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

A Critical Note on Treatment of a Severe Diltiazem Intoxication: High-Dose Calcium and Glucagon Infusions

The morbidity and mortality of a severe calcium channel blocker intoxication is high due to serious toxic cardiac effects. Its treatment is supported by low-quality evidence from the heterogeneous literature. We describe a case of a severe diltiazem intoxication and critically appraise the efficacy and role of high-dose calcium and glucagon infusions. A 53-year-old woman was admitted to the emergency department with a cardiogenic shock with complete AV block, not responding to atropine, isoprenaline and an external pacemaker. Later on, it became clear that she had a severe diltiazem intoxication which was successfully treated with isotone fluids, inotropes, vasopressors and continuous infusion of high-dose calcium and glucagon. The patient developed, however, an acute, necrotizing pancreatitis, probably related to iatrogenic high calcium levels. This case demonstrates lack of consensus regarding target levels of serum calcium for treatment of a severe diltiazem intoxication. Goal-directed tapering of calcium should prevent side effects of iatrogenic hypercalcaemia. The contribution of glucagon infusions is doubtful due to the instability of solubilized glucagon. This might explain why the effect of glucagon is variable in the literature.

Review of management in cardiotoxic overdose and efficacy of delayed intralipid use

We present the case of a 51-year-old woman admitted to our intensive care unit following an intentional overdose of a calcium channel antagonist and a beta blocker. The resultant hypotension was reversed with glucagon, noradrenaline, calcium and high-dose insulin. Despite these interventions, she remained vasoplegic and received a delayed, standard dose of intralipid. Subsequently, the vasoplegia resolved rapidly, and the vasopressor was stopped. Here, we review the management of overdose of calcium channel and beta-adrenergic receptor blockers, concentrating on the pharmacology of lipid emulsion therapy. There remain some unanswered questions about lipid emulsion therapy: treatment with lipid therapy is usually advocated as soon as possible; this case report suggests that it remains efficacious even if its administration were delayed.

Efficacy of isoproterenol for treating amlodipine overdose resulting in bradycardia

Case

Amlodipine predominantly affects vascular smooth muscle cells. Amlodipine overdose usually presents with vasodilatory shock, accompanied by reflex tachycardia rather than bradycardia.

An 81‐year‐old woman presented with impaired consciousness 8 h after ingesting 50 5‐mg amlodipine tablets with suicidal intent. On admission, her blood pressure was 50/40 mmHg and her heart rate was 45 b.p.m. Serum amlodipine level was extremely high (474.4 ng/mL), causing refractory bradycardia. She remained hypotensive despite fluid resuscitation, and therefore was administered dopamine and norepinephrine. She was also administered glucagon and calcium gluconate, and underwent high‐dose insulin euglycemic therapy.

Outcome

Although her blood pressure improved, bradycardia progressively worsened and isoproterenol infusion was initiated, which resulted in an improvement in her heart rate. The patient discharged on day 14 without any complications.

Conclusion

Isoproterenol is effective for treating bradycardia after amlodipine overdose.

The Use of Calcium Channel Blockers in the Treatment of Coronary Spasm and Atrioventricular Block

Calcium channel blockers have been used in the treatment of coronary artery spasm for many years. However, there is insufficient knowledge about their application to treat atrioventricular block caused by coronary spasm. Clinical data of five patients who were diagnosed with coronary spasm caused by atrioventricular block and treated with calcium channel blockers were retrospectively assessed. The patients had varying degrees of atrioventricular block (confirmed by Holter ECG) and myocardial ischemia-like ST-T changes. Two patients were II type I AVB, two patients II type II AVB, and the remaining one patient was III AVB. All patients were all diagnosed with right coronary artery spasm by coronary angiography. The patients were treated with calcium channel blockers. No patient reported recurrence of chest pain or chest discomfort. On Holter ECG monitoring, no significant myocardial ischemia or atrioventricular block was seen. In conclusion, calcium channel blockers are effective and safe in the treatment of atrioventricular block caused by coronary spasm.

