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| __NOTOC__
| | #REDIRECT [[Methyldopa#Warnings]] |
| {{Methyldopa}}
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| {{CMG}}; {{AE}} {{AK}}
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| ==Warnings==
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| '''It is important to recognize that a positive Coombs test, hemolytic anemia, and liver disorders may occur with methyldopa therapy. The rare occurrences of hemolytic anemia or liver disorders could lead to potentially fatal complications unless properly recognized and managed. Read this section carefully to understand these reactions.'''
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| With prolonged methyldopa therapy, 10 to 20 percent of patients develop a positive direct Coombs test which usually occurs between 6 and 12 months of methyldopa therapy. Lowest incidence is at daily dosage of 1 gram or less. This on rare occasions may be associated with hemolytic anemia, which could lead to potentially fatal complications. One cannot predict which patients with a positive direct Coombs test may develop hemolytic anemia.
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| Prior existence or development of a positive direct Coombs test is not in itself a contraindication to use of methyldopa. If a positive Coombs test develops during methyldopa therapy, the physician should determine whether hemolytic anemia exists and whether the positive Coombs test may be a problem. For example, in addition to a positive direct Coombs test there is less often a positive indirect Coombs test which may interfere with cross matching of blood.
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| Before treatment is started, it is desirable to do a blood count ([[hematocrit]], [[hemoglobin]], or red cell count) for a baseline or to establish whether there is anemia. Periodic blood counts should be done during therapy to detect [[hemolytic anemia]]. It may be useful to do a direct [[Coombs test]] before therapy and at 6 and 12 months after the start of therapy.
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| If [[Coombs test|Coombs-positive]] [[hemolytic anemia]] occurs, the cause may be methyldopa and the drug should be discontinued. Usually the anemia remits promptly. If not, [[corticosteroids ]]may be given and other causes of [[anemia ]]should be considered. If the hemolytic anemia is related to methyldopa, the drug should not be reinstituted.
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| When methyldopa causes Coombs positivity alone or with hemolytic anemia, the red cell is usually coated with gamma globulin of the [[lgG ]](gamma G) class only. The positive Coombs test may not revert to normal until weeks to months after methyldopa is stopped.
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| Should the need for transfusion arise in a patient receiving methyldopa, both a direct and indirect Coombs test should be performed. In the absence of hemolytic anemia, usually only the direct Coombs test will be positive. A positive direct Coombs test alone will not interfere with typing or cross matching. If the indirect Coombs test is also positive, problems may arise in the major cross match and the assistance of a hematologist or transfusion expert will be needed.
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| Occasionally, fever has occurred within the first three weeks of methyldopa therapy, associated in some cases with [[eosinophilia ]]or abnormalities in one or more liver function tests, such as serum [[alkaline phosphatase]], serum transaminases ([[SGOT]], [[SGPT]]), [[bilirubin ]]and [[prothrombin ]]time. [[Jaundice]], with or without fever, may occur with onset usually within the first two to three months of therapy. In some patients the findings are consistent with those of [[cholestasis]]. In others the findings are consistent with [[hepatitis ]]and hepatocellular injury.
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| Rarely fatal hepatic necrosis has been reported after use of methyldopa. These hepatic changes may represent hypersensitivity reactions. Periodic determination of hepatic function should be done particularly during the first 6 to 12 weeks of therapy or whenever an unexplained fever occurs. If fever, abnormalities in liver function tests, or jaundice appear, stop therapy with methyldopa. If caused by methyldopa, the temperature and abnormalities in liver function characteristically have reverted to normal when the drug was discontinued. Methyldopa should not be reinstituted in such patients.
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| Rarely, a reversible reduction of the white blood cell count with a primary effect on the [[granulocytes ]]has been seen. The granulocyte count returned promptly to normal on discontinuance of the drug. Rare cases of [[granulocytopenia ]]have been reported. In each instance, upon stopping the drug, the white cell count returned to normal. Reversible [[thrombocytopenia ]]has occurred rarely.
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| Contains sodium bisulfite, a sulfite that may cause allergic-type reactions including [[anaphylactic ]]symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. [[Sulfite ]]sensitivity is seen more frequently in asthmatic than in nonasthmatic people.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = METHYLDOPATE HYDROCHLORIDE INJECTION, SOLUTION [AMERICAN REGENT, INC.] | url = http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=f5f25053-a9f3-48b9-a412-078f5ee942fd | publisher = | date = | accessdate = 10 March 2014 }}</ref>
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| ==References==
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| {{Reflist|2}}
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| [[Category:Cardiovascular Drugs]]
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| [[Category:Drugs]]
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