What Is Fluralaner?
Fluralaner, CAS 864731-61-3, is an isoxazoline-class active ingredient with the molecular formula C22H17Cl2F6N3O3. It is supplied as a non-sterile API / intermediate – a raw material for the manufacture of formulated products – and is characterised by tight control of residual solvents, water, residue on ignition, heavy metals and assay.
The isoxazolines are a modern class of active ingredients; fluralaner is one of the best-known members. This guide covers the chemistry, production, specification and residual solvents, quality control, properties, applications, comparison within the class, regulatory documentation and supply. PolyBlueChem supplies Fluralaner to the specification below, with per-batch COA and SDS.
| CAS number | 864731-61-3 |
| Chemical class | Isoxazoline |
| Molecular formula | C22H17Cl2F6N3O3 |
| Form / grade | Non-sterile API / intermediate |
Chemistry and Structure
Fluralaner belongs to the isoxazoline class: its core is an isoxazoline ring (a five-membered ring containing one oxygen and one nitrogen), substituted with aromatic and halogenated groups. The molecule carries:
- An isoxazoline core – the defining structural feature of the class.
- Chlorine and fluorine substituents – the F6 and Cl2 in the formula; these strongly affect lipophilicity and stability.
- Amide and aromatic groups – the N3 and O3 in the formula come from the ring heteroatoms and the amide/ether functions.
The result is a relatively large, highly halogenated molecule (MW about 556 g/mol), which gives it the physical behaviour – low water solubility, high lipophilicity – that shapes its formulation and its handling as an API. The synthesis carries several organic solvents, which is why residual solvents are a key part of the specification.
How Fluralaner Is Produced
Fluralaner is made by a multi-step organic synthesis. The route builds the isoxazoline core and installs the halogenated aromatic substituents, then couples the fragments and purifies the product to API quality. In outline:
- Building the isoxazoline core – a nitrile oxide cycloaddition (or an equivalent route) forms the isoxazoline ring from suitable precursors.
- Installing the halogenated aryl groups – chlorinated and trifluoromethyl-bearing aromatic fragments are introduced.
- Coupling and amide formation – the fragments are joined; amide bonds are formed using common coupling chemistries (which is where solvents such as triethylamine, ethyl acetate and THF come in).
- Purification and isolation – the crude product is crystallised, filtered, washed and dried to the required purity, with the residual solvents driven down to specification.
Because the molecule is complex and carries multiple halogen atoms, the synthesis and purification are demanding – which is why the API is specified with both an assay and a set of residual-solvent limits rather than an assay alone.
Specifications
Fluralaner is supplied as a non-sterile API/intermediate to the following specification:
| Parameter | Specification |
|---|---|
| Strength | Non-sterile |
| Assay (calculated on the anhydrous basis, as C22H17Cl2F6N3O3) | 98.0 – 102.0% |
| Water content | Not more than 0.2% |
| Residue on ignition | Not more than 0.1% |
| Heavy metals | Not more than 20 ppm |
| Parameter | What it controls |
|---|---|
| Assay (98.0 – 102.0%) | Active content on the anhydrous basis; the primary potency check |
| Water content (0.2% max) | Moisture; affects stability, weighing and assay basis |
| Residue on ignition (0.1% max) | Inorganic residues |
| Heavy metals (20 ppm max) | Catalyst and reagent metal residues |
The assay is stated on the anhydrous basis, so the water content (0.2% max) matters directly to how the potency is calculated. A specification sheet and a per-batch certificate of analysis (COA) are available on request.
