Metamizole sodium's IC50 value for blocking COX-3 in insect cells is 52 μM, while its concentration for blocking COX-1 is 6.6 times greater [2]. The growth of pancreatic cancer cells is markedly inhibited by methimizole (1–500 μM; 48 hours) [3].

Rats treated with 500 mg/kg of metamizole sodium intraperitoneally twice a day for seven days show less development of neuropathic pain symptoms [4].

Cell proliferation assay [3]
Cell Types: Pancreatic cancer cell lines PaTu 8988t and Panc-1
Tested Concentrations: 1 μM, 10 μM, 100 μM, 250 μM, 500 μM
Incubation Duration: 48 hrs (hours)
Experimental Results: PaTu 8988t Dramatically inhibited cell proliferation cells line; 1-250 μM Dramatically inhibits cell proliferation of pancreatic cancer cell line Panc-1.

Animal/Disease Models: Male Wistar rat (270-300 g) with peripheral neuropathic pain [4]
Doses: 500 mg/kg
Route of Administration: intraperitoneal (ip) injection twice (two times) daily for 7 days
Experimental Results: Reduction of pro-nociceptive leukocytes The expression of interleukins (IL-1beta) and chemokines (CCL2, CCL4 and CCL7) in the DRG was measured 7 days after sciatic nerve injury.

Effects During Pregnancy and Lactation
◉ Overview of Lactation Use
After a mother takes metamizole, metamizole and its metabolites appear in large quantities in breast milk. Metamizole can also be detected in the blood and urine of breastfed infants and may have pharmacological effects on them. There has been one case of cyanosis in a breastfed infant, which was thought to be caused by metamizole in breast milk. The drug and its metabolites are cleared from breast milk within 48 hours after administration.
Due to adverse reactions including agranulocytosis, the U.S. Food and Drug Administration (FDA) has not approved metamizole for marketing in the United States, Canada, and many European countries. However, in other countries, metamizole is widely used during childbirth and lactation. The European Medicines Agency recommends against the use of metamizole by breastfeeding women; however, several drug advisory centers in Israel disagree. One manufacturer recommends discontinuing breastfeeding within 48 hours of administration. There are safer alternatives for pain relief during lactation.
◉ Effects on Breastfed Infants
A 42-day-old breastfed infant experienced two episodes of cyanosis within 30 minutes of his mother taking three doses of 500 mg metamizole, administered 18 hours, 7 hours, and 2 hours before the first episode. The third episode occurred 24 hours after admission. Metamizole was detected in the mother's breast milk and in the infant's serum and urine 24 hours after the last dose. No other cause of the cyanosis was found besides metamizole. After the mother discontinued metamizole, the infant did not experience any further cyanosis episodes until age 3. This reaction is thought to be possibly caused by metamizole in breast milk.
In a double-blind study, mothers at least 3 days postpartum who requested analgesia due to postpartum uterine pain were randomly assigned to receive either 1 gram of metamizole or a placebo. Infants born to mothers receiving the placebo experienced fewer and shorter crying episodes within 14 hours of administration. This effect was more pronounced in infants fed on demand than in those fed on a schedule. While this study appears to suggest that metamizole in breast milk has a pharmacological effect on infants, there is currently no clear explanation for the changes in infant behavior. A multicenter case-control study in Brazil compared 231 children under 2 years of age with leukemia and 411 children with various other non-malignant diseases. Researchers interviewed mothers to determine their use of analgesics during pregnancy and lactation. Breastfeeding mothers who took metamizole within three months postpartum had a 2-fold increased risk of acute lymphoblastic leukemia in their children and a 3.87-fold increased risk of MLL gene rearrangement in infants under one year old. ◉ Effects on lactation and breast milk: As of the revision date, no relevant published information was found.

[1]. A Jasiecka, et al. Pharmacological characteristics of metamizole. Pol J Vet Sci. 2014;17(1):207-14.
[2]. N V Chandrasekharan, et al. COX-3, a cyclooxygenase-1 variant inhibited by acetaminophen and other analgesic/antipyretic drugs: cloning, structure, and expression. Proc Natl Acad Sci U S A. 2002 Oct 15; 99(21): 13926-13931.
[3]. Manuela Malsy, et al. Effects of metamizole, MAA, and paracetamol on proliferation, apoptosis, and necrosis in the pancreatic cancer cell lines PaTu 8988 t and Panc-1. BMC Pharmacol Toxicol. 2017 Dec 6;18(1):77.
[4]. Renata Zajaczkowska, et al. Metamizole relieves pain by influencing cytokine levels in dorsal root ganglia in a rat model of neuropathic pain. Pharmacol Rep. 2020 Oct;72(5):1310-1322.

Metamizole sodium is the organic sodium salt of antipyrine, with a methyl (sulfonic acid methyl)amino group substituted at the C-4 position. It is commonly used as a potent analgesic and antipyretic. It possesses various pharmacological effects, including non-narcotic analgesia, antirheumatic drug, peripheral nervous system drug, antipyretic, prodrug, cyclooxygenase 3 inhibitor, and anti-inflammatory agent. It contains the methylaminopyrine (1-) structure. It is a drug with analgesic, anti-inflammatory, and antipyretic effects. It is sodium sulfonate of aminopyrine.

C13H16N3NAO4S

333.3386

333.075

68-89-3

Metamizole sodium hydrate;5907-38-0

522325

White to off-white solid powder

187ºC

1.504

0

6

4

22

552

0

S(C([H])([H])N(C([H])([H])[H])C1C(N(C2C([H])=C([H])C([H])=C([H])C=2[H])N(C([H])([H])[H])C=1C([H])([H])[H])=O)(=O)(=O)[O-].[Na+]

DJGAAPFSPWAYTJ-UHFFFAOYSA-M

InChI=1S/C13H17N3O4S.Na/c1-10-12(14(2)9-21(18,19)20)13(17)16(15(10)3)11-7-5-4-6-8-11;/h4-8H,9H2,1-3H3,(H,18,19,20);/q;+1/p-1

sodium;[(1,5-dimethyl-3-oxo-2-phenylpyrazol-4-yl)-methylamino]methanesulfonate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)