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S. Hoeller, M. Hornof; Chitosan-Thiomer: Development of a Novel Treatment Strategy for Dry. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6274.
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A new eye drop formulation containing a functionalized biopolymer - chitosan-N-acetylcysteine conjugate (chitosan-thiomer) is currently being developed by Croma-Pharma. It is postulated that interaction between thiol groups of the chitosan-thiomer and cysteine-rich mucin (MUC5AC) increases residence time of the polymer on the ocular surface and tear film stability in patients suffering from dry eye syndrome. The safety, biocompatibility and efficacy of this novel eye drop formulation were investigated in a number of pre-clinical tests and studies. Based on the data obtained the first clinical trial in humans will be planned.
In vivo and in vitro biocompatibility studies were performed with the raw material according to ISO 10993 guidelines. In "proof of principle"-studies the efficacy of chitosan-thiomer eye drops was evaluated in two different dry eye mouse models (botulinum toxin B and controlled-environment chamber). The dosage dependent ocular residence time was investigated in a rabbit model using microPET technology. Long-term irritation and delayed-type hypersensitivity tests with chitosan-thiomer eye drop formulation were conducted in rabbits.
An excellent biocompatibility and safe toxicological profile of chitosan-thiomer raw material was indicated in in vitro and in vivo studies. Efficacy studies in dry eye mouse models suggest that chitosan-thiomer eye drops may have some protective ocular surface properties. Additionally, it could be demonstrated that the residence time on the ocular surface of the new isotonic, buffered chitosan-thiomer eye drops in a rabbit model is increased in comparison with aqueous solutions and formulations containing unmodified chitosan.
Based on these promising results -excellent biocompatibility data, safe toxicological profile, prolonged residence time and protective influence on ocular surface- of the new recently developed chitosan-thiomer eye drops a phase I clinical trial with 30 healthy volunteers is planned for 2010.
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