Uloric works by blocking an enzyme called xanthine oxidase, which helps prevent uric acid production, lowering elevated uric acid levels, according to Takeda.
In 2005, the FDA refused to approve Uloric because there were slightly more deaths and heart problems in patients taking the drug than in patients taking allopurinol, another gout drug. As people with gout problems already are at higher risk of heart disease, the FDA issued an "approvable" letter, noting that Uloric could be approved if this safety question were addressed.
Takeda resolved the safety question by performing a large new phase III clinical trial that enrolled more gout patients than the two previous phase III trials combined. The new study found no more deaths and no more heart problems in patients taking Uloric than in patients taking allopurinol.
Based on those results, an FDA advisory committee recommended Uloric's approval in November 2008. The FDA often follows the recommendations of its advisory committees, but it's not obligated to do so.