Veterinary: none


Human: Biaxin

Human Availability:

  • Tablets: 250 mg, 500 mg
  • Suspension: 25 mg/mL, 50 mg/mL, 125 mg/5mL, 250 mg/5mL


Clarithromycin is a semi-synthetic macrolide antibiotic chemically related to erythromycin. It is bacteriostatic or bactericidal depending on the concentration given. Clarithromycin binds to the 50S subunit of bacterial ribosomes thereby blocking protein synthesis. It is active against both aerobic and anaerobic Gram-positive and Gram-negative microorganisms, as well as Mycoplasma pneumoniae and Mycobacterium avium.

Clarithromycin is absorbed rapidly from the gastrointestinal tract and distributed into body tissue and fluids. The drug is known to cross the placental barrier. Some studies have indicated that it is teratogenic at high doses, in rats, and therefore should be avoided in the pregnant doe.

The drug is principally excreted via the liver and kidneys; hence caution should be used in hepatic and renal impairment. The drug is also excreted in breast milk, but not noted to be clinically significant.


Used for respiratory infections as well as uncomplicated skin and skin structure infections.

Drug Interactions or Contraindications

  • Do not give with cisapride, pimozide, astemizole or terfendadine, as clarithromycin may inhibit the metabolizing of those drugs.
  • Clarithromycin may increase serum plasma levels of the following:
    • Cyclosporine
    • Digoxin
    • Disopyramide
    • Ranitidine bismuth citrate
    • Theophylline
  • Clarithromycin may also increase serum plasma levels of benzodiazepines and prolong CNS (central nervous system) effects if given together.

Adverse Reactions

CNS: loss of balance, behavioral changes

GI: Abdominal pain, diarrhea, poor appetite

Skin: itching

Dosage Recommendations

1.5 mg/lb to 5 mg/lb , PO, BID  3, 12.
Consider prolonging dose intervals in severe renal impairment.


3.5 mg/kg to 10 mg/kg, PO, q8hr to q12hr  42.


  • Because of its rapid absorption into tissue, there is less GI distress than with erythromycin.
  • May be given with or without food.
  • Also, in treating suspected polymicrobial infections, where a broader coverage may be needed, synergistic or combination drugs may be used. The following drugs may be seen used simultaneously with clarithromycin: aminopenicillins (e.g., amoxicillin), or enrofloxacin, or metronidazole. 42.
  • Store at room temperature in a tightly closed container, away from light.
  • Do not refrigerate reconstituted suspension.


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