Adapalene microemulsion for transfollicular drug delivery

Area of Science:

• Pharmaceutics
• Dermatology
• Nanotechnology

Background:

• Topical drug delivery often faces challenges with skin penetration.
• Transfollicular delivery offers a potential route for enhanced drug absorption.
• Adapalene is a retinoid used for treating acne and other skin conditions.

Purpose of the Study:

• To develop a microemulsion formulation of adapalene for effective transfollicular delivery.
• To characterize the microemulsion's physical properties and microstructure.
• To evaluate the in vitro transfollicular permeation of adapalene from the microemulsion.

Main Methods:

• Development of a pseudoternary phase diagram for microemulsion formulation (oleic acid, Tween 20, Transcutol®, deionized water).
• Characterization using Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Polarizing Light Microscopy (PLM), and Differential Scanning Calorimetry (DSC).
• In vitro permeation studies on porcine ear skin using Franz diffusion cells and analysis via differential tape stripping and Confocal Laser Scanning Microscopy (CLSM).

Main Results:

• Microemulsion microstructure shifted from oil-in-water to bi-continuous with increased water content.
• Adapalene penetration into hair follicles increased significantly (0.109 ± 0.03 to 0.292 ± 0.094 μg) with the shift in microstructure.
• CLSM images confirmed hair follicles as the primary pathway for adapalene microemulsion permeation.

Conclusions:

• The developed adapalene microemulsion effectively penetrates hair follicles.
• Microemulsion microstructure plays a crucial role in enhancing transfollicular drug delivery.
• This formulation shows significant promise for transfollicular drug delivery applications.