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2D Structure
Also known as: 554-57-4, Methenamide, Neptazaneat, Neptazane, Naptazane, N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)acetamide
Molecular Formula
C5H8N4O3S2
Molecular Weight
236.3  g/mol
InChI Key
FLOSMHQXBMRNHR-UHFFFAOYSA-N
FDA UNII
DA43GW06P1

A carbonic anhydrase inhibitor that is used as a diuretic and in the treatment of glaucoma.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)acetamide
2.1.2 InChI
InChI=1S/C5H8N4O3S2/c1-3(10)7-4-9(2)8-5(13-4)14(6,11)12/h1-2H3,(H2,6,11,12)
2.1.3 InChI Key
FLOSMHQXBMRNHR-UHFFFAOYSA-N
2.1.4 Canonical SMILES
CC(=O)N=C1N(N=C(S1)S(=O)(=O)N)C
2.2 Other Identifiers
2.2.1 UNII
DA43GW06P1
2.3 Synonyms
2.3.1 MeSH Synonyms

1. N Methylacetazolamide

2. N-methylacetazolamide

2.3.2 Depositor-Supplied Synonyms

1. 554-57-4

2. Methenamide

3. Neptazaneat

4. Neptazane

5. Naptazane

6. N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)acetamide

7. Chebi:6822

8. L584601

9. Methazolamide, (z)-

10. Nsc-758426

11. Acetamide, N-(5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3h)-ylidene)-

12. Acetamide, N-[5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3h)-ylidene]-

13. Mls000028532

14. Chembl288100

15. Da43gw06p1

16. Vvp808

17. W733b0s9sd

18. Vvp-808

19. N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2(3h)-ylidene)acetamide

20. Ncgc00016508-01

21. Metazolamide

22. Cas-554-57-4

23. Smr000058287

24. N-[(2e)-3-methyl-5-sulfamoyl-2,3-dihydro-1,3,4-thiadiazol-2-ylidene]acetamide

25. L-584601

26. Metazolamide [dcit]

27. Metazolamida

28. Methazolamidum

29. (ne)-n-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)acetamide

30. Acetamide, N-(5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3h)-ylidene)-, (n(z))-

31. Metazolamida [inn-spanish]

32. Methazolamidum [inn-latin]

33. 1164547-86-7

34. Hsdb 3269

35. Sr-05000001844

36. Einecs 209-066-7

37. Brn 0232387

38. Unii-w733b0s9sd

39. 2-acetylimino-3-methyl-.delta.(4)-1,3,4-thiadiazoline-5-sulfonamide

40. 5-acetylimino-4-methyl-.delta.(2)-1,3,4-thiadiazoline-2-sulfonamide

41. N-(4-methyl-2-sulfamoyl-.delta.2-1,3,4-thiadiazolin-5-ylidene)acetamide

42. N-(5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3h)-ylidene)acetamide #

43. Acetamide, N-(4-methyl-2-sulfamoyl-.delta.2-1,3,4-thiadiazolin-5-ylidene)-

44. (z)-methazolamide

45. Neptazane (tn)

46. Methazolamide,(s)

47. Methazolamide [usp:inn:ban:jan]

48. Methazolamide, Mza

49. Prestwick_1007

50. Methazolamide (mza)

51. Noname_433

52. Spectrum_001615

53. Opera_id_717

54. Chembl19

55. Mza3

56. Prestwick0_000802

57. Prestwick1_000802

58. Prestwick2_000802

59. Prestwick3_000802

60. Spectrum2_001543

61. Spectrum3_001914

62. Spectrum4_000190

63. Spectrum5_001006

64. 2-acetylimino-3-methyl-delta(sup 4)-1,3,4-thiadiazoline-5-sulfonamide

65. 5-acetylimino-4-methyl-delta(sup 2)-1,3,4-thiadiazoline-2-sulfonamide

66. Dsstox_cid_3281

67. Methazolamide [mi]

68. Methazolamide [inn]

69. Methazolamide [jan]

70. N-(4-methyl-2-sulfamoyl-delta(sup 2)-1,3,4-thiadiazolin-5-ylidene)acetamide

71. Cid_4100

72. Dsstox_rid_76956

73. Methazolamide [hsdb]

74. Unii-da43gw06p1

75. Dsstox_gsid_23281

76. Oprea1_161738

77. Schembl24686

78. Schembl24687

79. Bspbio_000663

80. Bspbio_003508

81. Kbiogr_000739

82. Kbioss_002095

83. Methazolamide [vandf]

84. 4-27-00-08221 (beilstein Handbook Reference)

