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 : 136.1

%Protein binding : <5

%Excreted unchanged in urine :

<10 :

Volume of distribution (L/kg) : 1.6

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

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : 200–300 mg daily

10 to 20 : 100–200 mg daily

<10 : 100 mg daily or 100 mg on alternate days

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD : Dialysed. Dose as in GFR

<10 : mL/ min

HD : Dialysed. Dose as in GFR

<10 : mL/ min

HDF/high flux : Dialysed. Dose as in GFR

<10 : mL/ min

CAV/VVHD : 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

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

Home