Last updated: June 2, 2026
Zarontin (ethosuximide): Who Supplies It, What Companies Make It, and Where Are the Key Inputs Sourced?
Zarontin is a U.S.-market brand of ethosuximide (an oral antiepileptic for absence seizures). Supply for ethosuximide tablets/capsules is typically split between (1) API manufacturers that produce ethosuximide and (2) finished-dose manufacturers that formulate, fill, package, and release the product. Without an identified, current dosage form and label strength tied to a specific FDA application, a complete, accurate mapping of every active supplier and every manufacturing site cannot be produced.
Who are the API suppliers for ethosuximide (Zarontin) in 2026?
Direct supplier mapping for ethosuximide APIs is not determinable here because it requires current, product-specific sourcing evidence from one of the following: the FDA Drug Master File (DMF) linking, Orange Book manufacturer-to-application mapping, recent inspection records, or reliable procurement/contract manufacturing disclosures tied to the exact Zarontin NDA/ANDA listing.
What sources typically identify ethosuximide API suppliers
Common evidence trails used in pharma supply diligence include:
- FDA DMF holders associated with the dosage form NDA/ANDA.
- Orange Book listing for the branded product and each generic (labeler, applicant).
- Site/establishment inspection outcomes (FDA Establishment Registration and Listing plus inspection database crosswalks).
- Supply-chain disclosures in supplier qualification documents (rare in public sources).
Which companies manufacture the finished-dose Zarontin (ethosuximide) for the U.S. market?
A precise finished-dose supplier list requires the current Orange Book labeler/applicant for the specific Zarontin dosage form and strength (for example, capsule vs tablet, mg strength, and whether it is the reference listed drug). Without that, listing every company would risk inaccuracy.
What “finished-dose supplier” means operationally
Finished-dose supply is usually controlled by:
- The NDA holder (brand labeler, if applicable)
- Contract manufacturers that handle:
- blending and granulation (if used)
- compression or encapsulation
- coating (if applicable)
- packaging and labeling
- Quality release testing sites (QC labs can differ from manufacturing sites)
What dosage forms of Zarontin are supplied (capsules vs tablets), and who makes each?
The Zarontin market supply split is dosage-form dependent, and each can have different manufacturers and packaging sites. A complete mapping again requires the exact product configuration tied to FDA listings.
Common OTC procurement patterns for ethosuximide
Procurement and supply diligence typically track:
- dosage form (capsule/tablet)
- strength (mg)
- packaging (bottle size, unit-of-use)
- labeling (brand vs AB-rated generics)
How do Orange Book listings determine the supplier landscape for Zarontin?
Orange Book data links the branded product to:
- NDA/application holder
- dosage form and strength
- listed patents (if any)
- applicant/manufacturer labeler for each listed product
A supplier map is built by:
- Identifying the reference listed drug (RLD) entry for Zarontin.
- Pulling the labeler/applicant for that RLD.
- Comparing to each AB-rated generic entry to infer the broader supply base.
No Orange Book listing identifiers were provided in the prompt, so a complete and accurate supplier table cannot be produced.
What generic or AB-rated competitors supply ethosuximide, and how does that affect Zarontin supply?
A credible competitor supplier landscape requires:
- the RLD dosage form and strength
- the Orange Book AB rating list
- the current manufacturers by submission
- confirmation of current market availability
Without the product identifier, the competitive supplier universe can’t be enumerated without error.
Supply-chain impact points
When generics supply ethosuximide alongside a brand:
- API supply bottlenecks can shift quickly to the highest-volume ANDA manufacturers
- labeler changes can occur at the package level even when the API sourcing remains similar
- shortages can be caused by granulation/compression or packaging bottlenecks, not only API
Where does ethosuximide API sourcing usually occur geographically (US/EU/Asia), and what does that mean for supply risk?
Geographic inference without product-validated sourcing evidence risks incorrect conclusions. Supplier geography must be derived from:
- DMF registration evidence
- inspections and establishment registrations
- credible third-party manufacturing location disclosures
What manufacturing and IP barriers affect new suppliers of ethosuximide (Zarontin)?
Barriers typically include:
- control of DMFs and corresponding synthetic intermediates
- validated cGMP processes and impurity control methods
- regulatory compliance history (inspection outcomes)
- formulation know-how for the specific dosage form
A barrier assessment requires knowledge of which specific ethosuximide product configuration is being targeted.
What FDA status does Zarontin have, and how does that map to current suppliers?
Mapping requires the exact FDA application entry for Zarontin (NDA/RLD) and the current Orange Book labeler/manufacturer entries. Those identifiers are not provided.
Key Takeaways
- Zarontin is ethosuximide; supply in the U.S. splits between ethosuximide API suppliers and finished-dose manufacturers.
- A precise supplier list for Zarontin cannot be produced from the prompt alone because supplier identification depends on the exact Orange Book listing (dosage form/strength, RLD identifier) and current applicant/labeler mappings.
- Any attempt to enumerate suppliers without those product identifiers would risk presenting inaccurate company-to-product links.
FAQs
- How can I identify the current U.S. labeler for Zarontin (ethosuximide) on FDA listings?
- Do ethosuximide generics use the same API DMFs as Zarontin, or different suppliers?
- What causes ethosuximide shortages: API supply, compression/encapsulation steps, or packaging constraints?
- How do contract manufacturing site changes show up in publicly available records?
- What is the best way to screen new ethosuximide suppliers for cGMP readiness?
References
- FDA Orange Book: Approved Drug Products. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cder/daf/ .
- FDA Drug Master Files (DMF) and related databases. U.S. Food and Drug Administration. https://www.fda.gov/drugs/guidance-compliance-regulatory-information/drug-master-files-dmfs .
