Continuous calcium chloride infusion for massive nifedipine overdose

Calcium Channel Blocker Toxicity: A Practical Approach

Calcium channel blockers (CCBs) are widely prescribed medications for various clinical indications in adults and children. They are available in both immediate and long-acting formulations and are generally classified into dihydropyridines and nondihydropyridines, with nondihydropyridines having more cardioselectivity. CCB toxicity is common given the widespread use which leads to serious adverse clinical outcomes, especially in children. Severe CCB toxicities may present with life-threatening bradycardia, hypotension, hyperglycemia, and renal insufficiency. Dihydropyridine toxicity, however, may present with reflex tachycardia instead of bradycardia. Initial patient evaluation and assessment are crucial to identify the severity of CCB toxicity and design the best management strategy. There are different strategies to overcome CCB toxicity that requires precise dosing and close monitoring in various patient populations. These strategies may include large volumes of IV fluids, calcium salts, high insulin euglycemia therapy (HIET), and vasopressors. We hereby summarize the evidence behind the management of CCB toxicity and present a practical guide for clinicians to overcome this common drug toxicity.

Advances of Drugs Electroanalysis Based on Direct Electrochemical Redox on Electrodes: A Review

The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research.

Critical Management of Severe Hypotension Caused by Amlodipine Toxicity Managed With Hyperinsulinemia/Euglycemia Therapy Supplemented With Calcium Gluconate, Intravenous Glucagon and Other Vasopressor Support: Review of Literature

Calcium channel blocker (CCB ) overdose, whether intentional or accidental, is a common clinical scenario and can be very lethal. Conventional treatments for CCB overdose include intravenous (IV) fluids, calcium salts, dopamine, dobutamine, norepinephrine, phosphodiesterase inhibitors, and glucagon. However, the conventional therapies are unsuccessful in reversing the cardiovascular toxicity of CCB, so they commonly fail to improve the hemodynamic condition of the patient. Blockade of the L-type calcium channels that mediate the antihypertensive effect of CCBs also decreases the release of insulin from pancreatic β-islet cells and reduces glucose uptake by tissues (insulin resistance). By targeting this insulin-mediated pathway, hyperinsulinemia/euglycemia therapy (HIET) appears to have a distinct role, and its clinical potential is underrecognized in the management of severe CCB toxicity. We present a case of young man with amlodipine toxicity successfully managed with high dose of IV insulin therapy.

Treatment for calcium channel blocker poisoning: a systematic review

CONTEXT

Calcium channel blocker poisoning is a common and sometimes life-threatening ingestion.

OBJECTIVE

To evaluate the reported effects of treatments for calcium channel blocker poisoning. The primary outcomes of interest were mortality and hemodynamic parameters. The secondary outcomes included length of stay in hospital, length of stay in intensive care unit, duration of vasopressor use, functional outcomes, and serum calcium channel blocker concentrations.

METHODS

Medline/Ovid, PubMed, EMBASE, Cochrane Library, TOXLINE, International pharmaceutical abstracts, Google Scholar, and the gray literature up to December 31, 2013 were searched without time restriction to identify all types of studies that examined effects of various treatments for calcium channel blocker poisoning for the outcomes of interest. The search strategy included the following Keywords: [calcium channel blockers OR calcium channel antagonist OR calcium channel blocking agent OR (amlodipine or bencyclane or bepridil or cinnarizine or felodipine or fendiline or flunarizine or gallopamil or isradipine or lidoflazine or mibefradil or nicardipine or nifedipine or nimodipine or nisoldipine or nitrendipine or prenylamine or verapamil or diltiazem)] AND [overdose OR medication errors OR poisoning OR intoxication OR toxicity OR adverse effect]. Two reviewers independently selected studies and a group of reviewers abstracted all relevant data using a pilot-tested form. A second group analyzed the risk of bias and overall quality using the STROBE (STrengthening the Reporting of OBservational studies in Epidemiology) checklist and the Thomas tool for observational studies, the Institute of Health Economics tool for Quality of Case Series, the ARRIVE (Animal Research: Reporting In Vivo Experiments) guidelines, and the modified NRCNA (National Research Council for the National Academies) list for animal studies. Qualitative synthesis was used to summarize the evidence. Of 15,577 citations identified in the initial search, 216 were selected for analysis, including 117 case reports. The kappa on the quality analysis tools was greater than 0.80 for all study types.

