Abstract
Transdermal drug administration presents several advantages and it is therefore favorable as an alternative drug delivery route. However, transdermal delivery of biopharmaceutical drugs is made difficult by the skin barrier. Microneedle application and iontophoresis are strategies which can be used to overcome this barrier. Therefore, recombinant human growth hormone (rhGH) was used as a model macromolecular drug and was transdermally delivered using microneedle application and iontophoresis. Methylene blue staining, stereomicroscopy and scanning electron microscope (SEM) imaging were used to characterize the microchannels produced. To optimize the iontophoresis protocol, the effects of molecular charge and current density on transdermal delivery were evaluated in an in vitro permeation study using excised rat skin tissues. Using the optimized iontophoresis protocol, the combination effects of iontophoretic delivery via microchannels were evaluated in three different experimental designs. The flux obtained with anodal iontophoresis in citrate buffer was approximately 10-fold higher that that with cathodal iontophoresis in phosphate buffered saline (PBS). Flux also increased with current density in anodal iontophoresis. The combination of iontophoresis and microneedle application produced higher flux than single application. These results suggest that anodal iontophoresis with higher current density enhances the permeation of macromolecules through microchannels created by microneedles. In conclusion, the combination of iontophoresis and microneedles is a potential strategy for the enhancement of transdermal delivery of macromolecular drugs.
Highlights
IntroductionAdministration of biopharmaceutical drugs such as proteins and peptides has been limited to invasive routes (e.g., intramuscular and subcutaneous injection), because of their poor absorption and enzymatic degradation
Administration of biopharmaceutical drugs such as proteins and peptides has been limited to invasive routes, because of their poor absorption and enzymatic degradation
Considering that microneedle treatment is an effective way to overcome the limitations of iontophoresis, the combination of two enhancers is a potential strategy for transdermal delivery of macromolecules
Summary
Administration of biopharmaceutical drugs such as proteins and peptides has been limited to invasive routes (e.g., intramuscular and subcutaneous injection), because of their poor absorption and enzymatic degradation. Even if self-administration is possible, patients should visit the clinic to learn the correct dosage regimen. As a result, these disadvantages can cause low patient compliance. Several studies investigating alternative routes of administration for macromolecules have been conducted to overcome these problems [1]. Tok Tok® microneedle (Figure 1) is designed to enhance transdermal drug delivery using a noTvhele aTpappproyaTcohk. Considering that microneedle treatment is an effective way to overcome the limitations of iontophoresis, the combination of two enhancers is a potential strategy for transdermal delivery of macromolecules. To investigate the possibility of transdermal delivery of macromolecules, the permeation-enhancing effect of iontophoretic delivery through microchannels made with a novel microneedle device (Tappy Tok Tok®) on transdermal delivery of rhGH was evaluated
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