Levothyroxine

Levothyroxine Sodium – Technical Information (Reference Only)

Chemical Information

• Synonyms:
  • L-Thyroxine sodium
  • Sodium 3,5,3′,5′-tetraiodothyronine
  • Eltroxin, Synthroid, Levoxyl (brand names)

• Formal Name:
  Sodium salt of L-thyroxine (T4)

• CAS Number:
  51-48-9 (Levothyroxine)

• Molecular Formula:
  C15H10I4NNaO4

• Molecular Weight:
  798.86 g/mol (sodium salt)

• Chemical Class:
  Thyroid hormone replacement

• Appearance:
  White to off-white crystalline powder

Structural / Spectral Information

• SMILES:
  C1=CC(=C(C=C1C[C@@H](C(=O)O)N)I)OCC2=CC(=C(C=C2I)O)I.[Na+]

• InChI:
  InChI=1S/C15H11I4NO4.Na/...

• InChI Key:
  YJQSZQMKZACNKS-QNHCQMGHSA-N

• λmax (UV):
  ~224 nm, 275 nm, 288 nm

Solubility

• Water: Slightly soluble

• Methanol: Soluble

• Ethanol: Soluble

• DMSO: Soluble

• Acidic/alkaline aqueous solutions: Soluble with pH adjustment

Formulation

• Supplied as Levothyroxine Sodium USP/EP grade

• Purity: ≥98% (research/analytical grade)

• Tablet strengths (commonly pharmaceutical use): 25 µg, 50 µg, 75 µg, 100 µg, 125 µg, 150 µg, 175 µg, 200 µg, 300 µg

• Also available as injectable solution in some clinical settings

Storage & Stability

• Storage Temperature: 2–8 °C (refrigerated) recommended for long-term stability, otherwise room temperature in sealed, light-protected container

• Shipping: Ambient temperature acceptable if dry and protected

• Stability: Stable for ≥2–3 years under recommended conditions

Safety / Handling

• Low acute toxicity

• Avoid inhalation of powder

• Use PPE (gloves, mask) when handling bulk material

• Sensitive to light and moisture; degrade if improperly stored