Identification of Drug-Drug Interactions In Vitro: A Case Study Evaluating the Effects of Sofosbuvir and Amiodarone on hiPSC-Derived Cardiomyocytes

Drug-drug interactions pose a difficult drug safety problem, given the increasing number of individuals taking multiple medications and the relative complexity of assessing the potential for interactions. For example, sofosbuvir-based drug treatments have significantly advanced care for hepatitis C virus-infected patients, yet recent reports suggest interactions with amiodarone may cause severe symptomatic bradycardia and thus limit an otherwise extremely effective treatment. Here, we evaluated the ability of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) to recapitulate the interaction between sofosbuvir and amiodarone in vitro, and more generally assessed the feasibility of hiPSC-CMs as a model system for drug-drug interactions. Sofosbuvir alone had negligible effects on cardiomyocyte electrophysiology, whereas the sofosbuvir-amiodarone combination produced dose-dependent effects beyond that of amiodarone alone. By comparison, GS-331007, the primary circulating metabolite of sofosbuvir, had no effect alone or in combination with amiodarone. Further mechanistic studies revealed that the sofosbuvir-amiodarone combination disrupted intracellular calcium (Ca²⁺) handling and cellular electrophysiology at pharmacologically relevant concentrations, and mechanical activity at supra-pharmacological (30x C_max) concentrations. These effects were independent of the common mechanisms of direct ion channel block and P-glycoprotein activity. These results support hiPSC-CMs as a comprehensive, yet scalable model system for the identification and evaluation of cardioactive pharmacodynamic drug-drug interactions.

NEWTON: Nimodipine Microparticles to Enhance Recovery While Reducing Toxicity After Subarachnoid Hemorrhage

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity and mortality. EG-1962 is a sustained-release microparticle formulation of nimodipine that has shown preclinical efficacy when administered intraventricularly or intracisternally to dogs with SAH, without evidence of toxicity at doses in the anticipated therapeutic range. Thus, we propose to administer EG-1962 to humans in order to assess safety and tolerability and determine a dose to investigate efficacy in subsequent clinical studies.

METHODS

We describe a Phase 1/2a multicenter, controlled, randomized, open-label, dose escalation study to determine the maximum tolerated dose (MTD) and assess the safety and tolerability of EG-1962 in patients with aSAH. The study will comprise two parts: a dose escalation period (Part 1) to determine the MTD of EG-1962 and a treatment period (Part 2) to assess the safety and tolerability of the selected dose of EG-1962. Patients with a ruptured saccular aneurysm treated by neurosurgical clipping or endovascular coiling will be considered for enrollment. Patients will be randomized to receive either EG-1962 (study drug: nimodipine microparticles) or oral nimodipine in the approved dose regimen (active control) within 60 h of aSAH.

RESULTS

Primary objectives are to determine the MTD and the safety and tolerability of the selected dose of intraventricular EG-1962 as compared to enteral nimodipine. The secondary objective is to determine release and distribution by measuring plasma and CSF concentrations of nimodipine. Exploratory objectives are to determine the incidence of delayed cerebral infarction on computed tomography, clinical features of delayed cerebral ischemia, angiographic vasospasm, and incidence of rescue therapy and clinical outcome. Clinical outcome will be determined at 90 days after aSAH using the extended Glasgow outcome scale, modified Rankin scale, Montreal cognitive assessment, telephone interview of cognitive status, and Barthel index.

CONCLUSION

Here, we describe a Phase 1/2a multicenter, controlled, randomized, open-label, dose escalation study to determine the MTD and assess the safety and tolerability of EG-1962 in patients with aSAH.

