Abstract
A microbiological assay for the measurement of methotrexate has been designed, using a chloramphenicol resistant mutant of Lactobacillus casei as the test organism. The method is simple, precise and inexpensive. Results are not significantly different from those obtained using a methotrexate radioassay kit employing a competitive protein binding technique. However, where patients are being treated with co-trimoxazole, the competitive protein binding technique is unsuitable for measuring methotrexate levels due to the cross reactivity of the binder. This is not a problem with the microbiological assay described here, which is able to measure methotrexate in the presence of large doses of trimethoprim. The methods were not affected by the presence of seven commonly encountered antibiotics. These had negligible effect on either method up to concentrations of 100 mg/l.
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Selected References
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- Davis R. E., Nicol D. J., Kelly A. An automated method for the measurement of folate activity. J Clin Pathol. 1970 Feb;23(1):47–53. doi: 10.1136/jcp.23.1.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Djerassi I., Rominger C. J., Kim J. S., Turchi J., Suvansri U., Hughes D. Phase I study of high doses of methotrexate with citrovorum factor in patients with lung cancer. Cancer. 1972 Jul;30(1):22–30. doi: 10.1002/1097-0142(197207)30:1<22::aid-cncr2820300105>3.0.co;2-b. [DOI] [PubMed] [Google Scholar]
- Falk L. C., Clark D. R., Kalman S. M., Long T. F. Enzymatic assay for methotrexate in serum and cerebrospinal fluid. Clin Chem. 1976 Jun;22(6):785–788. [PubMed] [Google Scholar]
- Jaffe N., Frei E., 3rd, Watts H., Traggis D. High-dose methotrexate in osteogenic sarcoma: a 5-year experience. Cancer Treat Rep. 1978 Feb;62(2):259–264. [PubMed] [Google Scholar]
- Myers C. E., Lippman M. E., Elliot H. M., Chabner B. A. Competitive protein binding assay for methotrexate. Proc Natl Acad Sci U S A. 1975 Sep;72(9):3683–3686. doi: 10.1073/pnas.72.9.3683. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Noble W. C., White P. M., Baker H. Assay of therapeutic doses of methotrexate in body fluids of patients with psoriasis. J Invest Dermatol. 1975 Feb;64(2):69–76. doi: 10.1111/1523-1747.ep12510255. [DOI] [PubMed] [Google Scholar]
- Paxton J. W. High-dose methotrexate therapy--an area of uncertainty. Aust N Z J Med. 1979 Dec;9(6):722–732. doi: 10.1111/j.1445-5994.1979.tb04209.x. [DOI] [PubMed] [Google Scholar]
- Raso V., Schreiber R. A rapid and specific radioimmunoassay for methotrexate. Cancer Res. 1975 Jun;35(6):1407–1410. [PubMed] [Google Scholar]
- Von Hoff D. D., Penta J. S., Helman L. J., Slavik M. Incidence of drug-related deaths secondary to high-dose methotrexate and citrovorum factor administration. Cancer Treat Rep. 1977 Jul;61(4):745–748. [PubMed] [Google Scholar]