Diltiazem

Last updated

Diltiazem
Diltiazem structure.svg
Diltiazem ball-and-stick.png
Clinical data
Pronunciation /dɪlˈtəzɛm/
Trade names Cardizem, Dilacor XR, Cartia XT, others
AHFS/Drugs.com Monograph
MedlinePlus a684027
License data
Pregnancy
category
Routes of
administration
By mouth, intravenous
Drug class Nondihydropyridine calcium channel blocker
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability 40%
Metabolism Liver
Elimination half-life 3–4.5 hours
Excretion Kidney
Bile duct
Identifiers
  • cis-(+)-[2-(2-Dimethylaminoethyl)-5-(4-methoxyphenyl)-3-oxo-6-thia-2-azabicyclo[5.4.0]undeca-7,9,11-trien-4-yl]ethanoate
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
PDB ligand
CompTox Dashboard (EPA)
ECHA InfoCard 100.050.707 OOjs UI icon edit-ltr-progressive.svg
Chemical and physical data
Formula C22H26N2O4S
Molar mass 414.52 g·mol−1
3D model (JSmol)
  • O=C2N(c3c(S[C@@H](c1ccc(OC)cc1)[C@H]2OC(=O)C)cccc3)CCN(C)C
  • 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 Yes check.svgY
  • Key:HSUGRBWQSSZJOP-RTWAWAEBSA-N Yes check.svgY
   (verify)

Diltiazem, sold under the brand name Cardizem among others, is a nondihydropyridine calcium channel blocker medication used to treat high blood pressure, angina, and certain heart arrhythmias. [8] It may also be used in hyperthyroidism if beta blockers cannot be used. [8] It is taken by mouth or injection into a vein. [8] When given by injection, effects typically begin within a few minutes and last a few hours. [8]

Contents

Common side effects include swelling, dizziness, headaches, and low blood pressure. [8] Other severe side effects include an overly slow heart beat, heart failure, liver problems, and allergic reactions. [8] Use is not recommended during pregnancy. [8] It is unclear if use when breastfeeding is safe. [1]

Diltiazem works by relaxing the smooth muscle in the walls of arteries, resulting in them opening and allowing blood to flow more easily. [8] Additionally, it acts on the heart to prolong the period until it can beat again. [9] It does this by blocking the entry of calcium into the cells of the heart and blood vessels. [10] It is a class IV antiarrhythmic. [11]

Diltiazem was approved for medical use in the United States in 1982. [8] It is available as a generic medication. [8] In 2021, it was the 84th most commonly prescribed medication in the United States, with more than 8 million prescriptions. [12] [13] An extended release formulation is also available. [8] [14]

Medical uses

Diltiazem is indicated for:

For supraventricular tachycardias (PSVT), diltiazem appears to be as effective as verapamil in treating re-entrant supraventricular tachycardia. [17]

Atrial fibrillation [18] or atrial flutter is another indication. The initial bolus should be 0.25 mg/kg, intravenous (IV).

Because of its vasodilatory effects, diltiazem is useful for treating hypertension. Calcium channel blockers are well tolerated, and especially effective in treating low-renin hypertension. [19]

It is also used as topical application for anal fissures because it promotes healing due to its vasodilatory property. [20]

Contraindications and precautions

Diltiazem is relatively contraindicated in the presence of sick sinus syndrome, atrioventricular node conduction disturbances, bradycardia, impaired left ventricle function, peripheral artery occlusive disease, and chronic obstructive pulmonary disease.

Side effects

A reflex sympathetic response, caused by the peripheral dilation of vessels and the resulting drop in blood pressure, works to counteract the negative inotropic, chronotropic and dromotropic effects of diltiazem. Undesirable effects include hypotension, bradycardia, dizziness, flushing, fatigue, headaches and edema. [21] Rare side effects are congestive heart failure, myocardial infarction, and hepatotoxicity. [22]

Diltiazem is one of the most common drugs that cause drug-induced lupus, along with hydralazine, procainamide, isoniazid, minocycline. [23]

Drug interactions

Because of its inhibition of hepatic cytochromes CYP3A4, CYP2C9 and CYP2D6, there are a number of drug interactions. [24] Some of the more important interactions are listed below.

