Posology
Adults
Allopurinol oral suspension should be introduced at low dosage e.g. 100 mg/day to reduce the risk of adverse reactions and increased only if the serum urate response is unsatisfactory. Extra caution should be exercised if renal function is poor (see section 4.2 Renal impairment). The following dosage schedules are suggested:
100 to 200 mg daily in mild conditions,
300 to 600 mg daily in moderately severe conditions
700 to 900 mg daily in severe conditions.
If dosage on a mg/kg bodyweight basis is required, 2 to 10 mg/kg bodyweight/day should be used.
Based on published articles higher baseline plasma urate will require a higher maintenance dose of allopurinol. A simple equation (UT = (1 –D/(ID50 + D)) ¥ (UP – UR) + UR,) can be used to estimate the continuing allopurinol dose likely to effectively lower the plasma urate concentrations to target.
Paediatric population
Children under 15 years: 10 to 20 mg/kg bodyweight/day up to a maximum of 400 mg daily. Use in children is rarely indicated, except in malignant conditions (especially leukaemia) and certain enzyme disorders such as Lesch-Nyhan syndrome.
Elderly
In the absence of specific data, the lowest dosage which produces satisfactory urate reduction should be used. Particular attention should be paid to advice in section 4.2 Renal impairment and section 4.4.
Renal impairment
Since allopurinol and its metabolites are excreted by the kidney, impaired renal function may lead to retention of the drug and/or its metabolites with consequent
prolongation of plasma half-lives. In severe renal insufficiency, it may be advisable to use less than 100 mg per day or to use single doses of 100 mg at longer intervals than one day. If facilities are available to monitor plasma oxipurinol concentrations, the dose should be adjusted to maintain plasma oxipurinol levels below 100 micromol/litre (15.2 mg/litre). Allopurinol and its metabolites are removed by renal dialysis. If dialysis is required two to three times a week consideration should be given to an alternative dosage schedule of 300-400 mg allopurinol oral suspension immediately after each dialysis with none in the interim. (See section 5.2)
Hepatic impairment
Reduced doses should be used in patients with hepatic impairment. Periodic liver function tests are recommended during the early stages of therapy.
Treatment of high urate turnover conditions, e.g. neoplasia, Lesch-Nyhan syndrome
It is advisable to correct existing hyperuricaemia and/or hyperuricosuria with allopurinol oral suspension before starting cytotoxic therapy. It is important to ensure adequate hydration to maintain optimum diuresis and to attempt alkalinisation of urine to increase solubility of urinary urate/uric acid. Dosage of allopurinol oral suspension should be at the lower end of the recommended dosage schedule.
If urate nephropathy or other pathology has compromised renal function, the advice given in section 4.2 Renal impairment should be followed.
These steps may reduce the risk of xanthine and/or oxipurinol deposition complicating the clinical situation. See also section 4.5 and section 4.8.
Monitoring Advice
The dosage should be adjusted by monitoring serum urate concentrations and urinary urate/uric acid levels at appropriate intervals.
Due to high Cmax of allopurinol oral suspension, complete blood count, liver function tests, renal function, and serum uric acid levels shall be measured every 2 to 5 weeks while titrating the dose until achieving the target serum uric acid level and every 6 months thereafter (see section 5.2).
Patients need counselling about the signs and symptoms of allopurinol hypersensitivity Syndrome (AHS) with a recommendation to discontinue allopurinol promptly if they develop skin rash concerning AHS, especially early in therapy.
Method of administration
For oral administration.
Please shake the bottle thoroughly before use.
Allopurinol oral suspension may be taken orally once a day after a meal. It is well tolerated, especially after food. Should the daily dosage exceed 300 mg and gastrointestinal intolerance be manifested, a divided doses regimen may be appropriate. Take Allopurinol oral suspension with a glass of water.
Measuring your dose
The syringe in the pack delivers:
• 30mg for every 0.5 ml graduation mark
• 60mg for every 1 ml graduation mark
The dosing syringe provided has only been demonstrated to deliver doses accurately at 1.5 mL volume and above (equivalent to 90mg allopurinol and higher). Alternative measuring devices should be considered if low allopurinol doses are to be administered.