CLARITHROMYCIN (Biaxin): What is used for?

What is Clarithromycin?

Clarithromycin is an active ingredient used for the treatment of pharyngitis, tonsillitis, sinusitis, chronic bronchitis, bacterial pneumonia, mild to moderate skin and soft tissue infection, folliculitis, cellulitis, erysipelas, localized or disseminated infection by M. avium or M. intracellulare, localized infection by M. chelonae, M. fortuitum and M. kansaii.
The product ingredient is Clarithromycin citrate.

The brand names of Clarithromyicin in United States are
Biaxin and Biaxin XL.

Clarithromycin Mechanism of Action (MOA)

It interferes with protein synthesis in sensitive bacteria by binding to the 50S ribosomal subunit.

Therapeutic indications, uses and benefits of Clarithromycin

Oral, in normal release and modified release forms:

Adults and children ≥12 years: pharyngitis, tonsillitis, sinusitis (diagnosed), acute bronchitis, acute exacerbation of chronic bronchitis, bacterial pneumonia (community-acquired), mild-moderate soft tissue and skin infection, folliculitis, cellulitis, erysipelas.

– Oral, in normal release forms:
Adults and children ≥12 years: localized or disseminated infection by M. avium or M. intracellulare, localized infection by M. chelonae, M. fortuitum and M. kansaii. Gastric or duodenal ulcer associated with H. pylori (along with appropriate antiulcer). Prevention of disseminated infection by M. avium complex in high-risk HIV patients (CD4 lymphocytes ≤ 50/mm 3 ).
Children > 12 months to 11 years: strep throat, bronchitis and bacterial pneumonia, acute otitis media, impetigo, folliculitis, cellulitis, abscesses.

– Intravenous (IV):
Adults: Parenteral treatment of pharyngitis or streptococcal tonsillitis if first-line treatment with beta-lactam is not possible or there is demonstrated sensitivity to S. pyogenes; diagnosed acute bacterial sinusitis; acute exacerbation of chronic bronchitis; infection of skin and soft, mild-moderate parts if beta-lactamics are not appropriate.

Clarithromycin Dosage

– Intravenous (IV).

Adults: 1 g/day divided into 2 equal doses, 60-minute IV perfusion, 2-5 days (may be extended depending on severity).

– Oral.

Adults and children ≥12 years: 250 mg/12 h; severe infection: 500 mg/12 h, 6-14 days.

Children 1-12 years: 7.5 mg/kg/12 h, 5-10 days; max. 500 mg/12 h. Infection with M. avium complex (associated with other antimicobacteria).
Adults and adolescents 12-18 years: 500 mg/12 h; children: 7.5 mg/kg/12 h until clinical benefit; prophylaxis: 500 mg/12 h.
Peptic ulcer associated with H. pylori, triple therapy: 500 mg/12 h + 1 g amoxicillin/12 h + 20 mg omeprazole/24 h, 10 days or 500 mg + 1 g amoxicillin + 20 mg omeprazole/12 h, 7 days; double therapy: 500 mg/8 h + 40 mg omeprazole/24 h, 2 weeks (in patients with poor therapeutic response, prolong treatment with 40 mg omeprazole up to 4 weeks.
Kidney failure, Clcr < 30 ml/min: ½ dose.

Modified-release tablets. Adults and children ≥ 12 years: 500 mg/24 h, with food, maximum 1 g/day, 6-14 days.

Method of administration of Clarithromycin

Oral use: The granulate must be reconstituted for administration.

Tablet: 250 mg/1., 500 mg/1.

Tablet, extended release: 500 mg/1., 1000 mg/1.

Granule, for suspension: 125 mg/5 mL., 250 mg/5mL.

Intravenous use: to be administered in a large proximal vein in the form of intravenous perfusion for 60 minutes, using a concentration of the solution of approximately 2 mg/ml. It should not be administered by bolus or intramuscular (IM) injection.

Contraindications of Clarithromycin

  • Hypersensitivity to macrolides.
  • Concomitance with: astemizole, cisapride, pimozide, terfenadine, disopyramide and quinidine for increasing the risk of QT interval prolongation and severe cardiac arrhythmias (ECG and monitoring serum level), ticagrelor or ranolazine, colchicine, ergotamine and dihydroergotamine from acute ergot toxicity of rye and with HMG-CoA reductase inhibitors (statins), which are extensively metabolized by CYP3A4 (lovastatin or simvastatin), due to the risk of rhabdomyolysis;
  • Hypokalemia.
  • Severe liver failure combined with renal failure.
  • Congenital or acquired prolongation of the QT interval.
  • Modified release tablets contraindicated with Clcr < 30 ml/minute.

