What if the patient who needs isoniazid after a positive purified protein derivative test 10 years ago (Item 110-17) cannot take it because of its side effects?
—Joel Stoia, PA-C, Dayton, Md.

I would need to know more about the side effects of isoniazid in this particular case. Hepatotoxicity is uncommon, seen in about 0.1% of patients who take the medication, provided one follows the American Thoracic Society guideline of five-times increase in liver function tests. If there were a bona fide severe adverse reaction to isoniazid, then second-line alternatives would have to be considered. There is disagreement whether this should be monotherapy with rifampin or dual therapy of pyrazinamide and rifampin. Expert consultation should be obtained to help determine the better course of action.
—Cedric W. Spak, MD, MPH (111-19)

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