[Effect of pulse current iontophoretic transdermal delivery of insulin on blood glucose in diabetic rats].

Iontophoresis of pulse current with various current intensity, frequency, on/off ratio and duration of treatment was used to facilitate the transdermal delivery of insulin in order to control blood glucose levels in diabetic rats. Male Sprague-Dawley rats were made diabetic by i.p. injection of streptozotocin (65 mg . kg-1 body weight). After two days, diabetic rats were anaesthetized with urethane (as 25% aqueous solution, 1.5 mg . g-1). Both the reservoir electrodes and the receptor electrodes were applied on the abdominal site of the diabetic rats. Iontophoresis was carried out using a prototype transdermal periodic iontophoretic system in order to provide the required direct current with desired pulse modes. The extent of reduction of blood glucose levels was found to be positively correlated with the current intensity, frequency and duration of treatment to some extent. But when the current intensity was over 0.8 mA/cm2 and the frequency was over 3000 Hz, the reduction of blood glucose levels did not continuously increase. Blood glucose levels were found to be better controlled when the on/off ratio of 1 : 1 was used.