The present invention provides a pharmaceutical composition for use in treating an ocular disease or condition, the composition comprising: a chitosan composition comprising a treated chitosan, a modified chitosan, a modified and treated chitosan or a mixture thereof, each modified and/or treated chitosan exhibiting a different chemical, physical and/or performance property or characteristic relative to the corresponding unmodified/untreated chitosan, and a therapeutic agent selected from a corticosteroid and a mixture of corticosteroids wherein: each treated chitosan is obtained by dialyzing chitosan against water and a salt and/or anionic solution, and each modified chitosan is obtained by one or more of covalent attachment of one or more functional groups to chitosan, non-covalent association of one or more atomic or molecular agents with chitosan and coaddition of one or more atomic or molecular agents with chitosan, the therapeutic agent is covalently bonded to at least one treated and/or modified chitosan directly or via a linker, and the chitosan composition is adapted to release a therapeutically effective amount of the therapeutic agent over a period of time. A process for manufacturing the pharmaceutical composition is also provided, the process comprising contacting the above chitosan composition with a therapeutically-effective amount of the above therapeutic agent under conditions such that the therapeutic agent is covalently bonded to at least one treated and/or modified chitosan.
