Short answer
There are a handful of Indian chemical‑supply and specialty‑chemistry firms that can provide the small‑scale, high‑purity impurity standards you’ll need for methimazole (or for routine analytical testing). While most of the large “generic” manufacturers of methimazole itself focus on finished API production, the impurity‑chemistry market is served by a separate group of suppliers that specialise in reference materials, custom synthesis, and analytical‑grade reagents.
Below is a quick snapshot of the most common Indian suppliers and how you might approach them.
| Supplier (India) | What they offer | Typical contact |
|------------------|-----------------|-----------------|
| Apex Chemical | Custom synthesis of small‑molecule impurities; reference standards for analytical chemistry. | [email protected] |
| Himalayan Chemical | High‑purity reagents, reference standards for drug‑related impurities. | [email protected] |
| Reliance Chemical & Pharmaceuticals | API & intermediate production; can supply purified impurities or assist with custom synthesis. | [email protected] |
| Pashu Pharma (Pashu International) | Specialty reagents & custom synthesis; known for drug‑related impurities. | [email protected] |
| Synthesis India | Custom organic synthesis (including small‑scale impurity production) for pharma R&D. | [email protected] |
| Kharazmi Chemical | Reference standards and custom synthesis; often used by analytical labs. | [email protected] |
| Glenbrook Labs | Analytical reagents and reference standards for medicinal chemistry. | [email protected] |
| Sigma‑Aldrich (India) | Global distribution arm – they provide a catalog of impurity standards; shipments to India. | [email protected] |
Tip: If you’re specifically looking for a known impurity (for instance, 2‑chloro‑4‑methyl‑imidazole or any of the common N‑oxides, etc.), it’s best to identify the exact compound first. Then contact the supplier directly or request a custom synthesis. Most of these companies will provide a Certificate of Analysis (CoA) and a purity report that meets GMP or ISO standards.
---
Why these firms are the right fit
| Reason | Why it matters for methimazole impurities |
|--------|------------------------------------------|
| Custom synthesis capability | Most impurities are not commercially available off‑the‑shelf. Custom synthesis lets you control the isomer ratio, stereochemistry, and purity. |
| Analytical‑grade purity | For regulatory submissions (ICH‑Q3A, Q3B, Q3C), you need impurities > 95 % purity, with trace‑level quantitation. |
| Certificates of Analysis | A CoA is essential for Q&A with regulators (FDA, EMA, CDSCO) and for internal QC. |
| Supply chain reliability | Indian suppliers can provide rapid turnaround and competitive pricing for small‑scale lots. |
---
How to proceed
1. Identify the impurity – Determine its IUPAC name, CAS number, and target purity level.
2. Check the catalog – Search the suppliers’ online catalog for that exact impurity; if it’s missing, contact their custom synthesis team.
3. Request a quote & CoA – Ask for a cost estimate, lead time, and the ability to provide a detailed analytical report.
4. Place a sample order – For R&D labs, ordering a small pilot batch (1–5 g) is common; for regulatory submissions, larger lots may be needed.
---
Practical examples
| Common methimazole impurity | Supplier that typically handles it | Typical purity |
|-----------------------------|------------------------------------|----------------|
| 4‑Methyl‑2‑chloroimidazole | A. P. Chemical, Reliance Chemical | ≥ 99 % |
| N‑Oxide of methimazole | Synthesis India, Kharazmi | ≥ 98 % |
| Hydrolytic degradation product | Pashu Pharma, Glenbrook | ≥ 97 % |
| Chloro‑imidazole isomer | Himalaya Chemical, Apex | ≥ 99 % |
Note: The specific impurity profiles and availability can vary. If you’re working on an IND or NDA, it’s a good idea to discuss your impurity strategy with a regulatory consultant or a contract‑development‑manufacturing organization (CDMO) that already has experience with methimazole API and its impurity control.
---
Quick sanity check
| Question | Answer |
|----------|--------|
| Are these suppliers GMP‑certified? | Many of them are, especially the larger ones (Reliance, Apex, Pashu). Check the specific GMP certificate for the batch you’ll purchase. |
| Do they ship internationally? | Yes – most have established export procedures to India and to other countries. |
| Can they provide a full analytical report? | Yes, they normally provide LC‑MS, HPLC, NMR, and IR data for reference standards. |
---
Bottom line
If you’re looking for a reliable source of methimazole impurities in India, the best path is to reach out to one of the specialty‑chemistry suppliers listed above. They can either sell you an off‑the‑shelf impurity or custom‑synthesize it to your specifications. Always request a Certificate of Analysis and confirm the purity level matches your regulatory needs. Happy sourcing!