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2D Structure
Also known as: 42399-41-7, D-cis-diltiazem, Cardizem, Dilt-cd, Diltiazemum, Anoheal
Molecular Formula
C22H26N2O4S
Molecular Weight
414.5  g/mol
InChI Key
HSUGRBWQSSZJOP-RTWAWAEBSA-N
FDA UNII
EE92BBP03H

A benzothiazepine derivative with vasodilating action due to its antagonism of the actions of CALCIUM ion on membrane functions.
Diltiazem is a Calcium Channel Blocker. The mechanism of action of diltiazem is as a Calcium Channel Antagonist.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
[(2S,3S)-5-[2-(dimethylamino)ethyl]-2-(4-methoxyphenyl)-4-oxo-2,3-dihydro-1,5-benzothiazepin-3-yl] acetate
2.1.2 InChI
InChI=1S/C22H26N2O4S/c1-15(25)28-20-21(16-9-11-17(27-4)12-10-16)29-19-8-6-5-7-18(19)24(22(20)26)14-13-23(2)3/h5-12,20-21H,13-14H2,1-4H3/t20-,21+/m1/s1
2.1.3 InChI Key
HSUGRBWQSSZJOP-RTWAWAEBSA-N
2.1.4 Canonical SMILES
CC(=O)OC1C(SC2=CC=CC=C2N(C1=O)CCN(C)C)C3=CC=C(C=C3)OC
2.1.5 Isomeric SMILES
CC(=O)O[C@@H]1[C@@H](SC2=CC=CC=C2N(C1=O)CCN(C)C)C3=CC=C(C=C3)OC
2.2 Other Identifiers
2.2.1 UNII
EE92BBP03H
2.3 Synonyms
2.3.1 MeSH Synonyms

1. Aldizem

2. Cardil

3. Cardizem

4. Crd 401

5. Crd-401

6. Crd401

7. Dilacor

8. Dilacor Xr

9. Dilren

10. Diltiazem Hydrochloride

11. Diltiazem Malate

12. Dilzem

13. Tiazac

2.3.2 Depositor-Supplied Synonyms

1. 42399-41-7

2. D-cis-diltiazem

3. Cardizem

4. Dilt-cd

5. Diltiazemum

6. Anoheal

7. (+)-diltiazem

8. Diltzac

9. Tiamate

10. Cardil

11. Dilren

12. Tiazac

13. Surazem

14. Diltiazem Free Base

15. (+)-cis-diltiazem

16. Diltiazen

17. (2s,3s)-5-(2-(dimethylamino)ethyl)-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydrobenzo[b][1,4]thiazepin-3-yl Acetate

18. Diltiazem (inn)

19. Chembl23

20. Dilcontin

21. Diltiazem Extended Release

22. Dilticard

23. Endrydil

24. Acalix

25. Dilzen

26. Dilta-hexal

27. Ee92bbp03h

28. Incoril Ap

29. Chebi:101278

30. 42399-41-7 (free Base)

31. (2s,3s)-5-[2-(dimethylamino)ethyl]-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepin-3-yl Acetate

32. [(2s,3s)-5-(2-dimethylaminoethyl)-2-(4-methoxyphenyl)-4-oxo-2,3-dihydro-1,5-benzothiazepin-3-yl] Acetate

33. Acetic Acid (2s,3s)-5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester

34. Ncgc00024309-05

35. Diltiazem [inn]

36. Dsstox_cid_2940

37. Diltiazem [inn:ban]

38. Dilacor-xr

39. Dsstox_rid_76797

40. Diltiazemum [inn-latin]

41. Dsstox_gsid_22940

42. (+)-cis-5-[2-(dimethylamino)ethyl]-2,3-dihydro-3-hydroxy-2-(p-methoxyphenyl)-1,5-benzothiazepin-4(5h)-one Acetate Ester

43. (2s-cis)-3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5h)-one

44. [(2~{s},3~{s})-5-[2-(dimethylamino)ethyl]-2-(4-methoxyphenyl)-4-oxidanylidene-2,3-dihydro-1,5-benzothiazepin-3-yl] Ethanoate

