title: Azithromycin pharmacokinetics and penetration to lymph.
abstract: The study of pharmacokinetics of azithromycin and penetration to peripheral human lymph was carried out in 14 healthy male volunteers taking 1 g orally after overnight fasting. Samples were analyzed by microbiological assay. The mean peak concentrations were 0.82 +/- 0.23 mg/l after 1.7 +/- 0.5 h in serum and 0.22 +/- 0.07 mg/l after 3.1 h in lymph. Nine of the 14 subjects showed a second and lower serum peak indicating the existence of enterohepatic circulation. The total areas under the serum concentrations curves (AUCs) till infinity were 7.9 +/- 3.1 mg. h/l compared to 4.4 +/- 1.2 mg.h/l in lymph. The mean lymph AUC was 68.1 +/- 20.7% of the serum AUC indicating a penetration ratio of 0.68. However, the actual amounts penetrating the tissues were much higher than this ratio suggests. Thus, after 6 h 81% of the drug was within the tissue compartment and after 120 h, 63% of the azithromycin was still present in the tissue compartment. The urinary recovery of azithromycin was 14.7 +/- 7.7% during the first 48 h. The serum curves and lymph curves displayed a distinctly slower phase of elimination after 12 h. The mean serum half-life was 5.4 +/- 3.4 h during the first 12 h (after the peak), whereas the value was 44.2 +/- 10.1 h during the interval 12-120 h. The corresponding half-life values for the peripheral lymph were 5.4 +/- 2.2 h and 50.8 +/- 11.6 h. Azithromycin possesses key pharmacokinetic properties that are prerequisites for a convenient once-daily dosage schedule which may improve patient compliance.
authors.affiliation: Department of Microbiology, University of Oslo, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Bergan
authors.forename: N P
authors.initials: NP
authors.lastname: Jørgensen
authors.forename: W
authors.initials: W
authors.lastname: Olszewski
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000328:Adult; D017963:Azithromycin; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D008196:Lymph / Q000378:metabolism*; D008297:Male; D012016:Reference Values; D014018:Tissue Distribution
chemical_list: D004917:Erythromycin; D017963:Azithromycin