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| ==Warning== | | ==Warning== |
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| Severe and sometimes fatal [[hepatitis]] associated with isoniazid therapy may occur and may develop even after many months of treatment. The risk of developing hepatitis is age related. Approximate case rates by age are: 0 per 1,000 for persons under 20 years of age, 3 per 1,000 for persons in the 20–34 year age group, 12 per 1,000 for persons in the 35–49 year age group, 23 per 1,000 for persons in the 50–64 year age group, and 8 per 1,000 for persons over 65 years of age. The risk of hepatitis is increased with daily consumption of alcohol. Precise data to provide a fatality rate for isoniazid-related hepatitis is not available; however, in a U.S. Public Health Service Surveillance Study of 13,838 persons taking isoniazid, there were 8 deaths among 174 cases of hepatitis.
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| Therefore, patients given isoniazid should be carefully monitored and interviewed at monthly intervals. Serum transaminase concentration becomes elevated in about 10–20 percent of patients, usually during the first few months of therapy, but it can occur at any time. Usually enzyme levels return to normal despite continuance of drug, but in some cases progressive liver dysfunction occurs. Patients should be instructed to report immediately any of the prodromal symptoms of hepatitis, such as fatigue, weakness, malaise, anorexia, nausea, or vomiting. If these symptoms appear or if signs suggestive of hepatic damage are detected, isoniazid should be discontinued promptly, since continued use of the drug in these cases has been reported to cause a more severe form of liver damage.
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| Patients with tuberculosis should be given appropriate treatment with alternative drugs. If isoniazid must be reinstituted, it should be reinstituted only after symptoms and laboratory abnormalities have cleared. The drug should be restarted in very small and gradually increasing doses and should be withdrawn immediately if there is any indication of recurrent liver involvement. Treatment should be deferred in persons with acute hepatic diseases.
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| RIFAMATE (rifampin and isoniazid capsules USP) is a combination of two drugs, each of which has been associated with liver dysfunction. Liver function tests should be performed prior to therapy with RIFAMATE and periodically during treatment.
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| ===Rifampin=== | | ===Rifampin=== |
Revision as of 03:30, 5 January 2014
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]
Warning
Rifampin
Rifampin has been shown to produce liver dysfunction. There have been fatalities associated with jaundice in patients with liver disease or receiving rifampin concomitantly with other hepatotoxic agents. Since an increased risk may exist for individuals with liver disease, benefits must be weighed carefully against the risk of further liver damage.
Several studies of tumorigenicity potential have been done in rodents. In one strain of mice known to be particularly susceptible to the spontaneous development of hepatomas, rifampin given at a level 2–10 times the maximum dosage used clinically resulted in a significant increase in the occurrence of hepatomas in female mice of this strain after one year of administration.
There was no evidence of tumorigenicity in the males of this strain, in males or females of another mouse strain, or in rats.
Isoniazid
See the boxed warning.[1]
References
Adapted from the FDA Package Insert.
