Adverse interaction between beta-adrenergic blocking drugs and verapamil--report of three cases

Heart insufficiency after combination of verapamil and metoprolol: A fatal case report and literature review

The combination of verapamil or diltiazem with beta-blockers should be avoided because of potentially profound adverse effects on AV (atrioventricular) nodal conduction, heart rate, or cardiac contractility. This effect is unpredictable but may be enhanced due to CYP2D6 poor metabolizer status which could be a special vulnerability factor.

[Cardiogenic shock after drug therapy for atrial fibrillation with tachycardia : Case report of an 89-year-old woman]

β-Blockers and calcium channel blockers are commonly used drugs in the treatment of atrial fibrillation with tachycardia. However, in patients with high myocardial susceptibility and vulnerability, combination therapy with β-blockers and non-dihydropyridine calcium channel blockers (verapamil or diltiazem) but also individual administration can cause drug-induced cardiogenic shock. Thus, the simultaneous administration of β-blockers and non-dihydropyridine calcium channel blockers is absolutely contraindicated. In case of acute heart failure, isolated application is also contraindicated. In the treatment of a cardiogenic shock induced by β-blockers and/or non-dihydropyridine calcium channel blockers, administration of intravenous calcium, glucagon or high-dose insulin is recommended.

Antihypertensive therapy: special focus on drug interactions

Today, the lifetime risk of patients aged 55-65 years to receive antihypertensive drugs approaches 60%. Yet, recent trials suggest that hypertension is not adequately controlled in the majority of patients. The prevalence of hypertension increases with advancing age, as does the prevalence of comorbid conditions and the total number of medications taken. Multi-drug therapy, advancing age and comorbid conditions are also key risk factors for adverse drug reactions and drug interactions. In this review, the authors evaluate the most frequently used antihypertensive drugs (diuretics, beta-adrenergic blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, angiotensin II receptor Type 1 blockers and alpha-adrenergic blockers) with special reference to pharmacodynamic and pharmacokinetic drug interactions. As the spectrum of drugs prescribed is constantly changing, safety yesterday does not imply safety today and safety today does not imply safety tomorrow. Furthermore, therapeutic efficacy should not be neglected over concerns regarding drug interactions. Many patients are at risk of clinically relevant drug interactions involving antihypertensive drugs but, presently, even more patients may be at risk of suffering from the consequences of their inadequately treated hypertension. In this respect, the authors discuss controversial viewpoints on the overall clinical relevance of drug interactions occurring at the level of cytochrome P450 metabolism.

An autopsy case of combined drug intoxication involving verapamil, metoprolol and digoxin

We present here a fatal poisoning case involving verapamil, metoprolol and digoxin. A 39-year-old male was found dead in his room, and a lot of empty packets of prescribed drugs were found near the corpse. The blood concentrations of verapamil, metoprolol and digoxin were 9.2 microg/ml, 3.6 microg/ml and 3.2 ng/ml, respectively. The cause of death was given as cardiac failure, hypotension and bradycardia due to a mixed drug overdose of verapamil, metoprolol and digoxin, based on the results of the autopsy and toxicological examination. We speculate that the toxicity of verapamil is potentiated by drug interaction with metoprolol and digoxin.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.

Cardiogenic shock triggered by verapamil and atenolol: a case report of therapeutic experience with intravenous calcium

Cardiogenic shock developed in a 72-year-old Japanese woman during combination therapy with verapamil and atenolol for recurrent supraventricular arrhythmia. She had coronary atherosclerosis, liver cirrhosis and bradycardia-tachycardia syndrome. Despite of the high-dose catecholamines and counterpulsation, she progressively deteriorated. Bolus administration of intravenous calcium chloride (CaCl2) immediately resolved her hemodynamic collapse.

