HRZE Rechallenge Protocol After Adverse Drug Reaction

Introduction to Rechallenge Protocol

The American Thoracic Society recommends that after an adverse reaction to HRZE therapy, all suspected hepatotoxic drugs must be stopped immediately if AST/ALT rises to 5 times normal or bilirubin increases, then reintroduced sequentially once liver function normalizes, starting with isoniazid, followed by rifampin, and finally pyrazinamide, with each drug given alone for 3-7 days while monitoring liver enzymes before adding the next agent 1, 2

The British Thoracic Society suggests that before attempting rechallenge, a risk-benefit analysis should be performed to confirm that rechallenge is necessary for optimal tuberculosis treatment, considering the potential risks and benefits of re-exposing the patient to the offending drug 1, 2

The National Institute for Health and Care Excellence recommends that during the sequential reintroduction of hepatotoxic drugs, ethambutol can be continued or added at any point as it is not hepatotoxic, using standard dosing of 15 mg/kg daily, and monitoring visual acuity monthly 1, 2, 4
The Centers for Disease Control and Prevention advises that rifampin should be added at full dose after isoniazid is tolerated, with close monitoring of liver enzymes every 2-3 days for the first week of combined therapy, due to the increased risk of hepatotoxicity 1, 2

The World Health Organization recommends that if pyrazinamide is definitively identified as the offending agent or cannot be safely reintroduced, treatment duration should be extended to 9 months total using rifampin and isoniazid, with ethambutol for the initial 2 months, to ensure effective treatment of tuberculosis 1, 2

The American College of Chest Physicians suggests that during rechallenge, liver function tests should be performed at baseline, and liver enzymes should be monitored twice weekly during the first 2 weeks, every 2 weeks for the remainder of the first 2 months, and monthly thereafter if stable 1, 2

The European Respiratory Society recommends that for patients with cutaneous reactions, antihistamine premedication may allow successful rechallenge, and the rechallenge sequence should start with ethambutol, then isoniazid, then rifampin, then pyrazinamide 1
The Infectious Diseases Society of America advises that for patients with peripheral neuropathy due to isoniazid, pyridoxine 25-50 mg daily should be added, and rechallenge with isoniazid can be attempted, but if neuropathy recurs, an alternative regimen should be used 1, 2