From Fig. 8, we see that the drug release pattern for all hydrogels tested can be divided into two phases. The first phase is the burst effect; the early release of drug molecules present on the surface of the hydrogel. The second phase is the continuous drug release process. Rapid drug release in phase one of the test could be due to a higher drug concentration gradient present at the beginning of the test. This higher gradient could act as a driving force for the release of the drug from the hydrogel network. Drug release rates steadily decreased with time. This decrease could have been caused by the thickness of the hydrogel that acted as a diffusion barrier