Objectives Lipopeptides are compounds derived from microorganisms that exhibit pronounced surface and emulsifying activity. The ability of lipopeptides to interact with stratum corneum lipids makes them candidates as transdermal penetration enhancers. We have investigated the potential of two lipopeptides, fengycin and surfactin, to act as enhancers for the transdermal penetration and skin accumulation of aciclovir.
Methods To investigate a possible synergistic effect, surfactin and fengycin were associated with anodal iontophoresis. Permeation experiments were performed using vertical diffusion cells and pig ear skin as barrier. Differential scanning calorimetry was used to study the interaction between fengycin and stratum corneum lipids.
Key findings The results obtained indicated that surfactin and fengycin were not suitable to enhance aciclovir flux across the skin, not even when associated with iontophoresis. Aciclovir flux was slightly decreased in passive conditions and unchanged (fengycin) or decreased (surfactin) in anodal iontophoretic conditions. When applied in passive conditions, fengycin and surfactin increased aciclovir concentration in the epidermis by a factor of 2.
Conclusions Surfactin and fengycin did not enhance aciclovir transport across the skin (not even when associated with iontophoresis) although they increased aciclovir concentration in the epidermis by a factor of 2.