Methyldopa
FDA Drug Information • Also known as: Methyldopa
- Brand Names
- Methyldopa
- Route
- ORAL
- Dosage Form
- TABLET, FILM COATED
- Product Type
- HUMAN PRESCRIPTION DRUG
Description
DESCRIPTION Methyldopa is an antihypertensive drug. Methyldopa, the L -isomer of alpha-methyldopa, is levo-3-(3,4-dihydroxyphenyl)-2-methylalanine. Its empirical formula is C 10 H 13 NO 4 , with a molecular weight of 211.22, and its structural formula is: Methyldopa is a white to yellowish white, odorless fine powder, and is soluble in water. Methyldopa Tablets, USP is supplied as tablets, for oral use, in two strengths: 250 mg and 500 mg of methyldopa per tablet. Inactive ingredients in the tablets are: lactose monohydrate, hypromellose , citric acid, corn starch, colloidal silicon dioxide, microcrystalline cellulose, ethyl cellulose, magnesium stearate, and polyethylene glycol. image description
What Is Methyldopa Used For?
INDICATION AND USAGE Hypertension.
Dosage and Administration
DOSAGE AND ADMINISTRATION ADULTS Initiation of Therapy The usual starting dosage of Methyldopa is 250 mg two or three times a day in the first 48 hours. The daily dosage then may be increased or decreased, preferably at intervals of not less than two days, until an adequate response is achieved. To minimize the sedation, start dosage increases in the evening. By adjustment of dosage, morning hypotension may be prevented without sacrificing control of afternoon blood pressure. When methyldopa is given to patients on other antihypertensives, the dose of these agents may need to be adjusted to effect a smooth transition. When Methyldopa is given with antihypertensives other than thiazides, the initial dosage of Methyldopa should be limited to 500 mg daily in divided doses; when Methyldopa is added to a thiazide, the dosage of thiazide need not be changed. Maintenance Therapy The usual daily dosage of Methyldopa is 500 mg to 2 g in two to four doses. Although occasional patients have responded to higher doses, the maximum recommended daily dosage is 3 g. Once an effective dosage range is attained, a smooth blood pressure response occurs in most patients in 12 to 24 hours. Since methyldopa 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 g 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. ( See PRECAUTIONS, Geriatric Use ) PEDIATRIC PATIENTS Initial dosage is based on 10 mg/kg of body weight daily in two to four doses. The daily dosage then is increased or decreased until an adequate response is achieved. The maximum dosage is 65 mg/kg or 3 g daily, whichever is less. ( See PRECAUTIONS, Pediatric Use )
Side Effects (Adverse Reactions)
ADVERSE REACTIONS Sedation, usually transient, may occur during the initial period of therapy or whenever the dose is increased. Headache, asthenia, or weakness may be noted as early and transient symptoms. However, significant adverse effects due to Methyldopa have been infrequent and this agent usually is well tolerated. The following adverse reactions have been reported and, within each category, are listed in order of decreasing severity. Cardiovascular: Aggravation of angina pectoris, congestive heart failure, prolonged carotid sinus hypersensitivity, orthostatic hypotension (decrease daily dosage), edema or weight gain, bradycardia. Digestive: Pancreatitis, colitis, vomiting, diarrhea, sialadenitis, sore or “black” tongue, nausea, constipation, distension, flatus, dryness of mouth. Endocrine: Hyperprolactinemia. Hematologic: Bone marrow depression, leukopenia, granulocytopenia, thrombocytopenia, hemolytic anemia; positive tests for antinuclear antibody, LE cells, and rheumatoid factor, positive Coombs test. Hepatic: Liver disorders including hepatitis, jaundice, abnormal liver function tests ( see WARNINGS ). Hypersensitivity: Myocarditis, pericarditis, vasculitis, lupus-like syndrome, drug-related fever, eosinophilia. Nervous System/Psychiatric: Parkinsonism, Bell's palsy, decreased mental acuity, involuntary choreoathetotic movements, symptoms of cerebrovascular insufficiency, psychic disturbances including nightmares and reversible mild psychoses or depression, headache, sedation, asthenia or weakness, dizziness, lightheadedness, paresthesias. Metabolic: Rise in BUN. Musculoskeletal: Arthralgia, with or without joint swelling; myalgia. Respiratory: Nasal stuffiness. Skin: Toxic epidermal necrolysis, rash. Urogenital: Amenorrhea, breast enlargement, gynecomastia, lactation, impotence, decreased libido.
Warnings and Precautions
WARNINGS 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 g 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 IgG (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 an 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 3 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...
Contraindications
CONTRAINDICATIONS Methyldopa is contraindicated in patients: — with active hepatic disease, such as acute hepatitis and active cirrhosis — with liver disorders previously associated with methyldopa therapy ( see WARNINGS ) — with hypersensitivity to any component of these products. — on therapy with monoamine oxidase (MAO) inhibitors.
Overdosage
OVERDOSAGE Acute overdosage may produce acute hypotension with other responses attributable to brain and gastrointestinal malfunction (excessive sedation, weakness, bradycardia, dizziness, lightheadedness, constipation, distention, flatus, diarrhea, nausea, vomiting). In the event of overdosage, symptomatic and supportive measures should be employed. When ingestion is recent, gastric lavage or emesis may reduce absorption. When ingestion has been earlier, infusions may be helpful to promote urinary excretion. Otherwise, management includes special attention to cardiac rate and output, blood volume, electrolyte balance, paralytic ileus, urinary function and cerebral activity. Sympathomimetic drugs [e.g., levarterenol, epinephrine, ARAMINE * (Metaraminol Bitartrate)] may be indicated. Methyldopa is dialyzable. The oral LD 50 of methyldopa is greater than 1.5 g/kg in both the mouse and the rat.
How Supplied
HOW SUPPLIED Methyldopa Tablets, USP , 250 mg, are White, round film coated tablets, debossed with “CE” over “87” on one side and plain on the other side. They are supplied as follows: NDC 62135-321-90 bottles of 90 NDC 62135-321-18 bottles of 180 Methyldopa Tablets, USP , 500 mg, are White, round film coated tablets, debossed with “CE” over “88” on one side and plain on the other side. They are supplied as follows: NDC 62135-322-90 bottles of 90 NDC 62135-322-18 bottles of 180 Storage Store Methyldopa Tablets at controlled room temperature 20° to 25°C (68° to 77°F) [see USP]. Manufactured for: Chartwell RX, LLC Congers, NY 10920 L71158 Rev. 11/2022
About This Information
This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.
What are side effects?
Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.
What are drug interactions?
Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.