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2D Structure
Also known as: 61-73-4, Basic blue 9, Methylthioninium chloride, Solvent blue 8, Swiss blue, Chromosmon
Molecular Formula
C16H18ClN3S
Molecular Weight
319.9  g/mol
InChI Key
CXKWCBBOMKCUKX-UHFFFAOYSA-M
FDA UNII
8NAP7826UB

A compound consisting of dark green crystals or crystalline powder, having a bronze-like luster. Solutions in water or alcohol have a deep blue color. Methylene blue is used as a bacteriologic stain and as an indicator. It inhibits GUANYLATE CYCLASE, and has been used to treat cyanide poisoning and to lower levels of METHEMOGLOBIN.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
[7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium;chloride
2.1.2 InChI
InChI=1S/C16H18N3S.ClH/c1-18(2)11-5-7-13-15(9-11)20-16-10-12(19(3)4)6-8-14(16)17-13;/h5-10H,1-4H3;1H/q+1;/p-1
2.1.3 InChI Key
CXKWCBBOMKCUKX-UHFFFAOYSA-M
2.1.4 Canonical SMILES
CN(C)C1=CC2=C(C=C1)N=C3C=CC(=[N+](C)C)C=C3S2.[Cl-]
2.2 Other Identifiers
2.2.1 UNII
8NAP7826UB
2.3 Synonyms
2.3.1 MeSH Synonyms

