Comparison of liposomal drug formulations for transdermal iontophoretic drug delivery.

This study was aimed to evaluate the in vitro transdermal direct/pulsed current iontophoretic delivery of an amphiphilic model compound from various lipid vesicle-encapsulated formulations compared to free-drug formulation. Conventional, pegylated, ultradeformable liposomes (transfersomes) and ethosomes loaded with a negatively charged drug diclofenac sodium (DS) were prepared and characterized. All the liposomes possessed an average size of ≈100-150nm and negative zeta potential. No changes in colloidal stability were detected after 8h incubation of any vesicle formulation under constant or pulsed iontophoretic current. DS was released from all the liposome formulations with a similar, limited rate (≈50% in 24h), leading therefore to significantly lower transdermal fluxes across full-thickness porcine skin compared to the respective free drug formulation. From the tested lipid vesicle formulations, the transfersomes resulted in the highest passive flux and the ethosomes in the highest iontophoretic flux under direct constant current treatment. Higher negative surface charge of the vesicle led to better transport efficiency due to the higher mobility of the drug carrier under electric field. Pulsed current iontophoresis had no advantage over constant current treatment in combination with any type of lipid vesicular nanocarriers, in contrast to what has been described earlier with drug-loaded polymeric nanocarriers.

Transdermal iontophoresis of flufenamic acid loaded PLGA nanoparticles.

The objective of this study was to test in vitro a drug delivery system that combines nanoencapsulation and iontophoresis for the transdermal delivery of lipophilic model drug using poly(lactic-co-glycolic acid) (PLGA) as the carrier polymer. Negatively charged fluorescent nanoparticles loaded with negatively charged flufenamic acid were prepared. The colloidal properties of the particles were stable under iontophoretic current (constant, pulsed and alternating) profiles and in contact with skin barrier. The release of the drug from the particles was not affected by iontophoresis and remained always limited (≈50%), leading to significantly lower transdermal fluxes across human epidermis and full thickness porcine skin compared to respective free drug formulation. From nanoparticles, pulsed current profile resulted in comparable or higher fluxes compared to constant current profile although fluorescence imaging was not able to confirm deeper distribution of nanoparticles in skin. Based on our results, there is no clear advantage with respect to drug permeation from nanoencapsulating flufenamic acid into PLGA nanoparticles compared to free drug formulation, either in passive or iontophoretic delivery regimens. However, pulsed current iontophoresis could be an effective alternative instead of traditional constant current iontophoresis to enhance transdermal permeation of drugs from nanoencapsulated formulations.