Comparison of electrophysiological effects of calcium channel blockers on cardiac repolarization

Dihydropyridine (DHP) calcium channel blockers (CCBs) have been widely used to treat of several cardiovascular diseases. An excessive shortening of action potential duration (APD) due to the reduction of Ca²⁺ channel current (I_Ca) might increase the risk of arrhythmia. In this study we investigated the electrophysiological effects of nicardipine (NIC), isradipine (ISR), and amlodipine (AML) on the cardiac APD in rabbit Purkinje fibers, voltage-gated K⁺ channel currents (I_Kr, I_Ks) and voltage-gated Na⁺ channel current (I_Na). The concentration-dependent inhibition of Ca²⁺ channel currents (I_Ca) was examined in rat cardiomyocytes; these CCBs have similar potency on I_Ca channel blocking with IC₅₀ (the half-maximum inhibiting concentration) values of 0.142, 0.229, and 0.227 nM on NIC, ISR, and AML, respectively. However, ISR shortened both APD₅₀ and APD₉₀ already at 1 µM whereas NIC and AML shortened APD₅₀ but not APD₉₀ up to 30 µM. According to ion channel studies, NIC and AML concentration-dependently inhibited I_Kr and I_Ks while ISR had only partial inhibitory effects (<50% at 30 µM). Inhibition of I_Na was similarly observed in the three CCBs. Since the I_Kr and I_Ks mainly contribute to cardiac repolarization, their inhibition by NIC and AML could compensate for the AP shortening effects due to the block of I_Ca.

Calcium channel antagonist and beta-blocker overdose: antidotes and adjunct therapies

Management of cardiovascular instability resulting from calcium channel antagonist (CCB) or beta-adrenergic receptor antagonist (BB) poisoning follows similar principles. Significant myocardial depression, bradycardia and hypotension result in both cases. CCBs can also produce vasodilatory shock. Additionally, CCBs, such as verapamil and diltiazem, are commonly ingested in sustained-release formulations. This can also be the case for some BBs. Peak toxicity can be delayed by several hours. Provision of early gastrointestinal decontamination with activated charcoal and whole-bowel irrigation might mitigate this. Treatment of shock requires a multimodal approach to inotropic therapy that can be guided by echocardiographic or invasive haemodynamic assessment of myocardial function. High-dose insulin euglycaemia is commonly recommended as a first-line treatment in these poisonings, to improve myocardial contractility, and should be instituted early when myocardial dysfunction is suspected. Catecholamine infusions are complementary to this therapy for both inotropic and chronotropic support. Catecholamine vasopressors and vasopressin are used in the treatment of vasodilatory shock. Optimizing serum calcium concentration can confer some benefit to improving myocardial function and vascular tone after CCB poisoning. High-dose glucagon infusions have provided moderate chronotropic and inotropic benefits in BB poisoning. Phosphodiesterase inhibitors and levosimendan have positive inotropic effects but also produce peripheral vasodilation, which can limit blood pressure improvement. In cases of severe cardiogenic shock and/or cardiac arrest post-poisoning, extracorporeal cardiac assist devices have resulted in successful recovery. Other treatments used in refractory hypotension include intravenous lipid emulsion for lipophilic CCB and BB poisoning and methylene blue for refractory vasodilatory shock.

Chronic P-glycoprotein inhibition increases the brain concentration of escitalopram: potential implications for treating depression

Recent preclinical studies have revealed a functionally important role for the drug efflux pump P‐glycoprotein (P‐gp) at the blood–brain barrier in limiting brain levels and thus antidepressant‐like activity of certain antidepressant drugs. Specifically, acute administration of P‐gp inhibitors, such as verapamil and cyclosporin A (CsA), has been shown to augment brain concentrations and functional activity of the antidepressant escitalopram in rodents. However, depression is a chronic disorder and current treatments require prolonged administration to elicit their full therapeutic effect. Thus, it is important to investigate whether acute findings in relation to P‐gp inhibition translate to chronic paradigms. To this end, the present study investigates whether chronic treatment with the P‐gp inhibitor verapamil and the antidepressant escitalopram results in enhanced brain distribution and antidepressant‐like effects of escitalopram. Verapamil (10 mg·kg⁻¹ i.p.) and escitalopram (0.1 mg·kg⁻¹ i.p.) were administered once daily for 22 days. On the final day of treatment, brain regions and plasma were collected for analysis of cortical and plasma escitalopram concentrations, and to determine the hippocampal expression of genes previously reported to be altered by chronic antidepressant treatment. Verapamil treatment resulted in a greater than twofold increase in brain levels of escitalopram, without altering plasma levels. Neither gene expression analysis nor behavioral testing revealed an augmentation of responses to escitalopram treatment due to verapamil administration. Taken together, these data demonstrate for the first time that P‐gp inhibition can yield elevated brain concentrations of an antidepressant after chronic treatment. The functional relevance of these increased brain levels requires further elaboration.

