USP Dissolution Test II: Sigmoid Dissolution Profiles from Directly Compressed Tablets

Unconventional dissolution methodologies

“…Because disintegration is usually much faster than dissolution, the semilog plot of (100 − fs) vs t yields a biexponential curve. Carstensen 44 If q is small and F/q , 1 w ln m ) −qθ + ln m0 If q is large w ln m ) −qθ + qθ2 + ln m0 6(F/q) 3…”

“…Table 2 in summary depicts four prominent theories used in dissolution profile analysis, namely Wagner's, 39 Kitazawa's, [40][41][42] El-Yazigi's, 43 and Carstensen's. 44 Wagner's theory 39 for the interpretation of percent dissolved-time plots of tablets and capsules relates the apparent first-order kinetics under sink conditions to the fact that a percent dissolved value at a certain time may be equivalent to the percent surface area generated at the same time. Kitazawa's theory [40][41][42] showed that the biphasic straight lines were obtained from plots of ln c s /(c s -c) vs t. The first segment was due to tablet disintegration or disruption of the capsule shell, while the second segment was obtained from this point onward to the end of the dissolution.…”

Electrochemical Determination of Dissolution Rates of Lyophilized Pharmaceutical Formulations

“…The introduction of multiple chemical components complicates matters further. However, Carstensen et al , indicated that diffusional limitations are responsible for the common log−linearity observed in typical dissolution profiles. Dissolution of most pharmaceutical formulations is assumed to be diffusion controlled .…”