The drug release system is a process in which a bioactive substance discharged from a drug product and enters the process of absorption, distribution and metabolism to deliver its pharmacological action. The drug release is maintained at a specific rate to maximize the benefits as well as to suppress the side impacts. The release rate behaviour is affected by physiological conditions such as ion charge, pH level and enzymatic environment. Since the intestinal tract itself varies broadly in a pH environment, hence it is important to study the profile of drug release in different pH conditions. Mathematical model turns out very useful in predicting the drug release as well as reducing experimental works. The objective of this work was to study the mathematical model in describing the drug release profile in gastrointestinal tract liquid simulation. The release profiles of furosemide and sodium-iron chlorophyllin encapsulation were studied in the pH ranges 1.3-1.5 and 6.8-7.4 to simulate the different part of gastrointestinal tract acidity. The Korsemeyer-Peppas, Weibull and Gompertz were applied in describing the profile. Korsmeyer-Peppas model shows more superior (R²>0.912) than Weibull and Gompertz in describing the release kinetic of furosemide and sodium-iron chlorophyllin encapsulations in both pHs of GTS. The n values of Korsmeyer-Peppas are mostly less than 0.5 suggesting the release mechanism was governed by diffusion.

The ultrasound-assisted depolymerization of κ-carrageenan has been studied at various temperatures and times. The κ-carrageenan with initial molecular weight of 545 kDa was dispersed in water to form a 5 g/L solution, which was then depolymerized in an ultrasound device at various temperatures and times. The viscosity of the solution was measured using Brookfield viscometer, which was then used to find the number-average molecular weight by Mark-Houwink equation. To obtain the kinetics of κ-carrageenan depolymerization, the number-average molecular weight data was treated using midpoint-chain scission kinetics model. The pre-exponential factor and activation energies for the reaction are 2.683×10-7 mol g-1 min-1 and 6.43 kJ mol-1, respectively. The limiting molecular weight varies from 160 kDa to 240 kDa, and it is linearly correlated to temperature. The results are compared to the result of thermal depolymerization by calculating the half life. It is revealed that ultrasound assisted depolymerization of κ-carrageenan is faster than thermal depolymerization at temperatures below 72.2°C. Compared to thermal depolymerization, the ultrasound-assisted process has lower values of Ea, ΔG‡, ΔH‡, and ΔS‡, which can be attributed to the ultrasonically induced breakage of non-covalent bonds in κ-carrageenan molecules.