Pharmacokinetics
Biaxin is quickly absorbed when taken orally. In general, it takes 2 to 3 hours for a 250 mg dose of clarithromycin to reach its mean peak plasma concentration (Cmax), and it takes 3 to 4 hours for a 500 mg dose. After giving 250 mg of BIAXIN to healthy young adults (n=14), the mean peak plasma concentration was 1.6 0.5 mcg/mL, and after giving 500 mg of BIAXIN, it was 2.2 0.7 mcg/mL. In general, as the dose is increased, the extent of absorption decreases.
Under fasting conditions, the bioavailability of clarithromycin suspension is comparable to that of clarithromycin tablets. Peak plasma concentrations, however, were reached more quickly (1 hour) after giving fasting subjects clarithromycin suspension than they were with the tablet formulation. 1.5 0.6 mcg/mL was the mean Cmax. .
The bioavailability of BIAXIN Tablets (500 mg twice daily for 7 days; n=24) and Filmtabs (500 mg twice daily for 7 days; n=17) was comparable.
The steady-state peak plasma concentrations of clarithromycin after oral administration of multiple doses of 500 mg BIAXIN tablets twice daily ranged from 1.4 mcg/mL to 4.1 mcg/mL, and Cmax values ranged from 2.3 mcg/mL to 9.3 mcg/mL. The estimated bioavailability of a 500 mg clarithromycin tablet given while fasting in healthy volunteers ranges from 60% to 70%. In healthy young adults, food slightly slows down and reduces the amount of clarithromycin absorbed, but it has no effect on the medication's pharmacokinetics.
Within 5 to 7 days, steady-state peak plasma concentrations of 8 to 15 mcg/mL have been reached in adult patients taking BIAXIN Filmtabs or BIAXIN Tablets. Within 5 to 14 days, steady-state peak plasma concentrations of 4 to 11 mcg/mL have been reached in pediatric patients receiving BIAXIN suspension.
The tissue distribution of clarithromycin and its 14-OH metabolite is excellent. The apparent volume of distribution (V/F) in healthy volunteers after a single oral administration of 500 mg of clarithromycin as tablets is roughly 31 L/kg.
