Klacid (Clarithromycin)

Klacid, a macrolide antibiotic, is employed to treat bacterial infections affecting the respiratory tract, sinuses, skin and gastrointestinal system.

• Community‑acquired pneumonia: eliminates the responsible pathogens and facilitates recovery of lung function.
• Acute bacterial sinusitis: reduces sinus inflammation by eradicating the infecting bacteria.
• Skin and soft‑tissue infections: clears bacterial involvement in cellulitis, abscesses and wound infections.
• Helicobacter pylori eradication (in combination therapy): contributes to bacterial clearance as part of a multi‑drug regimen for ulcer disease.

• Clarithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking peptide chain elongation. This action halts bacterial growth (bacteriostatic) and, at higher concentrations, can be bactericidal, leading to the elimination of susceptible microorganisms.

Adverse reactions may occur with clarithromycin therapy and are categorized by frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Diarrhea: loose stools, sometimes watery.
• Abdominal pain: cramping or discomfort.
• Taste disturbance: altered or metallic taste.
• Headache: mild, transient.
• Rash: mild skin erythema.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or jaundice.
• QT prolongation: cardiac rhythm disturbances.
• Severe allergic reactions: anaphylaxis, angioedema.
• Clostridioides difficile colitis: severe diarrhea due to bacterial overgrowth.

Before initiating clarithromycin, consider the following safety measures.

• Assess liver function: avoid use in patients with severe hepatic impairment.
• Review cardiac history: caution in individuals with known QT prolongation or arrhythmias.
• Evaluate drug interactions: check for concomitant use of CYP3A4 substrates.
• Monitor renal function: adjust therapy in severe renal impairment if needed.
• Pregnancy and breastfeeding: use only if the potential benefit outweighs risk.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture.

Clarithromycin can affect the metabolism of several co‑administered medicines.

Major Interactions (Avoid)

• Simvastatin: risk of severe myopathy; avoid concurrent use.
• Pimozide: may cause cardiac toxicity; contraindicated.
• Cisapride: can precipitate QT prolongation; avoid.

Moderate Interactions (Monitor Closely)

• Warfarin: may increase INR; monitor coagulation parameters.
• Carbamazepine: clarithromycin can raise carbamazepine levels; observe for toxicity.
• Theophylline: possible increased serum concentrations; adjust dose if needed.