Hydrogel increases diclofenac skin permeation and absorption.

Area of Science:

• Pharmacology
• Dermatology
• Materials Science

Background:

• Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for musculoskeletal pain and inflammation.
• Transdermal drug delivery rate is influenced by drug properties and formulation composition.

Purpose of the Study:

• To compare the ex vivo transdermal flux of three topical diclofenac formulations through human skin.
• To evaluate the impact of formulation type (hydrogel vs. emulsion gel) on diclofenac skin penetration.

Main Methods:

• Three diclofenac formulations were tested: a hydrogel (1% diclofenac sodium) and two emulsion gels (1.16% and 2.32% diclofenac diethylamine).
• Ex vivo human abdominal skin was used in Franz diffusion cells over 48 hours.
• Drug concentration was quantified using HPLC, and diclofenac distribution was visualized with Raman spectral imaging.

Main Results:

• The hydrogel formulation exhibited approximately 10 times higher transdermal flux than the 1.16% emulsion gel and twice the flux of the 2.32% emulsion gel after 5 hours.
• Raman spectroscopy revealed a homogeneous distribution in the hydrogel, contrasting with the non-homogeneous distribution in emulsion gels where diclofenac localized with the lipophilic phase.

Conclusions:

• Diclofenac hydrogel demonstrated superior transdermal penetration compared to both emulsion gel formulations.
• The hydrogel formulation may offer a faster onset of action in underlying tissues due to its enhanced absorption characteristics.