—As reported, digitalis prevents the described hypermagnesemic periodic paralysis. Lithium carbonate has the same effect. In the pathogenesis of these hypermagnesemic attacks, a renal disorder seems to play an important role. Both lithium carbonate and digitalis decrease electrolyte reabsorption in the tubular system,1,2 and lithium carbonate increases the urinary excretion of magnesium.3 Therefore, it seems that the renal mechanism has the more important therapeutic effect, which certainly holds true for lithium carbonate. Additionally, this drug has a negative effect on neuromuscular transmission.4A positive effect of digitalis on the release of acetylcholine at the neuromuscular junction is definitely plausible. Continuous and exact long-term measurement of the 24-hour electrolyte elimination, as well as the total urinary output with digitalis and lithium carbonate treatment, was not possible. The patient did not suffer from attacks, and, unfortunately, was not cooperative.
Emser W. Hypermagnesemic Paralysis, Digitalis, and Acetylcholine Release-Reply. Arch Neurol. 1984;41(2):135. doi:10.1001/archneur.1984.04050140033008