Excretion of indomethacin into saliva following intravenous administration to dogs.

Parotid saliva (Pr) and mandibular-sublingual saliva (MS) were collected separately by means of permanent fistulae in order to investigate the excretion of indomethacin in saliva of dogs receiving a single intravenous dose of 20 mg/kg. Drops of citric acid solution were placed on the tongue to stimulate salivary secretion. The concentrations of indomethacin both in saliva and plasma declined biexponentially with time. There was a good linear relationship between the drug concentration in each saliva and plasma. The Pr and MS levels were 7.4% and 4.4% of the plasma levels, respectively. Indomethacin concentrations in Pr were significantly higher than in MS (p less than 0.05). The roles of salivary pH and salivary protein binding were discussed in respect to the mechanism of salivary excretion of the drug.