Company InfoNewsInvestor InformationResearchDevelopmentCareersBusiness DevelopmentResourcesDrugs databaseBack to the home pageSearch  
Drugs database
Drugs A-Z

Brands A-Z

Drugs by categories

Drugs by manufacturer

Drugs by packager

Antibiotics for sale

Online Viagra bestellen in Nederland

Home / Drugs / Starting with M / Methyldopa

An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent. [PubChem]
CategoriesAntihypertensive Agents
Adrenergic alpha-Agonists
ManufacturersMerck and co inc
Merck research laboratories div merck co inc
Accord health care inc
Duramed pharmaceuticals inc sub barr laboratories inc
Halsey drug co inc
Ivax pharmaceuticals inc sub teva pharmaceuticals usa
Mutual pharmaceutical co inc
Mylan pharmaceuticals inc
Par pharmaceutical inc
Parke davis div warner lambert co
Pliva inc
Purepac pharmaceutical co
Roxane laboratories inc
Sandoz inc
Superpharm corp
Teva pharmaceuticals usa inc
Watson laboratories inc
Abraxis pharmaceutical products
Baxter healthcare corp anesthesia and critical care
Hospira inc
Luitpold pharmaceuticals inc
Marsam pharmaceuticals llc
Smith and nephew solopak div smith and nephew
Teva parenteral medicines inc
PackagersAdvanced Pharmaceutical Services Inc.
American Regent
A-S Medication Solutions LLC
Caremark LLC
Central Texas Community Health Centers
Direct Dispensing Inc.
Dispensing Solutions
Diversified Healthcare Services Inc.
Emcure Pharmaceuticals Ltd.
Endo Pharmaceuticals Inc.
H and H Laboratories
Heartland Repack Services LLC
Hospira Inc.
Ivax Pharmaceuticals
Kaiser Foundation Hospital
Luitpold Pharmaceuticals Inc.
Major Pharmaceuticals
Murfreesboro Pharmaceutical Nursing Supply
Nucare Pharmaceuticals Inc.
PD-Rx Pharmaceuticals Inc.
Physicians Total Care Inc.
Rebel Distributors Corp.
Remedy Repack
Sandhills Packaging Inc.
Southwood Pharmaceuticals
Teva Pharmaceutical Industries Ltd.
UDL Laboratories
United Research Laboratories Inc.
Watson Pharmaceuticals
SynonymsAlpha medopa
L-Methyl Dopa


For use in the treatment of hypertension.


Methyldopa is an aromatic-amino-acid decarboxylase inhibitor in animals and in man. Only methyldopa, the L-isomer of alpha-methyldopa, has the ability to inhibit dopa decarboxylase and to deplete animal tissues of norepinephrine. In man the antihypertensive activity appears to be due solely to the L-isomer. About twice the dose of the racemate (DL-alpha-methyldopa) is required for equal antihypertensive effect. Methyldopa has no direct effect on cardiac function and usually does not reduce glomerular filtration rate, renal blood flow, or filtration fraction. Cardiac output usually is maintained without cardiac acceleration. In some patients the heart rate is slowed. Normal or elevated plasma renin activity may decrease in the course of methyldopa therapy. Methyldopa reduces both supine and standing blood pressure. Methyldopa usually produces highly effective lowering of the supine pressure with infrequent symptomatic postural hypotension. Exercise hypotension and diurnal blood pressure variations rarely occur.

mechanism of action

Although the mechanism of action has yet to be conclusively demonstrated, the resultant hypotensive effect is most likely due to the drug's action on the CNS. Methyldopa is converted into the metabolite, alpha-methylnorepinephrine, in the CNS, where it stimulates the central inhibitory alpha-adrenergic receptors, leading to a reduction in sympathetic tone, total peripheral resistance, and blood pressure. Reduction in plasma renin activity, as well as the inhibition of both central and peripheral norepinephrine and serotonine production may also contribute to the drug's antihypertensive effect, although this is not a major mechanism of action. This is done through the inhibition of the decarboxylation of dihydroxyphenylalanine (dopa)—the precursor of norepinephrine—and of 5-hydroxytryptophan (5-HTP)—the precursor of serotonin—in the CNS and in most peripheral tissues.


The oral LD50 of methyldopa is greater than 1.5 g/kg in both the mouse and the rat. Symptoms of overdose include bloating, constipation, diarrhea, dizziness, extreme drowsiness, gas, light-headedness, nausea, severely low blood pressure, slow heartbeat, vomiting, and weakness.


Hepatic, extensively metabolized. The known urinary metabolites are: a-methyldopa mono-0-sulfate; 3-0-methyl-a-methyldopa; 3,4-dihydroxyphenylacetone; a-methyldopamine; 3-0-methyl-a-methyldopamine and their conjugates.


Absorption from the gastrointestinal tract is variable but averages approximately 50%.

half life

The plasma half-life of methyldopa is 105 minutes.

route of elimination

Methyldopa is extensively metabolized. The known urinary metabolites are: α-methyldopa mono-O-sulfate; 3-0-methyl-α-methyldopa; 3,4-dihydroxyphenylacetone; α-methyldopamine; 3-0-methyl-α-methyldopamine and their conjugates. Approximately 70 percent of the drug which is absorbed is excreted in the urine as methyldopa and its mono-O-sulfate conjugate. Methyldopa crosses the placental barrier, appears in cord blood, and appears in breast milk.

drug interactions

Carteolol: Possible hypertensive crisis

Dobutamine: Increased arterial pressure

Dopamine: Increased arterial pressure

Entacapone: Entacapone may increase the effect and toxicity of the sympathomimetic, methyldopa.

Ephedra: Increased arterial pressure

Ephedrine: Increased arterial pressure

Epinephrine: Increased arterial pressure

Fenoterol: Increased arterial pressure

Haloperidol: Methyldopa increases haloperidol effect or risk of psychosis

Iron: Iron decreases the absorption of dopa derivatives

Iron Dextran: Iron decreases the absorption of dopa derivatives

Isoproterenol: Increased arterial pressure

Levodopa: Methyldopa increases the effect and toxicity of levodopa

Lithium: Methyldopa may increase the adverse effects of lithium without affecting lithium serum levels. Monitor for signs and symptoms of lithium toxicity during concomitant therapy.

Mephentermine: Increased arterial pressure

Metaraminol: Increased arterial pressure

Methoxamine: Increased arterial pressure

Nadolol: Possible hypertensive crisis

Norepinephrine: Increased arterial pressure

Orciprenaline: Increased arterial pressure

Oxprenolol: Possible hypertensive crisis

Penbutolol: Possible hypertensive crisis

Phenylephrine: Increased arterial pressure

Phenylpropanolamine: Increased arterial pressure

Pindolol: Possible hypertensive crisis

Pirbuterol: Increased arterial pressure

Procaterol: Increased arterial pressure

Propranolol: Possible hypertensive crisis

Pseudoephedrine: Increased arterial pressure

Salbutamol: Increased arterial pressure

Sotalol: Possible hypertensive crisis

Terbutaline: Increased arterial pressure

Timolol: Possible hypertensive crisis

Tranylcypromine: The MAO inhibitor, Tranylcypromine, may increase the adverse effects of Methyldopa. Concomitant therapy is contraindicated.