Abstract
The effect of polycarbophil in different concentrations (0, 5, 10 and 20% w/w) on the bioavailability of diclofenac sodium from polyethylene glycol suppositories was studied in six beagle dogs. The in-vivo data showed that the 5% concentration of polycarbophil is the best concentration to be used in formulating polyethylene glycol suppositories containing diclofenac sodium. At this concentration, the suppositories showed a relative bioavailability of 115.17% compared to that of suppositories containing 0% polycarbophil. The other two concentrations of polycarbophil (10 and 20%) gave relative bioavailability of 56.46 and 50.21%, respectively. The 5% polycarbophil concentration resulted in the highest C
max (6.35 ± 1.06
μg/ml) compared to 5.54 ± 1.21, 1.98 ± 0.70 and 1.93 ± 1.06
μg/ml for suppositories containing 0, 10 and 20% polycarbophil, respectively. It was also noted that as the polycarbophil concentration increased in the formulation the T
max decreased indicating faster absorption. Also, the K
el values decreased and the t
1
2
values increased indicating slower release of the drug from the formulation as the polycarbophil concentration increased. Polycarbophil as a bioadhesive is capable of inducing faster absorption and its effect on plasma concentration and bioavailability is dependent on its percentage used in the formulation.