Residual Solvents
Because the synthesis uses several organic solvents, the specification sets limits on each of the main ones:
| Solvent | Specification |
|---|---|
| Triethylamine | 0.5% max |
| Methanol | 0.3% max |
| Ethyl acetate | 0.5% max |
| Tetrahydrofuran | 0.072% max |
Residual solvents are controlled because they are carried through the synthesis and can affect both the purity of the API and its suitability for the finished product. Residual-solvent limits are normally set with reference to the ICH Q3C guidance, which classifies solvents by their toxicological risk and sets permitted daily exposures; the limits above reflect the solvents used in this route and the customer’s specification.
| Solvent | Typical role in the synthesis |
|---|---|
| Triethylamine | Base / acid scavenger |
| Methanol | Reaction or crystallisation solvent |
| Ethyl acetate | Extraction and crystallisation solvent |
| Tetrahydrofuran | Reaction solvent |
Key Properties
| Property | Behaviour | Practical value |
|---|---|---|
| Class | Isoxazoline | A modern active-ingredient class |
| Molecular size | Large, halogenated (MW about 556) | Low water solubility; lipophilic |
| Form | Non-sterile API/intermediate | For formulated-product manufacture |
| Purity control | Assay plus residual solvents | Consistent, well-characterised material |
Applications
| Application | Role of Fluralaner |
|---|---|
| Pharmaceutical / veterinary manufacture | An active ingredient for the manufacture of formulated products, subject to registration and GMP requirements |
| Agrochemical manufacture | An active-ingredient raw material for crop-protection formulations, where permitted |
| Formulation development | As an API for developing products, subject to the applicable regulations |
This material is an active-ingredient raw material for manufacturing. Finished products must be made by appropriately licensed manufacturers; import, registration and use are governed by the regulations of the destination market.
Fluralaner and the Isoxazoline Class
Fluralaner is one of several isoxazoline active ingredients. They share the isoxazoline core but differ in substituents, which changes their physical properties and their regulatory and patent status.
| Aspect | Note |
|---|---|
| Shared core | Isoxazoline ring (one O, one N in a five-membered ring) |
| Differences | Halogen and aryl substituents; molecular weight; physical properties |
| Consequence | Different solubility, stability and formulation behaviour |
For a buyer, the choice within the class is a matter of the specific product being manufactured, its regulatory status and its patent position – not just chemical similarity. Confirm the exact active ingredient, its registration status and its documentation for your market.
Quality Control and Documentation
| Item | Note |
|---|---|
| Assay | 98.0 – 102.0% on the anhydrous basis |
| Residual solvents | Triethylamine, methanol, ethyl acetate, THF within limits |
| Water / residue on ignition / heavy metals | Controlled as per specification |
| COA | Per-batch certificate of analysis |
| SDS | Safety data sheet |
Buyers should agree the specification (including the residual-solvent limits) and check each batch COA against it.
Regulatory and Documentation
Fluralaner is an active-ingredient raw material, so its supply is regulated more heavily than an industrial chemical. This is a summary – not legal advice.
| Item | Note |
|---|---|
| Grade | Non-sterile API / intermediate, tested to the agreed specification |
| GMP | Active-ingredient manufacture is expected to follow GMP; buyers should confirm the relevant certification |
| COA / SDS | Per-batch COA and SDS |
| Regulatory documents | Additional documents may be needed for market registration – confirm availability |
| Market registration | Import, registration and use depend on the destination market’s rules |
Requirements vary widely by market and by product. Always confirm the grade, documentation and registration status for your specific use and destination before ordering.
Safety, Handling and Storage
Fluralaner is an active-ingredient raw material and must be handled as such. This section covers handling, not use.
- Handle as an API – use pharmaceutical-type handling: contained transfer, dust control, protective clothing and good industrial hygiene.
- Dust – avoid breathing the powder; use appropriate extraction.
- Segregation – store separately from other materials; keep sealed, cool and dry, away from light.
- No therapeutic or efficacy claims – this page describes a raw material for manufacturing; it is not medical or veterinary advice.
- Regulatory use only – supply, import and use are subject to the applicable regulations of the destination market.
Packaging, Logistics and Supply
| Item | Standard options |
|---|---|
| Packaging | 25 kg fibre drums with inner liner (or as agreed) |
| Documentation | Per-batch COA and SDS; further regulatory documents on request |
| Incoterms | FOB and CIF |
| Storage | Sealed, cool and dry, away from light |
As a specialty active-ingredient raw material, price depends on the complexity of the synthesis, the purity and the documentation provided. Buying on committed tonnage and confirming the grade and documents up front gives the best terms.
