Clarithromycin is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, H. pylori infection, and Lyme disease, among others. Clarithromycin can be taken by mouth as a pill or liquid.

Molecular Structure


Class of Drug

Antibiotic, macrolide.

Mechanism of Action

Inhibits RNA-dependent protein synthesis at the level of the 50S ribosome.

Susceptible organisms in vivo: Similar to erythromycin but more effective against gram negative organisms and more active against Hemophilus influenzae. Also used for Mycobacterium aviumintrace llulare and Helicobacter pylori.

Indications / Dosage / Route

Routes of Administration: Oral only.

Condition: Pharyngitis/tonsillitis

Dose: Adults: 250 mg ql2h, 10 days

Condition: Acute maxillary sinusitis

Dose: Adults: 500 mg ql2h, 14 days.

Condition: Acute exacerbation of chronic bronchitis (Streptococcus pneu¬moniae, Moraxella catarrhalis), pneumonia (S. pneumoniae. Mycoplasma pneumoniae)

Dose: Adults: 250 mg ql2h, 7-14 days.

Condition: Acute exacerbation of chronic bronchitis (H. influenzae)

Dose: Adults 500 mg ql2h, 7-14 days.

Condition: Uncomplicated skin and skin structure infections

Dose: Adults 250 mg ql2h.

Condition: All infections

DoseChildren 7.5 mg/kg ql2h.

Adjustment of Dosage

Kidney disease: None.

Liver disease: None.

Elderly: None

Pediatric: Safety and efficacy have not been established for children <6 months.

Food and Drug Interactions

Food: Taken without regard to food.

Pregnancy: Should not be used except if no alternative is available.

Lactation: No data available. May appear in breast milk. Best to avoid.

Contraindications: Hypersensitivity to macrolide antibiotics, concomitant administration of pimozide.

Warnings / Precautions

> Use with caution in patients with liver or kidney dysfunction.

Clinically Important Drug Interactions

> Drugs that decrease effects/toxicity of macrolides: rifampin, aluminum, magnesium containing antacids.

> Macrolides increase effects/toxicity of following drugs: oral anticoagulants, astemizole, benzodiazepines, bromocriptine, buspirone, carbamazepine, cisapride, cyclosporine, digoxin, ergot alkaloids, felodipine, grepafloxacin, statins, pimozide, sparfloxacin, tacrolimus.

Adverse Reactions

> Common: diarrhea, nausea, abdominal pain.

> Serious: pseudomembranous colitis, ventricular arrhythmias, nephritis, cholestatic jaundice, angioedema.

Parameters to Monitor

> Signs and symptoms of superinfection, in particular pseudomem¬branous colitis.

> Signs and symptoms of renal toxicity.

> Signs and symptoms of hearing impairment. Patients with kidney or liver disease are at highest risk.

Further Useful Info

> In general, clarithromycin has no major clinical advantages over azithromycin except in the treatment of pneumonia because of better S. pneumoniae activity.

> Like azithromycin, clarithromycin is used in M aviumintrace llulare infections in AIDS patients. It is also a component of many treatment regimens lor II. pylori.

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