II. Indications

III. Safety

  1. Long safety record in pregnancy

IV. Disadvantages

  1. Weak antihypertensive
  2. Less tolerated (Fatigue, Dizziness) than other agents

V. Contraindications

  1. Significant Liver Disease

VI. Pharmacokinetics

  1. Renal excretion (metabolized or 63% as unchanged in urine)

VII. Dosing: Hypertension in Pregnancy

  1. Start: 250 mg orally twice to three times daily
  2. Maintenance: 500 mg orally twice daily
  3. Maximum: Up to 3000 mg daily in divided doses

VIII. Dosing: Hypertensive Crisis

  1. Start: 250-500 mg IV every 6 hours (up to 1000 mg every 6 hours)

IX. Dosing: Pediatric Hypertension

  1. Dose: 10 mg/kg/day divided bid to qid
  2. Maximum: 65 mg/kg/day up to 3000 mg/day in divided doses

X. Mechanism

  1. See Alpha Adrenergic Central Agonist
  2. See Alpha Adrenergic Receptor
  3. Central Acting Adrenergic Agonist
    1. Activates alpha-2 receptors that inhibit CNS sympathetic signals (similar to Clonidine)
    2. Results in increased parasympathetic effects and side effects
  4. Methylnorepinephrine (Methyldopa) metabolite
    1. Weak Sympathomimetic that also decreases CNS sympathetic outflow

XI. Adverse Effects

  1. Somnolence
  2. Dry Mouth
  3. Orthostatic Hypotension or Dizziness
  4. Erectile Dysfunction
  5. Nightmares
  6. Involuntary movements
  7. Hepatotoxicity
  8. Sodium and water retention
    1. Reflex renin release in response to excessive Clonidine and renal hypoperfusion
    2. Discontinue for Congestive Heart Failure signs
  9. Hemolytic Anemia (rare, serious)
    1. Monitor Complete Blood Count

XII. Drug Interactions

  1. Tricyclic Antidepressants
    1. Decreased Clonidine antihypertensive effect
  2. CNS Depressants (e.g. Alcohol, Benzodiazepines, Barbiturates)
    1. Increase Clonidine related CNS effects (e.g. Somnolence)

XIII. References

  1. Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
  2. Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76

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Related Studies

Cost: Medications

Methyldopa (on 6/18/2017 at Walmart.com)
Methyldopa 250mg #60 tablets for $4.00 $0.07 each
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METHYLDOPA 250 MG TABLET Generic $0.10 each
METHYLDOPA 500 MG TABLET Generic $0.27 each

Ontology: Methyldopa (C0025741)

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
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
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