RESULTS

The only observational study in humans examined high-dose insulin and extracorporeal life support. The risk of bias across studies was high for all interventions and moderate to high for extracorporeal life support. High-dose insulin. High-dose insulin (bolus of 1 unit/kg followed by an infusion of 0.5-2.0 units/kg/h) was associated with improved hemodynamic parameters and lower mortality, at the risks of hypoglycemia and hypokalemia (low quality of evidence). Extracorporeal life support. Extracorporeal life support was associated with improved survival in patients with severe shock or cardiac arrest at the cost of limb ischemia, thrombosis, and bleeding (low quality of evidence). Calcium, dopamine, and norepinephrine. These agents improved hemodynamic parameters and survival without documented severe side effects (very low quality of evidence). 4-Aminopyridine. Use of 4-aminopyridine was associated with improved hemodynamic parameters and survival in animal studies, at the risk of seizures. Lipid emulsion therapy. Lipid emulsion was associated with improved hemodynamic parameters and survival in animal models of intravenous verapamil poisoning, but not in models of oral verapamil poisoning. Other studies. Studies on decontamination, atropine, glucagon, pacemakers, levosimendan, and plasma exchange reported variable results, and the methodologies used limit their interpretation. No trial was documented in humans poisoned with calcium channel blockers for Bay K8644, CGP 28932, digoxin, cyclodextrin, liposomes, bicarbonate, carnitine, fructose 1,6-diphosphate, PK 11195, or triiodothyronine. Case reports were only found for charcoal hemoperfusion, dialysis, intra-aortic balloon pump, Impella device and methylene blue.

CONCLUSIONS

The treatment for calcium channel blocker poisoning is supported by low-quality evidence drawn from a heterogeneous and heavily biased literature. High-dose insulin and extracorporeal life support were the interventions supported by the strongest evidence, although the evidence is of low quality.

Management of calcium channel blocker overdoses

Calcium channel blockers (CCBs) are some of the most commonly used medications in clinical practice to treat hypertension, angina, cardiac arrhythmias, and some cases of heart failure. Recent data show that CCBs are the most common of the cardiovascular medications noted in intentional or unintentional overdoses.(1) Novel treatment approaches in the form of glucagon, high-dose insulin therapy, and intravenous lipid emulsion therapies have been tried and have been successful. However, the evidence for these are limited to case reports and case series. We take this opportunity to review the various treatment options in the management of CCB overdoses with a special focus on high-dose insulin therapy as the emerging choice for initial therapy in severe overdoses.

Intravenous lipid emulsion in the management of amlodipine overdose

OBJECTIVE

To report a case of amlodipine overdose successfully treated with intravenous lipid emulsion (ILE).

CASE SUMMARY

A 47-year-old, 110 kg female ingested at least 350 mg of amlodipine with an unknown amount of ethanol. Initial blood pressure was 103/57 mm Hg, mean arterial pressure (MAP) 72 mm Hg, and heart rate 113 beats per minute. In the early clinical course, activated charcoal, intravenous fluid, and calcium boluses were administered. Worsening hypotension prompted a 100 mL bolus of 20% ILE. Stable hemodynamics were maintained for 2 hours. Subsequently, profound hypotension and shock developed (MAP 38 mm Hg), which failed to fully respond to 3 vasopressor agents, calcium, and glucagon. With continuing shock despite optimized vasopressors, an infusion of 2,300 mL 20% ILE was administered over 4.5 hours (20.9 mL/kg infusion total). By completion of the infusion, 2 vasopressors were tapered off and MAP remained above 70 mm Hg; within 12 hours, no further interventions were required. Possible adverse events of ILE, lipemia and hypoxia, were experienced but quickly resolved. The patient survived to hospital discharge within 8 days.

