Drug-release device treats retinal damage from diabetes

A team of engineers and scientists at the University of British Columbia (UBC) has developed a device that can be implanted behind the eye and release drugs to treat retinal damage caused by diabetes.

Diabetic retinopathy is the leading cause of vision loss among patients with diabetes. The disease is caused by the unwanted growth of capillary cells in the retina, which, in its advanced stages, can result in blindness.

’We wanted to come up with a safe and effective way to help diabetic patients safeguard their sight,’ said UBC’s associate professor of mechanical engineering, Mu Chiao.

A current treatment for diabetic retinopathy is laser therapy, which has side effects — among them laser burns or the loss of peripheral or night vision. Anti-cancer drugs may also be used to treat the disease. However, these compounds clear quickly from the bloodstream, so high dosages are required, thus exposing other tissues to toxicity.

In the new device, drug delivery is triggered through an external magnetic field. The team accomplished this by sealing the reservoir of an implantable device — which is no larger than the head of a pin — with an elastic magnetic polydimethylsiloxane (silicone) membrane. A magnetic field causes the membrane to deform and discharge a specific amount of the drug, much like squeezing water out of a flexible bottle.

In a series of lab tests, the UBC researchers loaded the implantable device with the drug docetaxel and triggered the drug release at a dosage suitable for treating diabetic retinopathy. They found that the implantable device kept its integrity with negligible leakage over 35 days.

They also monitored the drug’s biological effectiveness over a given period, testing it against two types of cultured cancer cells, including those found in the prostate. They found that they were able to achieve reliable release rates.

’The docetaxel retained its pharmacological efficacy for more than two months in the device and was able to kill off the cancer cells,’ said Dr Fatemeh Nazly Pirmoradi, who worked on the project for her doctoral thesis.

But Pirmoradi said it will be several years before the UBC device is ready for patient use.