A PK/PD approach on the effects of clarithromycin against oral and nasal microbiota of healthy volunteers.

ABSTRACT

OBJECTIVE: To assess the pharmacokinetics of clarithromycin (CLR) and its effects on oral and nasal microbiota in healthy volunteers in an open, randomized, two-period crossover design. METHODS: A single 500 mg oral dose of CLR (Group 1 Merck; Group 2 Klaricid) was administered observing a 1-week interval between doses. Blood samples were collected from pre-dose to 24 h. Plasmatic concentrations of CLR were quantified by the LC-MS-MS method. Saliva and nasal mucosa swabs were obtained previously and after 1.33, 2, 6 and 12 h of drug administration. Pharmacokinetics and PK/PD (t > MIC, %t > MIC and AUC0-24/MIC ratio) parameters were estimated. The microorganism counts were obtained on different culture media. RESULTS: No statistically significant differences were observed between the two formulations (p > 0.05) regarding the pharmacokinetic parameters. Total microorganisms, staphylococci and streptococci counts did not show statistical differences (p > 0.05) between the two groups during each sampling time. Considering the microorganisms of each group, no statistically significant differences were found after drug administration, but all differed from pre-dose counts (p < 0.05). The observed t > MIC ranged from 14.45 h (+/- 1.69) to 1.19 h (+/- 2.17) considering MICs of 0.25 microg/ml and 2.0 microg/ml, respectively. There was no correlation between any t > MIC, %t > MIC or AUC0-24 and bacterial reduction (between 0- and 12-h periods). However, the profile of reduction of microorganisms in both saliva and nasal samples were compatible with high values of t > MIC verified for both clarithromycin formulations. CONCLUSION: Both formulations of clarithromycin had similar pharmacokinetics and efficacy.