“…After the good results obtained in thinning fluid by the intrapleural use of trypsin, the enzyme was used as an aerosol for the liquefaction of viscid bronchial secretions. Several papers Limber et al, 1952;Peck and Levin, 1952;Unger andUnger, 1953a, 1953b;Yates and Goodrich, 1953;Wilson and Stevenson, 1957) have been published showing that trypsin as an aerosol may decrease the viscosity of sputum. More recently, crystallized alpha-chymotrypsin, when administered intramuscularly, has been reported to be effective in respiratory conditions such as bronchial asthma, bronchitis, and sinusitis (Parsons, 1958;Teitel et al, 1960;Taub, 1960).…”