Klacid Uno (Clarithromycin)

Clarithromycin is a macrolide antibiotic that targets a range of bacterial infections in the respiratory, sinus and skin compartments.

• Community‑acquired pneumonia: effective in treating adult patients with typical bacterial pathogens.
• Acute bacterial sinusitis: reduces symptoms and bacterial load in sinus infections.
• Skin and soft‑tissue infections: combats Staphylococcus and Streptococcus species causing cellulitis and abscesses.
• Helicobacter pylori eradication (in combination therapy): contributes to bacterial clearance when used with other agents.

• Clarithromycin binds to the 50S subunit of bacterial ribosomes, blocking the translocation step of protein synthesis. This inhibition prevents peptide chain elongation, halting bacterial growth and leading to a bacteriostatic effect against susceptible organisms.

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: frequent loose stools.
• Abdominal pain: cramping or discomfort.
• Taste disturbance: altered or metallic taste.
• Headache: mild tension‑type headache.
• Vomiting: occasional episodes.

Serious or Rare Side Effects

• Severe allergic reactions: rash, angioedema, anaphylaxis.
• Clostridioides difficile‑associated diarrhea: potentially life‑threatening colitis.
• QT interval prolongation: risk of cardiac arrhythmias.
• Hepatotoxicity: elevated liver enzymes or jaundice.
• Cardiac arrhythmias: especially in patients with pre‑existing heart disease.
• Anaphylaxis: rapid onset of systemic hypersensitivity.

Before prescribing clarithromycin, clinicians should consider several safety aspects.

• Assess renal function: adjust therapy in severe impairment.
• Monitor liver enzymes: watch for signs of hepatotoxicity.
• Avoid use in patients with known macrolide hypersensitivity: risk of severe allergic reaction.
• Consider ECG monitoring in patients with cardiac risk factors: potential QT prolongation.
• Use with caution during pregnancy: limited data on fetal safety.
• Store at ambient temperature: keep in the original pack, protect from moisture and light.

Clarithromycin interacts with several medicines; awareness of the interaction level guides clinical decisions.

Major Interactions (Avoid)

• Cisapride: increased risk of serious cardiac arrhythmias.
• Ergot alkaloids: risk of ergotism and severe vasospasm.
• Theophylline: elevated plasma concentrations leading to toxicity.
• Pimozide: heightened plasma levels causing extrapyramidal effects.

Moderate Interactions (Monitor Closely)

• Statins (simvastatin, lovastatin): increased risk of myopathy.
• Warfarin: enhanced anticoagulant effect, requiring INR monitoring.
• Carbamazepine: reduced clarithromycin exposure, potentially decreasing efficacy.