Scientists say biodegradable polymer nanoparticles show great promise as drug delivery devices for the eye. 

Using eye drops to administer drugs to the eyes can bring unwanted side effects and the inconvenience of frequent application. Prolonged drug release can be achieved using ophthalmic inserts, solid devices placed in the eye, but the inserts must then be removed when they are no longer needed. 

The solution to these problems can be provided by drug delivery systems based on biodegradable polymeric materials, says John Tsibouklis, an expert in biomaterials and drug delivery from the University of Portsmouth, UK. 

Biodegradable polymers can be combined with drugs in such a way that the drug is released from the material into the eye in a predesigned manner. The release of drug can be constant or cyclic over a long period, or triggered by the environment or a chemical signal. At the end of its useful life, the drug delivering polymer can be broken down naturally by the body.

Rein Ulijn, a biomedical materials specialist at the University of Manchester, UK, said a major challenge is to incorporate a two-way communication between the body and the polymeric materials to 'create systems that recognise a disease specific biochemical process and respond to it by releasing a drug.'

According to Tsibouklis, 'the formulation of biodegradable or bioerodible polymers as colloidal nano-systems holds significant promise for ophthalmic drug delivery.' However, 'formulation stability, particle size uniformity, control of drug release rate, and the large-scale manufacture of sterile preparations are major developmental issues that need to be addressed,' he said.

Sarah Corcoran