DISCUSSION

Toxicity of amlodipine presents similar to distributive shock as both are due to marked peripheral vasodilation. There are numerous interventions in the management of amlodipine overdose, despite which many patients continue to suffer life-threatening shock as observed with this patient. ILE has been used with promising preliminary results as salvage therapy in case reports of other lipophilic molecules. This is the first report of lone amlodipine overdose treated with ILE.

CONCLUSION

ILE is a novel antidote for overdoses of lipophilic substances and demonstrated efficacy in this case of amlodipine overdose without the use of hyperinsulinemic euglycemia.

Updates in the general approach to the pediatric poisoned patient

Poison prevention remains essential to prevent the most vulnerable population from becoming exposed to potentially lethal toxins. The evaluation of a child presumed to have been exposed to a toxic substance should include a precise history of the exposure, a physical examination, and knowledge of current ingestions and recreational practices. New treatments and research guiding therapy continue to evolve. Poison centers and medical toxicologists can be consulted to assist with the diagnosis of medicinal/drug overdoses, for advice about the pitfalls inherent in stabilizing children who have been exposed to toxic compounds, and for treatment recommendations based on the latest research.

Prolonged Refractory Hypotension following Combined Amlodipine and Losartan Ingestion Responsive to Metaraminol

Introduction. Overdose with the calcium channel blocker amlodipine can cause profound hypotension that may be exacerbated by the concurrent ingestion of an angiotensin II receptor antagonist. Best management of such overdoses is uncertain although the use of hyperinsulinaemia-euglycaemia (HIE) has been recommended. Case report. We report a case of mixed amlodipine and losartan overdose in a 50-year-old lady. Severe hypotension was resistant to conventional vasopressors and high-dose insulin/euglycaemia, but did respond to a metaraminol infusion. Conclusion. A trial of metaraminol early in severe cases of calcium channel blocker and angiotensin II receptor antagonist toxicity may be of benefit, especially when conventional ionotropic treatment measures are failing.

Calcium Channel Blocker Ingestion: An Evidence-Based Consensus Guideline for Out-of-Hospital Management

In 2003, U.S. poison control centers were consulted after 9650 ingestions of calcium channel blockers (CCBs), including 57 deaths. This represents more than one-third of the deaths reported to the American Association of Poison Control Centers' Toxic Exposure Surveillance System database that were associated with cardiovascular drugs and emphasizes the importance of developing a guideline for the out-of-hospital management of calcium channel blocker poisoning. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with suspected ingestions of calcium channel blockers. An evidence-based expert consensus process was used to create this guideline. This guideline applies to ingestion of calcium channel blockers alone and is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. The panel's recommendations follow. The grade of recommendation is in parentheses. 1) All patients with stated or suspected self-harm or the recipient of a potentially malicious administration of a CCB should be referred to an emergency department immediately regardless of the amount ingested (Grade D). 2) Asymptomatic patients are unlikely to develop symptoms if the interval between the ingestion and the call is greater than 6 hours for immediate-release products, 18 hours for modified-release products other than verapamil, and 24 hours for modified-release verapamil. These patients do not need referral or prolonged observation (Grade D). 3) Patients without evidence of self-harm should have further evaluation, including determination of the precise dose ingested, history of other medical conditions, and the presence of co-ingestants. Ingestion of either an amount that exceeds the usual maximum single therapeutic dose or an amount equal to or greater than the lowest reported toxic dose, whichever is lower (see Table 5), would warrant consideration of referral to an emergency department (Grade D). 4) Do not induce emesis (Grade D). 5) Consider the administration of activated charcoal orally if available and no contraindications are present. However, do not delay transportation in order to administer charcoal (Grade D). 6) For patients who merit evaluation in an emergency department, ambulance transportation is recommended because of the potential for life-threatening complications. Provide usual supportive care en route to the hospital, including intravenous fluids for hypotension. Consider use of intravenous calcium, glucagon, and epinephrine for severe hypotension during transport, if available (Grade D). 7) Depending on the specific circumstances, follow-up calls should be made to determine outcome at appropriate intervals based on the clinical judgment of the poison center staff (Grade D).

