title: Some pitfalls in antisecretory drug trials. Subject selection, collection period, and daytime variation.
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D002986:Clinical Trials as Topic; D005745:Gastric Acidity Determination; D005750:Gastric Juice / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010276:Parasympatholytics / Q000008:administration & dosage*; D010437:Peptic Ulcer / Q000188:drug therapy; D012636:Secretory Rate / Q000187:drug effects
chemical_list: D010276:Parasympatholytics