Background: The intracellular form of action of retinoids requires these agents to reach deeper layers of the skin with viable cells to ensure therapeutic efficiency. However, studies on swine skin models show that some retinoids have low skin permeability. Thus, the association of innovative formulations with technological strategies involving physical permeation promoters can be employed to increase the permeability of this active, ensuring a targeting effect of the active.
Aims: In this study, it was proposed the development and evaluation of the release and permeation profile of liquid crystalline systems with retinoic acid polymeric microparticles under passive or iontophoretic diffusional conditions.
Methods: For this study, release, permeation, and diffusional characterization assays were employed using the Franz diffusion cell model, associating or not the cathodic iontophoresis.
Results: Retinoic acid was considered stable in front of the electric current of 0.5mA/cm2 , because it did not show significant degradation (with maintenance from 96.03% to 98.57%), indicating the viability of such agents to be applied with iontophoresis. Controlled release profile was evidenced for microencapsulated systems. Comparatively, formulations F1, F3, and F5 presented a significantly higher RA release profile when compared to formulations with retinoic acid microencapsulated. A significant increase was observed in the absolute amount of RA retained in the skin with cathodic iontophoresis in all proposed formulations (P < .01). The increase was up to two times in relation to the passive condition.
Conclusions: The combination of iontophoresis technique with application of retinoic acid and microencapsulated retinoic acid allows the penetration of the active ingredient to deeper layers of the skin.
Keywords: drug delivery; iontophoresis; permeation; retinoic acid.
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