Klaricid (Clarithromycin)

Clarithromycin is a macrolide antibiotic used to treat infections caused by susceptible bacteria.

• Community‑acquired pneumonia: effective against typical and atypical pathogens, improving respiratory function.
• Skin and soft‑tissue infections: eradicates susceptible Gram‑positive and some Gram‑negative organisms.
• Upper respiratory tract infections: reduces bacterial load and alleviates symptoms.

• Clarithromycin binds to the 50S ribosomal subunit of susceptible bacteria, blocking the translocation step of protein synthesis. This inhibition prevents peptide chain elongation, halting bacterial growth and leading to a bacteriostatic effect against a broad spectrum of Gram‑positive, Gram‑negative, and atypical organisms.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Diarrhea: loose stools, often transient.
• Abdominal pain: cramping or discomfort.
• Taste disturbance: altered or metallic taste.
• Headache: mild to moderate intensity.
• Vomiting: occasional episodes.

Serious or Rare Side Effects

• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• QT prolongation: risk of cardiac arrhythmias.
• Severe allergic reactions: rash, angioedema, anaphylaxis.
• Clostridioides difficile‑associated diarrhea: severe colitis.
• Arrhythmias: ventricular tachycardia or fibrillation.
• Stevens‑Johnson syndrome/toxic epidermal necrolysis: severe skin reactions.

Clarithromycin should be used with caution in specific clinical situations.

• Renal impairment: monitor renal function and adjust therapy as needed.
• Hepatic dysfunction: assess liver enzymes before and during treatment.
• Cardiac risk: avoid in patients with known QT prolongation or electrolyte disturbances.
• Drug interactions: review concomitant medications for potential CYP3A4 effects.
• Pregnancy and lactation: evaluate risk‑benefit ratio before prescribing.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze.

Clarithromycin interacts with several drugs; careful assessment is required.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): may increase clarithromycin levels.
• QT‑prolonging agents (e.g., quinidine, sotalol): additive risk of arrhythmia.
• Ergot alkaloids (e.g., ergotamine): risk of ergotism.

Moderate Interactions (Monitor Closely)

• Warfarin: may increase INR and bleeding risk.
• Theophylline: may raise plasma concentrations, causing toxicity.
• Statins (especially simvastatin): increased risk of myopathy.