A rapid and sensitive electron-capture gas chromatographic procedure for analysis of metoprolol in rat brain and heart

A procedure for analysis of metoprolol-utilizing extraction followed by derivatization with pentafluoropropionic anhydride and analysis on a gas chromatograph equipped with a fused silica capillary column, an electron-capture detector and a printer/integrator is described. Propranolol was carried through the procedure as internal standard. The pentafluoropropionyl derivative of metoprolol yields a sharp peak on the gas chromatograph, and the structure of the derivative was confirmed using combined gas chromatography-mass spectrometry. The analytical method is linear, sensitive and reproducible and has been applied to analysis of metoprolol in brain and heart from rats treated with metoprolol intraperitoneally. Pretreatment of the rats with the antidepressant desipramine prior to metoprolol administration resulted in a marked increase in levels of metoprolol in both brain and heart, indicating a pharmacokinetic drug-drug interaction between desipramine and metoprolol.

Vascular selective calcium entry blockers in the treatment of cardiovascular disorders: focus on felodipine

Calcium entry through L-type calcium channels is essential for contraction of both arterial smooth muscle and the myocardium, and is important in cardiac conduction. First-generation calcium entry blockers lack or have a modest degree of vascular selectivity and inhibit cardiac function at doses producing therapeutic arterial dilatation. Such agents may cause deterioration in patients with left ventricular dysfunction, and their combination with a beta-adrenergic blocker may adversely affect cardiac contractility and conduction. Development of newer agents has focused on obtaining a higher degree of vascular selectivity. Felodipine is a highly vascular selective calcium entry blocker, with a vascular selectivity ratio greater than 100, as shown experimentally. Isradipine and nicardipine are also vascularly selective calcium entry blockers. Hemodynamic studies in patients with hypertension, coronary artery disease, congestive heart failure, or in patients receiving beta-adrenergic blockade, show that felodipine can produce profound arteriolar dilatation without the negative effects of left ventricular systolic performance. Furthermore, felodipine alone or when added to a beta-adrenergic blocker does not interfere with cardiac conduction. The primary mechanism that accounts for the efficacy of dihydropyridine calcium entry blockers in hypertension and angina pectoris is arterial dilation, whereas nondihydropyridines may also derive part of their effect from inhibition of cardiac performance. As some of these patients, most commonly the elderly, have concomitant left ventricular dysfunction, it should be advantageous to avoid myocardial depression in the treatment of their primary disease. Preliminary studies in patients with heart failure indicate that felodipine and amlopidine may improve hemodynamics, reduce neurohormonal activation, and increase exercise tolerance, but final conclusions must await the randomized clinical trials now underway.

Calcium antagonists. Drug interactions of clinical significance

The interaction of calcium antagonists, including the dihydropyridine calcium antagonists (e.g. nifedipine), verapamil and diltiazem, with drugs from other classes has major clinical ramifications as the use of drug combinations increases in frequency. Combinations are used in the treatment of disorders ranging from hypertension to cardiac rhythm disturbances, angina pectoris and peripheral vasospastic disease. In this era of organ transplantation, drugs like cyclosporin are coming into potential conflict with an ever-growing list of drugs. Drug combinations used as part of long term therapies are also making their appearance in toxic drug reactions, including antituberculous and anticonvulsant agents. Bronchodilators and H2-blockers also fall into this category of potential culprits of combined drug toxicity, and the interactions of calcium antagonists with beta-blockers and antiarrhythmic agents are also becoming a matter of concern.

Drug interactions in hypertensive patients. Pharmacokinetic, pharmacodynamic and genetic considerations

Antihypertensive treatment has proven benefits, and the number of patients being treated with these drugs is significant. Hypertensive patients may have other medical illnesses for which they receive medications, and interactions between antihypertensive agents and other drugs is likely. Some of these interactions may lead to undesirable effects or even loss of blood pressure control. However, drug interactions can also be beneficial when 2 antihypertensive drugs with different pharmacological actions are prescribed in combination and with a clear therapeutic objective in mind. Clinicians should be aware of the mechanisms and the consequences of the different types of interaction in hypertensive patients, so that a desired pharmacological response can be achieved with the fewest side effects in the patients.

