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Alfenta Dosage

Medically reviewed by Last updated on Feb 15, 2021.

Generic name: alfentanil hydrochloride
Dosage form: injection

The dosage of ALFENTA (alfentanil hydrochloride) should be individualized and titrated to the desired effect in each patient according to body weight, physical status, underlying pathological condition, use of other drugs, and type and duration of surgical procedure and anesthesia. In obese patients (more than 20% above ideal total body weight), the dosage of ALFENTA should be determined on the basis of lean body weight. The dose of ALFENTA should be reduced in elderly or debilitated patients (see PRECAUTIONS).

Vital signs should be monitored routinely.

See Dosage Guidelines for the use of ALFENTA: 1) by incremental injection as an analgesic adjunct to anesthesia with barbiturate/nitrous oxide/oxygen for short surgical procedures (expected duration of less than one hour); 2) by continuous infusion as a maintenance analgesic with nitrous oxide/oxygen for general surgical procedures; and 3) by intravenous injection in anesthetic doses for the induction of anesthesia for general surgical procedures with a minimum expected duration of 45 minutes; and 4) by intravenous injection as the analgesic component for monitored anesthesia care (MAC).

Maintenance of Analgesia: 3-5 mcg/kg q 5-20 min or 0.5 to 1 mcg/kg/min
Total dose: 8-40 mcg/kg
Incremental Injection
(To attenuate response to laryngoscopy and intubation)
Induction of Analgesia: 20-50 mcg/kg
Maintenance of Analgesia: 5-15 mcg/kg q 5-20 min
Total dose: Up to 75 mcg/kg
Continuous Infusion
(To provide attenuation of response to intubation and incision)
Infusion rates are variable and should be titrated to the desired clinical effect.
Induction of Analgesia: 50-75 mcg/kg
Maintenance of Analgesia: 0.5 to 3 mcg/kg/min (Average rate 1 to 1.5 mcg/kg/min)
Total dose: Dependent on duration of procedure
Anesthetic Induction Induction of Anesthesia: 130-245 mcg/kg
Maintenance of Anesthesia: 0.5 to 1.5 mcg/kg/min or general anesthetic
Total dose: Dependent on duration of procedure
At these doses, truncal rigidity should be expected and a muscle relaxant should be utilized.
Administer slowly (over 3 minutes).

Concentration of inhalation agents reduced by 30-50% for initial hour.
(For sedated and responsive, spontaneously breathing patients)
Induction of MAC: 3-8 mcg/kg
Maintenance of MAC: 3-5 mcg/kg q 5-20 min or 0.25 to 1 mcg/kg/min
Total dose: 3-40 mcg/kg
Continuous Infusion: 0.5-3 mcg/kg/min administered with nitrous oxide/oxygen in patients undergoing general surgery. Following an anesthetic induction dose of ALFENTA, infusion rate requirements are reduced by 30-50% for the first hour of maintenance.
Changes in vital signs that indicate a response to surgical stress or lightening of anesthesia may be controlled by increasing the alfentanil to a maximum of 4 mcg/kg/min and/or administration of bolus doses of 7 mcg/kg. If changes are not controlled after three bolus doses given over a five minute period, a barbiturate, vasodilator, and/or inhalation agent should be used. Infusion rates should always be adjusted downward in the absence of these signs until there is some response to surgical stimulation.
Rather than an increase in infusion rate, 7 mcg/kg bolus doses of ALFENTA or a potent inhalation agent should be administered in response to signs of lightening of anesthesia within the last 15 minutes of surgery. ALFENTA infusion should be discontinued at least 10-15 minutes prior to the end of surgery.

Usage in Children

Clinical data to support the use of ALFENTA in patients under 12 years of age are not presently available. Therefore, such use is not recommended.


The selection of preanesthetic medications should be based upon the needs of the individual patient.

Neuromuscular Blocking Agents

The neuromuscular blocking agent selected should be compatible with the patient's condition, taking into account the hemodynamic effects of a particular muscle relaxant and the degree of skeletal muscle relaxation required (see CLINICAL PHARMACOLOGY, WARNINGS and PRECAUTIONS sections).

In patients administered anesthetic (induction) dosages of ALFENTA, it is essential that qualified personnel and adequate facilities are available for the management of intraoperative and postoperative respiratory depression.

Also see WARNINGS and PRECAUTIONS sections.

For purposes of administering small volumes of ALFENTA accurately, the use of a tuberculin syringe or equivalent is recommended.

The physical and chemical compatibility of ALFENTA have been demonstrated in solution with normal saline, 5% dextrose in normal saline, 5% dextrose in water and Lactated Ringers. Clinical studies of ALFENTA infusion have been conducted with ALFENTA diluted to a concentration range of 25 mcg/mL to 80 mcg/mL.

As an example of the preparation of ALFENTA for infusion, 20 mL of ALFENTA added to 230 mL of diluent provides 40 mcg/mL solution of ALFENTA.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.


ALFENTA (alfentanil hydrochloride) is supplied in individually sealed dosage forms which pose no known risk to health-care providers having incidental contact. Accidental dermal exposure to ALFENTA should be treated by rinsing the affected area with water.

Protect from light. Storage: Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature].

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.