Microneedle rollers for skin drug delivery of macromolecules: experimental and theoretical considerations

In the present study, a microneedle device (Dermaroller ®) with different needle lengths (1 and 1.5 mm) were used to enhance the transport of a model macromolecular compound (FITC-Dextran 4.4 kDa) across the skin tissue. Transport studies were followed by tape stripping method, to monitor the drug distribution in the stratum corneum. The impact of dermarollers on morphology of the skin surface was examined by Scanning electron microscopy (SEM), which revealed a reduction of diameter of the induced skin pores caused by the dermarollers as a function of time, while optical microscopy studies revealed a disorganization to the lower part of the dermis. Modelling shown that an exponential, rather than a linear, dependence of the steady-state concentration on the thickness can qualitatively describe the tape-stripping data. The transport of the macromolecule across skin was significantly enhanced proportional to needle length.