Enzymatic assay for methotrexate in serum and cerebrospinal fluid.
We describe an assay for methotrexate in biological fluids. The assay is based on inhibition by methotrexate of dihydrofolate reductase from Lactobacillus casei. The lower limit of sensitivity in serum is 2 X 10(-8) mol (about 10 mug) of methotrexate per liter. Within-run precision is +/- 5% (coefficient of variation) and day-to-day variation is 18%. Advantages of the assay are ease of manipulation, high sensitivity, and specificity.
D005069:Evaluation Studies as Topic; D006801:Humans; D007780:Lacticaseibacillus casei / Q000201:enzymology; D008727:Methotrexate / Q000032:analysis* / Q000097:blood / Q000134:cerebrospinal fluid; D011786:Quality Control; D013762:Tetrahydrofolate Dehydrogenase; D013997:Time Factors
D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate