Last updated: October 20, 2014
Trade Names: Krystexxa
Class: Urate-oxidase enzyme; pegylated recombinant uricase; antigout agent
Preparations: 8 mg/ml for i.v. infusion
Dose: 8 mg every two weeks by slow i.v. infusion over at least 120 minutes
Indications: Chronic symptomatic gout refractory to conventional therapy
Mechanism of Action: A recombinant urate-oxidase that converts uric acid to allantoin
Contraindications: G-6PD deficiency, hypersensitivity
Precautions: Screen for G-6PD. Anaphylaxis and infusion reactions occur, administer under close supervision in a health care facility with ability to treat these. Premedicate with antihistamine and corticosteroid. Infusion reactions can be delayed – observe patient for 1-2 hours after infusion. Risk of infusion reaction with first and subsequent infusions; with subsequent infusions risk is greater in patients whose uric acid is more than 6 mg/dL. Delayed hypersensitivity reactions can occur. Monitor uric acid before repeat infusions and consider discontinuing treatment if uric acid more than 6 mg/dL (likely indicates high-titre antibodies). Treatment causes gout flares – prophylaxis should be used.
Pregnancy Risk: C
Monitoring: Monitor uric acid level before next infusion; usually decreases to less than 1 mg/dL. A lack of response after an initial response usually means that anti-pegloticase antibodies have formed and an increased risk of severe allergy.
Common: Infusion reactions (26%), formation of anti-pegloticase antibodies (90%), rash, pruritus, nausea, gout flare (40-67% even with colchicine or NSAID treatment)
Less common: Anaphylaxis (6.5%), exacerbation of heart failure
Patient Instructions: Allergy is common and can be serious; gout flares are common
Comments: An extremely expensive but very effective therapy usually reserved for patients with tophaceous gout refractory to conventional therapy. Tophi can decrease in size rapidly. Acute attacks of gout are frequent. Serious allergy is a problem. Optimal duration of therapy and safety of a repeated course after a drug-free interval are not defined.
Clinical Pharmacology: Rapid onset of action, marked reduction in uric acid within 24 hours; half-life 14 days
Sundy JS, Baraf HS, Yood RA, et al Efficacy and tolerability of pegloticase for the treatment of chronic gout in patients refractory to conventional treatment: two randomized controlled trials. JAMA 2011;306:711-20. PMID: 21846852.