Amoxicillin (Amoxil®) versus Clarithromycin (Biaxin®)
Based on "Antibiotic and Chemotherapy"
written by Roger G. Finch
Amoxicillin advantages over Clarithromycin
- Low potential for drug interactions.
- Amoxicillin treatment course costs less than clarithromycin.
Clarithromycin advantages over Amoxicillin
- Clarithromycin has a broader antimicrobial spectrum than amoxicillin.
- More convenient twice-daily dosing schedule.
- Safe for use in penicillin-allergic patients.
Difference between Amoxicillin and Clarithromycin
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Table 1. Comparison of Amoxicillin and Clarithromycin
| Amoxicillin | Clarithromycin |
| Brand names | |
| Amoxil® | Biaxin® |
| Drug class | |
| Penicillin antibiotic | Macrolide antibiotic |
| Dose formulations | |
| • Capsules • Suspension • Tablets • Tablets, chewable • Tablets, extended release |
• Tablets • Tablets, extended release • Suspension |
| Antimicrobial spectrum | |
| Gram-positive bacteria • Enterococcus faecalis • Staphylococcus spp. • Streptococcus pneumoniae • Alpha and beta-hemolytic streptococci. Gram-negative bacteria • Escherichia coli • Haemophilus influenzae • Neisseria gonorrhoeae • Proteus mirabilis • Helicobacter pylori • Amoxicillin is not active against beta-lactamase producing bacteria. |
Gram-positive bacteria • Staphylococcus aureus • Streptococcus pneumoniae • Streptococcus pyogenes Gram-negative bacteria • Haemophilus influenzae • Haemophilus parainfluenzae • Moraxella catarrhalis Other bacteria • Mycoplasma pneumoniae • Chlamydia pneumoniae • Mycobacterium avium complex (MAC) • Beta-lactamase production does not affect clarithromycin activity. |
| FDA-approved indications | |
| • Otitis media • Sinusitis • Streptococcal pharyngitis • Skin and skin structure infections • Pneumonia • In combination for treatment of H. pylori infection and duodenal ulcer disease. |
• Acute bacterial exacerbation of chronic bronchitis • Otitis media • Streptococcal pharyngitis • Community-acquired pneumonia • Sinusitis • Skin and skin structure infections |
| "Off-label" uses | |
| • Anthrax, inhalational post-exposure prophylaxis • Erysipeloid • Infective endocarditis (prophylaxis) • Lyme neuroborreliosis • Chlamydia infection in pregnant women |
• Infective endocarditis (prophylaxis) • Lyme disease • Pertussis |
| Mechanism of action | |
| • Bactericidal • Inhibits the synthesis of bacterial cell walls by binding to penicillin-binding proteins. |
• Bacteriostatic • Inhibits bacterial protein synthesis via binding to 50S ribosomal subunit. |
| Half-life | |
| • Immediate-release: 61.3 minutes • Extended-release: 90 minutes |
• Clarithromycin: 3-7 hours • 14-OH-clarithromycin metabolite: 5-9 hours |
| Oral bioavailability | |
| • 74-92% | • 50% |
| Metabolism, Elimination | |
| • Amoxicillin is eliminated in urine (60% as unchanged drug). |
• Clarithromycin undergoes hepatic metabolism via CYP3A4. The drug is converted to 14-OH clarithromycin, an active metabolite. • Clarithromycin is eliminated primarily via kidneys in urine (20-40% as unchanged drug; 10-15% as metabolite) and feces (29% to 40% mostly as metabolites). |
| Contraindications | |
| • Hypersensitivity to penicillins, cephalosporins |
• Hypersensitivity to macrolides • Coadministration with pimozide, cisapride, ergotamine, and dihydroergotamine • History of hepatic dysfunction associated with previous use of clarithromycin • Coadministration with colchicine in patients with renal or hepatic impairment |
| Side effects | |
| • Diarrhea • Nausea • Vomiting • Rash • Stomach pain • Serious allergic reactions (anaphylaxis, serum sickness-like reaction) |
• Abnormal taste • Diarrhea • Nausea • Vomiting • Abdominal pain • Dyspepsia • Heartburn |
| Drug interactions | |
| • Low risk for drug interactions | • Significant drug interactions potential |
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Head-to-head comparative studies
Sinusitis
Clarithromycin and amoxicillin appear to have comparable effectiveness in the treatment of sinusitis1.
| Results of comparison of clarithromycin and amoxicillin in the treatment of acute maxillary sinusitis1. | Amoxicillin | Clarithromycin |
|---|---|---|
| Regimen | 500 mg 3 times daily for 7 to 14 days | 500 mg 2 times daily for 7 to 14 days |
| Clinical success rate (based on direct observation of the patient) | 89% | 91% |
| Roentgenographic success rate | 92% | 78% |
| Dropout rates | 4% | 3% |
| Adverse effects | mild gastrointestinal side effects | |
Pneumonia
Amoxicillin and clarithromycin are equally effective in the treatment of community-acquired pneumonia in children.
In a randomized clinical trial3 the mean hospital stay in patients treated with amoxicillin was 3.3 days and with clarithromycin was 3.2 days. About 97% patients in both treatment groups achieved symptoms improvement.
Otitis media
Clarithromycin and amoxicillin are similarly effective in the treatment of acute ear infection (otitis media).
| Results of single blind, randomized, multicenter clinical trial2 comparing the safety and efficacy of clarithromycin and amoxicillin | Amoxicillin suspension | Clarithromycin suspension |
|---|---|---|
| Clinical success (cure and symptoms improvement) rates at 0 to 4 days posttreatment | 90% | 93% |
Erythema migrans (the rash characteristic of Lyme disease)
Clarithromycin works a little better than amoxicillin in the treatment of children with solitary erythema migrans.
| Results of comparative study4 of children with solitary erythema migrans | Amoxicillin | Clarithromycin |
|---|---|---|
| Average duration of erythema migrans after starting the antibiotic | 4 days | |
| Duration of Lyme borreliosis symptoms | 10 day | 7 days |
| Minor manifestations of Lyme borreliosis | 16 of 54 patients (29.6%) |
11 of 50 patients (22.0%) |
| Major manifestations of Lyme borreliosis | 2 patients (3.7%) |
Not detected |
| Side effects | 28.1% | 24.2% |
Further reading
References
- 1. Calhoun KH, Hokanson JA. Multicenter comparison of clarithromycin and amoxicillin in the treatment of acute maxillary sinusitis. Arch Fam Med. 1993 Aug;2(8):837-40. PubMed
- 2. Pukander JS, Jero JP, Kaprio EA, Sorri MJ. Clarithromycin vs. amoxicillin suspensions in the treatment of pediatric patients with acute otitis media. Pediatr Infect Dis J. 1993 Dec;12(12 Suppl 3):S118-21. PubMed
- 3. Aurangzeb B, Hameed A. Comparative efficacy of amoxicillin, cefuroxime and clarithromycin in the treatment of community-acquired pneumonia in children. J Coll Physicians Surg Pak. 2003 Dec;13(12):704-7. PubMed
- 4. Nizic T, Velikanje E, Ruzic-Sabljic E, Arnez M. Solitary erythema migrans in children: comparison of treatment with clarithromycin and amoxicillin. Wien Klin Wochenschr. 2012 Jul
Published: October 25, 2017
Last updated: October 25, 2017
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