چکیده (انگلیسی):

The objective of the present study was to develop a hydrodynamically
balanced system for celecoxib as single-unit
floating capsules. Various grades of low-density polymers
were used for formulation of these capsules. The capsules
were prepared by physical blending of celecoxib and the
polymer in varying ratios. The formulation was optimized on
the basis of in vitro buoyancy and in vitro release in citrate
phosphate buffer pH 3.0 (with 1% sodium lauryl sulfate).
Capsules prepared with polyethylene oxide 60K and
Eudragit RL100 gave the best in vitro percentage release
and were used as the optimized formulation. By fitting the
data into zero-order, first-order, and Higuchi models, we concluded
that the release followed zero-order kinetics, as the
correlation coefficient (R value) was higher for zero-order
release. For gamma scintigraphy studies, celecoxib was radiolabeled
with technetium-99m by the stannous reduction method.
To achieve the maximum labeling efficiency the process
was optimized by studying the reaction at various pH conditions
and stannous concentration levels. The radiolabeled
complex was added to the optimized capsule, and dissolution
studies were performed to ensure that there was no leaching
of radioactivity from the capsules. Gamma imaging was
performed in rabbits to assess the buoyancy of the optimized
formulation. The optimized formulation remained buoyant
during 5 hours of gamma scintigraphic studies in rabbits.