Glucagon Increases Beating Rate but Not Contractility in Rat Right Atrium. Comparison with Isoproterenol

This study evaluated the chronotropic and inotropic responses to glucagon in spontaneously beating isolated right atria of rat heart. For comparison, we also investigated the effects resulting from stimulating β-adrenoceptors with isoproterenol in this tissue. Isoproterenol increased both atrial frequency and contractility but glucagon only enhanced atrial rate. The transcript levels of glucagon receptors were about three times higher in sinoatrial node than in the atrial myocardium. Chronotropic responses to glucagon and isoproterenol were blunted by the funny current (If) inhibitor ZD 7288. Inhibitors of protein kinase A, H-89 and KT-5720 reduced the chronotropic response to glucagon but not to isoproterenol. Inhibition of ryanodine receptors and calcium/calmodulin dependent protein kinase II (important regulators of sarcoplasmic reticulum Ca2⁺ release), with ruthenium red and KN-62 respectively, failed to alter chronotropic responses of either glucagon or isoproterenol. Non selective inhibition of phosphodiesterase (PDE) with 3-isobutylmethylxantine or selective inhibition of PDE3 or PDE4 with cilostamide or rolipram respectively did not affect chronotropic effects of glucagon or isoproterenol. Our results indicate that glucagon increases beating rate but not contractility in rat right atria which could be a consequence of lower levels of glucagon receptors in atrial myocardium than in sinoatrial node. Chronotropic responses to glucagon or isoproterenol are mediated by If current but not by sarcoplasmic reticulum Ca2⁺ release, neither are regulated by PDE activity.

[The chemico-toxicological determination of dilthiasem]

The objective of the present study was to determine the optimal conditions for isolation of dilthiasem, its purification by the combination of the extraction and column chromatography techniques, and the development of the universal method for the detection of this compound in the biological material. Other research methods included thin layer chromatography (TLC), gas chromatography mass-spectrometry (GH-MS), extraction, low-pressure column chromatography, and spectrophotometry. The effectiveness of dilthiasem isolation from the biological material with the use of 12 organic substances, water, and aqueous solutions was compared. The use of acetone as the universal solvent for dilthiasem isolation from the tissues and biological fluids of the cadaveric organs was substantiated. It was shown that dilthiasem can be purified from endogenous substances contained in the biological materials by means of combined liquid-liquid extraction and chromatography on the 30 mcm Silasorb C-18 column. The new modifications of thin layer chromatography and gas chromatography mass-spectrometry (GH-MS) are proposed for the identification and quantitative determination of dilthiasem isolated from cadaveric blood and hepatic tissue.

A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement

The first descriptions of carbon monoxide (CO) and its toxic nature appeared in the literature over 100 years ago in separate publications by Drs. Douglas and Haldane. Both men ascribed the deleterious effects of this newly discovered gas to its strong interaction with hemoglobin. Since then the adverse sequelae of CO poisoning has been almost universally attributed to hypoxic injury secondary to CO occupation of oxygen binding sites on hemoglobin. Despite a mounting body of literature suggesting other mechanisms of injury, this pathophysiology and its associated oxygen centric therapies persists. This review attempts to elucidate the remarkably complex nature of CO as a gasotransmitter. While CO's affinity for hemoglobin remains undisputed, new research suggests that its role in nitric oxide release, reactive oxygen species formation, and its direct action on ion channels is much more significant. In the course of understanding the multifaceted character of this simple molecule it becomes apparent that current oxygen based therapies meant to displace CO from hemoglobin may be insufficient and possibly harmful. Approaching CO as a complex gasotransmitter will help guide understanding of the complex and poorly understood sequelae and illuminate potentials for new treatment modalities.