45. Surazem (tn)

46. Cas-42399-41-7

47. Hsdb 6528

48. Cardizem (hydrochloride)

49. Mk-793 (malate)

50. Einecs 255-796-4

51. Unii-ee92bbp03h

52. Brn 3573079

53. Tetrahydrobenzo

54. Ditiaz

55. Rg 83606 (hydrochloride)

56. Diltiazem Hci

57. 1,5-benzothiazepin-4(5h)-one, 3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-2-(4-methoxyphenyl)-, (2s,3s)-

58. D-(cis)-diltiazem

59. Tocris-0685

60. Diltiazem [mi]

61. Ditiaz [vandf]

62. Diltiazem [hsdb]

63. 103532-26-9

64. Prestwick0_000134

65. Prestwick1_000134

66. Prestwick2_000134

67. Prestwick3_000134

68. Diltiazem [vandf]

69. Diltiazem [who-dd]

70. Lopac0_000327

71. Schembl17776

72. Bspbio_000208

73. Bspbio_001311

74. Lithiumdicyclohexylamide

75. Bidd:gt0548

76. Spbio_002147

77. Bpbio1_000230

78. Gtpl2298

79. Dtxsid9022940

80. Bio1_000371

81. Bio1_000860

82. Bio1_001349

83. Hms1791b13

84. Hms1989b13

85. Hms2089h09

86. Zinc621893

87. [b][1,4]thiazepin-3-yl Acetate

88. (+)-5-(2-(dimethylamino)ethyl)-cis-2,3-dihydro-3-hydroxy-2-(p-methoxyphenyl)-1,5-benzothiazepin-4(5h)-one Acetate (ester)

89. 56209-45-1

90. Acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester

91. Cis-3-acetoxy-5-(2-(dimethylamino)ethyl)-2,3-dihydro-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5h)-one

92. Hy-b0632

93. Einecs 260-060-0

94. Methoxyphenyl)-4-oxo-2,3,4,5-

95. Tox21_110898

96. Ac-936

97. Bdbm50004704

98. Akos015897257

99. Tox21_110898_1

100. Ccg-204422

101. Db00343

102. Sdccgsbi-0050315.p002

103. Ncgc00024309-02

104. Ncgc00024309-04

105. Ncgc00024309-06

106. Ncgc00024309-07

107. Ncgc00024309-08

108. Ncgc00024309-09

109. Ncgc00024309-10

110. Ncgc00024309-11

111. Ncgc00024309-17

112. Ncgc00024309-21

113. Ncgc00024309-27

114. (2s,3s)-5-[2-(dimethylamino)ethyl]-2-[4-(methyloxy)phenyl]-4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepin-3-yl Acetate

115. [(2s,3s)-5-[2-(dimethylamino)ethyl]-2-(4-methoxyphenyl)-4-oxo-2,3-dihydro-1,5-benzothiazepin-3-yl] Acetate

116. Cs-0009567

117. Ethyl 3-amino-1,2,4-triazole-1-carboxylate

118. C06958

119. D07845

120. (2s,3s)-5-(2-(dimethylamino)ethyl)-2-(4-

121. A825887

122. Q422229

123. W-106274

124. Brd-k24023109-001-02-5

125. Brd-k24023109-003-03-9

126. Brd-k24023109-003-11-2

127. Brd-k24023109-003-20-3

128. 8-chloro-1-methyl-6-phenyl-4h-2,3,5,10b-tetraaza-benzo[e]azulene

129. (2s,3s)-5-(2-(dimethylamino)ethyl)-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydrobenzo[b][1,4]thiazepin-3-ylacetate

130. 1,5-benzothiazepin-4(5h)-one, 3-(acetyloxy)-5-(u2-(dimethylamino)ethyl)-2,3-dihydro-2-(4-methoxyphenyl)-, (+)-cis-

131. 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester(diltiazem)acetic Acid

132. Acetic Acid (s)-5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester

133. Acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester (diltiazem)

134. Acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester(cis-(+)-diltiazem)

135. Acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester; Hydrochloride

136. C9f

137. Cis-acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester

138. Diltiazem;acetic Acid 5-(2-dimethylamino-ethyl)-2-(4-methoxy-phenyl)-4-oxo-2,3,4,5-tetrahydro-benzo[b][1,4]thiazepin-3-yl Ester

