|Trade names||Krystexxa, Puricase|
|Biological half-life||10–12 days|
|Chemical and physical data|
|Formula||C1549H2430N408O448S8 (peptide monomer)|
|Molar mass||497 kg/mol (polymer-modified tetramer)|
|(what is this?)|
Pegloticase (trade name Krystexxa) is a medication for the treatment of severe, treatment-refractory, chronic gout. It is a third line treatment in those in whom other treatments are not tolerated. The drug is administered by infusion intravenously.
It was developed by Savient Pharmaceuticals. In September 2010, the FDA approved pegloticase for marketing in the United States after two clinical trials demonstrated the drug lowered uric acid levels and reduced deposits of uric acid crystals in joints and soft tissue. The European Medicines Agency (EMA) granted marketing authorization in 2013 for treatment of disabling tophaceous gout. In 2016 this authorization was ended in Europe.
It is an option for the 3% of people who are intolerant to other medications. Pegloticase is given as an intravenous infusion every two weeks, and has been found to reduce uric acid levels in this population. It is likely useful for tophi but has a high rate of side effects. About 40% of people develop resistance to the medication over time.
In individuals with glucose-6-phosphate dehydrogenase deficiency, pegloticase may precipitate a severe, life-threatening hemolysis with methemoglobinemia; it is therefore contraindicated in such individuals. Pegloticase may also show immunogenicity.
Mechanism of action
Pegloticase is a recombinant porcine-like uricase. Similarly to rasburicase, it metabolises uric acid to allantoin. This reduces the risk of precipitates, since allantoin is five to ten times more soluble than uric acid.
In contrast to rasburicase, pegloticase is pegylated to increase its elimination half-life from about eight hours to ten or twelve days, and to decrease the immunogenicity of the foreign uricase protein. This modification allows for an application just once every two to four weeks, making this drug suitable for long-term treatment.
Pegloticase is a tetrameric protein composed of four identical chains of about 300 amino acids each. Approximately nine of the 30 lysine residues in each chain are pegylated. These PEG chains consist of about 225 ethylene glycol units each (10 kg/mol PEG).
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