Klacid Uno (Clarithromycin)

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

• Community‑acquired pneumonia: eradicates the responsible pathogens and improves respiratory symptoms.
• Acute bacterial sinusitis: reduces sinus inflammation and promotes recovery.
• Skin and soft‑tissue infections: eliminates causative bacteria and aids wound healing.
• Helicobacter pylori eradication (as part of combination therapy): contributes to ulcer healing and infection clearance.
• Pharyngitis: resolves bacterial throat infection and relieves pain.

• Clarithromycin inhibits bacterial protein synthesis by binding to the 50S subunit of the ribosome, blocking peptide chain elongation. This action prevents bacterial growth and replication, leading to a bacteriostatic effect that allows the immune system to clear the infection.

Clarithromycin may cause a range of adverse reactions, most of which are mild and reversible.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Diarrhea: loose stools, often transient.
• Abdominal pain: cramping or discomfort.
• Taste disturbance: metallic or altered taste perception.
• Headache: mild tension‑type headache.
• 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 with abdominal pain.
• Hematologic abnormalities: neutropenia or thrombocytopenia.
• Stevens‑Johnson syndrome: severe skin blistering.

Clarithromycin should be used with caution in certain clinical situations.

• Hepatic impairment: adjust therapy and monitor liver function.
• Renal impairment: consider dose adjustment in severe cases.
• Cardiac risk: avoid in patients with known QT prolongation or electrolyte disturbances.
• Drug‑induced photosensitivity: advise protection from excessive sunlight.
• Pregnancy and lactation: use only if clearly needed after risk‑benefit assessment.
• Store at ambient temperature: keep below 25 °C, in the original container, protected from moisture and light.

Clarithromycin interacts with several medicines that affect its metabolism or cardiac safety.

Major Interactions (Avoid)

• Cisapride: risk of serious cardiac arrhythmias.
• Pimozide: may cause QT prolongation and ventricular tachycardia.
• Ergot alkaloids: increased risk of ergotism.
• Certain statins (e.g., simvastatin, lovastatin): heightened risk of myopathy.

Moderate Interactions (Monitor Closely)

• Warfarin: may enhance anticoagulant effect, monitor INR.
• Theophylline: increased plasma levels, watch for toxicity.
• Carbamazepine: may reduce clarithromycin levels, assess efficacy.
• Digoxin: potential increase in serum concentration.
• Antacids containing aluminum or magnesium: may reduce absorption, separate dosing.