Influence of microcrystal formulation on in vivo absorption of celecoxib in rats.

The objective of this study was to prepare celecoxib microcrystals using different stabilizers in order to evaluate the influence of microcrystal formulation on the in vitro dissolution rate and in vivo absorption after oral administration of celecoxib in rats. Three celecoxib microcrystals (MC1, MC2, and MC3) were prepared using solvent change method. Microcrystals were evaluated for morphology, particle size, crystallinity, solubility, in vitro dissolution, and in vivo absorption in rats. Scanning electron microscopy images showed distinct differences in the morphologies and dimensions of various celecoxib microcrystals. The particle size of all microcrystals was significantly (P<0.05) reduced relative to plain celecoxib. The DSC and XRD results revealed that MC1 retain drug crystallinity relative to control crystals, MC2, and MC3. All microcrystals showed marked increase in the drug dissolution parameters particularly MC1 that exhibited a prompt drug release and significantly (P<0.05) higher values of % dissolution efficiency as compared to control celecoxib and the other microcrystals. The influence of microcrystals on the in vivo absorption of celecoxib was studied in rats in comparison to plain drug. The results of in vivo absorption study in rats indicated that MC1 significantly improved the rate and extent of celecoxib absorption than plain celecoxib. The mean relative bioavailability of MC1 formulation to plain celecoxib was 157.55±20.18%. In conclusion, microcrystal formulation of celecoxib results not only in an enhancement of dissolution parameters but also improves the bioavailability of celecoxib in rats.