Diclofenac topical formulation

A process for making a topical formulation, comprising:

• adding hydroxypropyl cellulose to a mixture of dimethylsulfoxide, water, diclofenac sodium, propylene glycol, and ethanol, wherein the topical formulation consists of:
• diclofenac sodium present at 2% w/w;
• DMSO present at about 40 to about 50% w/w;
• ethanol present at 23-29 w/w %;
• propylene glycol present at 10-12% w/w;
• hydroxypropyl cellulose;
• and
• water to make 100% w/w;
• wherein the formulation has a viscosity of 500-5000 centipoise.