2.4 Create Date
2005-06-24
3 Chemical and Physical Properties
Molecular Weight 414.5 g/mol
Molecular Formula C22H26N2O4S
XLogP33.1
Hydrogen Bond Donor Count0
Hydrogen Bond Acceptor Count6
Rotatable Bond Count7
Exact Mass414.16132849 g/mol
Monoisotopic Mass414.16132849 g/mol
Topological Polar Surface Area84.4 Ų
Heavy Atom Count29
Formal Charge0
Complexity565
Isotope Atom Count0
Defined Atom Stereocenter Count2
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 10  
Drug NameCardizem
PubMed HealthDiltiazem (Intravenous route)
Drug ClassesBenzothiazepine, Calcium Channel Blocker, Cardiovascular Agent
Drug LabelCARDIZEM (diltiazem hydrochloride) is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5H)-one, 3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-2-...
Active IngredientDiltiazem hydrochloride
Dosage FormTablet
RouteOral
Strength60mg; 30mg; 90mg; 120mg
Market StatusPrescription
CompanyValeant Intl

2 of 10  
Drug NameCartia xt
PubMed HealthDiltiazem (By mouth)
Drug ClassesAntianginal, Antihypertensive, Cardiovascular Agent
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-methoxyphen...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 240mg
Market StatusPrescription
CompanyActavis Labs Fl

3 of 10  
Drug NameDilacor xr
Drug LabelDILACOR XR (diltiazem hydrochloride, USP) is a calcium ion influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength180mg; 120mg; 240mg
Market StatusPrescription
CompanyWatson Labs

4 of 10  
Drug NameDilt-cd
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-methoxyphen...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 240mg
Market StatusPrescription
CompanyApotex

5 of 10  
Drug NameDiltzac
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)-one,3-(acetyloxy)-5[2-(dimethylamino)ethyl]-2,-3-dihydro-2(4-methoxyphenyl)-, monohydrochloride...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 360mg; 240mg
Market StatusPrescription
CompanyApotex

6 of 10  
Drug NameCardizem
PubMed HealthDiltiazem (Intravenous route)
Drug ClassesBenzothiazepine, Calcium Channel Blocker, Cardiovascular Agent
Drug LabelCARDIZEM (diltiazem hydrochloride) is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5H)-one, 3-(acetyloxy)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-2-...
Active IngredientDiltiazem hydrochloride
Dosage FormTablet
RouteOral
Strength60mg; 30mg; 90mg; 120mg
Market StatusPrescription
CompanyValeant Intl

7 of 10  
Drug NameCartia xt
PubMed HealthDiltiazem (By mouth)
Drug ClassesAntianginal, Antihypertensive, Cardiovascular Agent
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-methoxyphen...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 240mg
Market StatusPrescription
CompanyActavis Labs Fl

8 of 10  
Drug NameDilacor xr
Drug LabelDILACOR XR (diltiazem hydrochloride, USP) is a calcium ion influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-Benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength180mg; 120mg; 240mg
Market StatusPrescription
CompanyWatson Labs

9 of 10  
Drug NameDilt-cd
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker or calcium antagonist). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)one,3-(acetyloxy)-5-[2-(dimethylamino) ethyl]-2,3-dihydro-2-(4-methoxyphen...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 240mg
Market StatusPrescription
CompanyApotex

10 of 10  
Drug NameDiltzac
Drug LabelDiltiazem hydrochloride is a calcium ion cellular influx inhibitor (slow channel blocker). Chemically, diltiazem hydrochloride is 1,5-benzothiazepin-4(5H)-one,3-(acetyloxy)-5[2-(dimethylamino)ethyl]-2,-3-dihydro-2(4-methoxyphenyl)-, monohydrochloride...
Active IngredientDiltiazem hydrochloride
Dosage FormCapsule, extended release
RouteOral
Strength300mg; 180mg; 120mg; 360mg; 240mg
Market StatusPrescription
CompanyApotex

4.2 Therapeutic Uses

Diltiazem ... may reduce the incidence of reinfarction in patients with a first non-Q-wave infarction who are not candidates for a beta-adrenergic receptor antagonist.

Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 860


... Diltiazem ... /has/ been shown to provide symptomatic relief in Raynaud's disease.

Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 860


Diltiazem ... /is/ indicated, alone or in combination with other agents, for treatment of hypertension. /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional 21 st ed. Volume 1. MICROMEDEX Thomson Health Care, Englewood, CO. 2001. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 730


... Parenteral diltiazem /is/ indicated in the treatment of supraventricular tachyarrhythmias. Diltiazem ... produces rapid conversion to sinus rhythm of paroxysmal supraventricular tachycardia (including those associated with accessory bypass tracts, such as Wolff-Parkinson-White [W-P-W] or Lown-Ganong-Levine [L-G-L] syndrome) in patients who do not respond to vagal maneuvers {161} when the atrioventricular (AV) node is required for reentry to sustain tachycardia {125}. Parenteral diltiazem ... also produces temporary control of rapid ventricular rate in atrial flutter or atrial fibrillation. ... /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional 21 st ed. Volume 1. MICROMEDEX Thomson Health Care, Englewood, CO. 2001. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 730


For more Therapeutic Uses (Complete) data for DILTIAZEM (16 total), please visit the HSDB record page.


4.3 Drug Warning

The toxic effects of sustained-release calcium channel blockers may be delayed more than 12 hr after ingestion. All patients with sustained-release calcium channel blocker overdose should be admitted to the hospital for observation, even if they are asymptomatic. /Calcium channel blockers/

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 533


Withdrawal of calcium channel blocking drugs from severely hypertensive patients, even in the absence of previous angina or myocardial infarction, may precipitate myocardial infarction. Worsening angina & myocardial infarction have been described after the withdrawal of calcium channel blocking agents in patients with normal coronary angiography who are being treated for ischemic chest pain. /Calcium channel blockers/

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 533


Patients with ventricular dysfunction, SA or AV nodal conduction disturbances, and systolic blood pressures below 90 mm Hg should not be treated with ... diltiazem, particularly iv.

Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 859


The most common adverse cardiovascular effect noted with IV diltiazem is symptomatic or asymptomatic hypotension, which occurred in 3.2 or 4.3%, respectively, of patients receiving the drug in clinical trials. Hypotension or postural hypotension also was noted in approximately 1% or less of patients receiving oral diltiazem. If symptomatic hypotension occurs, appropriate therapy (e.g., placement of the patients in the Trendelenburg's position, plasma volume expansion) should be initiated. Hypotension occurred secondary to the vasodilating action of diltiazem on vascular smooth muscle. Vasodilation or flushing occurred in 1.7% of patients receiving IV diltiazem and in approximately 1% or less of patients receiving oral diltiazem in clinical trials.

McEvoy, G.K. (ed.). American Hospital Formulary Service- Drug Information 2002. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2002 (Plus Supplements)., p. 1610


For more Drug Warnings (Complete) data for DILTIAZEM (18 total), please visit the HSDB record page.


4.4 Minimum/Potential Fatal Human Dose

At /blood/ levels /of diltiazem/ above 6,100 ug/L, most patients die.

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 537


4.5 Drug Indication

**Oral** Indicated for the management of hypertension, to lower blood pressure, alone or in combination with other antihypertensive agents. Indicated for use to improve exercise tolerance in patients with chronic stable angina. Indicated for the management of variant angina (Prinzmetal's angina). **Intravenous** Indicated for the short-term management of atrial fibrillation or atrial flutter for temporary control of rapid ventricular rate. Indicated for the rapid conversion of paroxysmal supraventricular tachycardias (PSVT) to sinus rhythm. This includes AV nodal reentrant tachycardias and reciprocating tachycardias associated with an extranodal accessory pathway such as the WPW syndrome or short PR syndrome. **Off-label** Indicated for off-label uses in anal fissures (as topical formulation), migraine prophylaxis, cramps in lower leg related to rest, pulmonary hypertension, idiopathic dilated cardiomyopathy, and proteinuria associated with diabetic nephropathy.


