Comparing the release rates of ciprofloxacin from different polymer structures with different linker chemistries

Abstract

Polymeric prodrugs of ciprofloxacin for inhalation are attractive alternatives to orally-administered free ciprofloxacin and inhalable liposomal formulations. This study investigated the release kinetics of ciprofloxacin from four different polymers synthesized from two types of monomeric ciprofloxacin prodrug, HBC containing the alkyl ester linker and CTM containing the phenyl ester linker. The four polymers synthesized and characterized were poly(O950-b-HBC), poly[O950-b-(HBC-co-MAA)], poly(O950-co-CTM) and poly[(O950-co-CTM)-b-(O950-co-HBC)]. The release rates were quantified using HPLC. The inclusion of the hydrophilic methacrylic acid (MAA) in the diblock copolymer of HBC increased the release rates. Unexpected levels of ciprofloxacin release were observed for the CTM polymers using H2O/ACN/acetic acid (94:5:1, v/v/v) as the mobile phase, while the contrary was obtained for poly(O950-co-CTM) with 2% aqueous acetic acid and acetonitrile (84:16, v/v) as the mobile phase. Hence, further analyses using the latter mobile phase will need to be performed before conclusions can be drawn regarding the CTM polymers.