Gastroscopic localization of a microencapsulated KCl preparation in the human stomach.

A slow release polymer-coated preparation of potassium chloride granules (Micro-K Extencaps) was initially thought not to be associated with gastric mucosal damage. Recent studies have shown that acute gastric ulcers occur with approximately the same frequency as in patients taking wax matrix KCl formulations. The development of acute gastric ulcers was not consistent with the proposed dispersion characteristics of the microencapsulated KCl preparation. The authors therefore endoscopically evaluated the dispersion characteristics of microencapsulated KCl in a double-blind, placebo-controlled study. Subjects received four capsules of Micro-K or matching placebo and endoscopy was performed 30, 60, or 120 min after each drug ingestion. The material was identified with the Olympus HM (high magnification) endoscope and then quantitatively aspirated using the 3.5-mm biopsy channel of the Pentax 34JA endoscope. Microencapsulated KCl particles dispersed poorly and were found adhering to the mucosa and to one another, as a semisolid mass, most frequently in the gastric antrum. In contrast, the placebo (ethyl cellulose) was widely dispersed throughout the stomach. The authors concluded that gastric emptying must be considered in three phases: liquids, solids, and solids which adhere to the mucosa. No unique dispersion characteristics of Micro-K Extencaps were identified, and adherence of the KCl to the gastric mucosa may explain its ability to cause occasional acute gastric ulceration.