Beta-blockers

Intravenous diltiazem should be used with caution with beta-blockers because, while the combination is most potent at reducing heart rate, there are rare instances of dysrhythmia and AV node block. [25]

Quinidine

Quinidine should not be used concurrently with calcium channel blockers because of reduced clearance of both drugs and potential pharmacodynamic effects at the SA and AV nodes. [26]

Fentanyl

Concurrent use of fentanyl with diltiazem, or any other CYP3A4 inhibitors, as these medications decrease the breakdown of fentanyl and thus increase its effects. [27]

Mechanism of action

180 mg Cardizem capsule 000197lg cardizem 180mg.jpg
180 mg Cardizem capsule

Diltiazem, also known as (2S,3S)-3-acetoxy-5-[2-(dimethylamino)ethyl]-2,3-dihydro-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one hydrochlorid has a vasodilating activity attributed to the (2S,3S)-isomer. [28] Diltiazem is a potent vasodilator, increasing blood flow and variably decreasing the heart rate via strong depression of A-V node conduction. It binds to the alpha-1 subunit of L-type calcium channels in a fashion somewhat similar to verapamil, another nondihydropyridine (non-DHP) calcium channel blocker. [29] Chemically, it is based upon a 1,4-thiazepine ring, making it a benzothiazepine-type calcium channel blocker.

It is a potent and mild vasodilator of coronary and peripheral vessels, respectively, [30] which reduces peripheral resistance and afterload, though not as potent as the dihydropyridine (DHP) calcium channel blockers. This results in minimal reflexive sympathetic changes.[ citation needed ]

Diltiazem has negative inotropic, chronotropic, and dromotropic effects. This means diltiazem causes a decrease in heart muscle contractility – how strong the beat is, lowering of heart rate – due to slowing of the sinoatrial node, and a slowing of conduction through the atrioventricular node – increasing the time needed for each beat. Each of these effects results in reduced oxygen consumption by the heart, reducing angina, typically unstable angina, symptoms. These effects also reduce blood pressure by causing less blood to be pumped out.

Research

Diltiazem is prescribed off-label by doctors in the US for prophylaxis of cluster headaches. Some research on diltiazem and other calcium channel antagonists in the treatment and prophylaxis of migraine is ongoing. [15] [31] [32] [33] [34] [35] [36] [ needs update ]

Recent research[ when? ] has shown diltiazem may reduce cocaine cravings in drug-addicted rats. [37] This is believed to be due to the effects of calcium blockers on dopaminergic and glutamatergic signaling in the brain. [38] Diltiazem also enhances the analgesic effect of morphine in animal tests, without increasing respiratory depression, [39] and reduces the development of tolerance. [40]

Diltiazem is also being used in the treatment of anal fissures. It can be taken orally or applied topically with increased effectiveness. [41] When applied topically, it is made into a cream form using either vaseline or Phlojel. Phlojel absorbs the diltiazem into the problem area better than the vaseline base. It has good short-term success rates. [42] [43]

Related Research Articles

An antianginal is a drug used in the treatment of angina pectoris, a symptom of ischaemic heart disease.

<span class="mw-page-title-main">Beta blocker</span> Class of medications used to manage abnormal heart rhythms

Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms (arrhythmia), and to protect the heart from a second heart attack after a first heart attack. They are also widely used to treat high blood pressure, although they are no longer the first choice for initial treatment of most patients.

Calcium channel blockers (CCB), calcium channel antagonists or calcium antagonists are a group of medications that disrupt the movement of calcium through calcium channels. Calcium channel blockers are used as antihypertensive drugs, i.e., as medications to decrease blood pressure in patients with hypertension. CCBs are particularly effective against large vessel stiffness, one of the common causes of elevated systolic blood pressure in elderly patients. Calcium channel blockers are also frequently used to alter heart rate, to prevent peripheral and cerebral vasospasm, and to reduce chest pain caused by angina pectoris.

<span class="mw-page-title-main">Verapamil</span> Calcium channel blocker medication

Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina, and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches. It is given by mouth or by injection into a vein.

Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a class of drugs that are used to suppress abnormally fast rhythms (tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia.

<span class="mw-page-title-main">Amlodipine</span> Medication against high blood pressure

Amlodipine, sold under the brand name Norvasc among others, is a calcium channel blocker medication used to treat high blood pressure, coronary artery disease (CAD) and variant angina. It is taken orally.

