[Penetration of clarithromycin to saliva and its effect on normal salivary bacterial flora]

Clarithromycin (TE-031, A-56268), a new macrolide antibiotic, was administered to rats, and the distribution of the drug in the submandibular gland was studied using microautoradiography. The study revealed good accumulation of 14C-TE-031 in both the acini and the excretory ducts. TE-031 was administered to each of 3 healthy male volunteers in a single dose of 300 mg, and its concentrations in the serum and saliva was detected. Mean values of various pharmacokinetic parameters were as follows for the serum and saliva, respectively. Cmax 1.49 micrograms/ml and 1.93 micrograms/ml; Tmax 2.91 hours and 2.66 hours; T 1/2 6.31 hours and 4.15 hours; AUC 18.58 micrograms.hr/ml and 17.70 micrograms.hr/ml. Regarding the salivary bacterial flora, the total bacterial count decreased as the salivary TE-031 concentration increased, but it recovered to the initial level in 12 hours after administration. During the 24-hour period following an administration of TE-031, the salivary bacteria did not acquire resistance to the drug. Therefore, TE-031 is an antibiotic which exerts little effect on the normal salivary bacterial flora in short-term administration. Although the results differed among the individuals, the penetration of TE-031 to saliva was superior to that to the serum. Thus, TDM of TE-031 using salivary samples is possible.