There is described a topical formulation. The topical formulation comprises: (i) diclofenac or a pharmaceutically acceptable salt thereof, (ii) a first compound, and (iii) a second compound. The first compound and second compound are different, and each is selected from the group consisting essentially of N-lauroyl sarcosine, sodium octyl sulfate, methyl laurate, isopropyl myristate, oleic acid, glyceryl oleate and sodium lauryl sulfoacetate. It has been discovered that certain combination of compounds are excellent penetration enhancers and, as such, can be incorporated in a topical formulation to facilitate administration of diclofenac or a pharmaceutically acceptable salt thereof. The increased penetration enhancement can also lead to a reduction in the total concentration of skin irritants in the formulation.