[Inhibition of acetylcholinesterases--a relevant side effect of ranitidine?].

Ranitidine inhibited in a dose-dependent manner acetylcholinesterases from human erythrocytes and gastric mucosa. The concentration for half-maximal inhibition was 1,5 X 10(-6) and 1,4 X 10(-6) mol/l, which resembles levels seen during therapy. Inhibition was of competitive type, the inhibitory constant measured 1,6 X 10(-6) mol/l. Pseudocholinesterase in serum was also inhibited, however, the levels required were about 25 times higher. As a consequence from our in vitro findings a stimulation of cholinergic mechanisms in ranitidine treatment should occur, e. g. stimulation of glandular secretion or increase of gastrointestinal motility.