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Methyl-Dopa

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Methyl-Dopa, Methyldopa, Alpha Methyldopa, Aldomet

  • See Also
  1. Alpha Adrenergic Central Agonist
  2. Clonidine
  3. Guanabenz (Wytensin)
  4. Guanfacine (Tenex)
  • Background
  1. As of 2021, methydopa is unavailable in U.S., and production has been discontinued
  • Indications
  1. Hypertension in Pregnancy
  • Safety
  1. Safe in Lactation
  2. Pregnancy Category B
    1. Long safety record in pregnancy
  • Contraindications
  1. Significant Liver Disease
  • 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
  • Pharmacokinetics
  1. Methyldopa is metabolized via alpha-methyl Dopamine to alpha-methylnorepinephrine (central alpha-2 Agonist)
  2. Renal excretion (metabolized or 63% as unchanged in urine)
  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
  1. Start: 250-500 mg IV every 6 hours (up to 1000 mg every 6 hours)
  1. Dose: 10 mg/kg/day divided bid to qid
  2. Maximum: 65 mg/kg/day up to 3000 mg/day in divided doses
  • Disadvantages
  1. As of 2021, methydopa is unavailable in U.S., and production has been discontinued
  2. Weak Antihypertensive
  3. Less tolerated (Fatigue, Dizziness) than other agents
  • Adverse Effects
  1. See Alpha Adrenergic Central Agonist
  2. Somnolence
  3. Dry Mouth
  4. Orthostatic Hypotension or Dizziness
  5. Nasal congestion
  6. Erectile Dysfunction
  7. Nightmares
  8. Involuntary movements
  9. Hepatotoxicity
  10. Sodium and water retention
    1. Reflex renin release in response to excessive Clonidine and renal hypoperfusion
    2. Discontinue for Congestive Heart Failure signs
  11. Hemolytic Anemia (rare, serious)
    1. Coombs positive
    2. Monitor Complete Blood Count
  • 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)
  • Resources
  1. Methydopa (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c8bea68b-3932-4538-b568-a296a8817291
  • References
  1. (2020) Med Lett Drugs Ther 62(1598): 73-80
  2. Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
  3. Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76