Effect of potassium chloride supplements on upper gastrointestinal mucosa

Eight controlled 1‐ or 2‐wk experiments involving 225 healthy male subjects and one study of 18 patients with hypertension, nine of whom were long‐term users of a wax‐matrix potassium chloride preparation, were conducted to evaluate the upper gastrointestinal safety of oral KCl supplements. All subjects in the short‐term studies had normal upper gastrointestinal tracts. Subjects were examined again after at least 7 days of treatment with one of three commonly prescribed wax‐matrix KCl tablets, KCl liquid, microencapsulated KCl, a potassium‐sparer, or placebo. Some received an anticholinergic drug with treatment to induce delayed gastric motility. Diet and compliance to treatment regimens were controlled. Results indicate that upper mucosal injury, particularly erosions (43%) and ulcerations (11%), were more frequent after wax‐matrix tablets. These changes occurred much less frequently after liquid KCl (0%), microencapsulated KCl (10.5% erosions, 1.2% ulcers), and the potassium‐sparing drug (0%). More serious and more frequent lesions were associated with slowed motility. No occult bleeding was noted. Symptomatic complaints did not correlate with endoscopic findings. In the long‐term study, patients with hypertension were examined endoscopically after 19 to 23 mo on KCl and again after 1 wk. Six of nine of the patients with hypertension treated for nearly 2 yr with a wax‐matrix KCl supplement had significant lesions. One had developed ulceration after 7 days. The incidence of lesions was lower in a carefully matched group of controls who received only placebo (erosions in three of nine; none had or developed ulcers). Incidence of upper mucosal injury with wax‐matrix tablets is higher than with other liquid or microencapsulated forms of KCl or with a potassium‐sparing drug. Clinical Pharmacology and Therapeutics (1984) 35 , 852–855; doi: 10.1038/clpt.1984.124