The FDA has approved intravenous glucarpidase (Voraxaze) to treat patients with toxic levels of methotrexate in their blood due to kidney failure. Glucarpidase is an enzyme that rapidly reduces methotrexate levels by breaking down the chemotherapy drug to a form that can be eliminated from the body. It has been granted orphan drug status.
A single clinical study of 22 patients evaluated the effectiveness of glucarpidase. All patients received the treatment. The study considered treatment a success if the methotrexate level fell below a critical level within 15 minutes and stayed below the critical level for 8 days. Of the 22 patients studied, 10 achieved this standard, but glucarpidase eliminated 95% of the methotrexate in all patients. The most common side effects observed were hypotension, headache, nausea, vomiting, flushing, and paraesthesia.
A separate clinical study evaluated the safety of glucarpidase in 290 patients experiencing problems clearing methotrexate from their blood. ■