Residual Solvent Control and ICH Q3C
Residual solvents are organic liquids left in an API from its synthesis. Because they can affect safety and product quality, they are controlled rather than ignored. The international framework is ICH Q3C (Impurities: Guideline for Residual Solvents), which classifies solvents by toxicological risk and sets limits.
| Class (ICH Q3C) | Character | Examples in this route |
|---|---|---|
| Class 2 | Solvents to be limited (non-genotoxic animal carcinogens or suspected) | Methanol, tetrahydrofuran |
| Class 3 | Solvents with low toxic potential | Ethyl acetate, triethylamine |
The specification for fluralaner caps each of the main process solvents:
| Solvent | Limit |
|---|---|
| Triethylamine | 0.5% max |
| Methanol | 0.3% max |
| Ethyl acetate | 0.5% max |
| Tetrahydrofuran | 0.072% max |
Driving the solvents down is a function of the isolation and drying steps: good crystallisation and drying give a product that meets the limits, batch after batch. Buyers should confirm the residual-solvent limits they require and check them on the COA.
Handling a Lipophilic, Highly Halogenated API
Fluralaner is a large, highly halogenated molecule (MW about 556, with six fluorine and two chlorine atoms). Its physical behaviour shapes how it is handled and formulated.
| Property | Practical consequence |
|---|---|
| High molecular weight | Potency is expressed per unit mass; weighing accuracy matters |
| Halogenation (F6, Cl2) | Lipophilic; low water solubility |
| Low water solubility | Formulation may need solvents or special techniques |
| Fine powder form | Dust control and contained handling for an API |
Because the molecule is lipophilic and poorly water-soluble, formulation development usually focuses on how to deliver the active ingredient effectively (for example through solvents, lipid systems or specific dosage forms). That is a downstream activity for the finished-product manufacturer; as a raw-material supplier we focus on delivering a consistent, well-characterised API, with the water content and residual solvents controlled.
Why the Assay Is on the Anhydrous Basis
The specification states the assay calculated on the anhydrous basis (98.0 – 102.0% as C22H17Cl2F6N3O3). This means the assay is corrected for the water content, so the potency figure reflects the active molecule rather than the wet weight.
| Term | Meaning |
|---|---|
| As-is basis | Assay on the material as weighed (including water) |
| Anhydrous basis | Assay corrected to exclude water |
| Water content | 0.2% max here; used to convert between the two bases |
Because the water content is capped at 0.2%, the difference between the two bases is small, but the anhydrous basis is the standard way to report potency for an API and both the water content and the assay should be read together on the COA.
Frequently Asked Questions about Fluralaner
What is Fluralaner?
Fluralaner (CAS 864731-61-3) is an isoxazoline-class active ingredient, supplied as a non-sterile API/intermediate for manufacturing.
What is the CAS number of Fluralaner?
864731-61-3; the formula is C22H17Cl2F6N3O3.
Why are residual solvents specified?
Because the synthesis uses several organic solvents; limits (triethylamine, methanol, ethyl acetate, THF) control what is carried through, with reference to ICH Q3C guidance.
What is the assay?
98.0 – 102.0%, calculated on the anhydrous basis as C22H17Cl2F6N3O3.
Is this a finished product?
No – it is an active-ingredient raw material for manufacturing. Finished products must be made by licensed manufacturers, subject to registration.
How is it supplied?
Non-sterile, in fibre drums, with per-batch COA and SDS; further documents on request.
Related reading
- Fluralaner: an isoxazoline-class active ingredient
- Fluralaner residual solvents and quality control
- How to buy Fluralaner API: grade, documents and regulatory
- Fluralaner (CAS 864731-61-3) – product page
PolyBlueChem supplies Fluralaner (CAS 864731-61-3) to the specification above, with per-batch COA and SDS. Contact us with your application, tonnage, documentation requirements and delivery port.