[Experimental study of the effects of bromelain on the sputum consistency in rabbits]

Effects of bromelain (BR) on rabbit sputum consistency were investigated in vitro and in vivo. On the sputum showing relatively low viscosity, BR and other enzymes such as serratiopeptidase (SP), the mixed preparation of pronase and pancreatin, and lysozyme exerted lowering effects; and the effect of BR was the most potent. However, bromhexine had virtually no effect. On the sputum showing relatively high viscosity, BR exerted more potent lowering effects on the viscosity and yield value of sputum than those of SP. Furthermore, 320,000 U/head BR and 120,000 U/head SP lowered the viscosity significantly and yield value of sputum in rabbits with oral administration for 3 days. The lowering effect on the yield value of BR was more potent than that of SP. BR also increased the sputum volume in rabbits. BR and SP showed tendencies to decrease the contents of acid glycoprotein and sialic acid in sputum. It can be considered that these results support the effectiveness of BR as an expectorant in clinical use.