1. Basic Blue 9

2. Blue 9, Basic

3. Blue N, Methylene

4. Blue, Methylene

5. Blue, Swiss

6. Blue, Urolene

7. Chromosmon

8. Methylene Blue N

9. Methylthionine Chloride

10. Methylthioninium Chloride

11. Swiss Blue

12. Urolene Blue

2.3.2 Depositor-Supplied Synonyms

1. 61-73-4

2. Basic Blue 9

3. Methylthioninium Chloride

4. Solvent Blue 8

5. Swiss Blue

6. Chromosmon

7. Methylene Blue Anhydrous

8. 3,7-bis(dimethylamino)phenothiazin-5-ium Chloride

9. Methylene Blue N

10. Methylene Blue Bb

11. C.i. Basic Blue 9

12. Methylenium Ceruleum

13. Tetramethylthionine Chloride

14. Bleu De Methylene

15. Methylene Blue Chloride

16. Methylthionine Chloride

17. External Blue 1

18. Methylene Blue A

19. Methylene Blue B

20. Methylene Blue D

21. Methylene Blue G

22. Calcozine Blue Zf

23. Methylene Blue Bd

24. Methylene Blue Bp

25. Methylene Blue Bx

26. Methylene Blue Bz

27. Methylene Blue Fz

28. Methylene Blue Gz

29. Methylene Blue Nz

30. Methylene Blue Sg

31. Methylene Blue Sp

32. Methylene Blue Zf

33. Methylene Blue Zx

34. Tetramethylene Blue

35. Methylene Blue 2b

36. Methylene Blue Bba

37. Methylene Blue Bpc

38. Methylene Blue Hgg

39. Methylene Blue Iad

40. Methylene Blue Jfa

41. Sandocryl Blue Brl

42. Methylenblau

43. Methylene Blue 2bf

44. Methylene Blue 2bn

45. Methylene Blue 2bp

46. M-b Tabs

47. Rember

48. Mitsui Methylene Blue

49. Methylthionium Chloride

50. Leather Pure Blue Hb

51. Modr Methylenova

52. Schultz No. 1038

53. Aizen Methylene Blue Bh

54. Aizen Methylene Blue Fz

55. Methylene Blue Polychrome

56. Methylene Blue Zinc Free

57. C.i. 52015

58. Yamamoto Methylene Blue B

59. D And C Blue Number 1

60. Methylene Blue (medicinal)

61. Phenothiazin-5-ium, 3,7-bis(dimethylamino)-, Chloride

62. Yamamoto Methylene Blue Zf

63. Ext D And C Blue No. 1

64. Methylene Blue I (medicinal)

65. Cloruro De Metiltioninio

66. Methylene Blue Nf (medicinal)

67. Methylthioninii Chloridum

68. Hidaco Methylene Blue Salt Free

69. Methylene Blue Bb (zinc Free)

70. Methylene Blue Usp (medicinal)

71. Lowacryl Blue 9

72. Chlorure De Methylthioninium

73. Methylene Blue Usp Xii (medicinal)

74. 3,7-bis(dimethylamino)phenazathionium Chloride

75. Methylene Blue Chloride (biological Stain)

76. X 138

77. Mfcd00012111

78. 12262-49-6

79. Ci 52015

80. Ci-52015

81. 8nap7826ub

82. Chebi:6872

83. 105504-42-5

84. Methylthioninium Chloride [inn]

85. [7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium;chloride

86. Urolene Blue

87. Provayblue

88. Nsc-215213

89. Nsc-617593

90. Azul De Metileno

91. Dsstox_cid_3296

92. N-[7-(dimethylamino)-3h-phenothiazin-3-ylidene]-n-methylmethanaminium Chloride

93. Ceruleum Methylenum

94. Dsstox_rid_76963

95. Dsstox_gsid_23296

96. Methylenum Coeruleum

97. Ci Basic Blue 9

98. Zinc Free Methylene Blue

99. Caswell No. 567

100. Methylenblau [german]

101. Methylthionini Chloridum

102. 3h-phenothiazine, 3-methochloride

103. Trx0014

104. Phenothiazin-5-ium, 3,7-bis(dimethylamino)-, Chloride (1:1)

105. Modr Methylenova [czech]

106. Chembl405110

107. Modr Zasadita 9

108. Modr Zasadita 9 [czech]

109. Cas-61-73-4

110. N-(7-(dimethylamino)-3h-phenothiazin-3-ylidene)-n-methylmethanaminium Chloride

111. Nsc3089

112. 152071-32-4

113. Ccris 833

114. Metiltioninio Cloruro [dcit]

115. Metiltioninio Cloruro

116. Modr Rozpoustedlova 8 [czech]

117. 3h-phenothiazine, 7-(dimethylamino)-3-(methylimino)-, 3-methochloride

118. Modr Rozpoustedlova 8

119. Nsc215213

120. Nsc617593

121. C.i. 52 015

122. Hsdb 1405

123. Ncgc00167496-01

124. Ncgc00167496-03

125. Phenothiazin-5-ium,7-bis(dimethylamino)-, Chloride

126. Einecs 200-515-2

127. Methylthioninii Chloridum [inn-latin]

128. Epa Pesticide Chemical Code 039505

129. Nsc 215213

130. Cloruro De Metiltioninio [inn-spanish]

131. Unii-8nap7826ub

132. Wln: T C666 Bs Ey Inj Euk1&1 Mn1&1 &g &421

133. Chlorure De Methylthioninium [inn-french]

134. Methylene Blue Usp

135. Methylene Azure Ii

136. Prestwick_326

137. Methylene Blue (inhibitor)

138. Schembl1351

139. Methylene Blue [mi]

140. Mls000719838

141. Methylene Blue [hsdb]

142. Basic Blue 9 [inci]

143. Dog (couch) Grass Powder

144. Dtxsid0023296

145. Hms2598o03

146. Pharmakon1600-01505444

147. Ci No 52015

148. Nsc-3089

149. Trx-0014

150. Tox21_112497

151. Tox21_302087

152. Nsc759135

153. S4535

154. Stk018918

155. Akos000486124

156. Akos015916406

157. Tox21_112497_1

158. Ccg-267696

159. Db09241

160. 4-(1-hydroxy-ethyl)-benzoicacid

161. Methylthioninium Chloride [mart.]

162. Ncgc00255351-01

163. Ac-15225

164. As-35256

165. Basic Blue 9;tetramethylthionine Chloride

166. Hy-14536

167. Methylene Blue, 1% W/v Aqueous Solution

168. Methylthioninium Chloride [who-dd]

169. Methylthioninium Chloride Proveblue

170. Smr000304367

171. Sy076497

172. Methylthioninium Chloride (methylene Blue)

173. Methylene Blue (c.i. 52015) Biochemica

174. Methylthioninium Chloride [ema Epar]

175. A0574

176. Ft-0622580

177. M0501

178. M2392

179. C00220

180. M-3598

181. Methylthioninium Chloride [ep Impurity]

182. 3,7-bis(dimethylamino)-5-phenothiazinium Chloride

183. Q422134

184. Methylthioninium Chloride Anhydrous [who-ip]

185. 3,7-bis(dimethylamino)-phenothiazin-5-ium Chloride Salt

186. Methylthioninii Chloridum Anhydrous [who-ip Latin]

187. Methylene Blue Solution (methanol Solution) [for Cell Staining]

188. 3-n,3-n,7-n,7-n-tetramethylphenothiazin-5-ium-3,7-diamine;chloride

189. N-(7-(dimethylamino)-3h-phenothiazin-3-ylidene)-n-methylmethanaminiumchloride

190. 1341-90-8

191. 6476-03-5

192. 97130-83-1

2.4 Create Date
2005-03-26
3 Chemical and Physical Properties
Molecular Weight 319.9 g/mol
Molecular Formula C16H18ClN3S
Hydrogen Bond Donor Count0
Hydrogen Bond Acceptor Count4
Rotatable Bond Count1
Exact Mass319.0909965 g/mol
Monoisotopic Mass319.0909965 g/mol
Topological Polar Surface Area43.9 Ų
Heavy Atom Count21
Formal Charge0
Complexity483
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count2
4 Drug and Medication Information
4.1 Therapeutic Uses

