Nevertheless, significant differences in dissolution rate were also shown in batch to batch comparison. Some generics from the same manufacturer with different batches of the same drug showed significant differences. This illustrates that substitution Ku-0059436 in vitro among generics themselves can be risky. Unfortunately, some other generic medicines in this dissolution test failed to achieve the 85% dissolution at 60 min. These differences in dissolution rate between the branded and their generic counterparts could impact the drugs’

effectiveness and side-effects profiles [27]. There are many potential factors that can explain the differences between the branded and their generic counterparts. Those include the manufacturer, apparatus type, surface area of a drug, surfactants, storage, dosage form and the level and type of excipients. Manufacturer of the drug can play a major part in its dissolution profile. In the literature, it is reported that there are variable clinical responses to the same dosage form of a drug product supplied by different manufacturers. For example, a study compared 19 different generic formulations of simvastatin tablets and capsules obtained from international manufacturers to the US innovator product regarding pharmaceutical quality. It revealed that manufacturing standards PR-171 clinical trial for the international generics were not equivalent

Diflunisal in quality aspects with the US innovator drug, a significant variability was also found among foreign-made tablets themselves [28]. Similarly, another study compared the dissolution behaviour of six diclofenac sodium prolonged release

tablets of different brands obtained from the national market. It reported that the release characteristics vary considerably among different manufacturers and that even identical formulations showed rather dissimilar release profiles. Therefore the interchangeability of these drugs is questioned [25]. The apparatus type (paddle vs. basket) can also affect the dissolution test and it depends largely on the physiochemical properties of the dosage form [29]. Another possible reason for the difference in dissolution rate is the difference in particle or surface area of the drug particles [30]. Solid dosage form may or may not disintegrate when interacting with gastrointestinal fluid after oral administration following their design. Since disintegration determines to a large extent the area of contact between the solid and liquid, it usually plays a vital role in the dissolution process. However, it should be noted that there is no automatic correlation between disintegration and dissolution, especially with poorly soluble drugs [29]. The use of surfactant such as sodium lauryl sulphate, which is essential for poorly soluble drugs such as simvastatin can also affect the dissolution rate [31].