Fentanyl

/ Janssen

The dosage of Fentanyl should be individualized according to age, body weight, physical status, underlying pathological condition, use of other drugs, and type of surgery and anesthesia. The initial dose should be reduced in the elderly and in debilitated patients. The effect of the initial dose should be taken into account in determining supplemental doses. To avoid bradycardia, it is recommended to administer a small intravenous dose of an anti-cholinergic just before induction. [Droperidol may be given to prevent nausea and vomiting.]
– Use as an analgesic supplement to general anaesthesia Low dose: 2 μg/kg. Fentanyl in small doses is most useful for minor, but painful, surgery. Moderate dose: 2-20 μg/kg. Where surgery becomes more complicated, a larger dose will be required. The duration of activity is dependent on dosage. High dose: 20-50 μg/kg. During major surgical procedures, in which surgery is longer, and during which the stress response would be detrimental to the well-being of the patient, dosages of 20-50 μg/kg of Fentanyl with nitrous oxide/oxygen have been shown to have an attenuating effect. When dosages in this range have been used during surgery, post-operative ventilation and observation are essential in view of the possibility of extended post-operative respiratory depression. Supplemental doses of 25-250 μg (0.5-5 ml) should be tailored to the needs of the patient and to the anticipated time until completion of the operation.
– Use as an anaesthetic agent When attenuation of the response to surgical stress is especially important, doses of 50-100 μg/kg may be administered with oxygen and a muscle relaxant. This technique provides anaesthesia without necessitating the use of additional anaesthetic agents. In certain cases, doses up to 150 μg/kg may be required to produce this anaesthetic effect. Fentanyl has been used in this fashion for open heart surgery and certain other major surgical procedures in patients for whom protection of the myocardium from excess oxygen demand is particularly indicated.
-Epidural Administration for Postoperative Management of Pain 100 mcg may be administered epidurally. The 2 ml ampoule should be diluted with 8 ml of 0.9% Sodium Chloride Injection, resulting in a final concentration of 10 mcg/ml. The quality and duration of epidural analgesia with fentanyl appears to be concentration-dependent below serum levels of 10 mcg/ml with no significant improvement obtained by increasing concentrations above this value. Additional boluses may be administered if there is evidence of lightening of analgesia.
Use in the elderly: As with other opioids, the dose should be reduced in elderly or debilitated patients.
Use in children: For induction and maintenance in children aged 2-12 years, a dose of 2- 3 μg/kg is recommended.

Surgical anesthesia and analgesic. See prescribing information for full details. Also epidural route for post-operative pain, adjunct to general anesthesia.

Known intolerance to either of its components or to other morphinomimetics. Respiratory depression, obstructive airways disease. Concurrent administration with monoamine oxidase inhibitors, or within 2 weeks of their discontinuation.

As with all potent opioids: Tolerance and dependence may occur. Respiratory depression is dose related and can be reversed by a specific narcotic antagonist such as naloxone, but additional doses of the latter may be necessary because the respiratory depression may last longer than the duration of action of the opioid antagonist. Profound analgesia is accompanied by marked respiratory depression, which can persist or recur in the postoperative period. Therefore, patients should remain under appropriate surveillance. Resuscitation equipment and narcotic antagonists should be readily available. Hyperventilation during anaesthesia may alter the patient’s responses to CO2, thus affecting respiration postoperatively. Induction of muscle rigidity, which may also involve the thoracic muscles, can occur, but can be avoided by the following measures: slow I.V. injection (ordinarily sufficient for lower doses), premedication with benzodiazepines and the use of muscle relaxants.
Non-epileptic (myo)clonic movements can occur. Bradycardia, and possibly cardiac arrest, can occur if the patient has received an insufficient amount of anticholinergic, or when Fentanyl is combined with non-vagolytic muscle relaxants. Bradycardia can be treated with atropine. Opioids may induce hypotension, especially in hypovolemic patients. Appropriate measures to maintain a stable arterial pressure should be taken. The use of rapid bolus injections of opioids should be avoided in patients with compromised intracerebral compliance; in such patients the transient decrease in the mean arterial pressure has occasionally been accompanied by a short-lasting reduction of the cerebral perfusion pressure. Patients on chronic opioid therapy or with a history of opioid abuse may require higher doses. It is recommended to reduce the dosage in the elderly and in debilitated patients. Opioids should be titrated with caution in patients with any of the following conditions: uncontrolled hypothyroidism; pulmonary disease; decreased respiratory reserve; alcoholism; or impaired hepatic or renal function. Such patients also require prolonged post-operative monitoring. If Fentanyl is administered with a neuroleptic, [such as droperidol], the user should be familiar with the special properties of each drug, particularly the difference in duration of action. When such a combination is used, there is a higher incidence of hypotension. Neuroleptics can induce extrapyramidal symptoms that can be controlled with anti-Parkinson agents. Caution is advised when Fentanyl is coadministered with drugs that affect the serotonergic neurotransmitter systems. The development of a potentially life-threatening serotonin syndrome may occur with the concomitant use of serotonergic drugs such as Selective Serotonin Re-uptake Inhibitors (SSRIs) and Serotonin Norepinephrine Reuptake Inhibitors (SNRIs), and with drugs which impair metabolism of serotonin (including Monoamine Oxidase Inhibitors [MAOIs]). This may occur within the recommended dose. Serotonin syndrome may include mental-status changes (e.g., agitation, hallucinations, coma), autonomic instability (e.g., tachycardia, labile blood pressure, hyperthermia), neuromuscular abnormalities (e.g., hyperreflexia, incoordination, rigidity), and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea). If serotonin syndrome is suspected, rapid discontinuation of Fentanyl should be considered. As with all opioid analgesics, care should be observed when administering fentanyl to patients with myasthenia gravis Administration in labour may cause respiratory depression in the new born infant.
See prescribing information for full details.

