title: Lipid-soluble inhibitors of dihydrofolate reductase. III: Quantitative thin-layer and high-performance liquid chromatographic methods for measuring plasma concentrations of the antifolate, 2,4-diamino-6-(2,5-dimethoxybenzyl)-5-methylpyrido-[2,3-d]pyrimidine.
abstract: Specific methods using high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) for the analysis of the potent antifolate, 2,4-diamino-6-(2,5-dimethoxybenzyl)-5-methylpyrido-[2,3-d]pyrimidine (I) in plasma were developed. The HPLC system employed paired-ion chromatography using a mobile phase of water-acetonitrile (65:35, v/v) in conjunction with a reversed-phase C-1 column and detection by UV absorbance measurement. The TLC system utilized a scanning densitometer operating in the reflectance mode with detection of I by fluorescence measurement. The lower limits of detection for the HPLC and TLC methods were approximately 0.005 micrograms/ml. The coefficients of variation for the measurement of drug concentrations over the range of 0.04-1.0 microgram/ml of plasma were 5 and 6%, respectively.
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods; D005493:Folic Acid Antagonists / Q000097:blood*; D006801:Humans; D011743:Pyrimidines / Q000097:blood*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D005493:Folic Acid Antagonists; D011743:Pyrimidines; C024530:piritrexim