Purpose: To measure the extent of solubility of the lipophilic drug, aceclofenac, in 13 oils as well as its in vitro permeability from these oils in order to develop optimized topical microemulsion and microemulsion-based gel for improved bioavailability.

Methods: UV spectrophotometeric method was used at the wavelength of 276 nm to measure the dissolved quantity of aceclofenac in each of the oils (almond oil, oleic acid, castor oil, paraffin oil, cinnamon oil, clove oil, canola oil, sesame oil, isopropyl myristate (ipm), sunflower oil, corn oil, coconuts oil and eucalyptus oil) at 25 °C. The in-vitro permeability of aceclofenac in each of these oils was determined at 32 ± 0.5 °C using Franz diffusion cell with phosphate buffer (pH 7.4) as medium with 0.45 µ cellulose acetate membrane. The solubility and permeability of aceclofenac were compared with the hydroalcoholic solution of aceclofenac.

Results: The highest solubility values of 9.153 and 8.560 mg/ml for aceclofenac were obtained with almond oil and oleic acid, respectively (p < 0.05). However the solubility and permeability of aceclofenac in hydro-alcoholic solution were 150.65 mg/ml and 14.91± 0.05 µg/cm²/h, respectively. Aceclofenac also showed higher permeability values (1.45± 0.04 and 1.21 ± 0.06) in almond oil and oleic acid, respectively, than in the other oils (p < 0.05). 

Conclusion: These findings show that almond oil and oleic acid are promising vehicles for aceclofenac as its enhanced solubility and permeability in these vehicles are suggestive of improved bioavailability.