Methyldopate Hydrochloride
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Questions & Answers
Side Effects & Adverse Reactions
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.
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.
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.
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.
If 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.
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.
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.
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.
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.
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.
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.
Legal Issues
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FDA Safety Alerts
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Manufacturer Warnings
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FDA Labeling Changes
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Uses
Hypertension, when parenteral medication is indicated. The treatment of hypertensive crises may be initiated with Methyldopate HCl Injection.
History
There is currently no drug history available for this drug.
Other Information
Methyldopate HCl Injection, USP, is an antihypertensive agent for intravenous use. Sterile, nonpyrogenic.
Methyldopate hydrochloride [levo-3-(3,4-dihydroxyphenyl)-2-methylalanine, ethyl ester hydrochloride] is the ethyl ester of methyldopa, supplied as the hydrochloride salt with a molecular weight of 275.73. Methyldopate hydrochloride is more soluble and stable in solution than methyldopa and is the preferred form for intravenous use.
The molecular formula for Methyldopate hydrochloride is C12H17NO4·HCl and the structural formula is:
Each mL contains:
Methyldopate Hydrochloride ......... 50 mg
Citric Acid (Anhydrous) ................. 5 mg
Edetate Disodium ......................... 0.5 mg
Monothioglycerol ........................... 2 mg
Water for Injection ................q.s. to 1 mL
Methylparaben 1.5 mg and Propylparaben 0.2 mg added as preservatives, Sodium Bisulfite 3.2 mg added as an antioxidant. pH adjusted with Sodium Hydroxide and/or Hydrochloric Acid.
Sources
Methyldopate Hydrochloride Manufacturers
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American Regent, Inc.
![Methyldopate Hydrochloride Injection, Solution [American Regent, Inc.]](/wp-content/themes/bootstrap/assets/img/loading2.gif)
Methyldopate Hydrochloride | American Regent, Inc.
Methyldopate HCl Injection when given intravenously in effective doses, causes a decline in blood pressure that may begin in four to six hours and last 10 to 16 hours after injection.
Add the desired dose of Methyldopate HCl Injection to 100 mL of Dextrose Injection 5%, USP. Alternatively the desired dose may be given in 5% dextrose in water in a concentration of 100 mg/10 mL. Give this intravenous infusion slowly over a period of 30 to 60 minutes.
Adults: The usual adult dosage intravenously is 250 mg to 500 mg at six hour intervals as required. The maximum recommended intravenous dose is 1 gram every six hours.
When control has been obtained, oral therapy with tablets may be substituted for intravenous therapy, starting with the same dosage schedule used for the parenteral route. The effectiveness and anticipated responses are described in the circular for tablets.
Since methyldopate has a relatively short duration of action, withdrawal is followed by return of hypertension usually within 48 hours. This is not complicated by an overshoot of blood pressure.
Occasionally tolerance may occur, usually between the second and third month of therapy. Adding a diuretic or increasing the dosage of methyldopa frequently will restore effective control of blood pressure. A thiazide may be added at any time during methyldopa therapy and is recommended if therapy has not been started with a thiazide or if effective control of blood pressure cannot be maintained on 2 grams of methyldopa daily.
Methyldopa is largely excreted by the kidney and patients with impaired renal function may respond to smaller doses. Syncope in older patients may be related to an increased sensitivity and advanced arteriosclerotic vascular disease. This may be avoided by lower doses.
Pediatric Patients: The recommended daily dosage is 20 to 40 mg/kg of body weight in divided doses every six hours. The maximum dosage is 65 mg/kg or 3 grams daily, whichever is less. When the blood pressure is under control, continue with oral therapy using tablets in the same dosage as for the parenteral route. (see PRECAUTIONS, Pediatric Use.)
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
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