Subcutaneous concentrations following topical iontophoretic delivery of diclofenac

A self-contained Wearable Electronic Disposable Drug Delivery (WEDD®) patch was used to demonstrate that diclofenac levels delivered by iontophoresis are greater than estimated minimal effective concentrations in local subcutaneous tissue and are also greater than either passive transdermal or intravenous delivery using hairless rats. In vitro iontophoretic delivery was evaluated to optimize donor cell formulation using Franz diffusion cells and 1000 NMWL Millipore ultrafiltration membrane. In vivo animal studies were done using patches powered with a 4-volt system, consisting of a 1-volt Zn anode and Ag/AgCl cathode with built in 3-volt lithium battery. Blood and microdialysis samples were collected at different time points after patch application. Current levels increased to 1.0 mA at 30 min, then fell to a steady state of~0.4 mA. Both WEDD® and passive patches produced measurable levels of diclofenac in the subcutaneous tissue below the application site (Cmax ± SE=113.3 ±61.7 ng/mL and 36.3 ±15.9 ng/mL, respectively). The dose delivered in six hours was calculated to be 0.226 ± 0.072 mg and 0.430 ±0.048 mg in passive and iontophoretic delivery, respectively. Diclofenac was not detected in the subcutaneous tissue after intravenous administration of 1.5 mg/kg diclofenac solution. The trend indicates that WEDD Ŵ can be used to successfully deliver diclofenac to subcutaneous tissue to concentrations higher when compared to either passive delivery or intravenous dosing of 1.5 mg/kg.