Diltiazem contraindications

Blockers are contraindicated in patients with severe bradycardia (heart rate less than 50 beats per minute) or AV conduction defects in the absence of a pacemaker. (3-Blockers should be used with particular caution in combination with other agents that depress AV conduction (e.g., digoxin, verapamil, and diltiazem) because of increased risk for bradycardia and heart block. Relative contraindications include asthma, bronchospastic disease, severe depression, and peripheral vascular disease. (3,-Selective blockers are preferred in patients with asthma or chronic obstructive pulmonary... 

In randomized, controlled, clinical trials, calcium channel blockers were as effective as p-blockers at preventing ischemic symptoms. Calcium channel blockers are recommended as initial treatment in IHD when /3-blockers are contraindicated or not tolerated. In addition, CCBs may be used in combination with /3-blockers when initial treatment is unsuccessful. However, the combination of a (1-blocker with either verapamil or diltiazem should be used with extreme caution since all of these drugs decrease AV nodal conduction, increasing the risk for severe bradycardia or AV block when used together. If combination therapy is warranted, a long-acting dihydropyridine CCB is preferred. (3-Blockers will prevent reflex increases in sympathetic tone and heart rate with the use of calcium channel blockers with potent vasodilatory effects. 

STE ACS class lla recommendation and NSTE ACS class I recommendation for patients with ongoing ischemia who are already taking adequate doses of nitrates and P-blockers or in patients with contraindications to or intolerance to P-blockers (diltiazem or verapamil for STE ACS and diltiazem, verapamil, or amlodipine for NSTE ACS). 

Adverse effects and contraindications of calcium channel blockers are described in Table 5-2. Verapamil, diltiazem, and first-generation dihydropyridines should also be avoided in patients with acute decompensated heart failure or left... 

As described in the previous section, calcium channel blockers should not be administered to most patients with ACS. Their role is a second-line treatment for patients with certain contraindications to P-blockers and those with continued ischemia despite P-blocker and nitrate therapy. Administration of either amlodipine, diltiazem, or verapamil is preferred.2 Agent selection is based on heart rate and left ventricular dysfunction (diltiazem and verapamil are contraindicated in patients with bradycardia, heart block, or systolic heart failure). Dosing and contraindications are described in Table 5-2. 

Dihydropyridine channel blockers (e.g., nifedipine) have little benefit on clinical outcomes beyond symptom relief. The role of verapamil and diltiazem appears to be limited to symptom relief or control of heart rate in patients with supraventricular arrhythmias in whom /l-blockers are contraindicated or ineffective. 

Good candidates for calcium channel antagonists include patients with contraindications or intolerance to /3-blockers, coexisting conduction system disease (excluding the use of verapamil and possibly diltiazem), Prinzmetal angina, peripheral vascular disease, severe ventricular dysfunction, and concurrent hypertension. Amlodipine is probably the agent of choice in severe ventricular dysfunction, and the other dihydropyridines should be used with caution if the EF is less than 40%. 

Centrally acting sympatholytics (e.g., clonidine) and calcium channel antagonists (e.g., diltiazem) may be useful for symptom control when contraindications to /3-blockade exist. 

Contraindications Acute MI, pulmonary congestion, hypersensitivity to diltiazem or other antihypertensives, second- or third-degree AV block (except in the presence of a pacemaker), severe hypotension (less than 90 mm Hg, systolic), sick sinus syndrome... 

In patients with unstable angina, immediate-release short-acting calcium channel blockers can increase the risk of adverse cardiac events and therefore are contraindicated (see Toxicity, above). However, in patients with non-Q-wave myocardial infarction, diltiazem can decrease the frequency of postinfarction angina and may be used. 

During the acute phase of thyrotoxicosis, B-adrenoceptor blocking agents without intrinsic sympathomimetic activity are extremely helpful. Propranolol, 20-40 mg orally every 6 hours, will control tachycardia, hypertension, and atrial fibrillation. Propranolol is gradually withdrawn as serum thyroxine levels return to normal. Diltiazem, 90-120 mg three or four times daily, can be used to control tachycardia in patients in whom blockers are contraindicated, eg, those with asthma. Other calcium channel blockers may not be as effective as diltiazem. Adequate nutrition and vitamin supplements are essential. Barbiturates accelerate T4 breakdown (by hepatic enzyme induction) and may be helpful both as sedatives and to lower T4... 

Contraindications Hypersensitivity to diltiazem Hypotension Sick sinus syndrome Second- or third-degree AV block Acute myocardial infarction and pulmonary congestion Hypersensitivity to Nifedipine Hypersensitivity to isradipine... 

Verapamil and diltiazem are prototypic calcium channel blockers. As indicated previously, these drugs influence cardiac function by blocking inward calcium movement through L channels. In so doing they block conduction velocity in SA and AV node cells. They are used therapeutically to treat reentry arrhythmias through the AV node as well as paroxysmal supraventricular tachycardias. In fact, verapamil has been reported to terminate 60-80 percent of paroxysmal supraventricular tachycardias within several minutes. However, because of their potent effect on AV conduction, these drugs are contraindicated in patients with preexisting conduction problems since they may produce complete AV block. 

