Application of an anionic polymer in the formulation of floating tablets containing an alkaline model drug.

BACKGROUND: Gastric residence time is the key factor affecting the bioavailability of active pharmaceutical ingredients absorbed mainly through the gastric mucous membrane and influencing the local activity of some drugs.

OBJECTIVES: The aim of this study was the development of a new composition of non-effervescent floating tablets and the evaluation of the effect of an anionic polymer and compressive force on the floating properties and release characteristics of tablets containing a model alkaline drug, chlorhexidine (CHX).

MATERIAL AND METHODS: Direct compression was applied to a polyacrylic acid derivative and sorbitol to fabricate the tablets. Drug release was analyzed using several kinetic models. The formulations floated on the surface of the fluid for 24 h. The values of the rate constants, statistical parameters, and half-release time (t0.5) were calculated.

RESULTS: The diffusion coefficient n falls between 0.54 ±0.02 and 0.81 ±0.03 for most formulations. The floating time (FT) and floating lag time (FLT) were found to depend on the amount of polymer incorporated in the formulations. A high compressive force sustained the release of the drug but reduced the FT and FLT. Based on the FT and t0.5, it was determined that the C1 composition is the optimal formulation with FT >24 h and t0.5 between 113 ±2 and 144 ±13 min, depending on the drug release model.

CONCLUSIONS: The application of an anionic polymer results in a prolonged release of the drug from the tablets and allows them to float on fluid surfaces.