NEW YORK (Reuters Health) – Biweekly injections of pegloticase may quickly lower uric acid and ease symptoms in some gout patients who don’t get better with usual treatment, according to a new study.

The research was funded by the pharmaceutical company Savient, which markets the drug as Krystexxa.

Pegloticase, which was approved for by the Food and Drug Administration for treatment of severe, refractory gout last year, is an enzyme that works by breaking down uric acid into a form that’s more easily excreted.

The new study, published in the Journal of the American Medical Association, includes data from two trials of a total of 212 people with chronic gout that were the basis of the FDA’s decision.

Because the drug has potentially serious side effects and is expensive, the ideal patient for the injections is “somebody who not only has had significant disabling or poor quality-of-life engendering disease or pain, but the need to resolve that quickly,” said study author Dr. Michael Becker, from the University of Chicago.

Patients with a contraindication to allopurinol (marketed as Lopurin or Zyloprim), or those who didn’t respond after three months of treatment, were randomized to receive biweekly or monthly pegloticase injections or placebo injections for six months. All patients had two-hour infusions every two weeks containing 250 mL of 0.9% sodium chloride with 8 mg pegloticase or a placebo (the monthly pegloticase group alternated between treatment and placebo injections).

Response rates — defined as plasma uric acid of less than 6.0 mg/dL for at least 80% of the time during both months three and six — were a combined 42% in patients getting biweekly treatment in the two trials, compared to 35% for monthly treatment and 0% for placebo patients.

In secondary end points assessed at weeks 13, 19, and 25, there was a significant improvement in physical function and quality of life in both pegloticase groups compared to the placebo, and an improvement in pain in the biweekly treatment group. Complete response of one or more tophi occurred in 40% of the biweekly group, 21% in the monthly group, and 7% of placebo patients.

Adverse events — most commonly gout flares — occurred in 90% of all patients. Flares were most frequent among those treated with pegloticase during the first few months of treatment. Infusion-related reactions were also common in patients getting pegloticase; serious reactions happened in 5% of the biweekly group and 8% of patients on monthly treatment.

Because of that, it would be “prudent” for all patients getting pegloticase injections to receive prophylaxis against an immune response, the researchers said.

In addition, Dr. Becker added, doctors should monitor what patients have stopped responding to the drug to minimize unnecessary risks.

“If you simply measure the urate levels prior to each infusion, you should be able to detect those people who have lost the ability to lower urate,” he said. “They’re not going to get any benefit and they’re going to be put at increased risk for flares.”

Dr. Becker emphasized that pegloticase should be administered carefully by specialists who have experience with the drug.

And, he added, it should only be used in patients who have run out of other treatment options and need symptoms to be resolved quickly.

“This is a foreign protein being infused at great cost both in time and money,” he told Reuters Health. “This is not a medication to be undertaken in a much larger group of patients.”

The drug runs about $60,000 for a year of treatment. Dr. Becker said that after symptoms have subsided in patients who respond to pegloticase, they can likely go back on oral medications.

The study’s investigators have received consulting fees or reimbursement from Savient, and company employees were involved in design of the trials.

JAMA, 2011.