Tetsuro Tabata

Stabilization of a new antiulcer drug (Lansoprazole) in the solid dosage forms

AbstractIn the previous study, we clarified that enteric granules were appropriate dosage forms of lansoprazole. The establishment of these formulations, however, was difficult because some of the excipients needed for these formulations are incompatible with the drug. We examined the effects of adding magnesium carbonate as an alkaline stabilizer and could get stable enteric granules. We also discuss the mechanism of stabilization.

Determination of manidipine enantiomers in human serum using chiral chromatography and column-switching liquid chromatography

A stereoselective and highly sensitive method using chiral chromatography and successive column-switching liquid chromatography is described for the determination of manidipine enantiomers in human serum. A human serum sample obtained after ingestion of manidipine was extracted twice with a mixture of n-hexane-diethyl ether under alkaline conditions. The enantiomers in the extract were separated on a chiral stationary phase column (Chiralcel OJ), and the effluents containing the respective enantiomers were collected. Each fraction was then analysed by column-switching liquid chromatography. The proposed stereoselective method offered high sensitivity: detection limits for both isomers were 0.2 ng/ml in human serum, both at a signal-to-noise ratio of 3. The method is suitable for the pharmacokinetic studies of manidipine enantiomers.

Manufacturing Method of Stable Enteric Granules of a New Antiulcer Drug (Lansoprazole)

AbstractIn our previous studies, we clarified that enteric granules are an appropriate dosage form for lansoprazole, and we demonstrated that enteric granules could be produced when magnesium carbonate was added as an alkaline stabilizer.These granules however were found to be some unstable under severe conditions because some of the excipients are incompatible with lansoprazole. We therefore attempted granulation not using these incompatible excipients and could obtain more stable enteric granules using a centrifugal fluid-bed granulator instead of an extruder-spheronizer. We also compared the absorption and dissolution properties of the enteric granules manufactured by these two methods.