Fentanyl
Mechanism :
Fentanyl is a pure opioid agonist whose principal therapeutic action is analgesia. Fentanyl interacts predominately with the opioid mu-receptor but also binds to kappa and delta-type opioid receptors. These mu-binding sites are discretely distributed in the human brain, spinal cord, and other tissues. Other opioid agonists include substances such as morphine, oxycodone, hydromorphone, codeine, and hydrocodone. Pharmacological effects of opioid agonists include anxiolysis, euphoria, feelings of relaxation, respiratory depression, constipation, miosis, cough suppression and analgesia.
Indication :
- Perioperative analgesia (off-label)
Contraindications :
Contraindicated in patients with known hypersensitivity to any of its components or the drug fentanyl. When used in patients not taking opioids chronically life-threatening hypoventilation could occur at any dose, hence contraindicated in the management of acute or postoperative pain.
Dosing :
Neonates: Analgesia:
Intermittent doses: Slow IV push: 0.5 to 3 mcg/kg/dose.
Continuous IV infusion: 0.5 to 2 mcg/kg/hour.
Neonates, Infants, Children upto 12 years:
Sedation/analgesia: Slow IV push: 1 to 4 mcg/kg/dose; may repeat every 2 to 4 hours
Continuous sedation/analgesia: Initial IV bolus: 1 to 2 mcg/kg, then 0.5 to 1 mcg/kg/hour; titrate upward. Max: 5 mcg/kg/hour.
Older Infants and Children 1 to 12 years:
Sedation for minor procedures/analgesia: IM or IV: 1 to 2 mcg/kg/dose; may repeat at 30 to 60 minute intervals. Note: Children 18 to 36 months of age may require 2 to 3 mcg/kg/dose.
Moderate to severe chronic pain: Transdermal patch:
Opioid-tolerant children ≥2 years receiving at least 60 mg oral
morphine equivalents per day:
Initial: 25 mcg/hour system or higher; dose may be increased after 3 days, based on the daily dose of supplementary nightly opioids required; use the ratio of 45 mg of oral
morphine equivalents per day to a 12.5 mcg/hour increase in transdermal patch dosage; change patch every 72 hours.
Adverse Effect :
Nausea, constipation, respiratory depression, hypotension, chest wall or jaw muscle rigidity (if given without muscle relaxants). Fentanyl, when used along with neuroleptic medication can cause chills and/or shivering, restlessness, post-operative hallucinatory episodes and extra-pyramidal symptoms.
Interaction :
CNS depressants, including other Opioids, Sedatives or Hypnotics, General Anesthetics, Phenothiazines, Tranquilizers, Skeletal Muscle Relaxants, Sedating Antihistamines: May produce increased depressant effects. Hypoventilation, hypotension, and profound sedation may occur.
MAO inhibitors: Severe and unpredictable potentiation by MAO inhibitors has been reported with opioid analgesics.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function Titrate according to response |
| 10-20 | 75% of normal dose. Titrate according to response |
| <10 | 50% of normal dose. Titrate according to response |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in GFR<10 mL/min |
| HD | Not dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Not dialysed. Dose as in GFR<10 mL/min |
| CAV/VVHD | Not dialysed. Dose as in GFR=10– 20 mL/min |
Hepatic Dose :
Injection: There are no dosage adjustments provided in the manufacturer’s labeling.
Transdermal (device):
Adolescents =18 years: There are no dosage adjustments provided in the manufacturer’s labeling. Fentanyl pharmacokinetics may be altered in hepatic disease.
Children =2 years: - Mild to moderate hepatic impairment: Initial: Reduce dose by 50%. Severe impairment: Use not recommended.
Transmucosal and nasal spray: Adolescents =18 years There are no dosage adjustments provided in the manufacturer’s labeling. Fentanyl pharmacokinetics may be altered in hepatic disease. Reduce initial dose and titrate to reach clinical effect with careful monitoring of patients, especially those with severe hepatic disease.