Noncardiogenic Pulmonary Edema after Amlodipine Overdose without Refractory Hypotension and Bradycardia

Amlodipine overdose can be life-threatening when manifesting as noncardiogenic pulmonary edema. Treatment remains challenging. We describe a case of noncardiogenic pulmonary edema without refractory hypotension and bradycardia after ingestion of 500 milligram amlodipine with suicidal intent. Mechanical ventilation, dexamethasone, atrovent HFA (ipratropium), pulmicort inhalation, and antibiotic therapy were used for the management. Length of hospital stay was 11 days. The patient was discharged with full recovery.

The Role of Magnesium in the Pathogenesis and Treatment of Glaucoma

Glaucoma is characterized by chronic optic neuropathy resulting in progressive vision loss. Not only is glaucoma considered as a condition of elevated intraocular pressure (IOP), but also other risk factors may play a role in the pathogenesis of glaucomatous optic nerve damage. Vascular dysregulation in ocular blood flow and oxidative stress are currently suggested as important risk factors for glaucomatous retinal ganglion cell loss. New treatment modalities that improve ocular blood flow and reduce oxidative stress have been investigated in many studies. Magnesium (Mg) is thought to be one of the molecules that has a treatment potential in glaucoma. Mg has been shown to improve blood flow by modifying endothelial function via endothelin-1 (ET-1) and endothelial nitric oxide (NO) pathways. Mg also exhibits neuroprotective role by blocking N-methyl-D-aspartate (NMDA) receptor-related calcium influx and by inhibiting the release of glutamate, and hence protects the cell against oxidative stress and apoptosis. Both improvement in ocular blood flow and prevention of ganglion cell loss would make magnesium a good candidate for glaucoma management. Further studies on the effect of Mg may open a new therapeutic era in glaucoma.

Mechanical circulatory support

The role for temporary and durable mechanical circulatory support is rapidly expanding. As the use of these technologies continues to grow, the emergency physician has an increasing opportunity to participate in the advancement of these potentially life-saving technologies. This review discusses the current role of the intra-aortic balloon pump in cardiogenic shock, describes the complications and management strategies for the critically ill patient with a left ventricular assist device, and explores the emerging role of ECMO in the emergency department for patients presenting in refractory cardiogenic shock and cardiac arrest.

Amlodipine poisoning revisited: Acidosis, acute kidney injury and acute respiratory distress syndrome

We report the case of an 18-year-old girl presenting with shock following ingestion of 85 mg of amlodipine and 850 mg of atenolol with suicidal intent. Subsequently, the patient developed severe metabolic acidosis, acute kidney injury, and acute respiratory distress syndrome, which were managed conservatively. The patient ultimately made a full recovery. Given the popularity of amlodipine and atenolol as antihypertensive drugs in this part of the world, it is likely that more such cases will be encountered in the future. Physicians should be aware of the severe complications that can develop with amlodipine overdose.

Utilization of hyperinsulinemia euglycemia and intravenous fat emulsion following poison center recommendations

Hyperinsulinemia euglycemia (HIE) and intravenous fat emulsion (IFE) may be beneficial in the treatment of calcium channel (CCB) and beta receptor (BB) antagonist toxicity. Many poison control centers (PCC) now recommend use. Healthcare providers may be unfamiliar with these treatments and may not institute them despite recommendations. We sought to determine how often HIE and IFE are recommended by a statewide PCC in CCB and BB toxicity, how often those recommendations are implemented, and whether a faxable information sheet increased adherence. All cases of CCB and BB exposure from January 2005-July 2011 where insulin or "other therapy" was coded were reviewed. Exclusion criteria included an incomplete PCC record, miscoding, and insulin administration as other than cardiovascular drug antidotal therapy. There were 215 CCB or BB exposures initially identified using the search criteria. HIE was recommended in 71 cases and started in one case prior to PCC recommendation. HIE was subsequently used in 30 cases after PCC recommendation (42 %). IFE was recommended by the PCC in 30 cases and implemented 10 times (33 %). In six cases, both HIE and IFE were implemented after recommendation. There was no statistical difference when recommendation was made via telephone or by faxable information sheet for HIE or IFE. HIE and IFE are two therapies that are potentially beneficial in the treatment of BB and CCB toxicity. Current national organization guidelines for use are limited. Exploration of reasons for not following recommendations and additional efforts to improve clinician education regarding HIE and IFE may be required to increase the utilization of these potentially lifesaving antidotes.