5 Pharmacology and Biochemistry
5.1 Pharmacology

Diltiazem is an antihypertensive and vasodilating agent that works by relaxing the vascular muscle and reducing blood pressure. This is related to the long-term therapeutic effects, as lowering the blood pressure reduces the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions. Diltiazem inhibits the influx of extracellular calcium ions across the myocardial and vascular smooth muscle cell membranes during depolarization. Diltiazem is classified as a negative inotrope (decreased force) and negative chronotrope (decreased rate). It is also considered a rate-control drug as it reduces heart rate. Diltiazem is exerts hemodynamic actions by reducing blood pressure, systemic vascular resistance, the rate-pressure product, and coronary vascular resistance while increasing coronary blood flow. Diltiazem decreases sinoatrial and atrioventricular conduction in isolated tissues and has a negative inotropic effect in isolated preparations. In supraventricular tachycardia, diltiazem prolongs AV nodal refractories. As the magnitude of blood pressure reduction is related to the degree of hypertension, the antihypertensive effect of diltiazem is most pronounced in individuals with hypertension. In a randomized, double-blind, parallel-group, dose-response study involving patients with essential hypertension, there was a reduction in the diastolic blood pressure by 1.9, 5.4, 6.1, and 8.6 mmHg in the patients receiving diltiazem at doses of 120, 240, 360, and 540 mg, respectively. In patients receiving placebo, there was a reduction in the diastolic blood pressure by 2.6 mmHg.In a randomized, double-blind study involving patients with chronic stable angina, variable doses of diltiazem administered at night all caused an increased exercise tolerance in the after 21 hours, compared to placebo. In the NORDIL study of patients with hypertension, the therapeutic effectiveness of diltiazem in reducing cardiovascular morbidity and mortality was assessed. When using the combined primary endpoint as fatal and non-fatal stroke, myocardial infarction, and other cardiovascular death, fatal and non-fatal stroke was shown to be reduced by 25% in the diltiazem group. Although the clinical significance to this effect remains unclear, it is suggested that diltiazem may exert a protective role against cerebral stroke in hypertensive patients.


5.2 MeSH Pharmacological Classification

Cardiovascular Agents

Agents that affect the rate or intensity of cardiac contraction, blood vessel diameter, or blood volume. (See all compounds classified as Cardiovascular Agents.)


Antihypertensive Agents

Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism. Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS. (See all compounds classified as Antihypertensive Agents.)


Vasodilator Agents

Drugs used to cause dilation of the blood vessels. (See all compounds classified as Vasodilator Agents.)


Calcium Channel Blockers

A class of drugs that act by selective inhibition of calcium influx through cellular membranes. (See all compounds classified as Calcium Channel Blockers.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
DILTIAZEM
5.3.2 FDA UNII
EE92BBP03H
5.3.3 Pharmacological Classes
Calcium Channel Blocker [EPC]; Calcium Channel Antagonists [MoA]
5.4 ATC Code

C - Cardiovascular system

C05 - Vasoprotectives

C05A - Agents for treatment of hemorrhoids and anal fissures for topical use

C05AE - Muscle relaxants

C05AE03 - Diltiazem


C - Cardiovascular system

C08 - Calcium channel blockers

C08D - Selective calcium channel blockers with direct cardiac effects

C08DB - Benzothiazepine derivatives

C08DB01 - Diltiazem


5.5 Absorption, Distribution and Excretion

Absorption

Diltiazem is readily absorbed from the gastrointestinal tract. Minimum therapeutic plasma diltiazem concentrations appear to be in the range of 50 to 200 ng/mL. Following oral administration of extended formulations of 360 mg diltiazem, the drug in plasma was detectable within 3 to 4 hours and the peak plasma concentrations were reached between 11 and 18 hours post-dose. Diltiazem peak and systemic exposures were not affected by concurrent food intake. Due to hepatic first-pass metabolism, the absolute bioavailability following oral administration is about 40%, with the value ranging from 24 to 74% due to high interindividual variation in the first pass effect. The bioavailability may increase in patients with hepatic impairment.


Route of Elimination

Due to its extensive metabolism, only 2% to 4% of the unchanged drug can be detected in the urine. The major urinary metabolite in healthy volunnteers was N-monodesmethyl diltiazem, followed by deacetyl N,O-didesmethyl diltiazem, deacetyl N-monodesmethyl diltiazem, and deacetyl diltiazem; however, there seems to be large inter-individual variability in the urinary excretion of DTZ and its metabolites.


Volume of Distribution

The apparent volume of distribution of diltiazem was approximately 305 L following a single intravenous injection in healthy male volunteers.


Clearance

Following a single intravenous injection in healthy male volunteers, the systemic clearance of diltiazem was approximately 65 L/h. After constant rate intravenous infusion, the systemic clearance decreased to 48 L/h.


The protein binding of diltiazem is 80-90%, & the volume of distribution is approx 5.3 L/kg. Clearance of diltiazem after oral ingestion follows first-order kinetics, with a half-life of 5-10 hr, independent of the amount ingested. In sustained release preparations, however, the peak absorption time is delayed & the half-life may be very prolonged because of continued GI absorption.

