Assessing the aquatic biodegradation potential of polymeric excipients for pharmaceutical formulation

Polymeric excipients (PEx) are essential in drug formulation but raise environmental concerns upon wastewater release post-administration due to their potential detrimental effects to life-histories of freshwater vertebrates and invertebrates. Ten pharmaceutical polymeric compounds were assessed in a stepwise environmental biodegradation assessment according to standard OECD 301 guidelines to thoroughly evaluate biodegradability of these compounds. Polyvinyl alcohol (PVA), polyethylene glycol (PEG), chitosan, maize starch, and sodium starch glycolate (SSG) were found to be ‘readily biodegradable,’ although PVA and PEG showed variation across employed test systems. PEG and PVA did not degrade in OECD 301D tests having low microbial density and diversity. In contrast, in the OECD 301F tests i.e., higher microbial density and diversity, PEG exhibited 73.0 ± 3.3 % biodegradation, while PVA showed 91.2 ± 8.0 % biodegradation with secondary effluent and activated sludge, respectively. Polyvinyl pyrrolidone (PVP), Copovidone, Kollidon CL, and Eudragit derivatives EPO and L100-55 were categorized as 'non-biodegradable' (< 10 % biodegradation). No increase in degradation was observed after 42 days. This indicates their environmental persistence. This study lays the groundwork for a comprehensive understanding of the biodegradation potential of pharmaceutical polymers. It considers the influence of test conditions, inoculum sources, and compound characteristics. The environmental persistence of certain PEx underlines the urgent need to use more environmentally biodegradable alternatives in drug formulation.