Purpose: To achieve percutaneous delivery of trolamine salicylate to muscle and joints for the
treatment of inflammatory muscle, tendon and joint diseases.
Methods: Trolamine salicylate permeability parameters through rat skin were evaluated with and
without chemical enhancers - Transcutol, eucalyptus oil, oleic acid and sodium lauryl sulfate – using the
permeability cell technique.
Results: The main barrier for trolamine salicylate permeability was the epidermis layer of the skin. Also,
partitioning from the aqueous donor phase into the skin was the rate-limiting step for drug flux.
Transcutol and eucalyptus oil were the most effective enhancers as they increased flux 11-fold. Sodium
lauryl sulfate disrupted the lipid structure of the skin and thus increased diffusion coefficient 3-fold.
Supersaturation technique did not increase flux. Propylene glycol in cosolvent system increased drug
solubility in donor phase and partitioning.
Conclusion: Trolamine salicylate exhibited less flux and diffusion coefficient through rat skin than
salicylic acid due to its hydrophilic property. Partitioning from vehicle into skin was the rate-limiting step
for trolamine salicylate permeability through rat skin