title: Respiratory and cough mechanics in antitussive trials. Responsivity of objective indices to the treatment of acute upper respiratory tract infections.
abstract: The relative responsitivy of nine expirographic and airway indices to antitussive therapy was studied in a randomized double-blind trial in which 60 adults without bronchopulmonary disorders, but suffering from common colds, were given oral doses of five drug formulations or placebo during their initial 48 h of symptoms. Thoracic gas volume (Vtg), nasal (Rn), lower (Ra), total t[Rn + Ra]) and specific (sRa) airway resistances were determined plethysmographically; forced vital capacity (FVC), forced expiratory volume for the first second (FEV1.0) and maximal mid-expiratory flow rate (MMEFR) were recorded spirometrically. Cough pressure at peak flow furnished an index of cough (CI). The measurements were made at baseline and for 4 h after drug; medication was continued for two additional doses and the indices determined again the following morning. Abnormal control means were noted for Rn and [Rn + Ra] (90.8%), cough resistance (83.3%), MMEFR (58.3%), Ra and sRa (30.0%), but less ofter for FEV1.0, Vtg and FVC (6.6, 5.1 and 0.0%, respectively). Nasal and total airways flow resistance means were as sensitive to active therapy and in discriminating the relative worth of medication as direct CI values, Ra and sRa were less reliable, and the three spirometric functions were the lease responsive. This ranking was consistent with the common central airways location of subepithelial receptors responsible for cough and the associated reflex bronchoconstriction. The greatest changes in cough resistance followed treatment with the most significant activity in the nasal, as well as the lower tract, component of total airway resistance.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance; D000996:Antitussive Agents / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D003139:Common Cold / Q000188:drug therapy* / Q000503:physiopathology; D003371:Cough / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010993:Plethysmography, Whole Body; D012119:Respiration; D013147:Spirometry; D014797:Vital Capacity
chemical_list: D000996:Antitussive Agents