Azithromycin (Zithromax®) versus Amoxicillin
Based on "Antibiotic and Chemotherapy"
written by Roger G. Finch
Main differences between Azithromycin and Amoxicillin
| Azithromycin | Amoxicillin |
| Brand names | |
| • Zithromax® • Z-pak® |
• Amoxil® |
| Drug class | |
| Macrolide antibiotic, bacteriostatic |
Penicillin antibiotic, bactericidal |
| Spectrum of activity | |
| Excellent activity against atypical pathogens | No activity against atypical pathogens |
| Half-life | |
| 40 hours | 1 hour |
| Oral bioavailability | |
| ~40% | 74-92% |
| Side effects | |
| • High rate of diarrhea and rash | |
| Special populations | |
| • Alternative antibiotic for patients with penicillin allergy • Good choice for patients with questionable compliance |
• Contraindicated in patients with penicillin allergy |
| Pregnancy category | |
| B | |
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Chronic obstructive pulmonary disease
Azithromycin and amoxicillin have similar efficacy and tolerability in the treatment of acute exacerbation of chronic obstructive pulmonary disease 6. Both antibiotics improve symptoms such as cough and shortness of breath.
| Results of randomized comparison between azithromycin and amoxicillin for infectious exacerbation of chronic obstructive pulmonary disease6 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | 500 mg/day for 3 days | 500 mg every 8 hours for 10 days |
| Cure or improvement on Day 10 | 85% | 78% |
| Cure or improvement at One month | 83% | 78% |
Chlamydia
Both amoxicillin and azithromycin are effective in the treatment of cervical Chlamydia trachomatis infection during pregnancy. However, azithromycin seems to have a lower rate of recurrent infection2. Amoxicillin is slightly better tolerated1.
| Results of randomized single-blind trial of women diagnosed with C. trachomatis2 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | single 1 g dose | 500 mg 3 times daily for 7 days |
| Number of patients tested positive at follow-up test of cure | 1 of 19 (5%) | 3 of 15 (20%) |
| Moderate to severe gastrointestinal side effects | 40% | 17% |
| Results of randomized controlled trial of pregnant women with C. trachomatis11 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | single 1 g dose | 500 mg 3 times daily for 7 days |
| Treatment efficacy rate | 64% | 58% |
| Number of women intolerant to study drug | 6 (10.9%) | 3 (5.5%) |
Ear infection (Otitis media)
Azithromycin is as effective as amoxicillin for the treatment of children with otitis media3. Diarrhea occurs more frequently with amoxicillin.
| Results of double blind, double dummy, multinational, clinical trial of children (6-30 months of age) with AOM 3 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | single 30 mg/kg dose | 90 mg/kg in 2 divided doses for 10 days |
| Clinical success rates | 84% | 84% |
| Clinical efficacies among all microbiologic modified intent-to-treat evaluable subjects | 80% | 83% |
| Side effects rate diarrhea |
20% 8.2% |
29% 17.5% |
| Compliance | 100% | 90% |
| Results of a double blind, randomised controlled trial of Aboriginal children with AOM5 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | single 30 mg/kg dose | 50 mg/kg in 2 divided doses for a min. of 7 days |
| Clinical failure rate | 50% (82 of 165) | 54% (83 of 155) |
| Proportion of children after the treatment with nasal carriage of Streptococcus pneumoniae Haemophilus influenzae |
27% 55% |
63% 85% |
| Nasal carriage of S. pneumoniae with intermediate or full resistance to penicillin | 10% | 16% |
| Carriage of azithromycin-resistant S. pneumoniae | 10% | 3% |
Lyme disease
Amoxicillin is better than azithromycin for erythema migrans4.
| Results of randomized, double-blind, double-dummy, multicenter study - treatment of erythema migrans skin lesions4 | Azithromycin | Amoxicillin |
|---|---|---|
| Regimen | 500 mg once daily for 7 days | 500 mg three times daily for 20 days |
| Complete resolution of disease at day 20 rate | 88% | 76% |
| Relapse rate | 16% | 4% |
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Further reading
- Azithromycin (Zithromax) facts
- Azithromycin vs Cefdinir
- Azithromycin vs Ciprofloxacin
- Azithromycin vs Clarithromycin
- Azithromycin vs Doxycycline
- Azithromycin vs Amoxicillin/Clavulanate
- Azithromycin vs Penicillin
References
- 1. Jacobson GF, Autry AM, Kirby RS, Liverman EM, Motley RU. Am J Obstet Gynecol. 2001 Jun;184(7):1352-4; discussion 1354-6. PubMed
- 2. Kacmar J, Cheh E, Montagno A, Peipert JF. A randomized trial of azithromycin versus amoxicillin for the treatment of Chlamydia trachomatis in pregnancy. Infect Dis Obstet Gynecol. 2001;9(4):197-202. PubMed
- 3. Arguedas A, Emparanza P, Schwartz RH, Soley C, Guevara S, de Caprariis PJ, Espinoza G. Pediatr Infect Dis J. 2005 Feb;24(2):153-61. PubMed
- 4. Luft BJ, Dattwyler RJ, Johnson RC, Luger SW, Bosler EM, Rahn DW, Masters EJ, Grunwaldt E, Gadgil SD. Azithromycin compared with amoxicillin in the treatment of erythema migrans. Ann Intern Med. 1996 May 1;124(9):785-91.
- 5. Morris PS, Gadil G, McCallum GB, Wilson CA, Smith-Vaughan HC, Torzillo P, Leach AJ. Single-dose azithromycin versus seven days of amoxycillin in the treatment of acute otitis media in Aboriginal children (AATAAC): a double blind, randomised controlled trial. Med J Aust. 2010 Jan 4;192(1):24-9. PubMed
- 6. Andre-Alves MR, Jardim JR, Frare e Silva R, Fiss E, Freire DN, Teixeira PJ. Comparison between azithromycin and amoxicillin in the treatment of infectious exacerbation of chronic obstructive pulmonary disease. J Bras Pneumol. 2007 Jan-Feb;33(1):43-50. PubMed
Published: January 12, 2014
Last updated: January 23, 2018
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