Pharmacology: Clarithromycin exerts its antibacterial action by binding to the 50S ribosomal subunit of susceptible organisms and inhibiting protein synthesis.
Microbiology: Clarithromycin is active in vitro against a variety of aerobic and anaerobic gram-positive and gram-negative organisms as well as most Mycobacterium avium complex (MAC) organisms.
Gram-positive aerobes: Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes.
Gram-negative aerobes: Haemophilus influenzae, Moraxella (Branhamella) catarrhalis.
Other aerobes: Mycoplasma pneumoniae.
Mycobacteriae: Mycobacterium avium complex (MAC) consisting of Mycobacterium avium and Mycobacterium intracellulare.
Pharmacokinetics: Clarithromycin is rapidly absorbed from the gastrointestinal tract after oral administration. The absolute bioavailability of clarithromycin 250 mg was approximately 50%. Food slightly delays both the onset of clarithromycin absorption and the formation of the antimicrobially active metabolite, 14-OH clarithromycin, but does not affect the extent of bioavailability. Therefore, clarithromycin may be given without regard to meals.