Effects of bromhexine on the secretions of saliva and tears.

Effects of bromhexine and pilocarpine on the secretions of submaxillary saliva in dogs and of tears in rabbits were investigated including their effects on lysozyme activity in an attempt to elucidate the efficacy of bromhexine on Sjögren's syndrome. Pilocarpine (0.3 mg/kg, p.o.) significantly increased spontaneous salivary flow rate, but bromhexine (20 and 40 mg/kg, p.o.) had almost no influence on spontaneous salivary flow rate. Pilocarpine increased total protein, saccharide, lysozyme and IgA secretions in saliva under electrical stimulation of the chorda tympani. Bromhexine did more markedly increase total lysozyme and IgA secretions in saliva, with minor increases in total protein and saccharide secretions. Pilocarpine (0.4 mg/kg, i.v.) had almost no influence on lysozyme concentration in tears, whereas it markedly increased tear secretion volume leading to an increase in total lysozyme secretion. On the other hand, bromhexine (4 and 8 mg/kg, i.v.) significantly increased both lysozyme concentration and total lysozyme secretion in tears from 50 min after injection, without influencing tear secretion volume. From these findings, it is suggested that bromhexine may work effectively on Sjögren's syndrome by acting to accelerate the secretions of lysozyme and IgA in saliva and tears, which are known to have antiinflammatory and bacteriocidal effects.