Clinical Trial Data: The safety of FENTANYL was evaluated in 376 subjects who participated in 20 clinical trials evaluating FENTANYL used as an anaesthetic. These subjects took at least one dose of FENTANYL and provided safety data. Adverse Drug Reactions (ADRs), as identified by the investigator,
See prescribing information for full details.

Effect of Other Drugs on Fentanyl: Drugs such as barbiturates, benzodiazepines, neuroleptics, halogenic gases and other, non-selective CNS depressants (e.g. alcohol) may potentiate the respiratory depression of narcotics. When patients have received such drugs, the dose of Fentanyl required will be less than usual. Fentanyl, a high clearance drug, is rapidly and extensively metabolized mainly by CYP3A4. Itraconazole (a potent CYP3A4 inhibitor) at 200 mg/day given orally for 4 days had no significant effect on the pharmacokinetics of IV Fentanyl. Oral ritonavir (one of the most potent CYP3A4 inhibitors) reduced the clearance of IV Fentanyl by two thirds; however, peak plasma concentrations after a single dose of IV Fentanyl were not affected.When Fentanyl is used in a single dose, the concomitant use of potent CYP3A4 inhibitors such as ritonavir requires special patient care and observation. Co-administration of fluconazole or voriconazole and Fentanyl may result in an increased exposure to Fentanyl. With continuous treatment, a dose reduction of Fentanyl may be required to avoid accumulation of Fentanyl, which may increase the risk of prolonged or
delayed respiratory depression. Bradycardia and possibly asystole can occur when fentanyl is combined with non-vagolytic muscle relaxants. The concomitant use of droperidol can result in a higher incidence of hypotension. It is usually recommended to discontinue MAO-inhibitors 2 weeks prior to any surgical or anesthetic procedure. However, several reports describe theuneventful use of Fentanyl during surgical or anesthetic procedures in patients on MAO-inhibitors.
Serotonergic Drugs: Coadministration of fentanyl with a serotonergic agent, such as a Selective Serotonin Re-uptake Inhibitor (SSRI) or a Serotonin Norepinephrine Reuptake Inhibitor (SNRI) or a Monoamine Oxidase Inhibitor (MAOI), may increase the risk of serotonin syndrome, a potentially life-threatening condition.
Effect of Fentanyl on Other Drugs: Following the administration of Fentanyl, the dose of other CNS-depressant drugs should be reduced. The total plasma clearance and volume of distribution of etomidate is decreased by a factor 2 to 3 without a change in half-life when administered with Fentanyl. Simultaneous administration of Fentanyl and intravenous midazolam results in an increase in the terminal plasma half-life and a reduction in the plasma clearance of midazolam. When these drugs are coadministered with Fentanyl their dose may need to be reduced.
See prescribing information for full details.

There are no adequate data from the use of Fentanyl in pregnant women. Fentanyl can cross the placenta in early pregnancy. Studies in animals have shown some reproductive toxicity. The potential risk for humans is unknown.
Administration (I.M. or I.V.) during childbirth (including cesarean section) is not recommended because Fentanyl crosses the placenta and because the fetal respiratory center is particularly sensitive to opiates. If Fentanyl is nevertheless administered, an antidote for the child should always be at hand. Fentanyl is excreted into human milk. Therefore, nursing is not recommended for 24 hours following the administration of this drug. The risk/benefit of breastfeeding following fentanyl administration should be considered.

Signs and Symptoms: An overdose of Fentanyl manifests itself as an extension of its pharmacologic actions. Depending on the individual sensitivity, the clinical picture is determined primarily by the degree of respiratory depression, which varies from bradypnea to apnea.
Treatment: In the presence of hypoventilation or apnea, oxygen should be administered and respiration should be assisted or controlled as indicated. A specific narcotic antagonist, such as naloxone, should be used as indicated to control respiratory depression. This does not preclude the use of more immediate countermeasures. The respiratory depression may last longer than the effect of the antagonist; additional doses of the latter may therefore be required. If depressed respiration is associated with muscular rigidity, an intravenous neuromuscular blocking agent might be required to facilitate assisted or controlled respiration. The patient should be carefully observed; body warmth and adequate fluid intake should be maintained. If hypotension is severe or if it persists, the possibility of hypovolemia should be considered, and if present, should be controlled with appropriate parenteral fluid administration.