Adverse effects Verapamil and diltiazem have negative inotropic properties and therefore may be contraindicated in patients with preexisting depressed cardiac function. Both drugs can also cause a decrease in blood pressure caused by peripheral vasodilation. 

C Diltiazem. Quinidine can be used to maintain normal sinus rhythm (NSR) after cardioversion of atrial fibrillation. Metoprolol is commonly used to control ventricular rate before conversion to NSR. However, this patient has two contraindications (COPD and diabetes) for beta-blocker use. Unlike diltiazem, amlodipine and nimodipine do not block AV nodal conduction therefore, they would be ineffective at rate control. 

Good candidates for calcium channel blockers in angina include patients with contraindications to or intolerance of /3-blockers, those with coexisting conduction system disease (except for verapamil and diltiazem), those with Prinzmetal s angina (vasospastic or variable-threshold angina), those with peripheral vascular disease, those with severe ventricular dysfunction (amlopidine is probably the calcium channel blocker of choice, and others need to be used with caution if the ejection fraction is less than 40%), and those with concurrent hypertension. 

Although earlier trials suggested that verapamil and diltiazem may provide improved benefit in selected patients, the large Incomplete Infarction Trial of European Research Collaborators Evaluating Prognosis post-Thrombolysis (INTERCEPT) has dampened the interest for the use of diltiazem in patients receiving fibrinolytics. In this trial, the use of extended-release diltiazem had no effect on the 6-month risk of cardiac death, MI, or recurrent ischemia. Therefore, the role of verapamil or diltiazem appears to be limited to relief of ischemia-related symptoms or control of heart rate in patients with supraventricular arrhythmias for whom /8-blockers are contraindicated or ineffective. ... 

Adverse effects and contraindications of calcium channel blockers are described in Table 16. Verapamil, diltiazem, and first-generation dihydropyridines also should be avoided in patients with acute decompensated heart failure or LV dysfunction because they can worsen heart failure and potentially increase mortality secondary to their negative inotropic effects. In patients with heart failure requiring treatment with a calcium channel blocker, amlodipine is the preferred agent. ... 

Heart block is a contraindication for the nondihydropyridines. The most common side effects are bradycardia and heart block (for the nondihydropyridines). Peripheral edema and headache are also common. Nondihydropyridines exacerbate bradycardic effects of /S-blockers, and verapamil raises digoxin serum concentrations by 70%. Diltiazem raises cyclosporine serum concentrations. Intravenous calcium salts inhibit the pharmacologic effect of CCBs. Generic formulations or similar products, but not necessarily generic equivalents to the original brand names, are available for verapamil, nifedipine, and diltiazem. 

The calcium channel blockers generally are considered seconder third-line options for preventive treatment when other drugs with established clinical benefit are ineffective or contraindicated. Verapamil is the most widely used calcium chaimel blocker for preventive treatment, but it provided only modest benefit in decreasing the frequency of attacks in two placebo-controlled studies." The therapeutic effect of verapamil may not be noted for up to 8 weeks after initiation of therapy. Side effects of verapamil may include constipation, hypotension, bradycardia, atrioventricular block, and exacerbation of congestive heart failure. Evaluations of nifedipine, nimodipine, diltiazem, and nicardipine have yielded equivocal results. ... 

In view of these effects the US manufacturers suggest halving the dose of cilostazol in the presence ofCYP3A4 inhibitors such as erythromycin, diltiazem, itraconazole, and ketoconazole. However, the UK manufacturers contraindicate CYP3A4 inhibitors, and they specifically name erythromycin, diltiazem, ketoconazole, cimetidine, and the protease inhibitors. Just why these recommendations differ is not clear. The US manufacturers suggest that other CYP3A4 inhibitors, such as azole anti-fungals (fluconazole, miconazole), SSRIs (fluoxetine, fluvoxamine, sertraline) and nefazodone, may also interact. ... 

The manufacturers of sertindole contraindicate the concurrent use of cimetidine, diltiazem, erythromycin, itraconazole, ketoco-nazole, terfenadine and verapamil because of an increased risk of cardiac arrhythmias. Carbamazepine and phenytoin reduce plasma sertindole levels whereas fluoxetine and paroxetine increase them. No clinically relevant interactions occur with alprazolam, antacids, food or tobacco smoking. 

Concurrent use is unquestionably valuable and uneventful in many patients, but severe adverse effects can develop. This is well established. A not dissimilar adverse interaction can occur with verapamil , (p.841). On the basis of 6 reports, the incidence of symptomatic bradyarrhythmia was estimated to be about 10 to 15%. It can occur with different beta blockers, even with very low doses, and at any time from within a few hours of starting treatment to 2 years of concurrent use. The main risk factors seem to be ventricular dysfunction, or sinoatrial or AV nodal conduction abnormalities. Note that these are usually contraindications to the use of diltiazem. Patients with normal ventricular function and no evidence of conduction abnormalities are usually not at risk. Concurrent use should be well monitored for evidence of adverse effects. Changes in the pharmacokinetics of the beta blockers may also occur, but these changes are probably not clinically important. 

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