A patient receiving isoniazid should be monitored for evidence of hepatotoxicity. Prompt discontinuation of the drug can reduce the risk of serious liver damage.
The patient should be instructed to discontinue isoniazid therapy and contact a physician if any of the following occur without alternative explanation:
(1) malaise
(2) fatigue
(3) weakness
(4) jaundice
(5) anorexia or loss of appetite
(6) nausea and/or vomiting
(7) dull mid-abdominal pain
Any change in medications or comorbid conditions should prompt an evaluation of the impact on isoniazid kinetics. These may increase or decrease the dosage requirements for the patient.
Liver function tests (particularly serum AST and ALT) are monitored before starting therapy and periodically while being treated. Isoniazid therapy is discontinued if either increases to >= 2 times the upper limit of normal. A minor increase in transaminases is common when starting therapy and this usually resolves on its own.
Monitoring is done more frequently if the patient has one or more risk factors for hepatotoxicity, especially if the patient is unwilling to make appropriate lifestyle changes that can reduce the risk of hepatotoxicity.
To read more or access our algorithms and calculators, please log in or register.
