An electrically modulated drug delivery device. II. Effect of ionic strength, drug concentration, and temperature.

The effects of various physicochemical parameters on the changes in drug delivery rate produced by an electrophoretic current are examined using a model system. It was shown that ionic strength has an inverse relationship with the change in delivery rate produced by a given current. Small changes in pH were measured during electrophoresis experiments which were considered to be insignificant. Drug reservoir concentration selection is critical in the design of an electrophoretic device and is based on achieving a balance between providing a suitable reservoir and allowing adequate electrophoretic control. Electrophoretic control is affected by temperature in a manner which can be predicted using the Arrhenius relationship. The low power requirements of the model system demonstrate the feasibility of using the principle of electrophoresis to control drug delivery rates in a therapeutic system.