Azithromycin

C. diff Risk

Medium

Oral Bioavailability

Moderate

Approximate Cost

IV-$9/d PO-$1/d

Dosing

Adult

Respiratory Infection
500mg po/IV on day 1 then 250mg daily for 4 days
OR
500 mg IV/PO daily for 3 days

Chlamydia trachomatis
1g PO x 1 dose

General Information

Common Usage

  • Community acquired pneumonia

  • Pertussis

  • Upper respiratory tract infections

  • Chlamydial infections

  • Mycobacterial infections

  • Mycobacterium avium complex (MAC) prophylaxis in HIV patients

Drug Monitoring

Monitor QTc in patients with increased risk

Adverse Effects

Prolongation of QTc interval - Association with increased cardiovascular mortality in observational studies.

Prolonged half life may contribute to macrolide resistance

May exacerbate muscle weakness in persons with myasthenia gravis. Use with caution.

Major Interactions

  • Other drugs that prolong QTc

  • Increase INR with warfarin

  • Increases cyclosporine levels

  • May increase digoxin levels

  • Increased risk of rhabdomyolysis with statins

Additional Information

Very high tissue penetration and concentration intracellularly means in vivo activity may not be predicted by in vitro testing - i.e. Salmonella spp

Pharmacology

Antimicrobial class: Macrolide

Pregnancy category: B

Average serum half life: 68.0

Biliary penetration: Therapeutic

CSF penetration: Poor

Lung penetration: Therapeutic

Urine penetration: Poor