Fenta Injection

/ Rafa

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.
To avoid bradycardia, it is recommended to administer a small intravenous dose of an anti-cholinergic just before anesthetic induction.
Use as an analgesic supplement to general anesthesia:
Low dose 2 mcg/kg: Fentanyl in small doses is most useful for minor surgery.
Moderate dose 2-20 mcg/kg: Where surgery becomes more complicated, a larger dose will be required. The duration of activity is dependent on dosage.
High dose 20-50 mcg/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, doses of 20-50 mcg/kg of fentanyl with nitrous oxide/oxygen have been shown to have an attenuating effect. When doses in this range have been used during surgery, postoperative ventilation and observation are essential in view of the possibility of extended post-operative respiratory depression.
Supplemental doses of 25-250 mcg (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 anesthetic agent: When attenuation of the response to surgical stress is especially important, doses of 50-100 mcg/kg may be administered with oxygen and a muscle relaxant. This technique provides anesthesia without necessitating the use of additional anesthetic agents. In certain cases, doses up to 150 mcg/kg may be required to produce this anesthetic 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.
Elderly and debilitated patients: As with other opioids, the initial dose should be reduced in elderly (>65 years of age) and in debilitated patients. The effect of the initial dose should be taken into account in determining supplemental doses.
Pediatrics: For induction and maintenance in children aged 2-12 years, a dose of 2- 3 mcg/kg is recommended.
Obese Patients: In obese patients there is a risk of overdosing if the dose is calculated based on body weight. Obese patients should be dosed based on estimated lean body mass rather than on body weight only.
Renal Impairment: In patients with renal impairment reduced dosing should be considered and these patients should be observed carefully for signs of fentanyl toxicity (see Pharmacokinetic properties).

For analgesic action of short duration during anesthetic periods (premedication,
induction and maintenance) and in the immediate postoperative period, as need arises.
As a narcotic analgesic supplement in general or regional anesthesia.
For administration with a neuroleptic [such as droperidol] as an anesthetic
premedication, for the induction of anesthesia, and as an adjunct in the maintenance of general and regional anesthesia.
For use as an anesthetic agent with oxygen in selected, high-risk patients (open heart surgery or certain neurological or orthopedic procedures).
By the epidural route for the postoperative management of pain following surgical procedures and cesarean sections, and as adjunct to general anesthesia.

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

WARNING: RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR
OTHER CNS DEPRESSANTS
Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death.
Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate.
Limit dosages and durations to the minimum required.
Follow patients for signs and symptoms of respiratory depression and sedation.
Tolerance and dependence: may occur.
Respiratory depression: As with all potent opioids, respiratory depression is dose related and can be reversed by a specific opioid antagonist, but additional doses 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 opioid antagonists should be readily available. Hyperventilation during anesthesia may alter the patient’s responses to CO2, thus affecting respiration postoperatively.
Muscle rigidity: Induction of muscle rigidity, which may also involve the thoracic muscles, can occur, but can be avoided by the following measures: slow IV injection (ordinarily sufficient for lower doses), premedication with benzodiazepines and the use of muscle relaxants.
Non-epileptic (myo) clonic movements can occur.
Cardiac disease: 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.
Special dosing conditions: 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.
Bile duct: As with other opioids, due to the anticholinergic effects, administration of fentanyl may lead to increases of bile duct pressure and, in isolated cases, spasms of the Sphincter of Oddi might be observed.
Interaction with neuroleptic: If fentanyl is administered with a neuroleptic, 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.
Serotonin syndrome: 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 Re-uptake 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.
Myasthenia gravis: 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.

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 opioid.
When patients have received such drugs, the dose of fentanyl required may 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 fentanyl.
Oral ritonavir (one of the most potent CYP3A4 inhibitors) reduced the clearance of fentanyl by two thirds; however, peak plasma concentrations after a single dose of 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 nonvagolytic muscle relaxants.
The concomitant use of droperidol can result in a higher incidence of hypotension.
Monoamine Oxidase Inhibitors (MAOI): It is usually recommended to discontinue MAOIs 2 weeks prior to any surgical or anesthetic procedure. However, several reports describe the uneventful use of fentanyl during surgical or anesthetic procedures in patients on MAOIs.
Serotonergic drugs: Coadministration of fentanyl with a serotonergic agent, such as a Selective Serotonin Re-uptake Inhibitor (SSRI) or a Serotonin Norepinephrine Re-uptake 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 co-administered with fentanyl their dose may need to be reduced.

Pregnancy: 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 during childbirth (including cesarean section) is not recommended because fentanyl crosses the placenta and may suppress spontaneous respiration in the newborn period. If fentanyl is administered, assisted ventilation equipment must be immediately available for the mother and infant if required. An opioid antagonist for the child must always be available.
Breast feeding: Fentanyl is excreted into human milk. Therefore, breast-feeding or use of expressed breast milk is not recommended for 24 hours following the administration of this drug.
The risk/benefit of breastfeeding following fentanyl administration should be
considered.

Symptoms and signs: An overdosage of fentanyl manifests itself as an extension of its pharmacologic actions.
Respiratory depression which can vary in severity from bradypnea to apnea may
occur.
Treatment: In the presence of hypoventilation or apnea, oxygen should be administered and respiration should be assisted or controlled as indicated. A specific opioid antagonist, 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.

Incompatibilities: The injectable solution must not be mixed with other products. If desired, Fenta injection may be mixed with sodium chloride or glucose intravenous infusions. Such dilutions are compatible with plastic infusion sets. These should be used within 24 hours of preparation.