alfentanil hydrochloride: clinical use

Prescribing considerations

• Administration is restricted to clinicians trained in general anaesthesia and management of potent-opioid respiratory effects.
• Review concurrent medicines, substance-use history and conditions affecting respiratory reserve, circulation or consciousness.
• Effects may be enhanced or prolonged in older or debilitated people and in hepatic or renal impairment.
• Neonates and very young children have variable pharmacokinetics and a greater risk of respiratory complications and muscle rigidity.
• Repeated exposure can cause tolerance, dependence, withdrawal and opioid use disorder, although addiction is not expected from intended intraoperative use alone.

Contraindications and cautions

• Hypersensitivity to alfentanil, another opioid or a formulation excipient.
• For the hameln product: obstructive airway disease or respiratory depression without ventilation.
• For the hameln product: concurrent or recent MAO-inhibitor treatment.
• For the hameln product: administration during labour or before cord clamping.
• The Kalceks SmPC states that alfentanil should not be used in myasthenia gravis because muscle rigidity may necessitate a muscle relaxant.

Monitoring

• Continuously assess ventilation, oxygenation, respiratory rate and consciousness.
• Monitor heart rate and arterial blood pressure, particularly with hypovolaemia, heart failure or other sedatives.
• Confirm adequate spontaneous breathing before discharge from recovery.
• Keep assisted-ventilation equipment and an opioid antagonist immediately available; respiratory depression may recur after reversal.
• Observe children until sustained spontaneous respiration has returned.

Clinical pharmacology

Alfentanil is a synthetic mu-opioid receptor agonist with rapid onset, short duration, high protein binding and predominantly hepatic CYP3A4 metabolism. Hepatic impairment reduces clearance, while renal impairment increases the unbound fraction despite little change in clearance.

Formulation and product differences

• Both selected products are clear, colourless intravenous solutions.
• Alfentanil Kalceks is supplied as single-use ampoules for injection or infusion; the hameln product includes ampoule and vial presentations.
• The products use slightly different pH-adjusting excipients and have product-specific container ranges, shelf lives and dilution instructions; check the relevant SmPC before preparation.

Injection

Route: Parenteral

Strengths: 500 micrograms/mL, 5 mg/mL