Warnings and Cautions with Clarithromycin

  • Assess risk/benefit in pregnancy.
  • Elderly.
  • Moderate-severe renal failure.
  • Liver failure.
  • Stop treatment if signs or symptoms of liver disease appear (anorexia, jaundice, dark urine, itching, or abdominal tenderness).
  • Risk of: C. difficile pseudomembranous colitis, exacerbation of myasthenia gravis, superinfection by non-sensitive organisms in prolonged treatment, uveitis (monitor).
  • Caution in concomitant treatment with: triazolobenzodiacepines (triazolam and midazolam), ototoxic drugs such as aminoglycosides (monitoring vestibular and auditory function during and after treatment), drugs that prolong the QT interval, insulin and/or hypoglycaemic agents (risk of hypoglycaemia, glucose control), oral anticoagulants (risk of severe bleeding and elevated INR and prothrombin levels, monitor), CYP3A4 cytochrome inducers.
  • Caution in coronary artery disease, severe heart failure, atrioventricular conduction disturbances or clinically relevant bradycardia, hypomagnesemia.
  • Sensitivity test in: community-acquired pneumonia.
  • Stop treatment in case of hypersensitivity reactions (anaphylaxis, Steve-Johnson syndrome, toxic epidermal necrolysis).
  • Periodic control of: hearing ability in treatment of M. avium infection, leukocyte and platelet count.
  • Possible cross-resistance with other macrolides, lincomycin and clindamycin.
  • Increased risk of rhabdomyolosis in concomitant treatment with HMG-CoA reductase.

Liver failure

Caution with Clarithromycin. It is excreted mainly by liver. Do not administer in severe liver failure combined with renal failure.

Renal insufficiency

Caution with Clarithromycin in moderate-severe renal failure. Clcr < 30 ml/min: ½ dose.

Interactions with Clarithromycin

  • Inhibits isoenzyme CYP3A4 from cytochrome 450.
  • Caution, increases concentrations of: phenytoin, carbamazepine, valproate, cyclosporine, tacrolimus, sirolimus, vinblastine, alprazolam, fluconazole, itraconazole (monitor for symptoms of increased or prolonged effect), ketoconazole, theophylline, methylprednisolone, cilostazol, digoxin (monitor your serum level by increasing exposure with severe arrhythmias), sildenafil, tadalafil, vardenafil (consider reducing doses of phosphodiesterase inhibitors), tolterodine (in poor metabolizers of CYP2D6), saquinavir.
  • Decreased plasma levels (increase those of the active metabolite, with different spectrum) by: efavirenz, nevirapine, rifampicin, rifabutin, rifapentine.
  • Decreases oral absorption of: zidovudine (space administration).
  • Reduce dose with: ritonavir, atazanavir; maximum dose 1,000 mg clarithromycin/day; Clcr 30-60 ml/min reduce clarithromycin to 50%, Clcr < 30 ml/min reduce to 75%.
  • Mutual elevation of serum levels with: omeprazole.
  • Risk of hypotension with: calcium channel blockers metabolized by CYP3A4 (verapamil, amlodipine, diltiazem).
  • Exposure decreased by: etravirine (consider therapeutic alternatives to Mycobacterium avium complex).

Pregnancy and Clarithromycin

Value risk/benefit. Safety not established. The possibility of adverse effects on embryofetal development cannot be excluded.


The safety of clarithromycin during lactation has not been established.
Clarithromycin is excreted in breast milk and should not be used during lactation.

Effects on driving ability

No data are available on effects on ability to drive or use machines taking Clarithromycin.
When performing these activities, consideration should be given to the possible occurrence of adverse effects such as dizziness, vertigo, confusion and disorientation.

Adverse reactions and side effects of Clarithromycin

Headache, perversion of taste, dysgeusia; insomnia.

Hearing loss (reversible with interruption of treatment), tinnitus.

Dyspepsia, nausea, abdominal pain.

Changes in PFH mild skin rashes, hyperhydrolysis.

Intravenous (IV): vasodilation, phlebitis, pain and inflammation at the injection site.

In addition: arrhythmia, myocardial infarction and cardiovascular mortality.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID:84029
NCI Thesaurus: C1054

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