Analgesic and anti-inflammatory controlled-released injectable microemulsion: Pseudo-ternary phase diagrams, in vitro, ex vivo and in vivo evaluation.
PURPOSE
Development of analgesic and anti-inflammatory controlled-released injectable microemulsions utilising lysine clonixinate (LC) as model drug and generally regarded as safe (GRAS) excipients.


METHODS
Different microemulsions were optimised through pseudo-ternary phase diagrams and characterised measuring droplet size, viscosity, ex vivo haemolytic activity and in vitro drug release. The anti-inflammatory and analgesic activity was tested in mice (Hot plate test) and rats (Carrageenan-induced paw edema test) respectively and their activity was compared to an aqueous solution of LC salt.


RESULTS
The aqueous solution showed a faster and shorter response whereas the optimised microemulsion increased significantly (p<0.01) the potency and duration of the analgesic and anti-inflammatory activity after deep intramuscular injection. The droplet size and the viscosity were key factors to control the drug release from the systems and enhance the effect of the formulations.


CONCLUSIONS
The microemulsion consisting of Labrafil®/Lauroglycol®/Polysorbate 80/water with LC (56.25/18.75/15/10, w/w) could be a promising formulation after buccal surgery due to its ability to control the drug release and significantly achieve greater analgesic and anti-inflammatory effect over 24h.
['Pineros|Isabel|I|', 'Slowing|Karla|K|', 'Serrano|Dolores R|DR|', 'de Pablo|Esther|E|', 'Ballesteros|Maria Paloma|MP|']
D000700:Analgesics D000818:Animals D000893:Anti-Inflammatory Agents D002626:Chemistry, Pharmaceutical D003002:Clonixin D003692:Delayed-Action Preparations D016503:Drug Delivery Systems D065546:Drug Liberation D004655:Emulsions D005079:Excipients D006801:Humans D007267:Injections D007273:Injections, Intramuscular D008239:Lysine D008297:Male D051379:Mice D010316:Particle Size D011136:Polysorbates D051381:Rats D017208:Rats, Wistar D014783:Viscosity
Analgesic Anti-inflammatory Controlled-release Injectable Microemulsion Lysine clonixinate Depot formulation Pseudo-ternary diagrams