An electrically modulated drug delivery device. III. Factors affecting drug stability during electrophoresis.

A number of factors affecting the stability of propranolol HCl during electrophoretic control were investigated. It was found that significant degradation of propranolol HCl and hydrolysis of water occurred when a current of 15 mA was used with platinized electrodes. This degradation was thought to be due to decomposition of propranolol HCl at the electrodes. Degradation could be significantly reduced by using uncoated platinum electrodes and currents in the range of 0 to 2.5 mA, while still allowing control of drug delivery rates. Electrode reaction processes were found at high ionic strengths and high drug concentrations but were not thought to be associated with drug decomposition.