Calcium channel antagonism and beta blockade in combination--a therapeutic alternative in cardiovascular disorders. A review

Calcium-channel antagonists and beta-adrenergic blocking agents have become important modalities in the cardiovascular therapeutic armamentarium. These drugs are often administered as monotherapy to a wide range of cardiological patients with angina pectoris, hypertension, arrhythmias, congestive heart failure, and other diseases. Since within each class these drugs exhibit pharmacologic differences, it follows that their effectiveness varies in different disease states and that they exhibit a wide variety of side effects. In an attempt to optimize therapy, the individual drugs from these two classes can be combined; and the efficaciousness and side-effect profile of various combinations between calcium-channel antagonists and beta blockers are discussed in this review. Recommendations as to which patients may benefit from a combination and as to which patients may be harmed by the combination therapy will be made. Very few studies have compared the safety and efficacy of a single agent with the combination and with placebo in a controlled randomized fashion. To determine which therapy is superior and to determine which combination one should recommend under what circumstances, such placebo-controlled, randomized trials are a necessity, and will hopefully be performed although the complexity is enormous.

Verapamil increases the toxicity of local anesthetics

The calcium channel blocker verapamil has, in addition to its other properties, been shown to be a local anesthetic. Its concurrent use in a patient undergoing regional anesthesia may, therefore, increase the potential risk for local anesthetic toxicity. To evaluate this possibility, the effect of verapamil on the median lethal dose (LD50) of lidocaine and bupivacaine in mice was determined. Immediate pretreatment with verapamil increased the mortality of mice given the LD50 dose of lidocaine to 74%, and in mice given the LD50 doses of bupivacaine, to 82%. In animals pretreated with verapamil and calcium chloride, the mortality associated with the administration of LD50 doses of lidocaine and bupivacaine decreased to 43% and 48%, respectively, thus returning the mortality rate back to the LD50 of the local anesthetics when administered alone. It seems that the combined administration of local anesthetic and verapamil results in a significant drug interaction: the resulting blockade of sodium and calcium channels apparently impairs membrane function to a greater degree than with either drug alone. Additional investigation is warranted, and caution should be exercised in giving verapamil to patients during regional anesthesia. Should an adverse drug interaction ensue, the administration of calcium may be beneficial.

The effect of combined therapy on the pharmacokinetics and pharmacodynamics of verapamil and propranolol in patients with angina pectoris

1. The pharmacokinetics and pharmacodynamics of oral verapamil and propranolol were studied in patients with stable angina pectoris during chronic mono- and dual therapy. 2. The peak plasma concentrations (Cmax) and areas under the plasma concentration-time curves (AUC) of verapamil were similar during combined treatment with propranolol (mean +/- s.d.: Cmax = 491 +/- 397 ng ml-1; AUC = 2075 +/- 1524 ng ml-1 h) or atenolol (mean +/- s.d.: Cmax = 372 +/- 320 ng ml-1; AUC = 1985 +/- 1660 ng ml-1 h). 3. No differences in Cmax and AUC were observed during verapamil monotherapy (mean +/- s.d.: Cmax = 287 +/- 105 ng ml-1; AUC = 1375 +/- 455 ng ml-1 h) vs combined treatment with propranolol (mean +/- s.d.: Cmax = 312 +/- 55 ng ml-1; AUC = 1566 +/- 486 ng ml-1 h). 4. Treatment with verapamil increased the Cmax (mean +/- s.d.: 227 +/- 117 vs 116 +/- 62 ng ml-1, P less than 0.05) and AUC (1389 +/- 617 vs 837 +/- 316 ng ml-1 h, P = 0.0625) of propranolol in all subjects. 5. Transient atrioventricular dissociation occurred in two patients 2 h after dosing with verapamil and propranolol or atenolol. 6. Close observation of patients is essential when beta-adrenoceptor antagonists and verapamil are used together.

Calcium antagonists and their potential for antihypertensive therapy

Calcium antagonists are potent arterial vasodilators devoid of relevant chronic sympathetic reflex activation and sodium and volume retention. This favorable hemodynamic profile of action renders them suitable for monotherapy of hypertension where they act to reduce an enhanced, calcium-influx-dependent vasoconstrictor mechanism which may be brought about by altered smooth muscle cation handling and increased intracellular free calcium concentrations. Clinical studies have proved their efficacy, safety, and good tolerability alone or in combination with other drugs in uncomplicated hypertension where they are particularly effective in older and low-renin and possibly black patients. These properties and their efficacy in the treatment of severe and accelerated hypertension or hypertensive emergencies make them a valuable addition to already available drug therapy.

