MSE 2016 - Full Program

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Lecture

Controlled release of antibacterial agents and anti-inflammatories from Alginate-Chitosan coated silicone based hydrogels

Tuesday (27.09.2016)
14:30 - 14:45
Part of:


Although eyedrops are the most common form of treatment for ophthalmic diseases, they present some drawbacks, since require frequent applications, lead to significant drug losses (> 95%) and may cause undesirable side effects due to the rapid drug absorption into the bloodstream. Several approaches were attempted to improve the ocular bioavailability of drugs. Among them, the development of drug loaded soft contact lenses (SCLs) has deserved particular attention, due to the high acceptance by patients and prolonged contact with the eye. However, these devices are not yet available in the market due to the difficulty of achieving a sustained controlled drug release which ensures a therapeutic concentration of the drugs in the eye for an adequate period.In this work, a silicone based hydrogel (TRIS/NVP/HEMA, 40:40:20 w/w) was coated with an alginate-chitosan multilayer to create a diffusion barrier and retard drug release. The hydrogel was produced by thermopolymerization and loaded by soaking in solutions of moxifloxacin, chlorohexidine, diclofenac and ketorolac. Samples were coated trough a layer-by-layer (LBL) process with alginate crosslinked by CaCl2, chitosan+glyoxal and a top final layer of alginate-CaCl2. Release kinetics was investigated in sink conditions in NaCl solution. Material properties such as wettability, surface roughness and optical properties (transmittance and refractive index) were investigated.According to QCM-D results, the multilayer is stable and resistant to lysozyme enzymatic degradation. Surprisingly, the barrier effect of the LBL coating is clearly most effective for the release of diclofenac, the smallest molecule. This may be related with the formation of unstable diclofenac-chitosan complexes that retard the release of the drug [1]. The characterization of the coating shows that it is dense, homogeneous and leads to a roughness within the values accepted for SCLs. The hydrophilicity of the coated hydrogel is high, the bulk refraction index is not affected and the light transmittance is slightly reduced. Further studies using adequately functionalized chitosan should be done to optimize the release control of each specific drug.[1]Y.Boonsongrit,A.Mitrevej,B.Mueller,Eur.J.Pharm.Biopharm.62(2006)267–74

Speaker:
Ph.D. Diana Silva
University of Lisbon
Additional Authors:
  • Dr. Luís F. V. Pinto
    Altakitin S.A., Rua José Gomes Ferreira, Arm. D, 2660-360 São Julião do Tojal, Lisboa, Portugal.
  • Prof. Dr. Luís F. Santos
    Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
  • Prof. Dr. Ana Paula Serro
    Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
  • Prof. Dr. Benilde Saramago
    Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.