Table 6.

In vitro evaluation parameters of various GRDDS.

GRDDS	Evaluation	Comment	References
Low-density system, raft-forming system	Floating Lag Time (FLT), total floating time (TFT), floating strength	The test is carried out in a simulated gastric fluid (SGF) at 37 °C. The time between introduction of dosage form and its buoyancy on the SGF (FLT) and the time during which the dosage form remains buoyant (TFT) were measured. The floating strength is measured using specifically designed basket holder connected with analytical balance. The reduction of weight on the analytical balance over time determines the floating strength.	[9,17,19,31,97,98]
Superporous hydrogel system, expandable system	Swelling studies	The test is carried out by placing the weighed amount of dosage form into the swelling medium (0.01 N HCl) and weight, diameter, and length of swollen samples are measured at predetermined time point.	[61,99]
Raft-forming and Mucoadhesion systems	Viscosity and Rheology	Viscosity of polymer affects the consistency of the dosage form upon contact with the gastric fluid. Brookfield/Ostwald’s viscometer and texture analyzer are commonly used.	[100]
Expandable system	In vitro unfolding study	The test is carried out by placing the folded dosage form into the dissolution medium and examining its unfolding behavior in different time interval.	[101]
Ion-exchange resin system	Particle size, ion exchange capacity, moisture content	Particle size analysis is carried out using a sieve shaker, laser diffraction, and coulter counter analyzer. The ion exchange capacity depends upon the functional group available for crosslinking. Moisture content can be measured with Karl Fischer.	[96,102,103,104]
Applicable for all GRDDS	In vitro drug release	The test is carried out in SGF at a predefined time interval (generally 0 to 12 h) using USP type-II apparatus at 50 rpm and maintained at 37 °C.	[9,27,72,80]
	Gel strength	The high gel strength is desirable for better mechanical integrity.	[9,105]
	Drug-excipient interaction study	It can be studied by using FT-IR spectroscopy, Differential scanning calorimetry, and High Performance Liquid Chromatography.	[17,106]