Klarix 500 mg Tablet

Macrolide antibiotic for:

• Chest infections: bronchitis, community-acquired pneumonia (including atypical)
• Sinusitis, sore throat, tonsillitis, ear infections
• Skin and soft-tissue infections
• H. pylori eradication (with a PPI and amoxicillin or metronidazole)
• Mycobacterium avium complex (MAC) infections
• Alternative for people allergic to penicillin

Adults: 250–500 mg twice daily for 7–14 days.

• Modified-release: 500–1,000 mg once daily with food.
• H. pylori: 500 mg twice daily with PPI + amoxicillin 1 g twice daily (or metronidazole) for 7–14 days.

Children (suspension 125 mg/5 ml or 250 mg/5 ml): 7.5 mg/kg twice daily (max 500 mg per dose) for 5–10 days.

• Guide: 8–11 kg 62.5 mg; 12–19 kg 125 mg; 20–29 kg 187.5 mg; 30–40 kg 250 mg — twice daily.

Kidney impairment (CrCl < 30): halve the dose.

• Allergy to macrolides
• History of QT prolongation or ventricular arrhythmia; low potassium
• Use with: astemizole, cisapride, pimozide, terfenadine, ergotamine, simvastatin, lovastatin, oral midazolam, colchicine (in kidney/liver impairment), ticagrelor, ranolazine, lomitapide
• Severe liver failure with kidney impairment

Common: taste disturbance (metallic/bitter), nausea, diarrhoea, stomach pain, indigestion, headache, insomnia, rash.

Less common: vomiting, thrush, raised liver enzymes, dizziness, anxiety.

Rare but serious: QT prolongation and irregular heartbeat, liver injury, severe skin reactions, C. difficile colitis, hearing loss (reversible), hallucinations, low blood sugar with diabetes drugs.

• Heart rhythm problems, coronary disease, elderly: caution; avoid with other QT drugs.
• Myasthenia gravis may worsen.
• Liver or kidney impairment: dose adjustment.
• Long-term use in coronary heart disease: possible increased cardiovascular risk.

Avoid in pregnancy, especially the first trimester, unless no alternative (azithromycin or erythromycin often preferred). Passes into milk — use only if needed.

Strong CYP3A4 inhibitor — many interactions:

• Contraindicated drugs listed above
• Atorvastatin (limit dose), warfarin (bleeding), digoxin (toxicity), calcium-channel blockers (low BP), ciclosporin, tacrolimus, carbamazepine, theophylline (raised levels)
• Sulphonylureas, insulin (low sugar)
• Rifampicin, efavirenz (reduce clarithromycin)
• Other QT-prolonging drugs

Nausea, vomiting, diarrhoea, abdominal pain; QT prolongation. Supportive care with ECG monitoring.

Store below 30°C. Reconstituted suspension: room temperature (do not refrigerate), use within 14 days.