<span class="mw-page-title-main">Amiodarone</span> Antiarrhythmic medication used for various types of irregular heartbeats

Amiodarone is an antiarrhythmic medication used to treat and prevent a number of types of cardiac dysrhythmias. This includes ventricular tachycardia (VT), ventricular fibrillation (VF), and wide complex tachycardia, as well as atrial fibrillation and paroxysmal supraventricular tachycardia. Evidence in cardiac arrest, however, is poor. It can be given by mouth, intravenously, or intraosseously. When used by mouth, it can take a few weeks for effects to begin.

<span class="mw-page-title-main">Nifedipine</span> Calcium channel blocker medication

Nifedipine, sold under the brand name Procardia among others, is a calcium channel blocker medication used to manage angina, high blood pressure, Raynaud's phenomenon, and premature labor. It is one of the treatments of choice for Prinzmetal angina. It may be used to treat severe high blood pressure in pregnancy. Its use in preterm labor may allow more time for steroids to improve the baby's lung function and provide time for transfer of the mother to a well qualified medical facility before delivery. It is a calcium channel blocker of the dihydropyridine type. Nifedipine is taken by mouth and comes in fast- and slow-release formulations.

<span class="mw-page-title-main">Sotalol</span> Medication

Sotalol, sold under the brand name Betapace among others, is a medication used to treat and prevent abnormal heart rhythms. Evidence does not support a decreased risk of death with long term use. It is taken by mouth or given by injection into a vein.

<span class="mw-page-title-main">Nadolol</span> Non-selective beta blocker used in the treatment of high blood pressure and chest pain

Nadolol, sold under the brand name Corgard among others, is a medication used to treat high blood pressure, heart pain, atrial fibrillation, and some inherited arrhythmic syndromes. It has also been used to prevent migraine headaches and complications of cirrhosis. It is taken orally.

Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia and tissue death (necrosis). Cerebral vasospasm may arise in the context of subarachnoid hemorrhage. Symptomatic vasospasm or delayed cerebral ischemia is a major contributor to post-operative stroke and death especially after aneurysmal subarachnoid hemorrhage. Vasospasm typically appears 4 to 10 days after subarachnoid hemorrhage.

<span class="mw-page-title-main">Ivabradine</span> Heart medication

Ivabradine, sold under the brand name Procoralan among others, is a medication, which is a pacemaker current (If) inhibitor, used for the symptomatic management of heart-related chest pain and heart failure. Patients who qualify for use of Ivabradine for coronary heart failure are patients who have symptomatic heart failure, with reduced ejection volume, and heart rate at least 70 bpm, and the condition not able to be fully managed by beta blockers.

<span class="mw-page-title-main">Nebivolol</span> Chemical compound

Nebivolol is a beta blocker used to treat high blood pressure and heart failure. As with other β-blockers, it is generally a less preferred treatment for high blood pressure. It may be used by itself or with other blood pressure medication. It is taken by mouth.

<span class="mw-page-title-main">Lercanidipine</span> Antihypertensive drug of the calcium channel blocker class

Lercanidipine is an antihypertensive drug. It belongs to the dihydropyridine class of calcium channel blockers, which work by relaxing and opening the blood vessels allowing the blood to circulate more freely around the body. This lowers the blood pressure and allows the heart to work more efficiently.

<span class="mw-page-title-main">Nisoldipine</span> Antihypertensive drug of the calcium channel blocker class

Nisoldipine is a pharmaceutical drug used for the treatment of chronic angina pectoris and hypertension. It is a calcium channel blocker of the dihydropyridine class. It is sold in the United States under the proprietary name Sular. Nisoldipine has tropism for cardiac blood vessels.

The term dromotropic derives from the Greek word δρόμος drómos, meaning "running", a course, a race. A dromotropic agent is one which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart.

<span class="mw-page-title-main">Pilsicainide</span> Chemical compound

Pilsicainide (INN) is an antiarrhythmic agent. It is marketed in Japan as サンリズム (Sunrythm). It was developed by Suntory Holdings Limited and first released in 1991. The JAN applies to the hydrochloride salt, pilsicainide hydrochloride.