85. Mls001146905

86. Divk1c_000582

87. Methazolamide [mart.]

88. Spectrum1503252

89. Spbio_001386

90. Spbio_002584

91. Methazolamide [usp-rs]

92. Methazolamide [who-dd]

93. Bpbio1_000731

94. Gtpl6828

95. Methazolamide (jan/usp/inn)

96. Us10172837, Methazolamide

97. Chembl1335656

98. Dtxsid1023281

99. Schembl13825893

100. Bdbm10881

101. Chebi:94513

102. Hms501n04

103. Kbio1_000582

104. Kbio2_002095

105. Kbio2_004663

106. Kbio2_007231

107. Kbio3_003013

108. Dtxsid50901331

109. Methazolamide, >=98% (hplc)

110. Ninds_000582

111. Bdbm315269

112. Hms1570b05

113. Hms1922m19

114. Hms2093a05

115. Hms2097b05

116. Hms2234l03

117. Hms3259h05

118. Hms3372g12

119. Hms3652e21

120. Hms3714b05

121. Hms3747o09

122. Pharmakon1600-01503252

123. Methazolamide [orange Book]

124. Hy-b0553

125. Tox21_110464

126. Bdbm50013792

127. Ccg-39321

128. Methazolamide [usp Monograph]

129. Mfcd00083416

130. Nsc758426

131. Zinc12503151

132. Akos015897587

133. Akos024464790

134. Akos026749792

135. N-(3-methyl-5-sulfamoyl-2,3-dihydro-1,3,4-thiadiazol-2-ylidene)acetamide

136. Zinc100019188

137. Zinc253917094

138. Ccg-266836

139. Cl 8490

140. Db00703

141. Ks-5328

142. Nc00618

143. Nsc 758426

144. Sb17307

145. Acetamide, N-(4-methyl-2-sulfamoyl-delta(sup 2)-1,3,4-thiadiazolin-5-ylidene)-

146. Idi1_000582

147. N-[(2e)-5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazol-2(3h)-ylidene]acetamide

148. Ncgc00016508-03

149. Ncgc00016508-04

150. Ncgc00016508-18

151. Ncgc00018188-01

152. Ncgc00018188-02

153. Ncgc00018188-03

154. Ncgc00018188-04

155. Ncgc00018188-05

156. Ncgc00018188-06

157. Ncgc00018188-07

158. Ncgc00022950-03

159. Ncgc00022950-04

160. Ncgc00178022-01

161. Ncgc00178022-02

162. Ac-32472

163. As-13272

164. Sbi-0051804.p002

165. Db-052736

166. A4364

167. Ab00490015

168. S4039

169. Sw197085-3

170. C07764

171. D00655

172. D81966

173. Ab00052336_04

174. 554m574

175. A830656

176. Methazolamide, Vetranal(tm), Analytical Standard

177. Q1149099

178. Sr-05000001844-1

179. Sr-05000001844-2

180. Sr-05000001844-3

181. Brd-k13356952-001-15-2

182. Brd-k71053238-001-03-6

183. Brd-k71053238-001-04-4

184. Q27276292

185. (e)-n-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2(3h)-ylidene

186. N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)ethanamide

187. (nz)-n-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2-ylidene)acetamide

188. Methazolamide, United States Pharmacopeia (usp) Reference Standard

189. (e)-n-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2(3h)-ylidene)acetamide

190. N-(4-methyl-2-sulfamoyl-.delta.(sup 2)-1,3,4-thiadiazolin-5-ylidene)acetamide

191. N-[(2z)-3-methyl-5-sulfamoyl-2,3-dihydro-1,3,4-thiadiazol-2-ylidene]acetamide

192. 2101958-72-7

2.4 Create Date
2005-03-25
3 Chemical and Physical Properties
Molecular Weight 236.3 g/mol
Molecular Formula C5H8N4O3S2
XLogP30.1
Hydrogen Bond Donor Count1
Hydrogen Bond Acceptor Count6
Rotatable Bond Count1
Exact Mass236.00378248 g/mol
Monoisotopic Mass236.00378248 g/mol
Topological Polar Surface Area139 Ų
Heavy Atom Count14
Formal Charge0
Complexity419
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 2  
Drug NameMethazolamide
PubMed HealthMethazolamide (By mouth)
Drug ClassesAntiglaucoma, Cardiovascular Agent
Drug LabelMethazolamide, a sulfonamide derivative, is a white crystalline powder, weakly acidic, slightly soluble in water, alcohol and acetone. The chemical name for methazolamide is: N-[5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazo1-2(3H)-ylidene]-acetamide and...
Active IngredientMethazolamide
Dosage FormTablet
RouteOral
Strength25mg; 50mg
Market StatusPrescription
CompanyAni Pharms; Sandoz; Mikart

