What Happens to Tablets and Capsules in the Stomach: Endoscopic Comparison of Disintegration and Dispersion Characteristics of Two Microencapsulated Potassium Formulations

Abstract

Previously we investigated gastric emptying and distribution of a capsule formulation of microencapsulated KCI and found the drug was usually present in clumps of KCI crystals held in place by gastric mucus. We therefore investigated whether a tablet formulation of microencapsulated KCI would have improved dispersion. We characterized the intragastric disintegration of capsules and tablets of microencapsulated KCI in 12 subjects. The capsule formulation floated in the gastric pool; one end would adhere to the gastric mucosa and the motion of the tethered capsule would pull the end of the capsule off. The KCI crystals would then be deposited in a mass. In contrast, the tablet formulation sank to the anatomically most dependent portion of the stomach. The tablet rapidly became soft and fragile but, if allowed to remain in one place and minimally disturbed, required a median of 12min to lose its shape. If allowed to reach the gastric antrum, the tablet was quickly ground by the antro-pyloric pump and widely dispersed. Once liberated in the stomach, the microencapsulated KCI crystals were bound into a more-or-less cohesive mass. The differences between KCI formulations, once the crystals were released, was minimal although the larger crystals from the tablet formulation appeared less adherent and cohesive; they dispersed more in a reticulated pattern when the stomach was distended. We conclude that formulation of a drug in a microencapsulated multiple-unit dosage form does not guarantee wide dispersion nor absence of high local concentration of drug.