Klacid Od (Clarithromycin)

Clarithromycin is used to treat infections caused by susceptible bacteria across several organ systems.

• Community‑acquired pneumonia: eradicates the causative bacterial pathogens and resolves pulmonary infection.
• Acute bacterial sinusitis: reduces sinus inflammation by eliminating the infecting organisms.
• Skin and soft‑tissue infections: clears susceptible Staphylococcus and Streptococcus species from affected tissues.
• Helicobacter pylori eradication (in combination therapy): contributes to bacterial eradication as part of a multi‑drug regimen for ulcer disease.

• Clarithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking translocation of the peptidyl‑tRNA. This action prevents elongation of the nascent peptide chain, leading to bacteriostatic activity against susceptible Gram‑positive, Gram‑negative, and atypical organisms.

Clarithromycin may cause a range of adverse reactions, from mild to severe.

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Diarrhea: frequent loose stools, sometimes watery.
• Abdominal pain: cramping or discomfort in the stomach area.
• Taste disturbance: altered or metallic taste perception.
• Headache: mild to moderate head pain.
• Vomiting: occasional expulsion of stomach contents.

Serious or Rare Side Effects

• Severe allergic reactions (anaphylaxis): rapid onset of hives, swelling, or breathing difficulty.
• QT interval prolongation: potential for cardiac arrhythmias.
• Hepatic dysfunction: elevated liver enzymes or jaundice.
• Clostridioides difficile‑associated diarrhea: severe colitis after antibiotic use.
• Stevens‑Johnson syndrome: serious skin and mucous membrane disorder.
• Cardiac arrhythmias: irregular heart rhythms beyond QT prolongation.

Before initiating clarithromycin therapy, consider the following safety measures.

• Assess renal function: adjust therapy if significant impairment exists.
• Monitor liver enzymes: watch for signs of hepatotoxicity during treatment.
• Avoid in known macrolide allergy: risk of hypersensitivity reactions.
• Use caution with QT‑prolonging drugs: increased risk of cardiac arrhythmia.
• Pregnancy and breastfeeding: discuss potential risks with the prescriber.
• Store at room temperature: keep in the original container, protect from moisture.

Clarithromycin can interact with several medicines; awareness helps prevent adverse outcomes.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may raise clarithromycin plasma levels.
• Statins such as simvastatin or lovastatin: increased risk of rhabdomyolysis.
• Other QT‑prolonging agents (e.g., quinidine, amiodarone): heightened arrhythmia risk.

Moderate Interactions (Monitor Closely)

• Warfarin: may potentiate anticoagulant effect, requiring INR monitoring.
• Carbamazepine: may reduce clarithromycin concentrations, diminishing efficacy.
• Theophylline: may increase theophylline levels, leading to toxicity.