Allopurinol

CLINICAL USE

  • Gout prophylaxis
  • Hyperuricaemia

    DOSE IN NORMAL RENAL FUNCTION


    100–900 mg/day (usually 300 mg/day)
    Doses above 300 mg should be given in
    divided doses

    PHARMACOKINETICS


  • Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
    136.1
  • %Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
    <5
  • %Excreted unchanged in urine &nbsp &nbsp :
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp :

  • Volume of distribution (L/kg) &nbsp &nbsp &nbsp :
    1.6

  • half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :
    1–2/Increased

    DOSE IN RENAL IMPAIRMENT


    GFR (mL/MIN)


  • 20 to 50 &nbsp &nbsp : 200–300 mg daily
  • 10 to 20 &nbsp &nbsp : 100–200 mg daily
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp :
    100 mg daily or 100 mg on alternate
    days

    DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES


  • CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:
    Dialysed. Dose as in GFR
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/
    min

  • HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :
    Dialysed. Dose as in GFR
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/
    min
  • HDF/high flux &nbsp :
    Dialysed. Dose as in GFR
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/
    min
  • CAV/VVHD &nbsp &nbsp &nbsp:
    Dialysed. Dose as in GFR=10–
    20 mL/min

    IMPORTANT DRUG INTERACTIONS


    Potentially hazardous interactions with other drugs

  • ACE inhibitors: increased risk of toxicity

    with captopril

  • Ciclosporin: isolated reports of raised

    ciclosporin levels (risk of nephrotoxicity)

  • Cytotoxics: effects of azathioprine and

    mercaptopurine enhanced with increased
    toxicity; avoid concomitant use with
    capecitabine

    ADMINISTRATION


    Reconstition


    –

    Route


    Oral

    Rate of Administration


    –

    Comments

  • In all grades of renal impairment

    commence with 100 mg/day and increase
    if serum and/or urinary urate response is
    unsatisfactory. Doses less than 100 mg/day
    may be required in some patients

  • Take as a single daily dose, preferably after

    food

    OTHER INFORMATION


    A parenteral preparation is available from

    Glaxo Wellcome on a named patient basis

  • HD patients may be given 300 mg post

    dialysis, i.e. on alternate days

  • Increased incidence of skin rash in

    patients with renal impairment

  • Efficient dialysis usually controls serum

    uric acid levels
    If a patient is prescribed azathioprine or

    6-mercaptopurine concomitantly, reduce
    azathioprine or 6-mercaptopurine dose by
    66–75%

  • Main active metabolite: oxipurinol –

    renally excreted; plasma protein binding
    17%; half-life: Normal/ESRF = 13–
    30/>125 hours – 1 week

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