Formulation and Evaluation of the In Vitro Performance of Topical Dermatological Products Containing Diclofenac Sodium

The selection of an appropriate vehicle in a semi-solid topical product is of utmost importance since the vehicle composition and microstructure can potentially cause changes in drug–vehicle or vehicle–skin interactions and affect drug release and subsequent permeation into and across skin. Hence, the aim of this study was to evaluate different semi-solid formulations containing diclofenac sodium for the physicochemical and structural performance of excipients used and various physiological factors governing permeation of drugs applied to skin.

The formulations (emulsion, emulgel, gel, and ointment) were prepared using conventional excipients and were found to be homogenous and stable. Rheological analysis demonstrated characteristic shear-thinning and viscoelastic behavior of formulations. The mean release rate of the gel formulation (380.42 ± 3.05 µg/cm²/h^0.5) was statistically higher compared to all other formulations. In vitro permeation using human skin showed a significantly greater extent of drug permeation and retention for the emulgel formulation (23.61 ± 1.03 µg/cm² and 47.95 ± 2.47 µg/cm², respectively).

The results demonstrated that the different formulations influenced product performance due to their inherent properties. The findings of this study demonstrated that a comprehensive physicochemical and structural evaluation is required to optimize the in vitro performance for dermatological formulations depending on the intended therapeutic effect.

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Materials

Diclofenac sodium and benzoic acid were purchased from Sigma Aldrich (St. Louis, MO, USA). Kollisolv^® PEG 400 (polyethylene glycol 400), Pluriol E^®, PEG 3350 (polyethylene glycol 3350), Kolliwax^® CSA 50 (cetostearyl alcohol), Kollisolv^®, and PG (propylene glycol) were kindly provided by BASF (Tarrytown, NY, USA). Liquid paraffin was obtained from EMD Millipore (Burlington, MA, USA). Span™ and Tween™ 60 were samples from Croda Inc. (Princeton, NJ, USA), Klucel^® (hydroxypropyl cellulose) was provided by Ashland Inc. (Bridgewater Township, NJ, USA), and Transcutol^® (Diethylene glycol monoethyl ether) was provided by Gattefosse Corp. (Paramus, NJ, USA). All other reagents used were of high purity or HPLC grade.

Manian, M.; Jain, P.; Vora, D.; Banga, A.K. Formulation and Evaluation of the In Vitro Performance of Topical Dermatological Products Containing Diclofenac Sodium. Pharmaceutics 2022, 14, 1892. https://doi.org/10.3390/pharmaceutics14091892

excipients formulation