A facile and sensitive video-analysis method for tracking floating lag-time and floating rate of gastro-retentive tablets

Floating effervescent tablets are designed to rapidly float in the gastric fluids by gas formation, after an initial lag-time. We developed here a method to characterise these dosage forms. Tablets were prepared containing various concentrations of hydroxypropyl methylcellulose (HPMC), dicalcium phosphate (DCP) and sodium bicarbonate (NB) as gelling agent, high-density model compound and gassing agent, respectively. Videos of the motion of tablets exposed to fluids for 6 h were recorded and then analysed to measure: i) tablet swelling; ii) floating kinetic until lag-time and iii) residual floating rate of the tablets over time. The developed technique was able to precisely track tablet motion and thus describe the floating performance of the dosage forms. Specifically, it was found that floating lag-time and floating fluctuations were influenced by the concentration of NB, more than DCP. Moreover, both swelling volume and residual floating rate over time were not affected by tablet composition, suggesting that density developments of the tablets were similar across formulations. Floating rate also remained constant over the test duration, which correlates well with previous findings on the floating force of HPMC/NB matrices. Overall, we showcase here a simple video-recording and -analysis technique to effectively characterise the performance of floating dosage forms.