanyl). Monitor and adjust dose. Also see TABLE 6 p. 1518.
Fentanyl - increases exposure
Antifungals, azoles (fluconazole, isavuconazole, posaconazole) are predicted to increase the exposure to opioids (alfentanil, buprenorphine, fentanyl, oxycodone). Monitor and adjust dose.
Fentanyl - increases exposure
Berotralstat is predicted to increase the exposure to opioids (alfentanil, fentanyl). Monitor and adjust dose.
Fentanyl - increases exposure
Nicardipine is predicted to increase the exposure to opioids (fentanyl). Monitor and adjust dose.
Unknown (26)
Drugs That Cause Serotonin Syndrome - increases risk of serotonin syndrome
Opioids (tapentadol) are predicted to increase the risk of serotonin syndrome when given with drugs that cause serotonin syndrome (see TABLE 13 p. 1520). Theoretical drugs that reduce serum potassium.
Fentanyl - increases exposure
Entrectinib is predicted to increase the exposure to opioids (alfentanil, fentanyl).
Fentanyl - decreases exposure
Mitotane is predicted to decrease the exposure to opioids (alfentanil, fentanyl).
Fentanyl - decreases exposure
Rifampicin is predicted to decrease the exposure to opioids (alfentanil, fentanyl).
Opioids - additive effect
Clozapine can cause constipation, as can opioids; concurrent use might increase the risk of developing intestinal obstruction. Also see TABLE 11 p. 1519
Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: exact
About this medicine
Fentanyl is a strong pain relief medication belonging to the opioid class.
What it treats
- severe pain relief
- pain after surgery
- chronic pain management
How it works
Fentanyl works by binding to specific receptors in the brain to reduce the feeling of pain.
Who it's for
This medication is typically prescribed for adults experiencing severe pain that is not well-managed by other pain relievers.
Drug class
Opioids
Cautions
- • Be careful if you are taking other drugs that slow your heart rate.
- • Avoid using it with other medications that can cause drowsiness.
- • Do not combine it with drugs that may lead to serotonin syndrome.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: Fentanyl
BNF-referencedFentanyl is a potent synthetic opioid analgesic, primarily used for managing severe pain, particularly in patients with chronic pain conditions or those undergoing surgical procedures. It is significantly more potent than morphine, making it an important medication in pain management, especially for opioid-tolerant individuals. Due to its high potency, fentanyl requires careful dosing and monitoring to prevent overdose and adverse effects.
Indications
- Acute pain
- Chronic intractable pain not currently treated with a strong opioid analgesic
- Palliative care
- Anesthesia
- Assisted ventilation
Dosage
Children: For children aged 16-17 years, an initial dose of 12 micrograms/hour via transdermal patch
Adults: Initially, fentanyl may be administered as 50-100 micrograms via slow intravenous injection, with subsequent doses adjusted according to patient response, typically in increments of 25-50 micrograms as required. For transdermal application, the initial dose is generally determined by previous opioid use, with adjustments made after assessing the analgesic effect.
Mechanism of action
Fentanyl binds to opioid receptors, particularly the mu opioid receptor, which are coupled to G-proteins. This binding activates the receptor, leading to a cascade of intracellular events that inhibit adenylate cyclase activity, reducing levels of cyclic AMP (cAMP). This action decreases calcium ion influx into the cell, resulting in hyperpolarization and decreased neuronal excitability, ultimately leading to reduced pain perception.
Pharmacodynamics
Fentanyl exerts strong analgesic effects through its activation of opioid receptors, resulting in pain relief. It has a rapid onset of action and a duration of several hours, making it suitable for acute and chronic pain management. However, it also possesses a risk of addiction and abuse, and its use should be closely monitored. Tolerance to its effects can develop with prolonged use, necessitating careful dosage adjustments.
Pharmacokinetics
Fentanyl is absorbed rapidly when administered via transdermal patches or intravenous routes. It undergoes extensive hepatic metabolism, primarily through CYP3A4 enzymes, and its elimination half-life varies based on the route of administration. The drug is excreted mainly via urine. In patients with hepatic impairment, dose adjustments are recommended due to altered pharmacokinetics.
Contra-indications
- Severe respiratory depression
- Acute or severe bronchial asthma
- Known or suspected gastrointestinal obstruction
- Hypersensitivity to fentanyl or any of its components
Adverse effects
- Respiratory depression
- Constipation
- Nausea
- Vomiting
- Sedation
- Confusion
- Dizziness
- Hypotension
- Bradycardia
- Physical dependence
- Addiction
Interactions
- Severe: brigatinib, ceritinib, lorlatinib (decreases concentration)
- Moderate: dronedarone, amiodarone, antifungal azoles (increases exposure)
- Moderate: berotralstat, nicardipine, cobicistat, crizotinib (increases exposure)
Precautions
- Caution in patients with hepatic impairment
- Caution in patients with renal impairment
- Caution in patients with a history of substance use disorder
- Gradual dose adjustment recommended to avoid withdrawal symptoms
- Monitor for signs of respiratory depression, especially after initiation or dose adjustment
Pregnancy
Fentanyl should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. It is classified as Category C.
