Diclofenac is a phenylacetic acid derivative classified as a non-selective COX inhibitor. Similar to other NSAIDs, it is characterized by anti-inflammatory, antipyretic, and analgesic effects. Long-term therapy with diclofenac might also lead to severe gastrointestinal, renal, or cardiovascular systems disorders. Aim of the study was to compare own formulation prepared from pharmaceutical raw materials with ready-to-use diclofenac product. : In the in vitro permeation experiments, human skin was excised from the abdomen of living patients as a result of plastic surgery. The transdermal semi-solid formulations were compounded using Pentravan, a ready-to-use transdermal base and hydrophilic gel base (Celugel). In vitro Penetration Studies, HPLC analysis, optical microscopy imaging, and a spreadability test were conducted. Rheological analysis provided insights into flow behavior, structure, and thixotropy. : Combination of Celugel with diclofenac sodium and the addition of substances acting as absorption enhancers, e.g., menthol, may provide an interesting alternative for enteral drugs, especially in patients with multimorbidity and polypharmacy. : Topical diclofenac sodium with of addition of permeation enhancers like menthol might provide higher drug concentrations in the surrounding tissues and better analgesic and anti-inflammatory effects in compare to commercially available product and may provide optimum effectiveness with minimal risk of adverse effects, particularly in elderly and polymedicated patients.