2 of 2  
Drug NameMethazolamide
PubMed HealthMethazolamide (By mouth)
Drug ClassesAntiglaucoma, Cardiovascular Agent
Drug LabelMethazolamide, a sulfonamide derivative, is a white crystalline powder, weakly acidic, slightly soluble in water, alcohol and acetone. The chemical name for methazolamide is: N-[5-(aminosulfonyl)-3-methyl-1,3,4-thiadiazo1-2(3H)-ylidene]-acetamide and...
Active IngredientMethazolamide
Dosage FormTablet
RouteOral
Strength25mg; 50mg
Market StatusPrescription
CompanyAni Pharms; Sandoz; Mikart

4.2 Therapeutic Uses

Carbonic Anhydrase Inhibitors; Diuretics

National Library of Medicine's Medical Subject Headings online file (MeSH, 1999)


CARBONIC ANHYDRASE INHIBITOR CHEMICALLY RELATED TO ACETAZOLAMIDE & HAVING SAME PROFILE OF CLINICAL INDICATIONS. ... IT IS INDICATED IN PATIENTS WHO DO NOT RESPOND TO ACETAZOLAMIDE OR IN THOSE WHO ARE INTOLERANT TO IT.

Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 867


ALTHOUGH UNDOUBTEDLY EFFECTIVE IN EVOKING DIURESIS, CARBONIC ANHYDRASE INHIBITORS ARE RELATIVELY INEFFECTIVE COMPARED TO NEWER & MORE EFFICACIOUS AGENTS. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 828


ACETAZOLAMIDE HAS BEEN GIVEN TO REDUCE INTRAOCULAR PRESSURE IN MGMNT OF GLAUCOMA. IT MAY...BE EMPLOYED FOR ITS ANTICONVULSANT ACTION FOR BOTH GRAND MAL & PARTICULARLY PETIT MAL EPILEPSY. ...ACETAZOLAMIDE APPEARS TO HAVE BENEFICIAL EFFECT IN MGMNT OF PERIODIC PARALYSIS EVEN WHEN ASSOCIATED WITH HYPOKALEMIA. /ACETAZOLAMIDE/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 828


For more Therapeutic Uses (Complete) data for METHAZOLAMIDE (9 total), please visit the HSDB record page.


4.3 Drug Warning

CONTRAINDICATIONS, PRECAUTIONS, & ADVERSE REACTIONS ARE SIMILAR TO THOSE OBSERVED WITH ACETAZOLAMIDE & OTHER CARBONIC ANHYDRASE INHIBITORS...

Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 867


SAFE USE OF THESE AGENTS DURING PREGNANCY HAS NOT BEEN ESTABLISHED. THESE AGENTS ARE CONTRAINDICATED IN PATIENTS WITH IDIOPATHIC RENAL HYPERCHLOREMIC ACIDOSIS, RENAL FAILURE, KNOWN DEPLETION OF SODIUM & OF POTASSIUM, ADDISON'S DISEASE, & PATIENTS KNOWN TO BE SENSITIVE TO THIS CLASS OF DRUGS. /CARBONIC ANHYDRASE INHIBITORS/

Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 866


IN EDEMATOUS PATIENT, DAILY ADMIN OF ACETAZOLAMIDE LEADS TO METABOLIC TYPE OF ACIDOSIS THAT IS ACCOMPANIED BY LOSS OF DIURETIC RESPONSE TO CONTINUED DRUG THERAPY. /ACETAZOLAMIDE/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 826


CAUTION IS EMPHASIZED IN USE OF CARBONIC ANHYDRASE INHIBITORS IN PATIENTS WITH OBSTRUCTIVE AIRWAY DISEASE.

PMID:1244265 COUDON WL, BLOCK AJ; CHEST 69 (1): 112-113 (1976)


For more Drug Warnings (Complete) data for METHAZOLAMIDE (9 total), please visit the HSDB record page.


4.4 Drug Indication

For treatment of chronic open-angle glaucoma and acute angle-closure glaucoma


5 Pharmacology and Biochemistry
5.1 Pharmacology

Methazolamide is topical carbonic anhydrase inhibitor. Methazolamide is indicated for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension who are insufficiently responsive to beta-blockers. Methazolamide is a sulfonamide derivative; however, it does not have any clinically significant antimicrobial properties. Although methazolamide achieves a high concentration in the cerebrospinal fluid, it is not-considered an effective anticonvulsant. Methazolamide has a weak and transient diuretic effect, therefore use results in an increase in urinary volume, with excretion of sodium, potassium and chloride.


5.2 MeSH Pharmacological Classification

Diuretics

Agents that promote the excretion of urine through their effects on kidney function. (See all compounds classified as Diuretics.)


Carbonic Anhydrase Inhibitors

A class of compounds that reduces the secretion of H+ ions by the proximal kidney tubule through inhibition of CARBONIC ANHYDRASES. (See all compounds classified as Carbonic Anhydrase Inhibitors.)


