Ramelteon is a synthetic melatonin receptor agonist used as an active pharmaceutical ingredient in sleep-related pharmaceutical formulations. It is identified by CAS 196597-26-9, molecular formula C₁₆H₂₁NO₂, and molecular weight 259.34 g/mol.
Ramelteon is the S-enantiomer of the molecule and acts primarily at the melatonin MT1 and MT2 receptors. TCI identifies Ramelteon as TAK-375 and describes it as a selective MT1 and MT2 receptor agonist.
Ramelteon is a small-molecule melatonin receptor agonist. Its stereochemical identity is important because the pharmaceutical substance is specifically the S-enantiomer.
The API is described as a white to almost-white powder to crystal. TCI reports a GC purity specification of NLT 98.0%, melting point of 114–118°C, and specific rotation of −55.0° to −60.0°.
| Parameter | Details |
|---|---|
| Product | Ramelteon |
| CAS | 196597-26-9 |
| Formula | C₁₆H₂₁NO₂ |
| Molecular Weight | 259.34 g/mol |
| Development Code | TAK-375 |
| Drug Class | Melatonin receptor agonist |
| Primary Targets | MT1 / MT2 |
| Stereochemistry | S-enantiomer |
| Physical Form | Solid |
| Appearance | White to almost-white powder to crystal |
| Melting Point | 114–118°C |
| Specific Rotation | −55.0° to −60.0° (c=1, CHCl₃) |
| Water Solubility | 11 mg/L at 25°C |
| Ethanol Solubility | Soluble |
TCI provides the physical-property and specification values above.
Ramelteon API is used in pharmaceutical development related to:
Ramelteon can be characterized using HPLC, GC, IR, NMR and mass spectrometry. TCI specifies minimum 98.0% GC purity, while FUJIFILM Wako lists 98.0% or higher by HPLC for its research-grade material.
Because Ramelteon is a defined S-enantiomer, specific rotation and stereochemical control are particularly relevant analytical characteristics.
Ramelteon manufacturing requires controlled synthesis and appropriate stereochemical control to ensure the required S-enantiomer is consistently obtained. Quality control can include identity testing, chromatographic purity, related substances, residual solvents, moisture and optical rotation.
TCI recommends storing Ramelteon in a cool and dark place below 15°C. TCI's current product page identifies the material as a solid and lists room-temperature handling with the recommendation for cool, dark storage.
FUJIFILM Wako recommends 2–10°C for its analytical/research product.
Typical API documentation can include:
Ramelteon is a stereochemically defined melatonin receptor agonist API requiring consistent control of identity, purity and stereochemical characteristics. Appropriate analytical testing and controlled storage help maintain consistent API quality for pharmaceutical manufacturing and development.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.20% |
| Heavy Metals | NMT 20 ppm |
| Individual Impurity | NMT 0.30% |
| Total Impurities | NMT 1.0% |
| Melting Point | 114–118°C |