II. Background
- As of 2021, methydopa is unavailable in U.S., and production has been discontinued
III. Indications
IV. Safety
- Safe in Lactation
- Pregnancy Category B
- Long safety record in pregnancy
V. Contraindications
- Significant Liver Disease
VI. Mechanism
- See Alpha Adrenergic Central Agonist
- See Alpha Adrenergic Receptor
- Central Acting Adrenergic Agonist
- Activates alpha-2 receptors that inhibit CNS sympathetic signals (similar to Clonidine)
- Results in increased parasympathetic effects and side effects
- Methylnorepinephrine (Methyldopa) metabolite
- Weak Sympathomimetic that also decreases CNS sympathetic outflow
VII. Pharmacokinetics
VIII. Dosing: Hypertension in Pregnancy
- Start: 250 mg orally twice to three times daily
- Maintenance: 500 mg orally twice daily
- Maximum: Up to 3000 mg daily in divided doses
IX. Dosing: Hypertensive Crisis
- Start: 250-500 mg IV every 6 hours (up to 1000 mg every 6 hours)
X. Dosing: Pediatric Hypertension
- Dose: 10 mg/kg/day divided bid to qid
- Maximum: 65 mg/kg/day up to 3000 mg/day in divided doses
XI. Disadvantages
- As of 2021, methydopa is unavailable in U.S., and production has been discontinued
- Weak Antihypertensive
- Less tolerated (Fatigue, Dizziness) than other agents
XII. Adverse Effects
- See Alpha Adrenergic Central Agonist
- Somnolence
- Dry Mouth
- Orthostatic Hypotension or Dizziness
- Nasal congestion
- Erectile Dysfunction
- Nightmares
- Involuntary movements
- Hepatotoxicity
-
Sodium and water retention
- Reflex renin release in response to excessive Clonidine and renal hypoperfusion
- Discontinue for Congestive Heart Failure signs
-
Hemolytic Anemia (rare, serious)
- Coombs positive
- Monitor Complete Blood Count
XIII. Drug Interactions
-
Tricyclic Antidepressants
- Decreased clonidine Antihypertensive effect
-
CNS Depressants (e.g. Alcohol, Benzodiazepines, Barbiturates)
- Increase Clonidine related CNS effects (e.g. Somnolence)
XIV. Resources
XV. References
- (2020) Med Lett Drugs Ther 62(1598): 73-80
- Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
- Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76
Images: Related links to external sites (from Bing)
Related Studies
Definition (NCI) | A phenylalanine derivative and an aromatic amino acid decarboxylase inhibitor with antihypertensive activity. Methyldopa is a prodrug and is metabolized in the central nervous system. The antihypertensive action of methyldopa seems to be attributable to its conversion into alpha-methylnorepinephrine, which is a potent alpha-2 adrenergic agonist that binds to and stimulates potent central inhibitory alpha-2 adrenergic receptors. This results in a decrease in sympathetic outflow and decreased blood pressure. |
Definition (MSH) | An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent. |
Concepts | Pharmacologic Substance (T121) , Neuroreactive Substance or Biogenic Amine (T124) , Amino Acid, Peptide, or Protein (T116) |
MSH | D008750 |
SnomedCT | 373542000, 84078002 |
LNC | LP16200-5, MTHU016766 |
English | Alphamethyldopa, alpha Methyl L Dopa, alpha Methyldopa, alpha-Methyl-L-Dopa, alpha-Methyldopa, methyldopa, L-Tyrosine, 3-hydroxy-alpha-methyl-, 3-Hydroxy-alpha-methyl-L-tyrosine, L-2-Amino-2-methyl-3-(3,4-dihydroxyphenyl)propionic Acid, Levo-3-(3,4-Dihydroxyphenyl)-2-methylalanine, O methyl DOPA, methyldopa (medication), Methyldopa [Chemical/Ingredient], alphamethyldopa, alpha-methyldopa, alpha methyldopa, METHYLDOPA, Methyldopa, Alpha methyldopa, Methyldopa (product), Methyldopa (substance) |
Swedish | Metyldopa |
Czech | methyldopa |
Finnish | Metyylidopa |
Russian | AL'FA-METILDOFA, METILDOPA, METILDOFA, METILDOPAT, АЛЬФА-МЕТИЛДОФА, МЕТИЛДОПА, МЕТИЛДОПАТ, МЕТИЛДОФА |
Japanese | α-メチルドーパ, メチルドパ, メチルドーパ, アルファ-メチルドーパ |
Spanish | alfa-Metildopa, metildopa (producto), metildopa (sustancia), metildopato, metildopa, Metildopa |
French | alpha-Méthyldopa, alpha-L-Méthyldopa, Méthyldopa |
Croatian | METILDOPA |
Polish | Metylodopa |
German | Alphamethyldopa, Methyldopa |
Italian | Metildopa |
Portuguese | alfa-Metildopa, Metildopa |
Ontology: Aldomet (C0591055)
Concepts | Pharmacologic Substance (T121) , Amino Acid, Peptide, or Protein (T116) |
MSH | D008750 |
English | aldomet, Aldomet, Biopat Brand of Methyldopa, Cahill May Roberts Brand of Methyldopa, Merck Brand of Methyldopa, Merck Sharp & Dohme Brand of Methyldopa, Methyldopa Biopat Brand, Methyldopa Merck Brand |