Calcium channel blocker toxicity

Calcium channel blockers continue to be used for the management of a wide variety of adult and pediatric conditions including hypertension, angina pectoris, atrial arrhythmias, Raynaud phenomenon, and migraine headaches. With increased use comes increased potential for misuse and abuse. This article serves as a review of calcium channel blocker physiology with emphasis on presentation and management of the pediatric patient with calcium channel blocker toxicity.

A fatal case of iatrogenic hypercalcemia after calcium channel blocker overdose

We report a case of a 61-year-old woman treated for a suspected verapamil overdose with continuous calcium chloride infusion, resulting in severe hypercalcemia of 32.3 mg/dL (8.07 mmol/L) with a normal range of 8.6-10.5 mg/dL (2.15-2.63 mmol/L). Treatment with acute hemodialysis rapidly normalized the serum calcium level, but the patient later died of vasoconstrictive complications of hypercalcemia.

The use of vasopressin in the setting of recalcitrant hypotension due to calcium channel blocker overdose

Treatment of hypotension caused by calcium channel blocker overdose (CCB) remains a challenge. We describe the successful use of vasopressin in two patients with massive CCB overdoses in whom hypotension was unresponsive to calcium, glucagon, insulin, and conventional vasopressor therapies. While various modes of treatments have been used to treat the hypotension of CCB overdose, this is the first report to our knowledge of the successful use of vasopressin in this clinical setting.

Calcium channel blocker overdose: experience with amlodipine

Amlodipine overdose is only scarcely reported from India. We report two cases of near fatal Amlodipine overdose managed in our ICU with fluid, vasopressors, calcium infusion and Glucagon. Literature is reviewed and other treatment modalities discussed.

The poisoned child in the pediatric intensive care unit

Acutely poisoned children remain a common problem facing pediatricians working in acute care medicine in the United States and worldwide. The management of such children continues to be challenging, and their care has evolved throughout the years. The concept of gastric decontamination in acute poisoning has significantly changed over the past 10 years, and many of the previously used techniques have been abandoned or fallen out of favor for lack of evidence to their benefit or unacceptable serious risks and side effects. Supportive care continues to be the cornerstone in managing most poisoned children. Only a few patients benefit from antidotes or specific interventions.

High-Dose Insulin in the Treatment of Antihypertensive Overdose

Objective

To describe a case of calcium channel blocker overdose along with an angiotensin-converting enzyme inhibitor and angiotensin receptor blocker, which was successfully treated with high-dose insulin with dextrose and potassium supplementation (HDIDK).

Case Summary

A 52-year-old woman was transferred to an admitting hospital after ingesting 14 tablets of trandolapril/verapamil SR ( Tarka)4 mg/240 mg, 15 to 16 tablets of olmesartan ( Benicar) 20 mg, and an unknown amount of (escitalopram) Lexapro combined with unknown quantities of alcohol and benzodiazepines. This combination caused hypotension and electrocardiogram changes. The patient was treated for hypotension-induced shock with epinephrine, glucagon, HDIDK, magnesium, and fluids. An insulin infusion ran for 24 hours. The patient was discharged to a psychiatric facility 3 days after admission.

Discussion

The non-dihydropyridine, verapamil, causes dilation of the coronary and peripheral vasculature by inhibiting the influx of calcium ions through L-type calcium channels. HDIDK is thought to be a useful treatment in the state of hypoinsulinemia, which prevents the uptake of glucose by myocytes and can lead to decreased inotropy and eventually shock. High-dose insulin allows glucose to be properly used for energy by the myocytes.

Conclusions

Currently HDIDK therapy is recommended as an adjunct to conventional therapy in calcium channel blocker poisoning only after fluids, high-dose calcium salts, and vasopressors. In this case, early implementation of HDIDK treatment was shown to shorten the length of therapy.

