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 ofrespiratory 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 mgIV 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 excitationor depression (hypertension or
    hypotension) in patients also receiving
    MAOIs (including moclobemide) – avoid
    concomitant use; possibly increased
    sedative effects with tricyclics
  • Antifungals: metabolism inhibited byfluconazole and ketoconazole (risk
    of prolonged or delayed respiratory
    depression); metabolism possibly inhibited
    by itraconazole
  • Antivirals: concentration possiblyincreased by ritonavir
  • Sodium oxybate: enhanced effect ofsodium oxybate – avoid concomitant use

    ADMINISTRATION

    Reconstition

    –

    Route

    IV bolus,

    IV infusion

    Rate of Administration

    See dose

    Comments

  • Alfentanil can be mixed with sodiumchloride 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 renalfailure, hence dose requirements may be
    reduced
  • IV administration: 500 microgramsalfentanil has peak effect in 90 seconds,
    and provides analgesia for 5–10 minutes
    (in unpremedicated adults)
  • Transient fall in BP and bradycardia mayoccur on administration
  • Analgesic potency = ¼ that of fentanylDuration of action = ⅓ that of an equi-

    analgesic dose of fentanyl

  • Onset of action = 4 times more rapid thanan equi-analgesic dose of fentanyl
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