Allopurinol

 

 

Allopurinol inhibits the conversion of hypoxanthine to xanthine and of xanthine to uric acid by inhibiting xanthine oxidase. Optimally, it's initiated one to two days before starting chemotherapy. Monitor patients for a skin rash or fever, which may indicate a hypersensitivity reaction. Other signs and symptoms of a hypersensitivity reaction include chills, nausea, vomiting, and a high serum eosinophil count. Common adverse reactions from allopurinol include central nervous system alterations, such as drowsiness or headache. Allopurinol therapy is started before chemotherapy because it helps prevent excess uric acid, but it won't reduce uric acid levels in patients who already have hyperuricemia. Another limitation of allopurinol is that it increases xanthine levels, which could precipitate in the kidneys. In addition, it interferes with the excretion of other drugs used to treat cancer, such as high-dose methotrexate, cyclophosphamide, e-mercaptopurine, and azathioprine. Allopurinol is never administered with capecitabine, because allopurinol may decrease its effectiveness.