5.3 ATC Code

S - Sensory organs

S01 - Ophthalmologicals

S01E - Antiglaucoma preparations and miotics

S01EC - Carbonic anhydrase inhibitors

S01EC05 - Methazolamide


5.4 Absorption, Distribution and Excretion

Absorption

Methazolamide is well absorbed from the gastrointestinal tract.


Volume of Distribution

17 to 23 L


.../CARBONIC ANHYDRASE INHIBITORS/...READILY ABSORBED FROM GI TRACT. PEAK PLASMA CONCN...WITHIN 2 HR. ... EXCRETED BY KIDNEY, BOTH ACTIVE TUBULAR SECRETION & PASSIVE REABSORPTION ARE INVOLVED. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 827


.../CARBONIC ANHYDRASE INHIBITORS/ ARE TIGHTLY BOUND TO CARBONIC ANHYDRASE &... PRESENT IN GREATER AMT IN THOSE TISSUES IN WHICH ENZYME IS PRESENT IN HIGH CONCN...ERYTHROCYTES & RENAL CORTEX. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 828


SOME CARBONIC ANHYDRASE INHIBITORS DO NOT PENETRATE ERYTHROCYTE. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 828


Methazolamide is absorbed more slowly from the GI tract and disappears more slowly from the plasma than does acetazolamide.

McEvoy, G.K. (ed.). American Hospital Formulary Service-Drug Information 19 98. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 1998 (Plus Supplements)., p. 2312


For more Absorption, Distribution and Excretion (Complete) data for METHAZOLAMIDE (6 total), please visit the HSDB record page.


5.5 Metabolism/Metabolites

AZETAZOLAMIDE DOES NOT UNDERGO METABOLIC ALTERATION. .../SOME CARBONIC ANHYDRASE INHIBITORS/ HAVE BEEN FOUND TO BE INACTIVE IN VITRO BUT ACTIVE IN VIVO, AS RESULT OF N-DEALKYLATION TO FORM AN ACTIVE METABOLITE. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 828


5.6 Biological Half-Life

14 hours


Half-life is ~14 hours. /From table/

Hardman, J.G., L.E. Limbird, P.B. Molinoff, R.W. Ruddon, A.G. Goodman (eds.). Goodman and Gilman's The Pharmacological Basis of Therapeutics. 9th ed. New York, NY: McGraw-Hill, 1996., p. 693


5.7 Mechanism of Action

Methazolamide is a potent inhibitor of carbonic anhydrase. Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport.


ANTICONVULSANT PROPERTIES...RESEMBLE THOSE OF CARBON DIOXIDE. IN ANIMALS, THEY ABOLISH THE TONIC EXTENSOR COMPONENT OF MAXIMAL ELECTROSHOCK CONVULSIONS, ELEVATE SEIZURE THRESHOLD, & PROTECT AGAINST AUDIOGENIC SEIZURES & THOSE PRODUCED BY WITHDRAWAL FROM HIGH CONCN OF CARBON DIOXIDE. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 218


MAJOR PHARMACOLOGICAL ACTION...IS INHIBITION OF ENZYME CARBONIC ANHYDRASE. STUDIES WITH PURIFIED ENZYME HAVE SHOWN THAT INHIBITION IS NONCOMPETITIVE. NONCATALYZED HYDRATION OR DEHYDRATION REACTION CAN TAKE PLACE...IN ABSENCE OF ENZYME. /CARBONIC ANHYDRAS INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 826


MORE THAN 99% OF ENZYME ACTIVITY IN THE KIDNEY MUST BE INHIBITED BEFORE PHYSIOLOGICAL EFFECTS BECOME APPARENT. THE ENZYME ITSELF IS DOMINANT TISSUE COMPONENT TO WHICH THE INHIBITORS BECOME BOUND. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 826


FOLLOWING ADMIN OF ACETAZOLAMIDE, THE URINE VOLUME PROMPTLY INCR. NORMALLY ACIDIC PH BECOMES ALKALINE. URINARY CONCN OF BICARBONATE ANION INCR AND IS MATCHED BY SODIUM AND SUBSTANTIAL AMT OF POTASSIUM. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 826


...THE DRUG HAS BEEN FOUND TO INHIBIT EPILEPTIC SEIZURES & TO DECR RATE OF SPINAL FLUID FORMATION. EXACT MECHANISMS BY WHICH CARBONIC ANHYDRASE INHIBITION IS RELATED TO THESE CHANGES IN FUNCTION ARE NOT CLEAR, & MULTIPLE FACTORS MAY BE INVOLVED. /CARBONIC ANHYDRASE INHIBITORS/

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 827