Enzyme Inhibitors

National Library of Medicine's Medical Subject Headings. Methylene Blue. Online file (MeSH, 2018). Available from, as of August 29, 2018: https://meshb.nlm.nih.gov/search


/CLINICAL TRIALS/ ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. The Web site is maintained by the National Library of Medicine (NLM) and the National Institutes of Health (NIH). Each ClinicalTrials.gov record presents summary information about a study protocol and includes the following: Disease or condition; Intervention (for example, the medical product, behavior, or procedure being studied); Title, description, and design of the study; Requirements for participation (eligibility criteria); Locations where the study is being conducted; Contact information for the study locations; and Links to relevant information on other health Web sites, such as NLM's MedlinePlus for patient health information and PubMed for citations and abstracts for scholarly articles in the field of medicine. Methylene blue is included in the database.

NIH/NLM; ClinicalTrials.Gov. Available from, as of August 29, 2018: https://clinicaltrials.gov/


Drug-induced methemoglobinemia. /Included in US product label/

NIH; DailyMed. Current Medication Information for Methylene blue injection (Updated: November 20, 2017). Available from, as of September 5, 2018: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=fde64824-2be5-4d85-8d57-5098ca6890bb


Methylene blue posses weak urinary antiseptic properties. Methylene blue directly inhibits calcium binding by oxalate and by organic stone matrix. The drug also acts as a crystal poison at the interface, reducing the tendency of calcium oxalate particles to aggregate. In addition, it reverses intracellular acidosis (such as that in renal tubule acidosis), apparently by competing with diphosphopyridine nucleotide as a hydrogen receptor.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


For more Therapeutic Uses (Complete) data for Methylene blue (32 total), please visit the HSDB record page.


4.2 Drug Warning

/BOXED WARNING/ WARNING: SEROTONIN SYNDROME WITH CONCOMITANT USE OF SEROTONERGIC DRUGS. Methylene Blue Injection may cause serious or fatal serotonergic syndrome when used in combination with serotonergic drugs. Avoid concomitant use of Methylene blue injection with selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors.

NIH; DailyMed. Current Medication Information for Methylene blue injection (Updated: November 20, 2017). Available from, as of September 5, 2018: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=fde64824-2be5-4d85-8d57-5098ca6890bb


Large IV doses of methylene blue may produce nausea, vomiting, abdominal pain, precordial pain, dizziness, headache, profuse sweating, dyspnea, hypertension, and mental confusion. Urinary tract irritation may occur. High IV dosage or high local concentrations of methylene blue may cause formation of methemoglobin and cyanosis.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


Hemolysis and hemolytic anemia may occur, especially in young infants and patients with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


Hypersensitivity, manifested as wheal and flare reactions at the injection site, has been reported. Severe hypersensitivity reactions, including anaphylaxis, generalized urticaria, and hypotension, tachycardia, and bronchospasm, have been reported following local instillation or injection of methylene blue.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


For more Drug Warnings (Complete) data for Methylene blue (20 total), please visit the HSDB record page.


4.3 Drug Indication

Indicated for the treatment of pediatric and adult patients with acquired methemoglobinemia. Other clinical applications of methylene blue include improvement of hypotension associated with various clinical states, an antiseptic in urinary tract infections, treatment of hypoxia and hyperdynamic circulation in cirrhosis of liver and severe hepatopulmonary syndrome, and treatment of ifofosamide induced neurotoxicity.


Acute symptomatic treatment of medicinal and chemical products- induced methaemoglobinaemia.

Methylthioninium chloride Proveblue is indicated in adults, children and adolescents (aged 0 to 17 years old).


5 Pharmacology and Biochemistry
5.1 MeSH Pharmacological Classification

Enzyme Inhibitors

Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. (See all compounds classified as Enzyme Inhibitors.)


5.2 FDA Pharmacological Classification
5.2.1 Pharmacological Classes
Oxidation-Reduction Agent [EPC]; Oxidation-Reduction Activity [MoA]
5.3 ATC Code

V03AB17


V - Various

V03 - All other therapeutic products

V03A - All other therapeutic products

V03AB - Antidotes

V03AB17 - Methylthioninium chloride


V - Various

V04 - Diagnostic agents

V04C - Other diagnostic agents

V04CG - Tests for gastric secretion

V04CG05 - Methylthioninium chloride


5.4 Absorption, Distribution and Excretion

Route of Elimination

Excreted in urine and bile. About 75% of an oral dose excreted in urine, primarily as stabilized colorless leukomethylene blue.


