Also available in 1 mL, 1 mg, 5 mg, 10 mg, 50 mg, 100 mg and bulk. Please contact Fisher for quotes. Allopurinol riboside is a metabolite of allopurinol with potency against parasites. Allopurinol riboside competitively inhibits the action of purine nucleoside phosphorylase on inosine with a Ki of 277 uM. Purity 99.21%