Triaxial compression of "cappable" formulations.

According to theory, "capping" (visible lamination) occurs at the uniaxial relaxation stage at the point at which the upper punch pressure is released. A method is described whereby the stress in a tablet prone to a "capping" problem can be released in a triaxial manner.

Determination of the ionization constants of compounds which precipitate during potentiometric titration using extrapolation techniques.

It is shown that the ionization constants of diacidic compounds can be determined by utilizing potentiometric titration data, even when a precipitate forms during the titration. The two methods presented are particularly useful for compounds for which the pK alpha values are close together. A third method is presented which can be used with monoacidic compounds or compounds for which the pK alpha values are far apart and form a precipitate during the titration.

Cimetidine-theophylline complex formation.

Cimetidine forms a complex with theophylline in vitro in both pH 7.4 buffer and human plasma. The increase in the amount of theophylline in solution is about 20% in the buffer system and about 36% in plasma.