Clarithromycin (Biaxin)

  • Generic name: Clarithromycin
  • Brand names: Biaxin, Klaricid, Klacid (Abbott Laboratories);
    Biaxin XL, Biaxin XL-Pak
  • Therapeutic class: Macrolide Antibiotic

What is Clarithromycin used for?

  • Acute maxillary sinusitis, acute otitis media.
  • Acute bacterial exacerbation of chronic bronchitis, pneumonia, Legionellosis
  • Lyme disease
  • Uncomplicated skin infections
  • Helicobacter pylori infection and peptic ulcers in dual or triple combination regimens.

What is Clarithromycin ER?

Clarithromycin extended-release (ER) is the generic equivalent of Biaxin® XL Filmtabs, which is marketed by Abbott Laboratories. In comparison to the regular clarithromycin, the extended-release formulation has slower and more prolonged absorption from the gastrointestinal tract, allowing for once-daily dosing and less gastrointestinal side effects.

Clarithromycin ER may provide a higher cure rate and lower costs than regular clarithromycin in the treatment of lower respiratory tract infections2.


  • Known hypersensitivity to clarithromycin or any macrolide.
  • Concurrent use with ergot derivatives, pimozide, cisapride, astemizole, terfenadine.
  • Concurrent use with colchicine in patients with renal or hepatic impairment.
  • History of cholestatic jaundice or hepatic dysfunction with prior clarithromycin use.
  • QT prolongation: Clarithromycin should not be used by patients with history of QT prolongation or ventricular cardiac arrhythmia, including torsades de pointes3. Clarithromycin has been associated with prolongation of the QT interval and infrequent cases of arrhythmia.
  • Concomitant use with HMG-CoA reductase inhibitors (statins) that are extensively metabolized by CYP3A4, due to the increased risk of myopathy, including rhabdomyolysis.
  • Note: Clarithromycin is NOT a sulfa drug. It lacks the sulfanilamide molecular structure which is responsible for sulfa alergy. You can take clarithromycin if you are allergic to sulfa drugs.

Clarithromycin drug interactions

  • Drugs that prolong the QT interval (e.g. antiarrhythmic agents, disopyramide, quinidine, tetrabenazine, thioridazine) - increased risk of QT interval prolongation and serious cardiac arrhythmias.
  • Drugs primarily metabolized by CYP3A4 (e.g. alfuzosin, benzodiazepines, carbamazepine, cilostazol, conivaptan, dronedarone, eplerenone, eszopiclone, lovastatin, simvastatin, lurasidone, methylprednisolone, sildenafil (Viagra), esomeprazole, lansoprazole, quinidine, romidepsin, salmeterol, tamsulosin) - plasma concentrations of these agents may be elevated, increasing the risk of adverse effects or toxicity.
  • HMG-CoA reductase inhibitors (statins) that are extensively metabolized by CYP3A4 (lovastatin, simvastatin)3.


  • 1. Clarithromycin prescribing information. PDR. 59th Edition. Montvale, NJ: Thomson PDR, 2005, p. 408.
  • 2. Halpern MT, Cifaldi MA, Schmier JK. Costs and outcomes of extended-release vs. immediate-release clarithromycin for lower respiratory tract infections. COPD. 2005 Jun;2(2):217-23.
  • 3. Safety Labeling Changes Approved By FDA Center for Drug Evaluation and Research. Biaxin Filmtab (clarithromycin tablets, USP), Biaxin XL Filmtab (clarithromycin extended-release tablets), Biaxin Granules (clarithromycin for oral suspension, USP). FDA
  • 4. Gerald G. Briggs, Roger K. Freeman, Sumner J. Yaffe Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. 8th Ed, Lippincott Williams & Wilkins, 2008. p. 298

Last updated: February, 2015

Advanced Consumer Info

Clarithromycin 500 mg
  • Pregnancy category: C
  • Breastfeeding: generally safe 4.
  • Mechanism of action: Clarithromycin is a bacteriostatic antibiotic. It binds to ribosomal receptor sites of susceptible organisms, inhibiting protein synthesis of bacterial cell wall.
  • Elimination half-life: 5 - 7 hours.
  • Advantages:
    Clarithromycin is the most effective antibiotic against Helicobacter pylori.
  • Disadvantages:
    Clarithromycin may cause metallic taste.