, Volume 11, Issue 12, pp 1742-1746

Effect of Current Magnitude and Drug Concentration on lontophoretic Delivery of Octreotide Acetate (Sandostatin®) in the Rabbit

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Abstract

The effect of current magnitude and drug concentration on transdermal iontophoretic delivery of octreotide acetate (Sandostatin®) was examined in the rabbit. Plasma samples were collected over 24 hours and octreotide concentrations were determined by a radioimmunoassay. Without an electrical current, negligible plasma concentrations of octreotide were obtained. Following initiation of iontophoresis, plasma concentrations of octreotide increased rapidly, although did not sustain at a plateau level during the dosing period. Octreotide concentrations declined rapidly after removal of the device. Increasing the electrical current from 50 µA/cm2 to 150 µA/cm2 yielded a proportional increase in the delivery. Increasing the drug concentration in the device from 2.5 mg/mL to 5 mg/mL resulted in approximately proportional increase in plasma octreotide concentrations; however, further increase in plasma concentrations was not observed for drug concentrations beyond 5 mg/mL. lontophoretic delivery at the conditions which yielded the highest octreotide concentrations in this study (5 mg/mL solution at 150 µA/cm2 for 8 hours) yielded an apparent bioavailability (which represents an underestimate of the absolute bioavailability determined when the patches are run to exhaustion) of approximately 8%.