Eplontersen is a transthyretin (TTR)-directed antisense oligonucleotide (ASO) developed for the treatment of hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis). It is a chemically modified, N-acetylgalactosamine (GalNAc)-conjugated antisense oligonucleotide designed to target TTR messenger RNA in hepatocytes.
Eplontersen is a GalNAc-conjugated 2′-O-2-methoxyethyl-modified chimeric gapmer antisense oligonucleotide containing a mixed phosphorothioate and phosphate diester backbone. The GalNAc ligand enables targeted delivery of the oligonucleotide to hepatocytes, where it selectively binds to TTR mRNA. This promotes degradation of both mutant and wild-type TTR mRNA and reduces the production of transthyretin protein in the liver.
Eplontersen is supplied as eplontersen sodium in the marketed pharmaceutical product. Eplontersen sodium is described as a white to yellow solid and is freely soluble in water and phosphate buffer. Its molecular formula is C₂₉₆H₄₁₇N₇₇O₁₅₆P₂₀S₁₃Na₂₀, with a molecular weight of 9046.1 Da.
Eplontersen selectively binds to transthyretin messenger RNA within hepatocytes. The resulting degradation of TTR mRNA decreases the synthesis and secretion of both mutant and normal transthyretin protein. Lower circulating TTR levels may reduce the formation and accumulation of transthyretin amyloid deposits associated with hereditary ATTR amyloidosis.
Eplontersen is indicated for the treatment of hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis) in adults with Stage 1 or Stage 2 polyneuropathy in the European product information. The recommended dose of Wainzua is 45 mg administered by subcutaneous injection once monthly.
Eplontersen differs from conventional small-molecule APIs because it is a complex therapeutic oligonucleotide. Its characterization relies on analytical techniques appropriate for oligonucleotide identity, sequence integrity, molecular mass, purity and related substances. EMA documentation describes characterization using techniques including NMR, high-resolution mass spectrometry, IP-HPLC-TOF-MS, fragmentation analysis, elemental analysis and UV spectrometry.
Eplontersen sodium is freely soluble in water and phosphate buffer/PBS. The active substance is described as an amorphous solid, with no polymorphic form reported in the EMA assessment.
The marketed finished product is a sterile, preservative-free aqueous solution for subcutaneous injection. Each dose contains 45 mg eplontersen equivalent to 47 mg eplontersen sodium in 0.8 mL.
Eplontersen API intended for pharmaceutical development and manufacturing should be evaluated against the applicable approved specification. Important quality attributes for an oligonucleotide substance include identity, molecular mass, full-length product content, purity, sequence-related impurities, degradation products, residual solvents or reagents, water content, elemental impurities and other applicable product-specific quality attributes.
The storage conditions for eplontersen drug substance should follow the applicable manufacturer's approved specification and stability data. For the marketed WAINUA finished product, the FDA label specifies refrigerated storage at 2°C to 8°C, protection from light, and no freezing or exposure to heat.
A reliable eplontersen API supplier should provide appropriate quality documentation, batch traceability, analytical data and regulatory documentation suitable for pharmaceutical development and manufacturing. Customers should verify the applicable specification, certificate of analysis and regulatory documentation for the intended application before procurement.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.2% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 2.0 – 4.0 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |
| Melting Point | 150°C – 154°C |