Half-dose glucarpidase: an effective rescue for toxic methotrexate plasma concentrations in a patient with bilateral primary vitreoretinal lymphoma.

We report the case of a 29-year-old man with bilateral primary vitreoretinal lymphoma receiving treatment with the MATRIX regimen.

During the fourth cycle, the patient developed acute kidney injury following intravenous high-dose methotrexate (3.5 g/m²), despite prophylactic measures including hydration, urinary alkalinization, and folinic acid rescue.

Plasma MTX concentrations remained elevated at 32 µmol/L at 23 hours and 20 µmol/L at 42 hours post-infusion.

Although the standard glucarpidase dose is 50 U/kg, emerging evidence supports the effectiveness of lower doses, which may offer similar clinical benefit while reducing costs.