BIOADHESIVE AND PHASE-CHANGE POLYMERS FOR OCULAR DRUG-DELIVERY

The tendency today is to find ocular delivery systems that are 'patient-friendly' and capable of bath lengthening pre-corneal contact time and slowing the release of drug from the vehicle. Most of the polymer systems in current use are hydrogels, with the disadvantage that water-soluble drugs will quickly diffuse out of the system. if the drug is sparingly soluble in water, and rate-limited dissolution occurs, a more favorable sustaining effect can be expected. However, to date, no mucoadhesive or phase change polymers, that begins as a solution, can truly sustain drug release beyond a short period of time. Newer polymers, that are biphasic in their activity, are needed to accomplish both retention and sustained release of the drug. It may be that the newer dendrimer or star polymers, or related polymers, holds the key for future developments.