Effects of a beta-blocking agent, timolol maleate, on saliva in healthy volunteers

The effects of timolol maleate on the secretion and composition of human saliva were studied in vivo. Eight healthy volunteers received orally 10 mg timolol maleate. Stimulated parotid saliva samples, resting whole saliva samples, and blood samples were collected immediately before and four times after the drug intake at intervals of 1 h. The levels of total protein, lysozyme, IgA, IgG and IgM, salivary peroxidase, myeloperoxidase, lactoferrin, amylase, thiocyanate (SCN-), and hypothiocyanite (OSCN-) were analyzed from saliva samples. Drug levels were measured both from parotid saliva and blood samples. Results were compared to the analyses of the samples collected in a similar way but without administration of any drugs. Decreased levels of total protein, lactoferrin, amylase, and salivary peroxidase were observed in parotid saliva after a single oral dose of timolol maleate. No such decrease was found in lysozyme, myeloperoxidase, SCN-, OSCN-, or immunoglobulins. Salivary flow rate was not significantly changed after drug intake. The results suggest that the beta-blocking drug may cause qualitative changes in the composition of saliva by inhibiting the synthesis and/or release of acinar proteins.