No abstract

Iontophoretic delivery of ACV resulted in high drug levels in skin layers to form a drug depot, which persisted over 2-3 days.

Background: Efficient iontophoretic transdermal delivery of hydrophilic drug molecules requires selection of appropriate aqueous formulation. In this study, oil/water cream and gel formulations were investigated for iontophoretic transdermal delivery of acyclovir (ACV), a model hydrophilic small-drug molecule, across hairless rat skin on Franz diffusion cells. Results: Iontophoresis (0.2 mA/cm2) enhanced ACV delivery from both 5% cream (pH 6.8) and 4% gel (pH 11) formulations. However, sixfold higher drug levels were delivered across the skin using gel formulation (12.25 ± 4.04 µg/cm2) as compared with cream formulation (2.03 ± 0.05 µg/cm2). Significantly higher drug levels were delivered when iontophoresis was performed at higher current density (0.32 mA/cm2; p < 0.05). Influence of formulation co-solvents (glycerin and propylene glycol) on drug delivery was also investigated in vitro using Franz cells and in vivo in hairless rats using microdialysis. Conclusion: Iontophoretic transdermal delivery of ACV was feasible and dependent on the selection of formulation components and delivery parameters.

The objective of this study was to investigate the effect of current on the delivery of acyclovir into and across the skin using hairless rat skin mounted on glass diffusion cells. Acyclovir was delivered under negative polarity from a formulation with a very basic pH. The effect of current intensity and duration of application on delivery of acyclovir was investigated. The amount in the skin was also determined by inserting a probe into the skin with a semipermeable membrane that allows sampling of the drug that has entered the skin. When the current intensity or duration was increased, greater drug levels were seen in the skin but not across the skin. It was found that even short duration of current application can deliver acyclovir into the skin and this has potential use for treatment of cold sores.