HPMA copolymer conjugate with pirarubicin: In vitro and ex vivo stability and drug release study

Publication date: 30 January 2018 Source:International Journal of Pharmaceutics, Volume 536, Issue 1 Author(s): Waliul Islam, Jun Fang, Tomas Etrych, Petr Chytil, Karel Ulbrich, Akihiro Sakoguchi, Katsuki Kusakabe, Hiroshi Maeda We have developed a tumor environment-responsive polymeric anticancer prodrug containing pirarubicin (THP) conjugated to N-(2-hydroxypropyl) methacrylamide copolymer (PHPMA), [P-THP], through a spacer containing pH-sensitive hydrazone bond, that showed remarkable therapeutic effect against various tumor models and in a human pilot study. Toward clinical development, here we report THP release profile from its HPMA copolymer conjugate, the conjugate stability, protein and cell-binding and solubility of P-THP. Size exclusion chromatography of P-THP (molecular weight 38 kDa) showed similar hydrodynamic volume as bovine serum albumin (BSA) in aqueous solution, with no apparent interactions with BSA, nor aggregation by itself. pH-responsive release of free THP was reconfirmed at pHs 6.5 and lower. The drug release was significantly affected by a type of used buffer. Phosphate buffer seems to facilitate faster hydrazone bond cleavage at pH 7.4 whereas higher stability was achieved in L-arginine solution which yielded only little cleavage and THP release, approx. 15% within 2 weeks at the same pH at 25 °C. Furthermore, ex vivo study using sera of different animal species showed very high stability of P-THP. Incubation with blood showed high st...
Source: International Journal of Pharmaceutics - Category: Drugs & Pharmacology Source Type: research