The efficiency of transdermal α-Arbutin delivery after albumin microbubbles treatment with ultrasound in mice

The application of transdermal delivery to a wider range of drugs is limited due to the significant barrier to penetration across the skin which is associated with the stratum corneum layer of the epidermis. In previous study in the literature, the feasibility and effects of the ultrasound (US) contrast agent, microbubbles (MBs) as the penetration enhancers for transdermal delivery in vivo were firstly demonstrated. In this study, the penetration depth, concentration, and efficiency of transdermal α-Arbutin delivery after MBs treatment with US in mice were demonstrated for 4 weeks. The penetration of α-arbutin on skin was enhanced by using ultrasound energy and MBs either for in vitro or for in vivo experiments. Experiment parameters were randomly divided into four groups (n=5 animals per group): (1) only penetrating α-Arbutin (C); (2) US combines with penetrating α-arbutin (U) (3) US combines with MBs contrast agent and penetrating α-arbutin (UB); (4) US combines with diluted MBs and penetrating α-arbutin (UBD). According to the results, the penetration depth of agarose phantom and pigskin of UBD group increase 47% and 84%, respectively. The in vitro skin permeation of 2% α-arbutin, UBD group was 83% greater than control group after 3 hour of permeation study. For in vivo study, the whitening effect (luminosity index) of mice skin in UBD group significantly increase 25% in one week, 34% in two weeks and tends towards stability in three weeks (37%) in C57BL/6J mice over a 4-week experimental period. Our results investigated that the treatments of ultrasound and MBs can increase skin permeability, enhance α-arbutin delivery to inhibit melanogenesis and not damage the skin in mice.