Toxicity of antihypertensives in unintentional poisoning of young children

BACKGROUND

Knowledge is limited about the toxicity of unintentional exposure to antihypertensives in young children (0-6 years of age).

OBJECTIVE

Our aim was to research symptoms and poisoning severity in unintentional poisonings in this group of age and determine adequate poisoning management.

METHODS

We performed a 10-year retrospective, explorative analysis of the Mainz Poison Center/Germany database with regard to circumstances of poison exposure, dosage, symptoms, and treatment. To be able to relate drug exposure with reported symptoms, analyses were restricted to single drug exposures. Written follow-up information was obtained in about 50% of all cases.

RESULTS

A total of 1489 cases were analyzed, of which 957 were single drug exposures with 421 exposures to beta-blocking agents, 364 to inhibitors of the renin-angiotensin system, 122 to calcium channel blockers, and 50 to antiadrenergic drugs. No severe (Poisoning Severity Score [PSS]=3) or fatal poisonings (PSS=4) were reported and, with the exception of atenolol, propranolol, irbesartan, isradipin, clonidine, and moxonidine, no poisonings with a PSS>1. We did not find a significant relationship between dosage, release formulation and symptoms, or PSS. All patients fully recovered without specific treatment.

CONCLUSIONS

In young children with unintentional, single drug exposure to the most popular antihypertensive medication (i.e., metoprolol, bisoprolol, ramipril, enalapril, lisinopril, captopril, candesartan, valsartan, amlodipine, and verapamil), only mild symptoms occurred, and hospital evaluation is not a must. However, children with recent exposure to clonidine or moxonidine should be evaluated at a hospital due to an increased likelihood of poisonings of at least moderate severity.

High dose insulin therapy, an evidence based approach to beta blocker/calcium channel blocker toxicity

Poison-induced cardiogenic shock (PICS) as a result of beta-blocker (β-blocker) or calcium channel blocker (CCB) overdose is a common and potentially life-threatening condition. Conventional therapies, including fluid resuscitation, atropine, cardiac pacing, calcium, glucagon, and vasopressors often fail to improve hemodynamic status. High-dose insulin (HDI) is an emerging therapeutic modality for PICS. In this article, we discuss the existing literature and highlight the therapeutic success and potential of HDI. Based on the current literature, which is limited primarily to case series and animal models, the authors conclude that HDI can be effective in restoring hemodynamic stability, and recommend considering its use in patients with PICS that is not responsive to traditional therapies. Future studies should be undertaken to determine the optimal dose and duration of therapy for HDI in PICS.

A simplified and structured teaching tool for the evaluation and management of pulseless electrical activity

Cardiac arrest victims who present with pulseless electrical activity (PEA) usually have a grave prognosis. Several conditions, however, have cause-specific treatments which, if applied immediately, can lead to quick and sustained recovery. Current teaching focuses on recollection of numerous conditions that start with the letters H or T as potential causes of PEA. This teaching method is too complex, difficult to recall during resuscitation, and does not provide guidance to the most effective initial interventions. This review proposes a structured algorithm that is based on the differentiation of the PEA rhythm into narrow- or wide-complex subcategories, which simplifies the working differential and initial treatment approach. This, in conjunction with bedside ultrasound, can quickly point towards the most likely cause of PEA and thus guide resuscitation.

Delayed neurological deterioration after subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated by effects of transient cerebral ischaemia during bleeding plus effects of the subarachnoid blood. Secondary effects of SAH include increased intracranial pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift, and herniation, all of which contribute to pathology. Many patients survive these phenomena, but deteriorate days later from delayed cerebral ischaemia (DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI is thought to be caused by the combined effects of angiographic vasospasm, arteriolar constriction and thrombosis, cortical spreading ischaemia, and processes triggered by EBI. Treatment for DCI includes prophylactic administration of nimodipine, and current neurointensive care. Prompt recognition of DCI and immediate treatment by means of induced hypertension and balloon or pharmacological angioplasty are considered important by many physicians, although the evidence to support such approaches is limited. This Review summarizes the pathophysiology of DCI after SAH and discusses established treatments for this condition. Novel strategies--including drugs such as statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial delivery of nimodipine or magnesium--are also discussed.

