POLY[N-(2-HYDROXYPROPYL)METHACRYLAMIDE] CONJUGATES OF METHOTREXATE - SYNTHESIS AND IN-VITRO DRUG-RELEASE

Two hexamethylenediamine (HMDA) derivatives of the anti-cancer drug me thotrexate (MTX) were synthesized in which either the alpha-carboxylic [HMDA-MTX(I)] or gamma-carboxylic [HMDA-MTX(II)] group of glutamic ac id in the methotrexate structure were modified by reaction with HMDA. Both HMDA-MTX(I) and HMDA-MTX(II) were coupled with poly[N-(2-hydroxyp ropyl)methacrylamide] via oligopeptide -GlyGly-, -GlyLeuGly- and -Gly- DL-PheLeuGly- spacers and physico-chemical characterization of the pol ymer-drug conjugates was performed. The in vitro release of HMDA-MTX(I ) and HMDA-MTX(II) or their respective amino acid derivatives from pol ymeric conjugates during their incubation with the thiol protease cath epsin B solution or with a mixture of lysosomal enzymes isolated from rat liver (tritosomes) was studied in detail. The results show that th e rate of release of HMDA-MTX(I) and HMDA-MTX(II) from the polymer car rier depends on the detailed structure of the drug and can be controll ed by modification of the structure of the oligopeptide spacer. The co urse of the reaction and the structure of the products of the enzyme-c atalysed hydrolysis (free drug or its amino acid derivative) were stud ied using HPLC and amino acid analysis. (C) 1997 Elsevier Science BN.