methyldopa (Aldomet)

Methyldopa is an oral medication used to lower blood pressure. Although the exact mechanism of action is not yet understood, methyldopa is thought to lower blood pressure by activating receptors (alpha-2 receptors) in the central nervous system and by reducing the concentration of epinephrine, norepinephrine, dopamine, and serotonin.

Epinephrine, norepinephrine, dopamine, and serotonin are neurotransmitters (chemicals) that nerves use to communicate. Reducing the concentration of these neurotransmitters causes blood vessels to dilate (relax or widen), and, as a result, blood pressure is reduced.

After oral administration maximum reduction in blood pressure occurs in four to six hours. When patients reach an effective dosage, a smooth blood pressure response usually occurs in 12 to 24 hours. Blood pressure usually returns to pretreatment levels 24 to 48 hours after stopping treatment because methyldopa is eliminated from the body quickly. The FDA approved methyldopa on December 20, 1962.

What brand names are available for methyldopa?

N/A

Is methyldopa available as a generic drug?

Yes

Do I need a prescription for methyldopa?

Yes

WARNING

• Methyldopa may cause anemia (low number of red blood cells). Before starting treatment, doctors may order certain blood tests to check blood levels of red blood cells. Additionally, periodic blood tests should be done during treatment to detect hemolytic anemia (spontaneous break-down of red blood cells). Methyldopa should be discontinued if hemolytic anemia occurs during treatment.
• Methyldopa should be used cautiously in patients who have a history of liver disease and should be avoided in patients with active liver disease including acute hepatitis and active cirrhosis.
• Methyldopa may cause water retention (edema or swelling of the legs) or weight gain in some patients and, therefore, should be used cautiously in heart failure patients.
• Methyldopa is removed by certain types of dialysis procedures. In certain dialysis patients, hypertension (high blood pressure) has occurred as a result of methyldopa being removed from the body during dialysis.
• Methyldopa should be used cautiously in patients with cerebrovascular disease because involuntary movements have been observed during treatment.

• The usual starting dose of methyldopa for adults is 250 mg two or three times a day in the first 48 hours.
• If needed, the dosage may be increased or decreased, preferably in intervals of no less than 48 hours (2 days).
• As methyldopa may cause sedation, evening administration is preferred.
• If methyldopa must be given with anti-hypertensive medications other than thiazides (diuretics), the starting dose of methyldopa should be limited to 500 mg per day in divided doses.
• The usual maintenance dose of methyldopa for blood pressure control is 500 to 2 grams in two to four divided doses. The maximum recommended daily dosage is 3 grams.

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Methyldopa should not be used with monoamine oxidase inhibitors (MAOIs), a class of medications used to treat depression. Examples of MAOIs include isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Ensam, Elderpryl, Zelapar), and rasagiline (Azilect). Combining these drugs with methyldopa may lead to dangerous side effects. At least 14 days should elapse between discontinuation of MAOIs and initiation of treatment with methyldopa.

Administration of methyldopa with iron supplements including ferrous sulfate and ferrous gluconate is not recommended as coadministration may decrease blood levels of methyldopa.

Patients taking methyldopa may require reduced doses of anesthetics during surgical procedures because of the risk of hypotension (low blood pressure). Patients undergoing surgical procedures should inform their doctor about all medications they are taking.

The safety of methyldopa in pregnant women has not been adequately evaluated.

Methyldopa is known to enter breast milk. It should be used cautiously in nursing mothers.

What preparations of methyldopa are available?

Oral tablets: 250 and 500 mg

How should I keep methyldopa stored?

Methyldopa should be stored at room temperature, between 15 C and 30 C 59 F and 86 F).