Volume of Distribution

10 mg/kg (in rats).


Clearance

3.00.7 L/min.


... The concentration of methylene blue in whole blood was measured using high-performance liquid chromatography in seven volunteers after IV and oral administration of 100 mg methylene blue with and without mesna. The distribution of methylene blue in different tissues was measured in rats after intraduodenal and IV application. The time course of methylene blue in whole blood after IV administration showed a multiphasic time course with an estimated terminal half-life of 5.25 hr. Following oral administration, the area under the concentration-time curve was much lower (9 nmol/min/mL vs 137 nmol/min/mL). Co-administration of mesna, which could influence distribution by ion-pairing, did not alter the pharmacokinetics. The urinary excretion of methylene blue and its leukoform was only moderately higher after IV administration (18% vs 28% dose). Intraduodenal administration to rats resulted in higher concentrations in intestinal wall and liver but lower concentrations in whole blood and brain than IV methylene blue. Differences in organ distribution of methylene blue are mainly responsible for the different pharmacokinetics after oral and IV administration. ...

PMID:10952480 Peter C et al; Eur J Clin Pharmacol 56 (3): 247-50 (2000)


Methylene blue is well absorbed from the GI tract, and peak plasma concentrations occur approximately 1-2 hours after an oral dose. ... Following distribution into tissues, methylene blue is rapidly reduced to leukomethylene blue (leucomethylthioninium chloride). Metabolism to leucomethylene blue may be less efficient in neonates than in older individuals. Methylene blue is excreted in urine and bile. About 75% of an oral dose of methylene blue is excreted in urine, mostly as stabilized colorless leukomethylene blue. On exposure to air, the urine turns green or blue, due to the presence of the oxidation product methylene azure (methylene blue sulfone). Some unchanged drug is also excreted in urine.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


BACKGROUND: Although blue dye is routinely used for lymphatic mapping, it is not used for lymphatic mapping in pregnancy-associated breast cancer, because of concern of fetal risk. METHODS: To investigate the safety of blue dye for lymphatic mapping in pregnant women, the pharmacokinetics of methylene blue dye were examined in 10 nonpregnant women, and the results were extrapolated to estimate maximal fetal exposure to the dye. RESULTS: Plasma and urine measurements indicated that the dye quickly distributed from the breast injection site to the circulation, with 32% of the total dose excreted in urine within 48 hours. Combined with existing data on organ distribution of methylene blue, the estimated maximal dose to the fetus is 0.25 mg (5% of the administered dose), likely further reduced by other physiologic factors related to pregnancy. CONCLUSIONS: The analysis suggests that methylene blue dye can be used for lymphatic mapping in pregnancy-associated breast cancer with minimal fetal risk.

PMID:21167367 Pruthi S et al; Am J Surg 201 (1): 70-5 (2011)


The disposition and urinary excretion pharmacokinetics of methylene blue were determined after its intravenous administration at 15 mg/kg to mature female sheep. Comparisons were made between methylene blue administered alone or subsequent to 50 mg/kg sodium nitrite. The overall elimination rate constant (beta) of methylene blue, 0.0076 +/- 0.0016 min-1, was not influenced by prior administration of sodium nitrite. However, the distribution rate was significantly altered by sodium nitrite. Very little of the methylene blue was eliminated in the urine either intact or as leukomethylene blue in spite of its relatively short half life. ...

PMID:6492250 Burrows GE; J Vet Pharmacol Ther 7 (3): 225-31(1984)


5.5 Metabolism/Metabolites

Following distribution into tissues, rapidly reduced to leukomethylene blue (leucomethylthioninium chloride). Metabolism to leucomethylene blue may be less efficient in neonates than in older individuals.


Methylene blue can be reduced to a colorless form, leukomethylene blue; together, these compounds form a reversible oxidation-reduction system. In low concentrations, methylene blue accelerates conversion of methemoglobin to hemoglobin. In patients with methemoglobinemia, methylene blue is reduced to leukomethylene blue by methemoglobin reductases in erythrocytes; leukomethylene blue then reduces methemoglobin to hemoglobin. In high concentrations, methylene blue oxidizes the ferrous iron of reduced hemoglobin to the ferric state, thereby changing hemoglobin to methemoglobin.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


Following distribution into tissues, methylene blue is rapidly reduced to leukomethylene blue (leucomethylthioninium chloride). Metabolism to leucomethylene blue may be less efficient in neonates than in older individuals.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


5.6 Biological Half-Life

56.5 hours (after IV dose).