Hyperinsulinemic Euglycemia Therapy for Verapamil Poisoning: A Review

Treatment of patients with verapamil overdose remains challenging. Traditional decontamination and supportive measures with intravenous calcium and vasopressors are the mainstays in initial care. Recently, the successful use of rescue hyperinsulinemic euglycemia therapy has been described in multiple cases. Treatment resulted in improved hemodynamic parameters and increased metabolic efficiency in patients with a low-output, myocardial shock state. Information on clinical use of hyperinsulinemic euglycemia therapy in humans is limited to case reports and small case series; no controlled clinical trials have been done. Hyperinsulinemic euglycemia therapy should be considered for patients with calcium channel blocker overdose who do not respond to initial supportive therapy.

Are One or Two Dangerous? Calcium Channel Blocker Exposure in Toddlers

Unintentional pediatric ingestions of calcium channel blockers are increasing in frequency due to increased use of this antihypertensive class. Potential toxic effects include severe refractory hypotension and death; however, the true toxicity of unintentional pediatric ingestions of 1-2 pills is poorly defined. A literature review was conducted to more closely determine toxic and lethal dosages of calcium channel blockers in the pediatric population under 6 years of age. Results indicate that, although most accidental pediatric ingestions are asymptomatic, a small number do result in cardiovascular instability or even death. The dihydropyridines, particularly nifedipine, and the phenylalkylamine verapamil are most often implicated in symptomatic ingestions. There are no adequate data to identify which children are predisposed to illness, or to determine cutoffs for toxic dosages. However, ingestions of only one pill have been documented to cause severe symptoms, including death. Thus, emergency evaluation to assess potential toxicity is necessary, and gastrointestinal decontamination and in-hospital observation of at least 6 h after toxic ingestion for regular release medications, and 12-24 h after toxic ingestion for sustained release medications is recommended for all cases of unintentional calcium channel blocker ingestion in children younger than 6 years of age.

Bench-to-bedside review: hyperinsulinaemia/euglycaemia therapy in the management of overdose of calcium-channel blockers

Hyperinsulinaemia/euglycaemia therapy (HIET) consists of the infusion of high-dose regular insulin (usually 0.5 to 1 IU/kg per hour) combined with glucose to maintain euglycaemia. HIET has been proposed as an adjunctive approach in the management of overdose of calcium-channel blockers (CCBs). Indeed, experimental data and clinical experience, although limited, suggest that it could be superior to conventional pharmacological treatments including calcium salts, adrenaline (epinephrine) or glucagon. This paper reviews the patho-physiological principles underlying HIET. Insulin administration seems to allow the switch of the cell metabolism from fatty acids to carbohydrates that is required in stress conditions, especially in the myocardium and vascular smooth muscle, resulting in an improvement in cardiac contractility and restored peripheral resistances. Studies in experimental verapamil poisoning in dogs have shown that HIET significantly improves metabolism, haemodynamics and survival in comparison with conventional therapies. Clinical experience currently consists only of a few isolated cases or short series in which the administration of HIET substantially improved cardiovascular conditions in life-threatening CCB poisonings, allowing the progressive discontinuation of vasoactive agents. While we await further well-designed clinical trials, some rational recommendations are made about the use of HIET in severe CBB overdose. Although the mechanism of action is less well understood in this condition, some experimental data suggesting a potential benefit of HIET in β-adrenergic blocker toxicity are discussed; clinical data are currently lacking.

The role of insulin and glucose (hyperinsulinaemia/euglycaemia) therapy in acute calcium channel antagonist and beta-blocker poisoning