Extent and pharmacokinetic mechanisms of oral atenolol-verapamil interaction in man

Chronic coadministration of oral verapamil with oral atenolol resulted in a variable increase in atenolol steady-state plasma concentrations in a group of 10 patients on chronic maintenance therapy. Individual subjects showed changes in area under the plasma atenolol concentration-time curve (AUC) of more than 100%, however group comparisons did not achieve statistical significance unless normalized for verapamil dose. Renal clearance of atenolol was shown to be decreased by more than 25% in 2 subjects studied using intravenous dosing of atenolol. This interaction is likely to contribute to the documented clinical intolerance of combinations of atenolol and verapamil.

Acute hemodynamic effects of intravenous nicardipine in patients treated chronically with propranolol for coronary artery disease

Intravenous nicardipine, 5 mg, was infused over 5 minutes in 2 comparable groups of 8 patients with chronic coronary artery disease but no clinical signs of heart failure. Eight patients had received no previous treatment and served as a control group; 8 other patients had received long-term treatment with large doses of propranolol. The hemodynamic responses to nifedipine were similar in the 2 groups, but was greater in patients taking propranolol. At 10 minutes, systemic vascular resistance decreased by 47% in patients taking propranolol and by 39% in the control group; mean aortic pressures decreased by 25% and 10%; heart rate increased by 23% and 19%; and cardiac index increased by 45% in both groups. At 20 minutes, left ventricular end-systolic volume index decreased by 20% in patients taking propranolol and 15% in the control patients; angiographic stroke index increased by 19% and 8%; left ventricular ejection fraction increased by 22% and 11%; and mean circumferential fiber velocity increased by 46% and 32%. Intravenous nicardipine infusion (5 mg) did not induce negative inotropic effects in patients with chronic coronary heart disease, and no evidence of congestive heart failure was seen, even in patients receiving large doses of propranolol. Nicardipine counteracted the potential deleterious effects of propranolol; increased peripheral vascular resistance and left ventricular stroke work and decreased cardiac output.

A double blind placebo controlled comparison of verapamil, atenolol, and their combination in patients with chronic stable angina pectoris

The efficacy and effect on cardiac function of verapamil 120 mg three times a day and atenolol 100 mg once a day, singly and in combination, were evaluated in 15 patients with angina pectoris. While they were on the combination treatment four patients withdrew from the study. Episodes of angina pectoris and glyceryl trinitrate consumption were significantly reduced only on the combination. On the combination only four patients developed evidence of ischaemia during exercise compared with seven on verapamil and ten on atenolol. ST segment depression at peak exercise, assessed by 16 point precordial mapping, was reduced by all active treatments from 7.1 on placebo to 2.7, 0.9, and 0.6 mm on atenolol, verapamil, and the combination respectively. Mean left ventricular ejection fraction fell significantly from 60% on placebo to 53% on the combination but was unchanged on verapamil and atenolol. Verapamil was an effective alternative to atenolol; the combination was the most effective treatment but was associated with a significant morbidity.

Calcium channel blockers and treatment of hypertension

Over the past years, research efforts have been focused on the pathophysiologic role of calcium ions, and the implication for the potential role of calcium channel blockers in the management of essential hypertension. Numerous studies have shown that nifedipine and verapamil are effective antihypertensive agents, initial experience with diltiazem is also encouraging. The magnitude of blood pressure reduction with these drugs is related to the pre-treatment blood pressure. In refractory hypertension, combination with other antihypertensive agents provide additive effect. In the elderly population and in patients with ischemic heart disease, supraventricular arrhythmia, bronchospastic disease, peripheral vascular disease or diabetes mellitus, the calcium channel blockers offer potential advantages over other antihypertensive agents. Experimental studies also suggest that these drugs may reverse ventricular hypertrophy. When long-term safety with these drugs is documented from well-controlled clinical trials, the calcium channel blockers may be our first line of therapy for the management of hypertension.

