Fentanyl is indicated for the management of severe pain that requires around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.

Pain

TOTAL DOSAGE:

• Small Dose: Administer 2 mcg/kg (0.002 mg/kg) (0.04 mL/kg) of fentanyl for minor but painful surgical procedures. Fentanyl in lower doses proves beneficial for alleviating pain during such procedures and may also offer postoperative pain relief.
• Moderate Dose: Administer a dose ranging from 2 to 20 mcg/kg (0.002 to 0.02 mg/kg) (0.04 to 0.4 mL/kg) for more extensive surgeries. This larger dose not only ensures ample analgesia but is expected to mitigate the stress response. However, due to resulting respiratory depression, artificial ventilation is necessary during anesthesia, and vigilant postoperative respiratory monitoring is crucial.
• High Dose: Administer a dose ranging from 20 to 50 mcg/kg (0.02 to 0.05 mg/kg) (0.4 to 1 mL/kg) for complex surgeries such as open-heart procedures and certain prolonged neurosurgical and orthopedic interventions. This dosage, when combined with nitrous oxide/oxygen, has demonstrated effectiveness in attenuating the stress response characterized by elevated levels of circulating growth hormone, catecholamine, ADH, and prolactin. Postoperative ventilation and observation are imperative due to the extended duration of respiratory depression. The primary goal of this approach is to achieve "stress-free" anesthesia.

MAINTENANCE DOSAGE:

• Low Dose: 2 mcg/kg (0.002 mg/kg) (0.04 mL/kg). Additional dosages of fentanyl are infrequently needed in these minor procedures.
• Moderate Dose : 2 to 20 mcg/kg (0.002 to 0.02 mg/kg) (0.04 to 0.4 mL/kg). 25 to 100 mcg (0.025 to 0.1 mg) (0.5 to 2.0 mL) may be administered intravenously or intramuscularly when movement and/or changes in vital signs indicate surgical stress or lightening of analgesia.
• High Dose: 20 to 50 mcg/kg (0.02 to 0.05 mcg/kg) (0.4 to 1.0 mL/kg). Maintenance dosage (ranging from 25 mcg (0.025 mg) (0.5 mL) to one-half the initial loading dose) will be dictated by the changes in vital signs which indicate stress and lightening of analgesia. However, the additional dosage selected must be individualized especially if the anticipated remaining operative time is short. 

Adverse reactions associated with Fentanyl are listed below:

• Nausea
• Vomiting
• Constipation
• Dizziness
• Somnolence
• Respiratory depression
• Hypotension

Nausea

Constipation

Dizziness

Respiratory Depression

Impaired Respiration: Exercise caution when administering Fentanyl to patients with chronic obstructive pulmonary disease, diminished respiratory reserve, or those with potential respiratory compromise. Opioids may further reduce respiratory drive and increase airway resistance in such individuals. In the context of anesthesia, controlled or assisted respiration can effectively manage this situation.

Impaired Hepatic or Renal Function: Administer Fentanyl citrate cautiously to individuals with liver or kidney dysfunction due to the crucial roles these organs play in drug metabolism and excretion.

Cardiovascular Effects: Fentanyl may induce bradycardia, which can be addressed with atropine. Use Fentanyl cautiously in patients with cardiac bradyarrhythmias.

Drug Interactions: CNS depressant drugs (e.g., barbiturates, tranquilizers, opioids, and general anesthetics) may have additive or potentiating effects with Fentanyl. Adjust the Fentanyl dose when co-administered with such drugs. Conversely, reduce the dose of other CNS depressants following Fentanyl citrate administration.

Carcinogenesis, Mutagenesis, Impairment of Fertility: No studies on carcinogenicity or mutagenicity have been conducted on Fentanyl citrate. In rat reproduction studies, a notable decrease in pregnancy rates occurred, particularly in the high-dose group.

Pregnancy — Category C: Fentanyl citrate has demonstrated effects on fertility and embryocidal impact in rat studies. While no teratogenic effects were observed, caution is advised in pregnant women, and Fentanyl should be used only if the potential benefits outweigh potential risks to the fetus.

Labor and Delivery: Due to insufficient data, the use of Fentanyl in labor and delivery is not recommended.

Nursing Mothers: The excretion of Fentanyl citrate in human milk is unknown. Caution is advised when administering Fentanyl citrate to nursing women.

Pediatric Use: The safety and efficacy of Fentanyl citrate in children under two years of age have not been established. Exercise caution and consider alternative options in this population.