Quick Facts
| CAS Number | 5907-38-0 |
|---|---|
| Molecular Formula | C13H16N3NaO4S · H2O |
| Molecular Weight | 333.34 (Sodium salt monohydrate) |
| Pharmacopoeia | CPV, EP |
| Packaging | 25 KG/DRUM |
Product Overview
Metamizole was first synthesized in 1920 by the German pharmaceutical company Hoechst AG (now part of Sanofi) as a derivative of antipyrine — one of the earliest synthetic analgesics. It was marketed under the brand name Novalgin and rapidly gained popularity across Europe and Latin America for its unique triple-action profile: potent analgesia, rapid antipyresis and smooth muscle spasmolysis — a combination no other drug class offered. The compound belongs to the pyrazolone chemical class and is known as dipyrone in many markets, analgin in /Eastern Europe/China and metamizole in Western Europe and pharmacopoeia nomenclature.
The mechanism of metamizole is multifaceted and still not fully characterized. The parent compound is a prodrug that hydrolyzes in the gastrointestinal tract to 4-methylaminoantipyrine (4-MAA), which is further metabolized to 4-aminoantipyrine (4-AA) — both active metabolites. These compounds inhibit cyclooxygenase (COX) enzymes in the central nervous system, activate the endogenous opioid and cannabinoid systems and directly relax smooth muscle through inhibition of calcium channels and phosphodiesterase. This multi-target pharmacology explains why metamizole is effective where pure COX inhibitors or pure opioids are not.
Metamizole's regulatory status is highly divergent globally: banned in the United States (FDA withdrawal 1977), UK, Sweden and approximately 30 other countries due to agranulocytosis risk, yet widely available over-the-counter in Germany, Spain, Brazil, India and most of Latin America, Africa, the Middle East and Asia. The risk of agranulocytosis is estimated at approximately 1-10 cases per million person-weeks of use — comparable to or lower than the GI bleeding risk from chronic NSAID use. This regulatory dichotomy has created a stable, regionally concentrated global API market where China and India supply the vast majority of metamizole sodium for the countries where it remains a primary analgesic.
In veterinary medicine, metamizole is one of the most commonly used injectable analgesics in swine and cattle production, particularly in China, Brazil and Eastern Europe. It is the drug of choice for MMA syndrome (mastitis-metritis-agalactia) in sows, gastrointestinal colic in cattle and acute fever management in food-producing animals. The veterinary metamizole market is substantial and growing alongside intensification of livestock production in developing regions. KingWish supplies GMP-certified metamizole sodium meeting CPV and EP standards.
Quality Specifications
| Assay (dried basis) | 99.0% - 101.0% (EP) |
|---|---|
| 4-Methylaminoantipyrine (impurity A) | ≤ 0.5% |
| 4-Formylaminoantipyrine (impurity B) | ≤ 0.2% |
| Sodium Content | 6.8% - 7.2% |
| Loss on Drying | 3.0% - 5.0% (monohydrate) |
| Solution Clarity and Color | Clear, colorless to slightly yellow |
| Heavy Metals | ≤ 10 ppm |
| Residual Solvents | Compliant with ICH Q3C |
| GMP Status | Manufactured under ICH Q7 GMP conditions |
Applications
- Pain management in swine and cattle: Injectable analgesic for colic, post-operative pain, MMA syndrome in sows and fever control in production animals.
- Gastrointestinal colic: Potent spasmolytic and analgesic for renal, biliary and gastrointestinal colic pain — a unique advantage over NSAIDs.
- Fever reduction in livestock: Rapid-acting antipyretic for acute febrile conditions in cattle, swine and equine patients.
- NSAID-alternative analgesic: Effective where NSAIDs are contraindicated due to GI ulceration risk, platelet inhibition, or renal impairment in dehydrated animals.
- Post-operative analgesia: IV/IM formulations for acute moderate-to-severe pain management in veterinary surgical recovery.
Sourcing Metamizole Sodium: Key Checks
Documentation
Request CoA with HPLC impurity profile — 4-methylaminoantipyrine is the key degradation marker. Verify sodium content, solution color and residual solvents. For EU markets, confirm CEP status. For veterinary use, CPV compliance.
Red Flags
Yellow to brown discoloration of solution indicates degradation. Elevated 4-methylaminoantipyrine above 0.5% suggests moisture exposure or improper storage. Sodium content outside 6.8-7.2% indicates inconsistent salt stoichiometry.
Packaging & Logistics
Standard: 25 KG/DRUM with airtight inner PE liner. Metamizole is hygroscopic — packaging must include desiccant. Store at 15-25 degrees Celsius, protected from light and moisture. Standard lead time 4-8 weeks.
Market Context
Globally bifurcated market: banned in ~30 countries but widely used in Latin America, Eastern Europe, Asia and Africa. Veterinary demand growing alongside livestock intensification. China and India dominate API production. Stable demand driven by unique triple-action profile.