<span class="mw-page-title-main">Efonidipine</span> Antihypertensive drug of the calcium channel blocker class

Efonidipine (INN) is a dihydropyridine calcium channel blocker marketed by Shionogi & Co. of Japan. It was launched in 1995, under the brand name Landel (ランデル). The drug blocks both T-type and L-type calcium channels. Drug Controller General of India (DCGI) has approved the use of efonidipine in India. It is launched under the brand name "Efnocar".

<span class="mw-page-title-main">Landiolol</span> Chemical compound

Landiolol (INN) is an ultra short-acting, β1-superselective intravenous adrenergic antagonist, which decreases the heart rate effectively with less negative effect on blood pressure or myocardial contractility. In comparison to other beta blockers, landiolol has the shortest elimination half-life, ultra-rapid onset of effect, and predictable effectiveness with inactive metabolites. The pure S-enantiomer structure of landiolol is believed to develop less hypotensive side effects in comparison to other β-blockers. This has a positive impact on the treatment of patients when reduction of heart rate without decrease in arterial blood pressure is desired. Landiolol was developed by modifying the chemical structure of esmolol to produce a compound with a higher rate of cardioselectivity and a greater potency without increasing its duration of action. It is sold as landiolol hydrochloride. Based on its positive benefit risk profile, landiolol has been granted the marketing authorization and introduced to the European markets under the brand names Rapibloc, Raploc, Runrapiq, Landibloc mid 2016. Landiolol is available in Japan under the brand names Onoact (50 mg) and Corbeta.

<span class="mw-page-title-main">AH-1058</span> Chemical compound

AH-1058 is a lipophilic antiarrhythmic calcium channel blocker synthesized by the Pharmaceutical Research Laboratories of Ajinomoto Co., Inc in Kawasaki, Japan. It is derived from cyproheptadine, a compound with known antiserotonic, antihistaminic and calcium channel blocking properties. The IUPAC name of AH-1058 is: 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-[E-3-(3-methoxy-2-nitro) phenyl-2-propenyl]piperidine hydrochloride.

