ZITHROMAX TRI-PAK (azithromycin)

Drug overview for ZITHROMAX TRI-PAK (azithromycin):

Generic name: AZITHROMYCIN (ay-ZITH-roe-MYE-sin)
Drug class: Macrolide Antibiotics
Therapeutic class: Anti-Infective Agents

Azithromycin is an azalide antibiotic, a subclass of macrolide antibiotics.

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph. Azithromycin is used orally in adults for the treatment of mild to moderate upper and lower respiratory tract infections and uncomplicated skin and skin structure infections caused by susceptible organisms. Oral azithromycin also is used for the treatment of urethritis or cervicitis caused by Chlamydia trachomatis or Neisseria gonorrhoeae, and for the treatment of chancroid caused by Haemophilus ducreyi.

Azithromycin is used orally for the treatment of disseminated infections caused by Mycobacterium avium complex (MAC) in patients with human immunodeficiency virus (HIV) infection and for prevention of disseminated MAC infection (both primary and secondary prophylaxis) in HIV-infected individuals. Azithromycin is used orally in children for the treatment of acute otitis media, community-acquired pneumonia, and pharyngitis or tonsillitis caused by susceptible organisms. IV azithromycin is used for the treatment of community-acquired pneumonia and acute pelvic inflammatory disease (PID) caused by susceptible organisms when initial IV therapy is considered necessary.

Potential advantages of azithromycin compared with erythromycin include improved oral bioavailability and tissue penetration, increased activity against infections caused by gram-negative organisms (e.g., Haemophilus influenzae), fewer adverse GI effects, and less frequent and less prolonged dosing (promoting better compliance with therapy). Controlled and uncontrolled clinical studies in patients with community-acquired upper or lower respiratory tract infections suggest that 3-5 days of oral therapy with azithromycin generally is as effective as 7-10 days of oral therapy with other macrolides (erythromycin, clarithromycin), a natural penicillin, amoxicillin (with or without clavulanic acid), or a cephalosporin (e.g., cefaclor). In addition, single-dose therapy with azithromycin for urethritis or cervicitis caused by Chlamydia trachomatis may be more cost-effective than longer courses of therapy with another anti-infective (e.g., doxycycline) in populations where noncompliance may be a problem.

(See Uses: Chlamydial Infections.) The relative lack of clinically important drug interactions with azithromycin also may be advantageous when oral macrolide therapy is considered for patients in whom multiple-drug therapy is prescribed (e.g., HIV-infected patients, patients receiving theophylline or carbamazepine). Considering the relative costs of drug therapy, erythromycin generally would be preferred for most infections in which oral macrolide therapy was indicated unless azithromycin would be expected to be more effective than erythromycin, the patient is intolerant of erythromycin (e.g., secondary to GI toxicity), or compliance with 3- or 4-times daily erythromycin dosing is considered a problem. Prior to initiation of azithromycin therapy, appropriate specimens should be obtained for identification of the causative organism(s) and in vitro susceptibility tests.

Azithromycin may be started pending results of susceptibility tests, but should be discontinued and other appropriate anti-infective therapy substituted if the organism is found to be resistant to the drug. (See Spectrum: In Vitro Susceptibility Testing.)