C. diff Risk


Oral Bioavailability


Approximate Cost


Spectrum Of Activity


Renally cleared, requires dosage adjustment with changes in renal function. Consult a pharmacist for renal dosing.

General Information

Common Usage

Second line for community aquired pneumonia (drug of choice if atypical), URTI, H. pylori, and mycobacterial infections

Drug Monitoring

Monitor QTc in patients with increased risk

Adverse Effects

  • GI upset, diarrhea

  • Rash

  • Prolongation of QTc interval

Major Interactions

Substrate of CYP3A4. Multiple CYP450 interactions possible - consult a pharmacist for more detail. May increase digoxin, carbamazepine level. Caution with QTc prolonging medications

Oral Liquids

Concentration: 25 mg/mL
Taste: palatable
Not all strengths of oral liquids are listed nor are available on IWK formulary

Tablet/Capsule Strengths

250 mg tablet

Tablets and capsules are preferred especially over an unpleasant tasting liquid.

Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary.


Antimicrobial class: Macrolide

Average serum half life: Adult: Clarithromycin: 3-7 hours
14-OH-clarithromycin (active metabolite): 5-9 hours

Route of Elimination: Urine (20-40% as unchanged drug, additional 10%-15% as active metabolite); feces (29% to 40% mostly as metabolites)