Shock due to amlodipine overdose

Amlodipine is a commonly prescribed calcium channel blocker. Its toxicity is the leading cause of drug overdose seen in the practice of cardiovascular medicine. It can lead to profound hypotension and shock. Management involves early and aggressive supportive measures and calcium infusion in large doses to overcome competitive blockade. We report one such case that presented with amlodipine overdose and was successfully managed.

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.

Oxyntomodulin increases intrinsic heart rate through the glucagon receptor

Two hormones from the gastrointestinal tract, glucagon and oxyntomodulin (OXM), vigorously elevate the intrinsic heart rate (I_HR) of mice. We have previously shown that OXM influences murine heart rate (HR) independent of the glucagon-like peptide 1 (GLP-1) receptor. Here, we demonstrate using radiotelemetry in mice deficient in the glucagon receptor (Gcgr −/−) that both OXM and glucagon require the glucagon receptor for their chronotropic effects on the heart. Furthermore, we found that other hormones associated with hunger and satiety (ghrelin, leptin, and PYY_3-36) had no effect on I_HR, while cholecystokinin moderately elevated the I_HR. Finally, the resting HR of Gcgr −/− mice was higher than in control mice (Gcgr +/+ and Gcgr +/−) at thermal neutral temperature (30°C). Using atropine, we demonstrated that Gcgr −/− mice have diminished parasympathetic (PNS) influence of the heart at this temperature. Gcgr −/− mice displayed a normal bradycardia as compared to controls in response to administration of either methacholine (to activate the muscarinic acetylcholine receptor) or methoxamine (to activate the baroreflex through agonism of the α1 adrenergic receptor agonist) suggesting that vagal pathways are intact in the Gcgr −/− mice. As OXM is an agonist of the GLP-1 receptor and Gcgr with antidiabetic activity, we suggest OXM may be an alternative to glucagon in the treatment of overdose of beta-blockers to elevate HR in clinical conditions.

A review of emergency cardiopulmonary bypass for severe poisoning by cardiotoxic drugs

Cardiovascular collapse remains a leading cause of death in severe acute drug intoxication. Commonly prescribed medications such as antidysrhythmics, calcium channel antagonists, and beta adrenergic receptor antagonists can cause refractory cardiovascular collapse in massive overdose. Emergency cardiopulmonary bypass (ECPB), a modality originating in cardiac surgery, is a rescue technique that has been successfully implemented in the treatment of refractory cardiogenic shock and cardiac arrest unresponsive to traditional medical interventions. More recently a growing number of animal studies, case reports, and case series have documented its use in refractory hemodynamic collapse in poisoned patients. This article will review current ECPB techniques and explore its growing role in the treatment of severely hemodynamically compromised poisoned patients.

Venoarterial extracorporeal membrane oxygenation for the management of massive amlodipine overdose

A 50-year-old man was admitted to the intensive care unit with respiratory failure and shock after suffering a massive overdose of amlodipine, lisinopril and hydrochlorothiazide. Despite mechanical ventilation, vasopressors, calcium gluconate, hyperinsulinemia-euglycemia therapy, methylene blue and intravenous fat emulsion, the patient's respiratory and hemodynamic status deteriorated. Venoarterial extracorporeal membrane oxygenation (ECMO) was initiated to provide cardiopulmonary support in the setting of profound respiratory failure and refractory shock. The patient was placed on ECMO 19 hours after arrival to the hospital, after which vasopressor and ventilatory requirements decreased significantly. The patient was decannulated from ECMO after 8 days and was discharged home after a 56-day hospitalization. Early institution of ECMO should be considered for the management of respiratory failure and refractory shock in the setting of calcium channel blocker overdose when medical therapies are insufficient.

