Klacid (Clarithromycin)

• Klacid is a macrolide antibiotic that targets bacterial infections in several organ systems.
• Respiratory tract infections: eradicates susceptible pathogens and improves clinical symptoms.
• Skin and soft tissue infections: reduces bacterial load and promotes healing.
• Helicobacter pylori infection: used in combination regimens to achieve eradication.

• Clarithromycin binds to the 50S subunit of bacterial ribosomes, inhibiting translocation of the peptidyl‑tRNA. This blocks protein synthesis, leading to a bacteriostatic effect against susceptible Gram‑positive, Gram‑negative and atypical organisms.

Common adverse reactions are reported with clarithromycin therapy.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Diarrhea: loose stools, sometimes watery.
• Abdominal pain: cramping or discomfort.
• Altered taste: metallic or bitter sensation.
• Headache: mild to moderate intensity.
• Vomiting: occasional episodes.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• QT interval prolongation: may predispose to cardiac arrhythmias.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Clostridioides difficile-associated diarrhea: severe colitis.
• Stevens‑Johnson syndrome/toxic epidermal necrolysis: life‑threatening skin reactions.
• Cardiac arrhythmias: including torsades de pointes.

• Before initiating Klacid, clinicians should consider several safety aspects.
• Assess liver function: monitor hepatic enzymes in patients with pre‑existing liver disease.
• Monitor cardiac QT interval: avoid in patients with known prolongation or concurrent QT‑prolonging drugs.
• Use with caution in renal impairment: dose adjustment may be required.
• Avoid in known macrolide allergy: discontinue if hypersensitivity occurs.
• Review concomitant medications: assess for interactions that affect clarithromycin metabolism.
• Store at room temperature: keep in the original packaging, protect from moisture and direct sunlight.

Clarithromycin interacts with several drug classes that can alter safety or efficacy.

Major Interactions (Avoid)

• Cisapride: risk of severe QT prolongation.
• Pimozide: can cause life‑threatening arrhythmias.
• Ergot alkaloids: may precipitate ergotism.
• Simvastatin/Lovastatin: increased risk of myopathy.
• Colchicine: heightened toxicity, especially in renal dysfunction.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: reduced efficacy, consider backup method.
• Carbamazepine: decreased clarithromycin levels.
• Phenytoin: may lower plasma concentrations.
• Rifampin: induces metabolism, reducing effectiveness.
• Digoxin: increased serum levels, monitor for toxicity.