DESIGN, DEVELOPMENT AND EVALUATION OF NOVEL GAULTHERIA OIL MICROEMULSIONS WITH ENHANCED LOADING OF PIROXICAM FOR TOPICAL DELIVERY IN THE TREATMENT OF ARTHRITIS

Objective: In the present research, the plant oil of Gaultheria procumbens (family: Ericaceae), an extensively utilized ethnic drug to treat arthritis and get rid of pain, was selected to formulate Micro Emulsions (MEs). The objective of this research was to examine the suitability of gaultheria oil in formulating MEs containing Non-Steroidal Anti-Inflammatory Drug (NSAID) for topical use. Methods: A new water-in-oil Piroxicam Micro Emulsions (PMs) consisting of gaultheria oil, tween 20 and Poly Ethylene Glycol (PEG) 600 were formulated using D-optimal design expert software for optimization of formulation and also to enhance the loading capacity of a model NSAID piroxicam has been demonstrated. The pseudo-ternary phase drawing has been depicted on a constant surfactant/co-surfactant (S-mix) ratio (1:1). Then the prepared PMs were evaluated for percentage (%) transmittance, pH determination, refractive index (RI), viscosity measurement, % drug content, particle size, zeta potential, in vitro cumulative drug release and stability studies. Results: The pre-formulation studies showed high solubility of drug (piroxicam) with gaultheria oil, tween 20 and PEG 600, thereby confirming its suitability for formulation. Fourier Transform Infrared Spectroscopy (FTIR) proved drug excipient compatibility by retaining the characteristic peaks even after formulation. D-optimal design expert software was proved to be beneficial in the formulation and optimization process and matched the experimental results. Optimized Piroxicam Micro Emulsion (PM) formulation PM 8 showed satisfactory results regarding % transmittance (98.84±1.04), pH (7.41±0.01), RI (1.4421±0.002), viscosity (469.53±0.61), % drug content (96.32±0.19), particle size (185.5 nm±0.24 nm), zeta potential (-25.34±0.51), in vitro cumulative drug release in 6 h (42.62 %±0.11 %) and 12 h (86.42 %±0.21 %). The drug release kinetics study showed a zero-order release mechanism confirmed by Korsmeyer-peppas model. Stability studies as per International Council for Harmonization (ICH) guidelines demonstrated the stability of PM 8 for its physical appearance, phase separation, % transmittance, pH and % drug content for 90 d. Conclusion: Thus, it can be concluded that the present investigation study can be beneficial for improved loading of model NSAID piroxicam in the interfacial film of PM with gaultheria oil as a promising vehicle aimed at the topical conveyance of drugs in the management of arthritis.