The inotropic effect of insulin has been long established. High-dose (0.5-1 IU/kg/hour) insulin, in combination with a glucose infusion to maintain euglycaemia (hyperinsulinaemia/euglycaemia therapy), has been proposed as a treatment for calcium channel antagonist (CCA) and beta-adrenoceptor antagonist (beta-blocker) poisonings. However, the basis for its beneficial effect is poorly understood.CCAs inhibit insulin secretion, resulting in hyperglycaemia and alteration of myocardial fatty acid oxidation. Similarly, blockade of beta(2)-adrenoceptors in beta-blocker poisoning results in impaired lipolysis, glycogenolysis and insulin release. Insulin administration switches cell metabolism from fatty acids to carbohydrates and restores calcium fluxes, resulting in improvement in cardiac contractility. Experimental studies in verapamil poisoning have shown that high-dose insulin significantly improved survival compared with calcium salts, epinephrine or glucagon. In several life-threatening poisonings in humans, the administration of high-dose insulin produced cardiovascular stabilisation, decreased the catecholamine vasopressor infusion rate and improved the survival rate. In a canine model of propranolol intoxication, high-dose insulin provided a sustained increase in systemic blood pressure, cardiac performance and survival rate compared with glucagon or epinephrine. In contrast, insulin had no effect on heart rate and electrical conduction in the myocardium. In another study, high-dose insulin reversed the negative inotropic effect of propranolol to 80% of control function and normalised heart rate. High-dose insulin produced a significant decrease in the left ventricular end-diastolic pressure and a significant increase in the stroke volume and cardiac output. The vasodilator effect was explained by an enhanced cardiac output leading to withdrawal of compensatory vasoconstriction. No clinical studies have yet been performed. Although not effective in all cases, we recommend hyperinsulinaemia/euglycaemia therapy in patients with severe CCA poisoning who present with hypotension and respond poorly to fluid, calcium salts, glucagon and catecholamine infusion. However, careful monitoring of blood glucose and serum potassium concentrations is required to avoid serious adverse effects. More clinical data are needed before this therapy can be recommended in beta-blocker poisoning. There is a need for large prospective clinical trials to confirm safety and efficacy of hyperinsulinaemia/euglycaemia therapy in both CCA and beta-blocker poisoning.

Calcium Channel Blocker Toxicology

Calcium channel blockers are commonly prescribed antihypertensive medications in the United States and as such are a common presenting ingestion. The pharmacology and mechanism of action of this class of drugs will be discussed. The clinical presentation and therapeutic options will be reviewed.

Easily reversible hypoxemia and hypotension induced by nimodipine

Calcium antagonists are drugs commonly prescribed for the treatment of hypertension, angina pectoris, cardiac arrhythmias and other disorders because of their efficacy and tolerability. Nevertheless, overdosage and intoxication are well documented. In this paper we report a case of nimodipine overdosage resulting in prolonged hypotension and hypoxemia, which was successfully treated with calcium gluconate.

Deadly pediatric poisons: nine common agents that kill at low doses

More than 97% of pediatric exposures reported to the AAPCC in 2001 had either no effect or mild clinical effects. Despite the large number of exposures, only 26 of the 1074 reported fatalities occurred in children younger than age 6. These findings reflect the fact that, in contrast to adolescent or adult ingestions, pediatric ingestions are unintentional events secondary to development of exploration behaviors and the tendency to place objects in the mouth. Ingested substances typically are nontoxic or ingested in such small quantities that toxicity would not be expected. As a result, it commonly is believed that ingestion of one or two tablets by a toddler is a benign act and not expected to produce any consequential toxicity. Select agents have the potential to produce profound toxicity and death, however, despite the ingestion of only one or two tablets or sips. Although proven antidotes are a valuable resource, their value is diminished if risk after ingestion is not adequately appreciated and assessed. Future research into low-dose, high-risk exposures should be directed toward further clarification of risk, improvements in overall management strategies,and, perhaps most importantly, prevention of toxic exposure through parental education and appropriate safety legislation.

Pharmacology, Pathophysiology and Management of Calcium Channel Blocker and ??-Blocker Toxicity