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 533


Although the absorption of ... agents /like diltiazem/ is nearly complete after oral admin, their bioavailability is reduced, in some cases markedly, because of first-pass hepatic metab. The effects of these drugs are evident within 30-60 min of an oral dose ... . During repeated oral admin, bioavailability and half-life may incr because of saturation of hepatic metabolism. A major metabolite of diltiazem is desacetyldiltiazem, which has about 1/2 of diltiazem's potency as a vasodilator.

Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 858


Diltiazem is excreted into human milk.

Briggs, G.G, R.K. Freeman, S.J. Yaffe. A Reference Guide to Fetal and Neonatal Risk. Drugs in Pregnancy and Lactation. 4th ed. Baltimore, MD: Williams & Wilkins 1994., p. 288


The pharmacokinetic changes of diltiazem ... and its main metabolite, deacetyldiltiazem (DAD) were studied after oral admin of diltiazem to normal rabbits and mild and medium folate-induced renal failure rabbits. Diltiazem 10 mg/kg was given to the rabbits ... orally (n=6). Plasma concns of diltiazem and DAD were determined by a high performance liquid chromatography assay. The area under the plasma concn-time curves (AUC) and max plasma concn (Cmax) of diltiazem were significantly increased in mild and medium folate-induced renal failure rabbits. The metabolite ratio of the diltiazem to DAD were significantly decreased in mild and medium folate-induced renal failure rabbits. The volume of distribution (Vd) and total body clearance (CLt) of diltiazem were significantly decreased in mild and medium folate-induced renal failure rabbits. The elimination rate constant (beta) of diltiazem was significantly decreased in folate-induced renal failure rabbits, but that of DAD was significantly increased. These findings suggest that the hepatic metab of diltiazem was inhibited ... .

PMID:11534767 Choi JS, et al; Arch Pharm Res 24(4): 333-337 (2001)


The pharmacokinetics of diltiazem in rabbits after subconjunctival and topical admin was studied. Diltiazem successfully penetrated the aq humor of rabbit eyes. The peak aq concns were 3.8 +/- 0.4 ug/ml after topical application and 15.3 +/- 1.1 ug/ml after subconjunctival injection. The peak aq concn was achieved 1/2 hrs after admin in both cases.

PMID:10744205 Oruc S, et al; Eur J Ophthalmol 10(1): 46-50 (2000)


5.6 Metabolism/Metabolites

Diltiazem is subject to extensive first-pass metabolism, which explains its relatively low absolute oral bioavailability. It undergoes N-demethylation primarily mediated by CYP3A4. CYP2D6 is responsible for O-demethylation and esterases mediate deacetylation. There was large inter-individual variability in the circulating plasma levels of metabolites in healthy volunteers. In healthy volunteers, the major circulating metabolites in the plasma are N-monodesmethyl diltilazem, deacetyl diltiazem, and deacetyl N-monodesmethyl diltiazem, which are all pharmacologically active. Deacetyl diltiazem retains about 25-50% of the pharmacological activity to that of the parent compound. Deacetyl diltiazem can be further transformed into deacetyl diltiazem N-oxide or deacetyl O-desmethyl diltiazem. N-monodesmethyl diltilazem can be further metabolized to N,O-didesmethyl diltiazem. Deacetyl N-monodesmethyl diltiazem can be further metabolized to deacetyl N,O-didesmethyl diltiazem, which can be glucuronidated or sulphated. Diltiazem can be O-demethylated by CYP2D6 to form O-desmethyl diltiazem.


A major metabolite of diltiazem is desacetyldiltiazem, which has about 1/2 of diltiazem's potency as a vasodilator.

Hardman, J.G., L.E. Limbird, P.B., A.G. Gilman. Goodman and Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York, NY: McGraw-Hill, 2001., p. 858


Diltiazem undergoes extensive metabolism in hepatic and extrahepatic tissues. Deacetyldiltiazem (M1) and N-demethyldiltiazem (MA) are 2 of the main basic metabolites of diltiazem that retain pharmacological activity. This drug impairs its own metab after chronic admin in the adult patient.

PMID:11465404 Fraile LJ, et al; Xenobiotica 31(4): 177-185 (2001)


Diltiazem has known human metabolites that include N-Demethyldiltiazem and O-Demethyldiltiazem.

