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Methylene Blue

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Methylene Blue, Methylthioninium Chloride

  • Indications
  1. Methemoglobinemia
    1. Converts methemoglobin to Hemoglobin when administered IV
  2. Surgical Dye
    1. Trace lymphatic chain during oncology surgery (identify sentinel Lymph Node)
  • Precautions
  1. Methylene Blue supplements
    1. Off-label consumer use as a mitochrondrial, cognition or athletic booster
    2. No evidence of any benefit for these "booster" uses and risk of adverse effects (avoid)
  • Mechanism
  1. Primary
    1. Synthetic dye
    2. Binds negatively charged ions (e.g. Nucleic Acids)
  2. Alzheimer Disease (investigational)
    1. Inhibits misfolding/aggregation of amyloid beta and tau Proteins (Alzheimer Disease)
    2. Oral formulation (138 mg/day) may improve cognition for 6 months in alzheimer Dementia
      1. However, no effect when combined with standard treatments (e.g. Aricept, Namenda)
      2. Hashmi (2023) Cureus 15(10):e46732 +PMID: 38022191 [PubMed]
  • Adverse Effects
  1. Common systemic effects
    1. Gastrointestinal upset
    2. Dysuria
    3. Blue-Green Urine Discoloration
  2. Serious
    1. Hemolytic Anemia
    2. Serotonin Syndrome (when combined with other serotonergic agents)
  • Drug Interactions
  1. Serotonergic agents (e.g. SSRI, St Johns Wort)
  2. Avoid within 2 weeks of surgery
  • Safety
  1. Unknown safety in pregnancy (avoid)
  2. Unknown safety in Lactation (avoid)
  • References
  1. (2025, Jan) Presc Insights 33(1):420116