ACTION OF DRUGS BENEFICIAL IN MYASTHENIA GRAVIS I. EFFECT OF PROSTIGMINE AND GUANIDINE ON SERUM AND MUSCLE POTASSIUM

¹ From the Department of Pharmacology, State University of Iowa, Iowa City

1. Prostigmine and guanidine produce a decrease in serum potassium in dogs and rats and an elevation of muscle potassium in rats.

2. The signs of prostigmine intoxication parallel more closely in dogs the depression of serum potassium than they do the acetylcholine esterase inhibition.

3. The serum potassium response to prostigmine in patients with Myasthenia gravis is not constant. The direction of change seems to depend on the initial level of serum potassium, and whether the therapy has included potassium chloride.

4. The duration of relief of symptoms in Myasthenia gravis after prostigmine follows more closely the change in serum potassium (whether elevated or lowered) than it does the decrease in activity of acetylcholine esterase.