Cardiovascular and pharmacokinetic consequences of combined administration of verapamil and propranolol in dogs

Verapamil and propranolol, alone and in combination, were given intravenously to anesthetized dogs to analyze the interaction between drug-induced cardiovascular effects and the resulting changes in pharmacokinetics. Dosing regimens were used that produced steady state plasma levels of both drugs, and the observed effects were clearly related to the plasma concentrations of the agents. When given alone, at stable "therapeutic" levels in plasma, verapamil or propranolol decreased spontaneous heart rate, increased atrioventricular conduction time, and had opposite effects on cardiac output. At the same doses, the combined infusion of the 2 drugs rapidly resulted in profound depression in cardiac function; in addition, plasma concentrations of both agents increased into ranges associated with cardiovascular toxicity. When verapamil doses were reduced, combined infusion with propranolol decreased atrioventricular conduction and cardiac output, but drug plasma concentrations (and associated effects) remained stable. When reduced doses of propranolol were added to infusion of verapamil, similar effects on cardiovascular function occurred, but plasma drug levels increased progressively throughout the remainder of the study period. In all combinations studied, beta blockade with propranolol decreased liver plasma flow and, therefore, the systemic clearance of verapamil. The in vitro effects of propranolol on verapamil metabolism were small, although significant, and not clinically relevant. These acute studies suggest that the hemodynamic effects resulting from verapamil and propranolol in combination may significantly diminish clearance of 1 or both drugs, thereby resulting in accumulation during continued administration, increased drug effects with increasing plasma concentrations, and potentially lethal drug toxicity.

Cardiogenic shock associated with calcium-channel and beta blockers: reversal with intravenous calcium chloride

Two cases in which oral ingestion of beta blocker and slow calcium-channel blocker was associated with profound hypotension and bradycardia are reported, including one case in which serum levels of both drugs were documented in the normal range at a time of severe clinical toxicity. Though unresponsive to usual therapeutic interventions, both patients showed an immediate and dramatic response to intravenous calcium chloride. It is recommended that intravenous calcium chloride be considered in any patient using routine doses of these two agents who presents with hypotension and/or bradycardia.

Combination therapy with calcium-channel blockers and beta blockers for chronic stable angina pectoris

Combination therapy using calcium-channel blockers and beta blockers in patients with refractory chronic stable angina has gained much popularity, but remains highly controversial because of the potential for serious additive deleterious hemodynamic or electrophysiologic reactions. In studies involving patients with preserved left ventricular function receiving chronic oral beta blockers, short-term administration of intravenous verapamil has been shown to cause a further lowering in heart rate and blood pressure while prolonging atrioventricular node conduction; additive cardiodepressant effects were noted, including a tendency toward increased left and right heart filling pressures. Nifedipine, on the other hand, when added acutely to beta blockers, causes an increase in heart rate, a decrease in blood pressure and either no change or a slight improvement in most cardiac performance variables. Controlled, double-blind clinical trials have demonstrated that combinations of calcium-channel blockers and beta blockers result in augmented symptom benefit compared with either drug class alone. The predominant mechanism responsible for such improvement is increased lowering of myocardial oxygen demand by virtue of additive diminution in heart rate, blood pressure and, consequently, pressure-rate product both at rest and during exercise. Verapamil (and possibly diltiazem) plus beta blockers appears to have the greatest therapeutic efficacy but also the highest frequency of harmful adverse cardiac effects, whereas nifedipine plus beta blockers is generally safer but also less efficacious. Factors that should be carefully considered by clinicians contemplating combination therapy are the choice of calcium-channel blocker, the dose of calcium-channel blocker and beta blocker, the presence of antecedent left ventricular dysfunction or conduction system disease and the possibility of drug interactions. Concomitant calcium-channel blocker and beta-blocker therapy is an important contribution to the pharmacologic management of resistant patients who remain symptomatic during single drug treatment. However, the possibility of additive adverse cardiac effects mandates careful patient selection and close clinical monitoring.

Calcium antagonists--drug interactions

Evaluations of drug interactions should be done with caution. One needs to be aware of the reported interactions and apply the information on an individual basis. This review may therefore serve as a guide to the more common drug interactions and when drug therapy should be monitored closely in clinical practice. Major drug interactions with calcium antagonists are summarized in Table 2.

Probable adverse interaction between oral metoprolol and verapamil

A combination of an oral beta-adrenergic blocking agent and verapamil has been advocated as a safe treatment for angina. A case of Wenckebach type atrioventricular block occurring in a patient on metoprolol and verapamil is reported. It is suggested that this combination is used with caution.