Abstract
In the present study, we have investigated the potential of a nanoemulsion (thermodynamically stable transparent dispersions of oil and water having a droplet size <200 nm) formulation for the topical delivery of COX-2 inhibitors using etoricoxib as a model drug. Various oil-in-water nanoemulsions were prepared by the spontaneous emulsification method. The nanoemulsion area was identified by constructing pseudo-ternary phase diagrams. The prepared nanoemulsions were subjected to thermodynamic stability testing. Those that passed these tests were characterized for viscosity, droplet size and differential scanning calorimetry. Topical permeation of etoricoxib through porcine abdominal skin was estimated using the Franz diffusion cell. The ex vivo skin permeation profile of optimized formulations was compared with that of etoricoxib conventional gel. A significant increase in permeability was observed in optimized nanoemulsion formulations consisting of 2 % w/w of etoricoxib, 20 % w/w of Triacetin, 38 % w/w of a surfactant mixture (Cremophor RH 40:Transcutol P), and 42 % w/w of water. The anti-inflammatory effects of this formulation on carrageenan-induced paw edema in rats showed a significant increase in the percent inhibition value (84.61 % with the nanoemulsion gel and 92.30 % with the nanoemulsion) as compared with the conventional gel (69.23 %) after 6 h when compared with etoricoxib conventional gel. These results suggest that nanoemulsions can serve as potential vehicles for improved transdermal delivery of anti-inflammatory agents such as etoricoxib.
Highlights
Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs to reduce pain and inflammation (Escribano et al 2003; Lee et al 2003)
In the present study, we have investigated the potential of a nanoemulsion formulation for the topical delivery of COX-2 inhibitors using etoricoxib as a model drug
A significant increase in permeability was observed in optimized nanoemulsion formulations consisting of 2 % w/w of etoricoxib, 20 % w/w of Triacetin, 38 % w/w of a surfactant mixture (Cremophor RH 40:Transcutol P), and 42 % w/w of water
Summary
Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs to reduce pain and inflammation (Escribano et al 2003; Lee et al 2003). COX-2 inhibitors that have been introduced in medical practice are recommended orally for patients with chronic inflammatory degenerative diseases such as rheumatoid arthritis and osteoarthritis (Li et al 2005), and as anti-inflammatory, antipyretic, and analgesic agents (Yang et al 2002). An improved nanoemulsion formulation of COX-2 inhibitors such as etoricoxib with a high degree of permeation could be useful in the treatment of locally inflamed skin and inflammatory and painful states of supporting structures of the body, such as bones, ligaments, joints, tendons, and muscles (Alvarez-Figueroa and Blanco-Mendez 2001). There has been an increased interest during recent years in the use of topical vehicle systems that could modify drug permeation through the skin. Many of the dermal vehicles contain chemical enhancers and solvents to achieve these goals
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