Allopurinol fever with

The daily dose of allopurinol is 300-600 mg. In combination with benzbromarone, the daily allopurinol dose is reduced to 100 mg. In general, allopurinol is well tolerated. The incidence of side effects is 2-3%. Exanthems, pruritus, gastrointestinal problems, and dty mouth have been observed. In rare cases, hair loss, fever, leukopenia, toxic epidermolysis (Lyell syndrome), and hqDatic dysfunction have been reported. Allopurinol inhibits the metabolic inactivation of the cytostatic dtugs azathioprine and 6-mercaptopurine. Accordingly, the administered doses of azathioprine and 6-mercaptopurine must be reduced if allopurinol is given simultaneously. 

The major side effects of allopurinol are skin rash, urticaria, leukopenia, GI problems, headache, and increased frequency of acute gouty attacks with the initiation of therapy. An allopurinol hypersensitivity syndrome characterized by fever, eosinophilia, dermatitis, vasculitis, and renal and hepatic dysfunction occurs rarely but is associated with a 20% mortality rate. 

Allopurinol is the antihyperuricemic drug of choice in patients with a history of urinary stones or impaired renal function, in patients who have lymphoproliferative or myeloproliferative disorders and need pretreatment with a xanthine oxidase inhibitor before initiation of cytotoxic therapy to protect against acute uric acid nephropathy, and in patients with gout who are overproducers of uric acid. The major side effects of allopurinol are skin rash, leukopenia, occasional gastrointestinal toxicity, and increased frequency of acute gouty attacks with the initiation of therapy. An allopurinol hypersensitivity syndrome characterized by fever, eosinophilia, dermatitis, vasculitis, and renal and hepatic dysfunction is a rare side effect, but is associated with a 20% mortality rate. ... 

Allopurinol may cause a cutaneous reaction (3%) that is predominantly pruritic and maculopapular in nature, is accompanied by fever, malaise, or muscle ache, and the incidence increases with renal impairment. Because the onset of skin rash may be followed by severe hypersensitivity reactions, allopurinol should be discontinued by patients who develop such rashes. Patients with impaired renal function require less drug and careful observation. 

These interaetions are not elearly established, and the reaction appears to he rare and unpredictable. All that can he constructively said is that patients taking both drugs should he very closely monitored for any signs of hypersensitivity (e.g. skin reactions) or low white cell count (sore throat, fever), especially if they have renal impairment. The UK manufacturer of captopril recommends that diffeiential white hlood cell counts should be performed before adding allopurinol, then every 2 weeks during the first 3 months of treatment, and periodically thereafter. Similar caution and advice is given by the UK manufacturers of several other ACE inhibitors. For other possible interactions with ACE inhihitors that might result in an increased risk of leucopenia see also ACE inhihitors + Azathioprine , p.l8 and ACE inhibitors + Procainamide , p.33. 

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