In our previous study 1 on the effect of different doses of an anticholinergic drug in the same patient, we found that suppression of gastric acidity to pH 4.5 or higher did not occur at any dose without accompanying dryness of the mouth but that the dose producing dryness of the mouth did not necessarily bring about such pH values of acidity. However, if the dose of these drugs was increased to one increment below that which produced uncomfortable symptoms of parasympathetic inhibition, such as blurring of vision, palpitation, dizziness, headache, weakness, flushing of the face, and/or excessive dryness of the mouth and throat, suppression of acidity to pH 4.5 or higher occurred consistently with the effective drugs. This dose we termed the optimal effective dose (O. E. D.).
The present study was undertaken to investigate the value of the optimal effective dose of anticholinergic drugs and to appraise its