In vitro and in vivo characteristics of a thermogelling rectal delivery system of etodolac.

Rectal etodolac-Poloxamer gel systems composed of Poloxamer and bioadhesive polymers were developed and evaluated. Hydroxypropylmethyl cellulose, poly)vinyl) pyrrolidone, methyl cellulose, hydroxyethylcellulose, and carbopol were examined as mucoadhesive polymers. The characteristics of the rectal gels differed according to the properties of mucoadhesive polymers. The physicochemical properties such as gelation temperature, gel strength, and bioadhesive force of various formulations were investigated. The analysis of release mechanism showed that the release of etodolac was proportional to the square root of time, indicating that etodolac might be released from the suppositories by Fickian diffusion. The anti-inflammatory effect of etodolac-Poloxamer gel system was also studied in rats. Moreover, liquid suppository of etodolac did not cause any morphological damage to the rectal tissues. These results suggested that in situ gelling liquid suppository with etodolac and mucoadhesive polymer was a physically safe, convenient, and effective rectal dosage form for etodolac.