S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560


5.7 Biological Half-Life

The plasma elimination half-life is approximately 3.0 to 4.5 hours following single and multiple oral doses. The half-life may slightly increase with dose and the extent of hepatic impairment. The apparent elimination half-life for diltiazem as extended-release tablets after single or multiple dosing is 6 to 9 hours. The plasma elimination half-life is approximately 3.4 hours following administration of a single intravenous injection. The elimination half-lives of pharmacologically active metabolites are longer than that of diltiazem.


Clearance of diltiazem after oral ingestion follows first-order kinetics, with a half-life of 5-10 hr ... .

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 533


5.8 Mechanism of Action

Excitation of cardiac muscle involves the activation of a slow calcium inward current that is induced by L-type slow calcium channels, which are voltage-sensitive, ion-selective channels associated with a high activation threshold and slow inactivation profile. L-type calcium channels are the main current responsible for the late phase of the pacemaker potential. Acting as the main Ca2+ source for contraction in smooth and cardiac muscle, activation of L-type calcium channels allows the influx of calcium ions into the muscles upon depolarization and excitation of the channel. It is proposed that this cation influx may also trigger the release of additional calcium ions from intracellular storage sites. Diltiazem is a slow calcium channel blocker that binds to the extracellular site of the alpha-1C subunit of the channel, which is thought to be the S5-6 linker region of the transmembrane domain IV and/or S6 segment of domain III. Diltiazem can get access to this binding site from either the intracellular or extracellular side, but it requires a voltage-induced conformational changes in the membrane. Diltiazem inhibits the influx of extracellular calcium across the myocardial and vascular smooth muscle cell membranes. In isolated human atrial and ventricular myocardium, diltiazem suppressed tension over the range of membrane potentials associated with calcium channel activity but had little effect on the tension-voltage relations at more positive potentials. This effect is thought to be mediated by the voltage-dependent block of the L-type calcium channels and inhibition of calcium ion release from the ER stores, without altering the sodium-calcium coupled transport or calcium sensitivity of myofilaments. Through inhibition of inward calcium current, diltiazem exerts a direct ionotropic and energy sparing effect on the myocardium. Diltiazem fslows atrioventricular nodal conduction, which is due to its ability to impede slow channel function. Reduced intracellular calcium concentrations equate to increased smooth muscle relaxation resulting in arterial vasodilation and therefore, decreased blood pressure. The decrease in intracellular calcium inhibits the contractile processes of the myocardial smooth muscle cells, causing dilation of the coronary and systemic arteries, increased oxygen delivery to the myocardial tissue, decreased total peripheral resistance, decreased systemic blood pressure, and decreased afterload. Through its actions on reducing calcium levels in cardiac and vascular smooth muscles, diltiazem causes a reduction in the contractile processes of the myocardial smooth muscle cells and vasodilation of the coronary and systemic arteries, including epicardial and subendocardial. This subsequently leads to increased oxygen delivery to the myocardial tissue, improved cardiac output due to increased stroke volume, decreased total peripheral resistance, decreased systemic blood pressure and heart rate, and decreased afterload. Diltiazem lowers myocardial oxygen demand through a reduction in heart rate, blood pressure, and cardiac contractility; this leads to a therapeutic effect in improving exercise tolerance in chronic stable angina.


The effects of D-cis- and L-cis-diltiazem on the hydrogen peroxide (H2O2)-induced derangements of mechanical function and energy metab, and accumulation of intracellular Na+ were studied in isolated rat hearts. The intracellular concn of Na+ ([Na+]i) in the myocardium was measured using a nuclear magnetic resonance technique. H2O2 (600 uM) increased the left ventricular end-diastolic pressure, decreased the tissue level of ATP, and increased the release of lactate dehydrogenase from the myocardium. These alterations induced by H2O2 were significantly attenuated by D-cis-diltiazem (15 uM) or L-cis-diltiazem (15 uM). H2O2 (1 mM) produced a marked incr in the myocardial [Na+]i, which was effectively inhibited by ... D-cis-diltiazem (15 uM) or L-cis-diltiazem (15 uM). ... The protective action of D-cis- and L-cis-diltiazem may be due to their ability to inhibit the H2O2-induced incr in [Na+]i, at least in part.

PMID:10422783 Xiao CY, et al; Eur J Pharmacol 374(3): 387-398 (1999)