title: Variations in theophylline, ephedrine hydrochloride and phenobarbital tablets manufactured by thirteen firms.
mesh_terms: D001702:Biopharmaceutics; D002854:Chromatography, Paper; D004345:Drug Industry; D004809:Ephedrine / Q000592:standards*; D005569:Formularies as Topic; D006801:Humans; D010634:Phenobarbital / Q000032:analysis / Q000592:standards*; D012995:Solubility; D013053:Spectrophotometry; D013607:Tablets / Q000592:standards; D013806:Theophylline / Q000032:analysis / Q000592:standards*; D013997:Time Factors; D014481:United States
chemical_list: D013607:Tablets; D013806:Theophylline; D004809:Ephedrine; D010634:Phenobarbital