Magnetophoresis in combination with chemical enhancers for transdermal drug delivery

The objective of the present work was to investigate the effect of combination of a novel physical permeation enhancement technique, magnetophoresis with chemical permeation enhancers on the transdermal delivery of drugs.The in vitro drug transport studies were carried out across the freshly excised abdominal skin of Sprague-Dawley rats using transdermal patch systems (magnetophoretic and non-magnetophoretic) of lidocaine hydrochloride (LH). LH gel prepared using hydroxypropyl methylcellulose (HPMC) was spread over the magnets as a thin layer. To investigate the effect of chemical permeation enhancers, menthol, dimethyl sulfoxide, sodium lauryl sulfate and urea (5% w/v) were incorporated in the gels prior to loading on the patch system.The flux of lidocaine from magnetophoretic patch was ~3-fold higher (3.07 ± 0.43 µg/cm(2)/h) than that of the control (non-magnetophoretic patch) (0.94 ± 0.13 µg/cm(2)/h). Incorporation of chemical permeation enhancers in the gel enhanced the magnetophoretic delivery flux by ~4 to 7-fold.The enhancement factor due to combination of chemical permeation enhancer was additive and not synergistic. Mechanistic studies indicated that magnetophoresis mediated drug delivery enhancement was via appendageal pathway.