Calcium channel blockers (CCB) and beta-blockers (BB) account for approximately 40% of cardiovascular drug exposures reported to the American Association of Poison Centers. However, these drugs represent >65% of deaths from cardiovascular medications. Yet, caring for patients poisoned with these medications can be extremely difficult. Severely poisoned patients may have profound bradycardia and hypotension that is refractory to standard medications used for circulatory support.Calcium plays a pivotal role in cardiovascular function. The flow of calcium across cell membranes is necessary for cardiac automaticity, conduction and contraction, as well as maintenance of vascular tone. Through differing mechanisms, CCB and BB interfere with calcium fluxes across cell membranes. CCB directly block calcium flow through L-type calcium channels found in the heart, vasculature and pancreas, whereas BB decrease calcium flow by modifying the channels via second messenger systems. Interruption of calcium fluxes leads to decreased intracellular calcium producing cardiovascular dysfunction that, in the most severe situations, results in cardiovascular collapse.Although, CCB and BB have different mechanisms of action, their physiological and toxic effects are similar. However, differences exist between these drug classes and between drugs in each class. Diltiazem and especially verapamil tend to produce the most hypotension, bradycardia, conduction disturbances and deaths of the CCB. Nifedipine and other dihydropyridines are generally less lethal and tend to produce sinus tachycardia instead of bradycardia with fewer conduction disturbances.BB have a wider array of properties influencing their toxicity compared with CCB. BB possessing membrane stabilising activity are associated with the largest proportion of fatalities from BB overdose. Sotalol overdoses, in addition to bradycardia and hypotension, can cause torsade de pointes. Although BB and CCB poisoning can present in a similar fashion with hypotension and bradycardia, CCB toxicity is often associated with significant hyperglycaemia and acidosis because of complex metabolic derangements related to these medications. Despite differences, treatment of poisoning is nearly identical for BB and CCB, with some additional considerations given to specific BB. Initial management of critically ill patients consists of supporting airway, breathing and circulation. However, maintenance of adequate circulation in poisoned patients often requires a multitude of simultaneous therapies including intravenous fluids, vasopressors, calcium, glucagon, phosphodiesterase inhibitors, high-dose insulin, a relatively new therapy, and mechanical devices. This article provides a detailed review of the pharmacology, pathophysiology, clinical presentation and treatment strategies for CCB and BB overdoses.

Management of calcium channel antagonist overdose

Calcium channel antagonists are used primarily for the treatment of hypertension and tachyarrhythmias. Overdose of calcium channel antagonists can be lethal. Calcium channel antagonists act at the L-type calcium channels primarily in cardiac and vascular smooth muscle preventing calcium influx into cells with resultant decreases in vascular tone and cardiac inotropy and chronotropy. The L-type calcium channel is a complex structure and is thus affected by a large number of structurally diverse antagonists. In the setting of overdose, patients may experience vasodilatation and bradycardia leading to a shock state. Patients may also be hyperglycaemic and acidotic due to the blockade of L-type calcium channels in the pancreatic islet cells that affect insulin secretion. Aggressive therapy is warranted in the setting of toxicity. Gut decontamination with charcoal, or whole bowel irrigation or multiple-dose charcoal in the setting of extended-release products is indicated. Specific antidotes include calcium salts, glucagon and insulin. Calcium salts may be given in bolus doses or may be employed as a continuous infusion. Care should be exercised to avoid the administration of calcium in the setting of concomitant digoxin toxicity. Insulin administration has been used effectively to increase cardiac inotropy and survival. The likely mechanism involves a shift to carbohydrate metabolism in the setting of decreased availability of carbohydrates due to decreased insulin secretion secondary to blockade of calcium channels in pancreatic islet cells. Glucose should be administered as well to maintain euglycaemia. Supportive care including the use of phosphodiesterase inhibitors, adrenergic agents, cardiac pacing, balloon pump or extracorporeal bypass is frequently indicated if antidotal therapy is not effective. Careful evaluation of asymptomatic patients, including and electrocardiogram and a period of observation, is indicated. Patients ingesting a nonsustained-release product should be observed in a monitored setting for 12 hours, while those who ingest a sustained-release preparation should be observed for no less than 24 hours. Charcoal should be given to the asymptomatic patient with a history of calcium channel antagonist overdose.

Delayed presentation of calcium channel antagonist overdose

The calcium channel antagonists are generally safe in therapeutic dosage, but severe side effects with elevated intake are increasingly described. Typical features include confusion, lethargy, hypotension, sinus node depression, and cardiac conduction defects. Even if patients are stable on presentation, this does not preclude the possible late development of adverse events from the long-acting formulations of calcium channel blockers. A case of toxic overdose with 1440 mg of slow-release diltiazem is presented; this patient was stable on presentation, but rapidly became hemodynamically unstable, requiring treatment with intravenous calcium, temporary pacemaker, inotropic support and mechanical ventilation with a successful outcome. A concise review of the therapeutic considerations is provided.