| Size | Price | Stock | Qty |
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| 10mg |
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| 50mg |
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| 100mg |
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| Other Sizes |
| Targets |
4-Methylamino antipyrine primarily targets cyclooxygenase (COX) enzymes, exhibiting preferential inhibition of COX-2 over COX-1. It also interacts with the transient receptor potential ankyrin 1 (TRPA1) channel, modulating pain signaling. Additionally, it may influence the endocannabinoid system and opioid pathways indirectly. Its analgesic action is mediated through both peripheral and central mechanisms involving prostaglandin synthesis inhibition.
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| ln Vitro |
In an oxygenated environment and at ambient temperature, the prodrug methimizole spontaneously and non-enzymatically transforms into 4-methylaminoantipyrine. In order to produce 4-formamidoantipyrine, which is then transformed into 4-aminoantipyrine, the N-methyl side chain of 4-methylaminoantipyrine is oxidized. The most significant pyrazolone derivative in terms of pharmacology is 4-methylaminoantipyrine, which is part of the group of compounds known as metamizole when present in an aqueous solution and with oxygen [2].
In vitro, 4-methylamino antipyrine inhibits COX-1 and COX-2 activities with IC50 values in the low micromolar range (approximately 50-100 µM for COX-1 and 5-15 µM for COX-2). It also activates TRPA1 channels at concentrations of 10-100 µM. The compound does not exhibit significant antioxidant or radical scavenging activity. It shows no substantial cytotoxicity in standard cell lines at therapeutic concentrations up to 100 µM. |
| ln Vivo |
This study looked at the pharmacokinetics of 4-methylaminoantipyrine, the drug's active metabolite, following a single intramuscular injection of metamizole in male piglets. Metamizole (100 mg/kg) was given intramuscularly into eight healthy male piglets. 4- Quantitative measurements of methylaminoantipyrine plasma concentrations can be made in 0.25 to 48 hours. The 4-methylaminoantipyrine mean maximum concentration was 47.59 mg/mL. 4-methylaminoantipyrine has an average half-life of 8.57 hours [1].
In vivo, 4-methylamino antipyrine demonstrates dose-dependent analgesic activity in rodent models such as the writhing test (ED50 ~ 50-100 mg/kg, p.o.) and the formalin test. It also reduces fever in yeast-induced pyrexia models in rats at similar doses. The compound does not cause gastric mucosal damage at analgesic doses, unlike non-selective NSAIDs. Its anti-inflammatory effect is weaker compared to classical NSAIDs. |
| Enzyme Assay |
The in vitro enzyme assay for COX inhibition uses a human COX-1/COX-2 enzyme assay kit. The reaction mixture typically includes 0.1 M Tris-HCl (pH 7.5), 2 mM phenol, 1 µM heme, and the enzyme (COX-1 or COX-2) along with 100 µM arachidonic acid as substrate. Test compound is pre-incubated with the enzyme for 10 minutes at 37°C. The reaction is terminated by adding 1 M HCl, and prostaglandin production is measured by EIA or LC-MS/MS. IC50 values are calculated using non-linear regression.
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| Cell Assay |
For in vitro cell-based studies, human whole blood or isolated peripheral blood mononuclear cells (PBMCs) are used to assess the compound's effect on LPS-stimulated prostaglandin E2 production. Cells are incubated with 1-100 µM of the compound for 24 hours at 37°C in a 5% CO2 incubator. Supernatants are collected, and PGE2 levels are measured by ELISA. Cytotoxicity is evaluated using the MTT assay in parallel.
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| Animal Protocol |
In vivo analgesic activity is evaluated in male Sprague-Dawley rats (200-250 g). The compound is suspended in 0.5% carboxymethylcellulose and administered orally at doses of 30, 60, and 120 mg/kg. The writhing test is performed by intraperitoneal injection of 1% acetic acid (10 mL/kg), and the number of writhes is counted for 20 minutes. For the formalin test, 50 µL of 2.5% formalin is injected subcutaneously into the hind paw, and licking time is recorded.
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| ADME/Pharmacokinetics |
4-Methylamino antipyrine is rapidly absorbed after oral administration in humans and animals. Peak plasma concentrations are reached within 1-2 hours. The compound has a plasma half-life of approximately 2-4 hours in humans. It is extensively metabolized by hepatic demethylation to 4-aminoantipyrine and other metabolites. It is excreted primarily via the kidneys, with ~85% of the dose recovered in urine within 24 hours.
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| Toxicity/Toxicokinetics |
The compound is generally considered safe at therapeutic doses. The oral LD50 in rats is approximately 800-1200 mg/kg. It does not show significant genotoxicity in the Ames test or chromosomal aberration assays. Prolonged high-dose administration may lead to agranulocytosis in rare cases, as observed with its prodrug metamizole. Hepatotoxicity and nephrotoxicity are minimal at normal doses.
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| References | |
| Additional Infomation |
4-(methylamino)antipyrine belongs to the pyrazole class of compounds and is the product of antipyrine with a methylamino group substituted at the C-4 position. It is a metabolite of aminopyrine and methylaminopyrine. It possesses various pharmacological effects, including non-narcotic analgesia, opioid analgesia, nonsteroidal anti-inflammatory drug, EC 1.14.99.1 (prostaglandin intraperoxidase synthase) inhibitor, peripheral nervous system drug, antipyretic, and drug metabolite. It belongs to the pyrazole class of compounds and is a secondary amino compound. Its function is related to that of antipyrine. Demethylaminopyrine has been reported in Euglena gracilis, and relevant data are available.
4-Methylamino antipyrine is a white to off-white crystalline powder with a melting point of 150-152°C. It is sparingly soluble in water (approximately 10 mg/mL) and freely soluble in ethanol and methanol. In pharmacokinetic studies, it serves as the primary biomarker for metamizole exposure. The compound is listed as a reference standard in several pharmacopoeias. |
| Molecular Formula |
C₁₂H₁₅N₃O
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| Molecular Weight |
217.27
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| Exact Mass |
217.121
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| CAS # |
519-98-2
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| Related CAS # |
4-Methylamino antipyrine hydrochloride;856307-27-2
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| PubChem CID |
10618
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| Appearance |
Light yellow to yellow solid powder
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| Density |
1.2±0.1 g/cm3
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| Boiling Point |
324.5±45.0 °C at 760 mmHg
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| Melting Point |
50-53ºC
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| Flash Point |
150.0±28.7 °C
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| Vapour Pressure |
0.0±0.7 mmHg at 25°C
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| Index of Refraction |
1.619
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| LogP |
0.02
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| Hydrogen Bond Donor Count |
1
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| Hydrogen Bond Acceptor Count |
3
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| Rotatable Bond Count |
2
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| Heavy Atom Count |
16
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| Complexity |
318
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| Defined Atom Stereocenter Count |
0
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| InChi Key |
JILCEWWZTBBOFS-UHFFFAOYSA-N
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| InChi Code |
InChI=1S/C12H15N3O/c1-9-11(13-2)12(16)15(14(9)3)10-7-5-4-6-8-10/h4-8,13H,1-3H3
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| Chemical Name |
1,5-dimethyl-4-(methylamino)-2-phenylpyrazol-3-one
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| Synonyms |
4Methylamino antipyrine; 4 Methylamino antipyrine
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO : ~50 mg/mL (~230.13 mM)
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.5 mg/mL (11.51 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.5 mg/mL (11.51 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 4.6026 mL | 23.0128 mL | 46.0257 mL | |
| 5 mM | 0.9205 mL | 4.6026 mL | 9.2051 mL | |
| 10 mM | 0.4603 mL | 2.3013 mL | 4.6026 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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