Biaxin - Clinical Pharmacology

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Middle Ear Fluid Serum

Analyte (µg/mL) (µg/mL)

Clarithromycin 2.5 1.7

14-OH Clarithromycin 1.3 0.8

In adults given 250 mg clarithromycin as suspension (n=22), food appeared to decrease mean peak plasma clarithromycin concentrations from 1.2 (± 0.4) µg/mL to 1.0 (± 0.4) µg/mL and the extent of absorption from 7.2 (± 2.5) hr µg/mL to 6.5 (± 3.7) hr µg/mL. When children (n=10) were administered a single oral dose of 7.5 mg/kg suspension, food increased mean peak plasma clarithromycin concentrations from 3.6 (± 1.5) µg/mL to 4.6 (± 2.8) µg/mL and the extent of absorption from 10.0 (± 5.5) hr µg/mL to 14.2 (± 9.4) hr µg/mL.

Clarithromycin 500 mg every 8 hours was given in combination with omeprazole 40 mg daily to healthy adult males. The plasma levels of clarithromycin and 14-hydroxy-clarithromycin were increased by the concomitant administration of omeprazole. For clarithromycin, the mean C max was 10% greater, the mean C min was 27% greater, and the mean AUC 0-8 was 15% greater when clarithromycin was administered with omeprazole than when clarithromycin was administered alone. Similar results were seen for 14-hydroxy-clarithromycin, the mean C max was 45% greater, the mean C min was 57% greater, and the mean AUC0-8 was 45% greater.

Clarithromycin concentrations in the gastric tissue and mucus were also increased by concomitant administration of omeprazole.

Clarithromycin Tissue Concentrations 2 hours after Dose (µg/mL)/(µg/g)

Treatment N antrum fundus N mucus

Clarithromycin 5 10.48 ± 2.01 20.81 ± 7.64 4 4.15 ± 7.74

Clarithromycin +

Omeprazole 5 19.96 ± 4.71 24.25 ± 6.37 4 39.29 ± 32.79

4

3

2

1

0

40 8 1216 20 24

Steady-State Clarithromycin Plasma Concentration-Time Profiles

Time After Dosing (hours)

Mean Plasma Concentration (mcg/mL)

Biaxin-XL: 2 x 500 mg q24h

Biaxin: 500 mg q12h

For information about other drugs indicated in combination with BIAXIN, refer to the CLINICAL PHARMACOLOGY section of their package inserts.

Microbiology:

Clarithromycin exerts its antibacterial action by binding to the 50S ribosomal subunit of susceptible microorganisms resulting in inhibition of protein synthesis.