Formulation and in vitro evaluation of gastroretentive drug delivery systems of amoxicillin trihydrate

Amoxicillin trihydrate has a short biological half life. Floating drug delivery systems of this drug were prepared with the objective of increasing overall gastric retention time in order to prolong the release. The floating tablets were prepared by using Hydroxy Propyl Methyl Cellulose (HPMC) polymers at different drug to polymer ratio with gas generating agents like sodium bicarbonate and citric acid. The granules were prepared by wet granulation technique using polyvinyl pyrrolidone (PVP) K30dissolved in isopropyl alcohol and were compressed into tablets. Initially the granules were evaluated for characteristics like bulk density, true density, angle of repose, true density and Carr's index. The prepared tablets were evaluated for hardness, friability, uniformity of weight, in vitro buoyancy and in vitro drug release. The studies revealed that the optimized formulation F11 containing the drug and HPMC K4M polymer in the ratio 1:1, lactose, sodium bicarbonate and citric acid showed floating lag time of 22 minutes and remained buoyant for more than 24 hrs and it released 42.88% of the drug in 6 hours. The results indicate that the prepared floating tablets of amoxicillin trihydrate provide a better option for increasing the bioavailability than the conventional dosage forms and appear suitable for further pharmacokinetic and pharmacological studies.