Alfentanil

CLINICAL USE

Opioid analgesic:

Short surgical procedures

Intensive care sedation

DOSE IN NORMAL RENAL FUNCTION

IV injection: Spontaneous respiration: up to — 500 micrograms over 30 seconds; supplemental dose: 250 micrograms assisted ventilation: 30–50 — micrograms/kg; supplemental dose: 15 micrograms/kg

By IV infusion with assisted ventilation: loading dose 50–100 micrograms/kg as bolus or fast infusion over 10 minutes, followed by 0.5–1 micrograms/kg/minute. Discontinue infusion 30 minutes before anticipated end of surgery

For analgesia and suppression of respiratory activity during intensive care with assisted ventilation: by IV infusion 2 mg/hour, adjusted according to response (usual range 0.5–10 mg/hour)

For more rapid initial control give 5 mg IV in divided portions over 10 minutes (slower if hypotension or bradycardia develops); additional doses of 0.5–1 mg may be given by IV injection during short painful procedures

PHARMACOKINETICS

Molecular weight : 453 (as hydrochloride)

%Protein binding : 92

%Excreted unchanged in urine : 0.4

Volume of distribution (L/kg) : 0.4–1

half-life – normal/ESRD (hrs) : 1–2 (average 90 minutes)/ Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD : Not dialysed. Dose as in normal renal function

HD : Not dialysed. Dose as in normal renal function

HDF/high flux : Unknown dialysability. Dose as in normal renal function

CAV/VVHD : Not dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antidepressants: possible CNS excitation or depression (hypertension or hypotension) in patients also receiving MAOIs (including moclobemide) – avoid concomitant use; possibly increased sedative effects with tricyclics

Antifungals: metabolism inhibited by fluconazole and ketoconazole (risk of prolonged or delayed respiratory depression); metabolism possibly inhibited by itraconazole

Antivirals: concentration possibly increased by ritonavir

Sodium oxybate: enhanced effect of sodium oxybate – avoid concomitant use

ADMINISTRATION

Reconstition

–

Route

IV bolus,

IV infusion

Rate of Administration

See dose

Comments

Alfentanil can be mixed with sodium chloride 0.9%, glucose 5%, or compound sodium lactate injection (Hartmann’s solution) at a concentration of 0.5 mg/ mL, but can be used at 2 mg/mL or even undiluted at 5 mg/mL.

OTHER INFORMATION

Free fraction of drug is increased in renal failure, hence dose requirements may be reduced

IV administration: 500 micrograms alfentanil has peak effect in 90 seconds, and provides analgesia for 5–10 minutes (in unpremedicated adults)

Transient fall in BP and bradycardia may occur on administration

Analgesic potency = ¼ that of fentanyl Duration of action = ⅓ that of an equi- analgesic dose of fentanyl

Onset of action = 4 times more rapid than an equi-analgesic dose of fentanyl

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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