Metaxalone API: what formulators ask before the first batch

Grade selection, packaging and the documentation set for muscle relaxant formulations.

What Metaxalone is used for

Metaxalone (CAS 1665-48-1) is an oxazolidinone-class skeletal muscle relaxant, used as the active ingredient in formulations for musculoskeletal pain and spasm. Full specification and sourcing detail is available on our Metaxalone API product page.

Bulk density and flow are part of the specification

Metaxalone’s powder characteristics — bulk and tapped density, flow properties — directly affect tableting and encapsulation performance downstream. Formulators evaluating a new supplier should ask for this data alongside standard assay and impurity results, not treat it as a secondary or optional check.

Grade selection that matches your filing

As with any API, confirm which pharmacopoeial grade (IP/BP/USP/EP) your filing requires before requesting a quote — grade determines the specific impurity limits and identification tests your regulatory submission needs to reference, and switching grades later means re-filing, not a simple substitution.

The question formulators most often skip: route and process consistency

A supplier’s synthetic route affects not just the impurity profile but also powder characteristics like particle morphology, which in turn affects flow and compressibility. Ask directly whether the manufacturing route and process parameters are fixed, and whether you would be notified of any change — this is a standard part of the buyer’s checklist for choosing an API manufacturer worth applying specifically here.

Packaging, storage and documentation before the first PO

• Batch-specific Certificate of Analysis including bulk/tapped density and flow data, not just assay
• Confirmed pharmacopoeial grade matching your filing
• Current GMP certification type and scope
• Route and process-consistency confirmation

Standard packing is 1 kg, 5 kg and 25 kg HDPE drums with double LDPE liners; other configurations on request. Metaxalone should be stored in a tightly closed container, protected from light and moisture, at controlled room temperature.

If you are also sourcing other pain-management or neurology APIs

Our Pregabalin API guide and Flupirtine Maleate sourcing guide cover two other compounds commonly sourced by pain-management formulators alongside Metaxalone, each with its own distinct specification and regulatory considerations.

A short checklist before you commit

• Bulk/tapped density and flow data requested alongside standard assay results
• Grade confirmed against your filing requirements
• Route and process consistency confirmed in writing
• Sample CoA reviewed before committing to a bulk order

Frequently asked questions

Why do bulk density and flow properties matter for this compound specifically? They directly affect downstream tableting and encapsulation performance — two batches with identical assay results can still behave differently in your formulation process if their powder characteristics differ.

Is Metaxalone available as a standard catalogue product or does it require custom development? It is available as a standard, already-manufactured API — see our API Manufacturing page for how standard sourcing works.

What should I ask for if I need a specific particle morphology or flow profile? Discuss your formulation requirements directly with the supplier before ordering — if your specification falls outside standard production parameters, this may require a contract manufacturing conversation rather than a standard order.

Is a sample available before I commit to a bulk order? Yes — evaluation samples are issued with a batch Certificate of Analysis so your QC team can test against your own specification before a bulk order.