Two bronchodilator tablets compared with a placebo.
D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000494:pharmacology*; D002986:Clinical Trials as Topic; D006801:Humans; D010879:Piperazines / Q000627:therapeutic use*; D010919:Placebos; D013806:Theophylline / Q000627:therapeutic use*
D001993:Bronchodilator Agents; D010879:Piperazines; D010919:Placebos; D013806:Theophylline