C. diff Risk


Oral Bioavailability


Approximate Cost




500mg PO BID
Clarithromycin XL 1 g PO daily

General Information

Common Usage

  • CAP

  • Pertussis

  • URTI

  • H. pylori and mycobacterial infections

Drug Monitoring

Monitor QTc in patients with increased risk

Adverse Effects

  • Neutropenia

  • GI upset

  • Prolongation of QTc interval

  • Drug interactions

Major Interactions

Recommend review of patient medications due to high frequency of significant interactions

  • ¬†CYP450 interactions ++

  • Other QTc prolonging agents

  • Statins - increased rhabdo

  • CCBs - hypotension, AKI

  • Colchicine - increased bone marrow toxicity

  • Increased anticonvulsant levels

  • Increased tacrolimus levels

Additional Information

Very high tissue penetration and concentration intracellularly means in vivo activity may not be predicted by in vitro testing.


Antimicrobial class: Macrolide

Pregnancy category: C

Average serum half life: 5.0

Urine penetration: Poor

CSF penetration: Poor

Biliary penetration: Therapeutic

Lung penetration: Therapeutic