Following IV administration, the estimated half-life of methylene blue is 5-6.5 hours.

American Society of Health-System Pharmacists; Drug Information 2018. Bethesda, MD. 2018


... The concentration of methylene blue in whole blood was measured using high-performance liquid chromatography in seven volunteers after IV and oral administration of 100 mg methylene blue with and without mesna. The distribution of methylene blue in different tissues was measured in rats after intraduodenal and IV application. The time course of methylene blue in whole blood after IV administration showed a multiphasic time course with an estimated terminal half-life of 5.25 hr. ...

PMID:10952480 Peter C et al; Eur J Clin Pharmacol 56 (3): 247-50 (2000)


5.7 Mechanism of Action

* Main mechanism of action involves inhibition of nitric oxide synthase and guanylate cyclase. * In Alzheimers Disease: a mechanistic study found that methylene blue oxidizes cysteine sulfhydryl groups on tau to keep tau monomeric. One preclinical treatment study in tauopathy mice reported anti-inflammatory or neuroprotective effects mediated by the Nrf2/antioxidant response element (ARE); another reported insoluble tau reduction and a learning and memory benefit when given early. * In Methemoglobinemia: Methylene Blue acts by reacting within RBC to form leukomethylene blue, which is a reducing agent of oxidized hemoglobin converting the ferric ion (fe+++) back to its oxygen-carrying ferrous state(fe++). * As antimalarial agent: Methylene Blue, a specific inhibitor of P.falciparum glutathione reductase has the potential to reverse CQ resistance and it prevents the polymerization of haem into haemozoin similar to 4-amino-quinoline antimalarials. * For ifosfamide induced neurotoxicity: Methylene blue functions as an alternate electron acceptor. It acts to reverse the NADH inhibition caused by gluconeogenesis in the liver while blocking the transformation of chloroethylamine into chloroacetaldehyde. In addition, it inhibits various amine oxidase activities, which also prevents the formation of chloroacetaldehyde.


The mechanism of modulation of cyclic guanosine monophosphate accumulation by methylene blue, a putative inhibitor of soluble guanylate cyclase, was investigated in cultured rabbit pulmonary arterial smooth muscle cells. Control or methylene blue pretreated rabbit pulmonary arterial smooth muscle were stimulated with sodium nitroprusside, nitrosothiols or endothelium derived relaxing factor released basally from bovine pulmonary arterial endothelial cells, in short term cocultures. The putative endothelium-derived relaxing factor, S-nitroso-L-cysteine, a stab1e deaminated analog of S-nitroso-L-cysteine, S-nitroso-3-mercaptoproprionic acid and sodium nitroprusside produced concentration-dependent (1-100 uM) increase (1.5- to 12-fold) in rabbit pulmonary arterial smooth muscle cells cyclic guanosine monophospate levels. Methylene blue pretreatment inhibited S-nitroso-L-cysteine and sodium nitroprusside induced cyclic guanosine monophosphate accumulation by 51% to 100%, but S-nitroso-3-mercaptoproprionic acid mediated responses were not altered by methylene blue. The inhibition profile of methylene blue on nitrovasodilator induced cyclic guanosine monophosphate accumulation was quantitatively reproduced by extracellular generation of superoxide anion with xanthine (100 uM) and xanthine oxidase (5 mU). Similarly to methylene blue pretreatment, superoxide anion generation had no effects on base-line cyclic guanosine phosphate levels or cyclic guanosine phosphate responses elicited by S-nitroso-3-mercaptoproprionic acid. Furthermore, methylene blue induced a dose and time dependent generation of superoxide anion from rabbit pulmonary arterial smooth muscle cells, as evidenced from spectrophotometric determination of cytochrome c reduction. Inhibition of cyclic guanosine monophosphate accumulation in response to S-nitroso-L-cysteine and sodium nitroprusside by methylene blue was completely prevented by superoxide dismutase but not catalase. Selective pretreatment of endothelial cells with methylene blue before co-culture with untreated rabbit pulmonary arterial smooth muscle produced a reduction in rabbit pulmonary arterial smooth muscle cyclic guanosine monophosphate levels of a magnitude comparable with that seen in cocultures of methylene blue pretreated rabbit pulmonary arterial smooth muscle with untreated endothelial cells, and which was partially prevented by superoxide dismutase.

PMID:1328604 Marczin N et al; J Pharmacol Exp Ther 263 (1): 170-9 (1992)