Krystexxa (pegloticase)

What it is

Krystexxa (pegloticase) is an enzyme medicine for adults with chronic gout that has not responded to the usual uric-acid-lowering pills, or who cannot take them. Gout is caused by uric acid building up and forming crystals in the joints and tissues. Krystexxa works differently from the pills: it is a version of an enzyme (most mammals have it; humans do not) that converts uric acid into a substance the kidneys can easily remove. It can lower uric acid very quickly and, over time, shrink tophi — the chalky lumps of uric acid that form under the skin in long-standing gout.

Before starting

Before starting, we check a blood enzyme test called G6PD in patients who may be at risk of deficiency, because people with that deficiency cannot receive Krystexxa safely — their red blood cells can be damaged by it. We also measure your uric acid level as a baseline. Before every infusion, your uric acid is checked again: this is how we know the medicine is still working, because if uric acid stops staying low, infusion reactions become more likely and treatment is usually stopped at the right time rather than continued. Medicines are given before each infusion (typically an antihistamine and a steroid) to make reactions less likely, and Krystexxa is often paired with a weekly low dose of methotrexate, which helps the body keep responding to it.

How it’s given

It is given as an IV infusion — medicine dripped slowly into a vein over at least 2 hours — in our infusion suite, once every 2 weeks. You will be observed during the infusion and for a period afterwards, especially early in treatment. Plan half a day for the first visits; the routine becomes familiar quickly. In the first months, gout flares are common as stored uric acid dissolves — this is a sign the medicine is working, and we usually prescribe flare-prevention medicine alongside.

What to expect

Uric acid typically falls to very low levels after the first one or two infusions — far faster than pills achieve. Tophi shrink gradually over months as the deposits dissolve, and flares become less frequent once the uric acid stores are cleared. The most common side effects are gout flares during the early months, nausea, bruising around the IV site, and cold-like symptoms. Infusion reactions (flushing, itching, chest tightness) can occur, most often when the medicine has stopped working for a patient — which is exactly why we check uric acid before every dose and stop treatment if it rises. Tell the team immediately about any symptoms during an infusion.

Everyday guidance

Keep the every-2-week schedule: gaps let uric acid climb back and reduce the chance the medicine keeps working. Take the accompanying methotrexate and flare-prevention medicines exactly as prescribed — they are part of why treatment succeeds. Do not resume old uric-acid pills unless your provider tells you to; your uric acid level is managed by the infusions now. Keep lab appointments before each infusion even when you feel well. If you notice new lumps, redness, or a flare that is worse than usual, call us rather than waiting. Our number is (361) 400-7700.