References

  1. 1 2 "Diltiazem Use During Pregnancy". Drugs.com. 4 May 2020. Retrieved 5 May 2020.
  2. "Dilcardia SR 120 mg Prolonged-release hard capsules – Summary of Product Characteristics (SmPC)". emc. 22 March 2018. Archived from the original on 28 August 2021. Retrieved 13 April 2020.
  3. "Angitil SR/XL Capsules – Summary of Product Characteristics (SmPC)". (emc). 7 May 2019. Retrieved 13 April 2020.
  4. "Cardizem- diltiazem hydrochloride tablet, coated". DailyMed. 2 June 2020. Retrieved 23 October 2022.
  5. "Cardizem CD- diltiazem hydrochloride capsule, coated, extended release". DailyMed. 30 April 2020. Retrieved 23 October 2022.
  6. "Cardizem LA- diltiazem hydrochloride tablet, extended release". DailyMed. 2 May 2019. Retrieved 23 October 2022.
  7. "Active substance(s): diltiazem" (PDF). European Medicines Agency. 11 January 2018.
  8. 1 2 3 4 5 6 7 8 9 10 11 "Diltiazem Hydrochloride Monograph for Professionals". Drugs.com. AHFS. Retrieved 28 December 2018.
  9. Cardiovascular Pharmacotherapeutics. Cardiotext Publishing. 2011. pp. 251–52. ISBN   978-1-935395-62-1 . Retrieved 28 December 2018.
  10. 2010 Nurse's Drug Handbook . Jones & Bartlett Learning. 2010. p.  320. ISBN   978-0-7637-7900-9.
  11. Milne GW (2005). Gardner's Commercially Important Chemicals: Synonyms, Trade Names, and Properties. John Wiley & Sons. p. 223. ISBN   978-0-471-73661-5 . Retrieved 28 December 2018.
  12. "The Top 300 of 2021". ClinCalc. Archived from the original on 15 January 2024. Retrieved 14 January 2024.
  13. "Diltiazem - Drug Usage Statistics". ClinCalc. Retrieved 14 January 2024.
  14. "Diltiazem hydrochloride – diltiazem hydrochloride extended-release tablets tablet, extended release". DailyMed. 1 April 2019. Retrieved 13 April 2020.
  15. 1 2 Grossman E, Messerli FH (2004). "Calcium antagonists". Progress in Cardiovascular Diseases. 47 (1): 34–57. doi:10.1016/j.pcad.2004.04.006. PMID   15517514.
  16. Claas SA, Glasser SP (May 2005). "Long-acting diltiazem HCl for the chronotherapeutic treatment of hypertension and chronic stable angina pectoris". Expert Opinion on Pharmacotherapy. 6 (5): 765–776. doi:10.1517/14656566.6.5.765. PMID   15934903. S2CID   39272285.
  17. Gabrielli A, Gallagher TJ, Caruso LJ, Bennett NT, Layon AJ (October 2001). "Diltiazem to treat sinus tachycardia in critically ill patients: a four-year experience". Critical Care Medicine. 29 (10): 1874–1879. doi:10.1097/00003246-200110000-00004. PMID   11588443. S2CID   25104288.
  18. Wattanasuwan N, Khan IA, Mehta NJ, Arora P, Singh N, Vasavada BC, et al. (February 2001). "Acute ventricular rate control in atrial fibrillation: IV combination of diltiazem and digoxin vs. IV diltiazem alone". Chest. 119 (2): 502–506. doi:10.1378/chest.119.2.502. PMID   11171729.
  19. Basile J (November 2004). "The role of existing and newer calcium channel blockers in the treatment of hypertension". Journal of Clinical Hypertension. 6 (11): 621–629, quiz 630–631. doi: 10.1111/j.1524-6175.2004.03683.x . PMC   8109670 . PMID   15538095. S2CID   23440538.
  20. Griffin N, Acheson AG, Jonas M, Scholefield JH (October 2002). "The role of topical diltiazem in the treatment of chronic anal fissures that have failed glyceryl trinitrate therapy". Colorectal Disease. 4 (6): 430–435. doi:10.1046/j.1463-1318.2002.00376.x. PMID   12790914. S2CID   32959944.
  21. Ramoska EA, Spiller HA, Winter M, Borys D (February 1993). "A one-year evaluation of calcium channel blocker overdoses: toxicity and treatment". Annals of Emergency Medicine. 22 (2): 196–200. doi:10.1016/S0196-0644(05)80202-1. PMID   8427431.
  22. Talreja O, Cassagnol M (2019). "Diltiazem". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID   30422532.
  23. Solhjoo M, Ho CH, Chauhan E (2019). "article-24529". Drug-Induced Lupus Erythematosus. Treasure Island (FL): StatPearls Publishing. PMID   28722919 . Retrieved 20 November 2019.
  24. Ohno Y, Hisaka A, Suzuki H (2007). "General framework for the quantitative prediction of CYP3A4-mediated oral drug interactions based on the AUC increase by coadministration of standard drugs". Clinical Pharmacokinetics. 46 (8): 681–696. doi:10.2165/00003088-200746080-00005. PMID   17655375. S2CID   41343222.
  25. Edoute Y, Nagachandran P, Svirski B, Ben-Ami H (April 2000). "Cardiovascular adverse drug reaction associated with combined beta-adrenergic and calcium entry-blocking agents". Journal of Cardiovascular Pharmacology. 35 (4): 556–559. doi: 10.1097/00005344-200004000-00007 . PMID   10774785.
