The U.S. Food and Drug Administration (FDA) approved the first biologic medication to treat gout in 2010.

Pegloticase, which will be sold under the brand name Krystexxa, is an enzyme that breaks down uric acid so it can be eliminated by the body. It is given by intravenous infusion every two weeks in a doctor's office or clinic.

The drug is indicated for people with severe gout who have not been helped by other medications.

In clinical trials, 1 out of 4 patients receiving pegloticase experienced a severe allergic reaction. For that reason, the FDA has advised doctors to prescribe corticosteroids and antihistamine medications before treatment to minimize the risks.

Other side effects observed in clinical trials included gout flares, nausea, bruising, irritation of the nasal passages, constipation, chest pain and vomiting.