Milsaperidone is a pharmaceutical active ingredient belonging to the atypical antipsychotic class and is structurally classified as a piperidinyl-benzisoxazole derivative. It is also known as (S)-hydroxy iloperidone and has the molecular formula C₂₄H₂₉FN₂O₄ with a molecular weight of 428.50 g/mol. Milsaperidone is described as a white to off-white finely crystalline powder.
Milsaperidone has activity at dopamine and serotonin receptor systems and is associated with the pharmacological management of psychiatric disorders. In February 2026, the U.S. FDA approved milsaperidone under the brand name Bysanti for schizophrenia and for the acute treatment of manic or mixed episodes associated with bipolar I disorder in adults.
Milsaperidone is the active pharmaceutical ingredient of Bysanti and is chemically related to iloperidone. FDA substance records identify milsaperidone by CAS Number 501373-88-2 and FDA UNII 7SV1ZOG031. Its systematic chemical name is associated with the (αS)-stereoisomer of the compound.
The compound is relevant to pharmaceutical research and manufacturing involving atypical antipsychotic medicines. Its chemical identity, stereochemistry and analytical characterization are important considerations for API quality control and pharmaceutical development.
Milsaperidone is associated with atypical antipsychotic pharmaceutical applications. Following its U.S. approval in February 2026, milsaperidone is indicated for the treatment of schizophrenia and for the acute treatment of manic or mixed episodes associated with bipolar I disorder in adults.
Milsaperidone is also being investigated in clinical development for additional psychiatric applications, including as adjunctive therapy in major depressive disorder. A Phase 3 clinical study is registered for this application.
Quality evaluation of Milsaperidone API should include appropriate identity, assay, purity and impurity testing using validated analytical procedures. Depending on the applicable specification, analytical characterization may include chromatographic analysis, identification testing, water or moisture determination and assessment of specified and unspecified impurities.
The final release specification should be based on the applicable customer, regulatory and manufacturing requirements rather than assumed generic limits.
Milsaperidone API should be stored and handled according to the applicable approved product/API specification, stability data and safety documentation. Appropriate controls should be maintained to protect the material from conditions that could adversely affect its quality or stability.
For commercial pharmaceutical use, storage conditions should follow the manufacturer's approved specification and applicable regulatory requirements.
Milsaperidone API can be supplied in packaging appropriate for pharmaceutical raw materials and the required quantity. Packaging configuration should be selected to protect the material from contamination, moisture and other environmental factors during storage and transportation.
Available pack sizes and packaging configurations should be confirmed according to project and customer requirements.
Milsaperidone received its first U.S. approval in February 2026 for schizophrenia and acute manic or mixed episodes associated with bipolar I disorder in adults. It is also undergoing clinical evaluation for other potential psychiatric applications.
Regulatory status can vary by country, and product availability or intended use should always be evaluated against the applicable local regulatory framework.
Milsaperidone is an atypical antipsychotic active pharmaceutical ingredient and a piperidinyl-benzisoxazole derivative.
The CAS number of Milsaperidone is 501373-88-2.
The molecular formula is C₂₄H₂₉FN₂O₄.
The molecular weight is 428.50 g/mol.
Milsaperidone is described in the U.S. prescribing information as a white to off-white finely crystalline powder.
Milsaperidone is used as an active pharmaceutical ingredient in medicines for schizophrenia and the acute treatment of manic or mixed episodes associated with bipolar I disorder in adults in the United States.
Milsaperidone is chemically related to iloperidone and is described in scientific and regulatory sources as an active metabolite of iloperidone. They are distinct chemical substances and should not be treated as interchangeable APIs.
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 20 ppm |
| pH (1% Solution) | 5.0 – 7.0 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 2.0% |
| Water Content | NMT 1.0% |
| Specific Rotation | +20° to +30° |
| Melting Point | 165°C – 170°C |
| Solubility | Slightly soluble in water; soluble in acidic aqueous media; solubility is pH-dependent |