Active Ingredient: Glucarpidase
Glucarpidase is indicated to reduce toxic plasma methotrexate concentration in adults and children (aged 28 days and older) with delayed methotrexate elimination or at risk of methotrexate toxicity.
For this indication, competent medicine agencies globally authorize below treatments:
Intravenous
50 - 50 [iU] per kg of body weight
From 50 To 50 [iU] per kg of body weight once every day
The recommended dose is a single dose of 50 Units per kilogram (kg) by bolus intravenous (IV) injection over 5 minutes.
Once the diagnosis of delayed methotrexate (MTX) elimination or risk for MTX toxicity is established, glucarpidase should be administered without delay; for patients with delayed MTX elimination the optimal time window for administration is within 48–60 hours from the start of the high dose MTX infusion. Folinic acid, also known as leucovorin, is a competitive substrate of glucarpidase that may compete for the MTX binding sites. It is therefore recommended that folinic acid should not be administered within the 2 hours before or after glucarpidase administration to minimise any potential interaction.
Recommendations for intervention with glucarpidase are considered when plasma MTX levels are greater than 2 standard deviations of the mean expected MTX excretion curve.
Recommendations are detailed below:
| MTX Dose: | ≤1 g/m² | 1-8 g/m² | 8-12 g/m² |
| Infusion duration: | Over 36-42 hours | Over 24 hours | Over ≤6 hours |
| Hours following start of MTX infusion | Threshold plasma MTX concentration (µM) | ||
| 24 hours | - | -* | ≥50 |
| 36 hours | - | ≥30 | ≥30 |
| 42 hours | - | ≥10 | ≥10 |
| 48 hours | ≥5 | ≥5 | ≥5 |
* start supportive care when ≥120 µM.
As a further guide for patients receiving short infusion MTX regimens, glucarpidase administration may be considered as detailed below:
| MTX Dose: | 3-3.5 g/m² | 5 g/m² |
| Hours following start of MTX infusion | Threshold plasma MTX concentration (µM) | |
| 24 hours | ≥20 | - |
| 36 hours | - | ≥10 |
| 48 hours | ≥5 | ≥6 |
Intracellular MTX will continue to inhibit reduction of folate to its active form following glucarpidase administration thus folinic acid will continue to be needed no earlier than 2 hours post glucarpidase administration in order to replenish the intracellular source of biologically active folate.
Bolus intravenous (IV) injection over 5 minutes.
Flush intravenous line before and after administration.
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