Klacid Sr (Clarithromycin)

Clarithromycin is employed to treat bacterial infections affecting several organ systems.

• Community‑acquired pneumonia: effective in treating bacterial pneumonia caused by susceptible organisms.
• Acute bacterial sinusitis: reduces sinus inflammation and clears infection.
• Skin and soft‑tissue infections: combats susceptible Staphylococcus and Streptococcus species.
• Helicobacter pylori eradication regimens: used in combination therapy to eliminate H. pylori infection.

• Clarithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking peptide chain elongation. This action prevents bacterial growth and replication, leading to a bacteriostatic effect against susceptible Gram‑positive and some Gram‑negative organisms.

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

Common Side Effects

• Nausea: occasional upset stomach.
• Diarrhea: loose stools, often self‑limiting.
• Abdominal pain: mild cramping.
• Altered taste: metallic or bitter sensation.
• Headache: transient.
• Rash: mild skin irritation.

Serious or Rare Side Effects

• Severe allergic reactions: anaphylaxis or angioedema.
• Clostridioides difficile‑associated diarrhea: persistent watery stools.
• Elevated liver enzymes: signs of hepatic stress.
• QT interval prolongation: potential cardiac arrhythmias.
• Hepatotoxicity: rare liver injury.
• Stevens‑Johnson syndrome: severe skin reaction.

Before prescribing Clarithromycin, consider the following safety measures.

• Pregnancy: Category B – use only when the benefit outweighs potential risk.
• Renal impairment: dose adjustment may be required in patients with reduced kidney function.
• Hepatic impairment: monitor liver function tests during therapy.
• Drug interactions: avoid concomitant use with strong CYP3A4 inhibitors that can raise clarithromycin levels.
• QT prolongation risk: monitor ECG in patients with existing cardiac disease or electrolyte disturbances.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture.

Clarithromycin interacts with several medicines; clinicians should assess risk before co‑administration.

Major Interactions (Avoid)

• Erythromycin, ketoconazole, ritonavir: may markedly increase clarithromycin plasma concentrations.
• Cisapride: combined use can cause serious cardiac arrhythmias.
• Pimozide: risk of QT prolongation and arrhythmia.

Moderate Interactions (Monitor Closely)

• Warfarin: clarithromycin may enhance anticoagulant effect, requiring INR monitoring.
• Theophylline: increased serum levels may precipitate toxicity.
• Simvastatin, lovastatin: higher risk of myopathy; consider dose reduction or alternative statin.