Therapeutic monitoring of methotrexate in chemotherapy

Methotrexate is a cytostatic drug, folic acid antagonist, used in chemotherapy and immunosuppression in adults and in children. Its use in high doses is an absolute indication for therapeutic drug monitoring. Methotrexate is a highly toxic drug and requires dosage of specific antidote, calcium folinate. This rescue therapy helps to prevent methotrexate toxic effects and bone marrow suppression. Monitoring methotrexate concentration also helps to diagnose patients with decreased MTX elimination rate, who would benefit from glucarpidase treatment, an enzyme which degrades methotrexate molecules or theophylline, which is neuroprotective and increases renal elimination. Based on methotrexate serum concentration also time of forced diuresis and urine alkalinization is appointed in order to prevent acute nephrotoxicity. Of great importance is the fact that delayed elimination may be result of drug-drug interaction, part of which may be prevented. The purpose of this paper is to highlight the role of therapeutic drug monitoring in the prevention of methotrexate toxic effects.