Accepted: 20.9.2003 Correspondence to:

Objective: To study the pharmacokinetics of ofloxacin using salivary drug concentration when administered alone or in combination with rifampicin (R), isoniazid (H) and pyrazinamide (Z) and also to assess the saliva to plasma concentration ratio. Material and Methods: Twelve healthy male volunteers were investigated on four different occa-sions with an interval of at least one week between occasions. They were administered ofloxacin, either alone or in combination with R, H and Z. A partially balanced incomplete block design was adopted and the subjects were randomly allocated to each group. Salivary and plasma concentra-tions of ofloxacin were measured at 1, 2, 3, 6 and 8 h after drug(s) administration using validated methods. Results: There were no significant differences between various pharmacokinetic parameters when ofloxacin was administered alone or in combination with R, H and Z. The mean saliva to plasma ratio of ofloxacin concentration was around 0.6. The bioavailability indices of ofloxacin in the saliva and plasma were similar in all the groups. Conclusion: Several pharmacokinetic parameters could be calculated using salivary concentra-tions of ofloxacin. The determination of ofloxacin levels in saliva may be useful in therapeutic drug monitoring and pharmacokinetic studies. KEY WORDS: Anti-TB drugs, ofloxacin, pharmacokinetics, saliva