  26. Narimatsu A, Taira N (August 1976). "Effects of atrio-ventricular conduction of calcium-antagonistic coronary vasodilators, local anaesthetics and quinidine injected into the posterior and the anterior septal artery of the atrio-ventricular node preparation of the dog". Naunyn-Schmiedeberg's Archives of Pharmacology. 294 (2): 169–177. doi:10.1007/bf00507850. PMID   1012337. S2CID   21986119.
  27. "Drug interactions: Interactions between fentanyl and drugs that inhibit CYP3A4". Archived from the original on 3 December 2017. Retrieved 26 June 2019.
  28. Matsumae H, Akatsuka H, Shibatani T (2010). "Diltiazem Synthesis". Encyclopedia of Industrial Biotechnology. pp. 1–20. doi:10.1002/9780470054581.eib603. ISBN   978-0-471-79930-6.
  29. O'Connor SE, Grosset A, Janiak P (1999). "The pharmacological basis and pathophysiological significance of the heart rate-lowering property of diltiazem". Fundamental & Clinical Pharmacology. 13 (2): 145–153. doi:10.1111/j.1472-8206.1999.tb00333.x. PMID   10226758. S2CID   20440286.
  30. Gordon SG, Kittleson MD (2008). "Drugs used in the management of heart disease and cardiac arrhythmias". Small Animal Clinical Pharmacology. Elsevier. pp. 380–457. doi:10.1016/b978-070202858-8.50019-1. ISBN   978-0-7020-2858-8.
  31. Montastruc JL, Senard JM (April 1992). "[Calcium channel blockers and prevention of migraine]" [Calcium channel blockers and prevention of migraine]. Pathologie-Biologie (in French). 40 (4): 381–388. PMID   1353873.
  32. Kim KE (February 1991). "Comparative clinical pharmacology of calcium channel blockers". American Family Physician. 43 (2): 583–588. PMID   1990741.
  33. Andersson KE, Vinge E (March 1990). "Beta-adrenoceptor blockers and calcium antagonists in the prophylaxis and treatment of migraine". Drugs. 39 (3): 355–373. doi:10.2165/00003495-199039030-00003. PMID   1970289. S2CID   13621196.
  34. Paterna S, Martino SG, Campisi D, Cascio Ingurgio N, Marsala BA (July 1990). "[Evaluation of the effects of verapamil, flunarizine, diltiazem, nimodipine and placebo in the prevention of hemicrania. A double-blind randomized cross-over study]". La Clinica Terapeutica. 134 (2): 119–125. PMID   2147612.
  35. Smith R, Schwartz A (May 1984). "Diltiazem prophylaxis in refractory migraine". The New England Journal of Medicine. 310 (20): 1327–1328. doi:10.1056/NEJM198405173102015. PMID   6144044.
  36. Peroutka SJ (November 1983). "The pharmacology of calcium channel antagonists: a novel class of anti-migraine agents?". Headache. 23 (6): 278–283. doi:10.1111/j.1526-4610.1983.hed2306278.x. PMID   6358127. S2CID   40215836.
  37. Common Heart Drug May Reduce Cocaine Cravings. Sciencedaily.com (28 February 2008). Retrieved on 21 October 2012.
  38. Mills K, Ansah TA, Ali SF, Mukherjee S, Shockley DC (July 2007). "Augmented behavioral response and enhanced synaptosomal calcium transport induced by repeated cocaine administration are decreased by calcium channel blockers". Life Sciences. 81 (7): 600–608. doi:10.1016/j.lfs.2007.06.028. PMC   2765982 . PMID   17689567.
  39. Kishioka S, Ko MC, Woods JH (May 2000). "Diltiazem enhances the analgesic but not the respiratory depressant effects of morphine in rhesus monkeys". European Journal of Pharmacology. 397 (1): 85–92. doi:10.1016/S0014-2999(00)00248-X. PMID   10844102.
  40. Verma V, Mediratta PK, Sharma KK (July 2001). "Potentiation of analgesia and reversal of tolerance to morphine by calcium channel blockers". Indian Journal of Experimental Biology. 39 (7): 636–642. PMID   12019755.
  41. Jonas M, Neal KR, Abercrombie JF, Scholefield JH (August 2001). "A randomized trial of oral vs. topical diltiazem for chronic anal fissures". Diseases of the Colon and Rectum. 44 (8): 1074–1078. doi:10.1007/BF02234624. PMID   11535842. S2CID   40406260.
  42. Nash GF, Kapoor K, Saeb-Parsy K, Kunanadam T, Dawson PM (November 2006). "The long-term results of diltiazem treatment for anal fissure". International Journal of Clinical Practice. 60 (11): 1411–1413. doi: 10.1111/j.1742-1241.2006.00895.x . PMID   16911570. S2CID   23510129.
  43. Sajid MS, Rimple J, Cheek E, Baig MK (January 2008). "The efficacy of diltiazem and glyceryltrinitrate for the medical management of chronic anal fissure: a meta-analysis". International Journal of Colorectal Disease. 23 (1): 1–6. doi:10.1007/s00384-007-0384-x. PMID   17846781. S2CID   13015745.