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Methyldopa information from DrugsUpdate  

See Available Brands of Methyldopa in India

L - Caution when used during lactation
FI - Food *
LI - Lab *

Methyldopa (L-α-Methyl-3,4-dihydroxyphenylalanine; Aldomet, Aldoril, Dopamet, Dopegyt, etc) is a psychoactive drug used as a sympatholytic or antihypertensive. Its use is now deprecated following introduction of alternative safer classes of agents. However, it continues to have a role in otherwise difficult to treat hypertension and gestational hypertension (also known as pregnancy-induced hypertension (PIH)).

Pharmacodynamics

Pharmacokinetics

Methyldopa stimulates α2-adrenoceptors which results in reduced sympathetic tone and fall in BP.

Onset

4-6 hours

Duration

48 hours (oral); 10-16 hours (IV).

Absorption
Variable and incomplete from the GI tract, via amino acid active transport system (oral).

Distribution
Crosses the placenta; penetrates the blood-brain barrier; enters the breast milk. Protein-binding: Minimal.

Metabolism

Extensively hepatic. CNS: Decarboxylation to α-methyl-noradrenaline.

Excretion

Via urine (as unchanged drug and as o-sulfate conjugate); prolonged in renal impairment; 1.7 hour (elimination half-life).

Methyldopa Indications / Methyldopa Uses

Information Not Available

Methyldopa Adverse Reactions / Methyldopa Side Effects

Peripheral oedema; drug fever, mental depression, anxiety, nightmares, drowsiness, headache; dry mouth; orthostatic hypotension, sinus bradycardia, sodium retention, sexual dysfunction, gynaecomastia, hyperprolactinaemia, thrombocytopenia, positive Coombs' test, transient leukopenia or granulocytopenia, cholestasis or hepatitis and heptocellular injury, increased liver enzymes, jaundice, cirrhosis, dyspnoea, SLE-like syndrome.

Potentially Fatal: Hepatic necrosis, haemolytic anaemia.

Precautions

Methyldopa should be used with caution in patients with a history of previous liver disease or dysfunction.

Some patients taking Methyldopa experience clinical edema or weight gain which may be controlled by use of a diuretic. Methyldopa should not be continued if edema progresses or signs of heart failure appear.

Hypertension has recurred occasionally after dialysis in patients given Methyldopa because the drug is removed by this procedure.

Rarely, involuntary choreoathetotic movements have been observed during therapy with Methyldopa in patients with severe bilateral cerebrovascular disease. Should these movements occur, stop therapy.


Overdosage
Symptoms: Hypotension, sedation, bradycardia, dizziness, constipation or diarrhoea, flatus, nausea, vomiting. Management: Supportive and symptomatic. Can be removed by hemodialysis.

Special Precautions

History of haemolytic anaemia, depression, parkinsonism, renal or hepatic impairment. May impair ability to drive or operate machinery. Monitor blood counts and perform LFTs. Elderly.

Other Drug Interactions

Reduced hypotensive effects with phenothiazines, TCAs and possibly, amphetamines. Additive hypotensive effects with levodopa; psychosis may also occur. Reduced absorption and effects with oral iron preparations. Reduced doses of general anaesthetics may be required. Effect of ephedrine may be reduced.

Potentially Fatal: Increased risk of severe hypertension with MAOIs. Increased lithium toxicity.

Other Interactions

Food Interaction
Hypertension may be exacerbated with ephedra, yohimbe and ginseng. CNS depression may be increased when used with valerian, St John's wort, kava kava and gotu kola. Natural licorice causes sodium and water retention and increases potassium loss. Garlic may increase antihypertensive effect.

Dosage

Oral
Hypertension
Adult: Monotherapy: Initially, 250 mg bid-tid for 2 days; adjust according to response not more than every 2 days. Maintenance: 0.5-2 g daily. Max: 3 g daily. Combination therapy: Initial dose should not exceed 500 mg daily in divided doses.
Child: Initially, 10 mg/kg or 300 mg/m2 daily in 2-4 divided doses; increase as necessary. Max: 65 mg/kg, 2 g/m2 or 3 g daily, whichever is least.
Elderly: Initially, 125 mg bid; gradually increase according to response. Max: 2 g daily.
Renal impairment: May respond to smaller doses.

Intravenous
Hypertension
Adult: As methyldopate hydrochloride: 250-500 mg in 100 ml of 5% glucose injected over 30-60 minutes every 6 hours. Max: 1 g every 6 hours.
Child: As methyldopate hydrochloride: 20-40 mg/kg/24 hours or 0.6-1.2 g/m2/24 hours in equally divided doses every 6 hours. Max 65 mg/kg, 2 g/m2 or 3 g daily, whichever is least.
Renal impairment: May respond to smaller doses.

Incompatibility
Incompatible with amphotericin B, methohexital.

Food(before/after)

May be taken with or without food.

List of Contraindications

Methyldopa and Pregnancy

Teratogenic Effects. Pregnancy Category B

Methyldopa and Lactation

Caution when used in lactation

Methyldopa appears in breast milk. Therefore, caution should be exercised when Methyldopa is given to a nursing woman.

Methyldopa and Children

There are no well-controlled clinical trials in pediatric patients. Information on dosing in pediatric patients is supported by evidence from published literature regarding the treatment of hypertension in pediatric patients.

Methyldopa and Geriatic

Of the total number of subjects (1685) in clinical studies of Methyldopa, 223 patients were 65 years of age and over while 33 patients were 75 years of age and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function.

Methyldopa and Other Contraindications

Phaeochromocytoma, active liver disease. Patients in whom previous methyldopa treatment resulted in liver abnormalities or direct Coombs' positive haemolytic anaemia.

Storage

Information Not Available

Lab interference

Information Not Available

Methyldopa brands in India:

Aldopam TAB Alphadopa Dopagyt Emdopa Gynapres Sembrina

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