Clarithromycin

Macrolide·Infectious Diseases - Macrolides

Atypical CAP, H. pylori eradication, severe MAC complex in HIV

Authority requiredPBSMACROLIDEKlacid, Clarac250 mg tablet+2

Max Dose

1000 mg/day

Half-life

5-7 h

CYP Inhibitor

CRITICAL

Metallic Taste

COMMON

Rapid Summary

Overview

Highly potent macrolide. Exceptional coverage for atypical pneumonias and H. pylori. However, it is one of the most dangerous inhibitors of liver enzymes in modern medicine.

Maximum Dose

Max 1000 mg/day (e.g., 500 mg BD).

Clinical Focus

Completely shuts down CYP3A4. Co-administration with Statins, DOACs, or Colchicine causes fatal multi-organ toxicity.

Bottom Line

Clarithromycin is a macrolide for respiratory infections and H. pylori eradication, but is a potent CYP3A4 inhibitor with significant drug interactions and QTc prolongation risk.

Formulation & Access

Brand Names

Klacid, Clarac

Oral Routes

Tablets (250 mg, 500 mg). Oral liquid.

Prescribing & PBS

Authority Required (PBS) for specific indications.

Indications & Use

Primary

PBSTGA

Atypical CAP, H. pylori eradication, severe MAC complex in HIV.

Clinical Place

Preferred over erythromycin due to BD dosing and better GI tolerance. Highly effective but dangerous due to interactions.

Quick reference

Class & Role

Macrolide — Highly potent macrolide.

Route / Formulation

Tablets (250 mg, 500 mg). Oral liquid. (Klacid, Clarac)

Usual Dose & Max

PO 250-500 mg BD for 5-7 days. Max 1000 mg/day (e.g., 500 mg BD).

Key Indication Doses

Community Acquired Pneumonia: PO 250-500 mg BD for 5-7 days. H. Pylori Eradication: PO 500 mg BD (with Amoxicillin and a PPI). MAC (Mycobacterium avium): PO 500 mg BD (Long term, specialist only). Renal Impairment: Halve the dose if eGFR < 30.

Best Uses

Clarithromycin is a macrolide for respiratory infections and H. pylori eradication, but is a potent CYP3A4 inhibitor with significant drug interactions and QTc prolongation risk.

Avoid / Cautions

Concurrent use of Colchicine, Statins (Simvastatin/Atorvastatin), Ticagrelor, or Ergotamines. Baseline QTc > 500 ms. Pregnancy Category B3 (Azithromycin is preferred).

Key Risks

Cardiovascular: QTc prolongation, risk of Torsades de Pointes and sudden cardiac death (especially in the elderly). Gastrointestinal: Severe bitter/metallic taste in the mouth (dysgeusia), nausea, diarrhea. Hepatic: Hepatotoxicity, jaundice.

Key Interactions

Absolute blockade of CYP3A4 and P-glycoprotein. Causes Atorvastatin to trigger rhabdomyolysis, Colchicine to cause fatal bone marrow failure, and Apixaban/Rivaroxaban to cause major bleeding. You MUST withhold these drugs while the patient is on Clarithromycin. Synergistic QTc prolongation with Amiodarone, Haloperidol, Sotalol.

Monitoring

Review the patient's entire medication list through a drug-interaction checker before prescribing. Baseline ECG for high-risk patients.

Clinical Pearl

If a patient on 80mg Atorvastatin gets pneumonia and needs Clarithromycin, physically cross the Statin off the drug chart for the 7-day course. Missing a week of statin will not cause a heart attack; mixing them will cause fatal rhabdomyolysis.

Access

Authority requiredKlacid, Clarac250 mg tablet

Brand: Klacid, Clarac
PBS status: Authority required
Formulation: Tablets (250 mg, 500 mg)

Clarithromycin

Macrolide·Infectious Diseases - Macrolides

Atypical CAP, H. pylori eradication, severe MAC complex in HIV

Authority requiredPBSMACROLIDEKlacid, Clarac250 mg tablet+2

Max Dose

1000 mg/day

Half-life

5-7 h

CYP Inhibitor

CRITICAL

Metallic Taste

COMMON

Rapid Summary

Overview

Highly potent macrolide. Exceptional coverage for atypical pneumonias and H. pylori. However, it is one of the most dangerous inhibitors of liver enzymes in modern medicine.

Maximum Dose

Max 1000 mg/day (e.g., 500 mg BD).

Clinical Focus

Completely shuts down CYP3A4. Co-administration with Statins, DOACs, or Colchicine causes fatal multi-organ toxicity.

Bottom Line

Clarithromycin is a macrolide for respiratory infections and H. pylori eradication, but is a potent CYP3A4 inhibitor with significant drug interactions and QTc prolongation risk.

Formulation & Access

Brand Names

Klacid, Clarac

Oral Routes

Tablets (250 mg, 500 mg). Oral liquid.

Prescribing & PBS

Authority Required (PBS) for specific indications.

Indications & Use

Primary

PBSTGA

Atypical CAP, H. pylori eradication, severe MAC complex in HIV.

Clinical Place

Preferred over erythromycin due to BD dosing and better GI tolerance. Highly effective but dangerous due to interactions.

Quick reference

Class & Role

Macrolide — Highly potent macrolide.

Route / Formulation

Tablets (250 mg, 500 mg). Oral liquid. (Klacid, Clarac)

Usual Dose & Max

PO 250-500 mg BD for 5-7 days. Max 1000 mg/day (e.g., 500 mg BD).

Key Indication Doses

Best Uses

Clarithromycin is a macrolide for respiratory infections and H. pylori eradication, but is a potent CYP3A4 inhibitor with significant drug interactions and QTc prolongation risk.

Avoid / Cautions

Concurrent use of Colchicine, Statins (Simvastatin/Atorvastatin), Ticagrelor, or Ergotamines. Baseline QTc > 500 ms. Pregnancy Category B3 (Azithromycin is preferred).

Key Risks

Key Interactions

Monitoring

Review the patient's entire medication list through a drug-interaction checker before prescribing. Baseline ECG for high-risk patients.

Clinical Pearl

Access

Authority requiredKlacid, Clarac250 mg tablet

Brand: Klacid, Clarac
PBS status: Authority required
Formulation: Tablets (250 mg, 500 mg)