Abstract
Conjugation of methotrexate (MTX) (MW 454) with different molecular weights of polyethylene glycol (PEG) including methoxy-peg (mpeg) 750 D and 5000 D and diol-peg 35000 D led to compounds that are physicochemically highly different from the parent compound, MTX. In this study, an HPLC system consisting of C8 column and UV detector (λ=342 nm), using a mixture of 30:70 v/v phosphate-citrate buffer (pH 4): methanol mobile phase, was validated for quantification of the esters. Three other HPLC methods using three mixture of buffer phosphate-citrate (pH 6): methanol at 30:70, 40:60 and 50:50 v/v, respectively, was set for estimation of partition coefficients the esters. Eight reference standard materials were selected from literature covering the retention times lower and higher than esters. An identical log P (4.3) was obtained for all three esters, despite their different molecular weights (i.e. 1200, 5500 and 35500 D theoretically). In addition the log P obtained differs from that of the parent drug (-1.4). This high difference comes probably from different ability of drug and esters in ionization of carboxylic acid groups.
Keywords
Polymer conjugation Pegylation Validation HPLC Methotrexate Partition coefficient
Copyright
© 2022, Author(s). This open-access article is available under the Creative Commons Attribution 4.0 (CC BY 4.0) International License (https://creativecommons.org/licenses/by/4.0/), which allows for unrestricted use, distribution, and reproduction in any medium, provided that the original work is properly cited.