Breast-feeding
Fentanyl is excreted in breast milk; use caution when administering to breastfeeding mothers.
Storage
Store at room temperature, in a tightly closed container, away from moisture and light. Keep out of reach of children.
Formulations
- Transdermal patches (various strengths)
- Injectable solution (IV)
- Oral tablets
- Sublingual tablets
- Intranasal formulations
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
Molecular reference: Fentanyl
PubChem CID 3345Molecular formula: C22H28N2O
Mechanism of action
Fentanyl binds to opioid receptors, especially the mu opioid receptor, which are coupled to G-proteins. Activation of opioid receptors causes GTP to be exchanged for GDP on the G-proteins which in turn down regulates adenylate cyclase, reducing concentrations of cAMP. Reduced cAMP decreases cAMP dependant influx of calcium ions into the cell. The exchange of GTP for GDP results in hyperpolarization of the cell and inhibition of nerve activity. The aim of the present study was to describe the activity of a set of opioid drugs, including partial agonists, in a cell system expressing only mu opioid receptors. Receptor activation was assessed by measuring the inhibition of forskolin-stimulated cyclic adenosine mono phosphate (cAMP) production. Efficacies and potencies of these ligands were determined relative to the endogenous ligand beta-endorphin and the common mu agonist, morphine. Among the ligands studied naltrexone, WIN 44,441 and SKF 10047, were classified as antagonists, while the remaining ligands were agonists. Agonist efficacy was assessed by determining the extent of inhibition of forskolin-stimulated cAMP production. The rank order of efficacy of the agonists was fentanyl = hydromorphone = beta-endorphin > etorphine = lofentanil = butorphanol = morphine = nalbuphine = nalorphine > cyclazocine = dezocine = metazocine >or= xorphanol. The rank order of potency of these ligands was different from that of their efficacies; etorphine > hydromorphone > dezocine > xorphanol = nalorphine = butorphanol = lofentanil > metazocine > nalbuphine > cyclazocine > fentanyl > morphine >>>> beta-endorphin. These results elucidate the relative activities of a set of opioid ligands at mu opioid receptor and can serve as the initial step in a systematic study leading to understanding of the mode of action of opioid ligands at this receptor. Furthermore, these results can assist in understanding the physiological effect of many opioid ligands acting through mu opioid receptors. Diabetic neuropathy is one of the most frequent complications of diabetes mellitus. Therefore, the present study was designed to investigate the anti-hyperalgesic mechanism of fentanyl in a mouse model of streptozotocin-induced diabetic neuropathy. The antinociceptive response was assessed by recording the latency in a tail-flick test. The tail-flick latency in diabetic mice was significantly shorter than that in non-diabetic mice. Fentanyl, at doses of 3 and 10 ug/kg, s.c., produced a dose-dependent increase in the tail-flick latencies in diabetic mice. While fentanyl (3 ug/kg, s.c.) did not produce a significant inhibition of the tail-flick response in non-diabetic mice, it significantly prolonged the tail-flick latency in diabetic mice to the same level as the baseline latency in non-diabetic mice. Although pretreatment with naloxone (3 mg/kg, s.c.) completely antagonized fentanyl-induced antinociception in non-diabetic mice, it had no effect on the antinociceptive effect of fentanyl in diabetic mice. Pretreatment with either of the voltage-gated sodium channel openers fenvarelarte and veratridine practically abolished the antinociceptive effects of fentanyl in diabetic mice. However, neither fenvarelate nor veratridine affected the antinociceptive effect of fentanyl in non-diabetic mice. These results suggest that the anti-hyperalgesic effect of fentanyl is mediated through the blockade of sodium channels in diabetic mice, whereas opioid receptors mediate the antinociceptive effect of fentanyl in non-diabetic mice. Tolerance to opioids frequently follows repeated drug administration and affects the clinical utility of these analgesics. Studies in simple cellular systems have demonstrated that prolonged activation of opioid receptors produces homologous receptor desensitization by G-protein receptor kinase mediated receptor phosphorylation and subsequent beta-arrestin binding. To define the role of this regulatory mechanism in the control of the electrophysiologica
Pharmacodynamics
Fentanyl produces strong analgesia through its activation of opioid receptors. It has a duration of action of several hours and a wider therapeutic index as patients develop tolerance to opioids. Fentanyl is associated with a risk of addiction and abuse and should not be mixed with alcohol or benzodiazepines.
Biological pathways
Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.
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The same active ingredient registered across other registries we cover - including different brands.
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