Severe diltiazem poisoning treated with hyperinsulinaemia-euglycaemia and lipid emulsion

Introduction. Calcium channel blockers (CCBs) drugs are widely used in the treatment of cardiovascular diseases. CCB poisoning is associated with significant cardiovascular toxicity and is potentially fatal. Currently, there is no specific antidote and the treatment of CCB poisoning is supportive; however, this supportive therapy is often insufficient. We present a clinical case of severe diltiazem poisoning and the therapeutic approaches that were used. Case Report. A 55-year-old male was admitted to the intensive care unit (ICU) after voluntary multiple drug intake, including extended release diltiazem (7200 mg). The patient developed symptoms of refractory shock to conventional therapy and required mechanical ventilation, a temporary pacemaker, and renal replacement therapy. Approximately 17 hours after drug intake, hyperinsulinaemia-euglycaemia with lipid emulsion therapy was initiated, followed by progressive haemodynamic recovery within approximately 30 minutes. The toxicological serum analysis 12 h after drug ingestion revealed a diltiazem serum level of 4778 ng/mL (therapeutic level: 40–200 ng/mL). Conclusions. This case report supports the therapeutic efficacy of hyperinsulinaemia-euglycaemia and lipid emulsion in the treatment of severe diltiazem poisoning.

Massive calcium channel blocker overdose: intravenous insulin and glucose as a therapy

We describe a case of massive overdosage with cardiac medications that proved resistant to conventional support, including fluid replacement, inotropes, mechanical ventilation, cardiac pacing and haemofiltration. The use of a high-dose insulin and glucose infusion proved to be beneficial in the acute management although the patient has been left with significant impairment of cardiac function.

Life-threatening calcium channel blocker overdose and its management

A young woman presented to the emergency department with complaints of nausea, vomiting, pain in the abdomen and difficulty in breathing after ingestion of 56 tablets of amlodipine 5 mg each (total 280 mg of amlodipine). She was managed using hyperinsulinaemia/euglycaemia therapy and other measures like calcium gluconate, glucagon and vasopressors. She was discharged from hospital in a stable condition after 5 days.

Antidotes for toxicological emergencies: a practical review

PURPOSE

Appropriate therapies for commonly encountered poisonings, medication overdoses, and other toxicological emergencies are reviewed, with discussion of pharmacists' role in ensuring their ready availability and proper use.

SUMMARY

Poisoning is the second leading cause of injury-related morbidity and mortality in the United States, with more than 2.4 million toxic exposures reported each year. Recently published national consensus guidelines recommend that hospitals providing emergency care routinely stock 24 antidotes for a wide range of toxicities, including toxic-alcohol poisoning, exposure to cyanide and other industrial agents, and intentional or unintentional overdoses of prescription medications (e.g., calcium-channel blockers, β-blockers, digoxin, isoniazid). Pharmacists can help reduce morbidity and mortality due to poisonings and overdoses by (1) recognizing the signs and symptoms of various types of toxic exposure, (2) guiding emergency room staff on the appropriate use of antidotes and supportive therapies, (3) helping to ensure appropriate monitoring of patients for antidote response and adverse effects, and (4) managing the procurement and stocking of antidotes to ensure their timely availability.

CONCLUSION

Pharmacists can play a key role in reducing poisoning and overdose injuries and deaths by assisting in the early recognition of toxic exposures and guiding emergency personnel on the proper storage, selection, and use of antidotal therapies.

Amlodipine poisioning complicated with acute non-cardiogenic pulmonary oedema

Amlodipine poisoning is an uncommon presentation with potentially life threatening complications. As there are few cases of severe poisoning documented, management guidelines are limited. The authors present the case of a 22-year-old female who presented to hospital 6 h after ingesting 280 mg of amlodipine. She was treated with aggressive fluid resuscitation and calcium gluconate infusion. She went on to develop acute non-cardiogenic pulmonary odema for which she needed a frusemide infusion. She stayed in hospital for 5 days and was discharged after a psychiatric review with no long-term complications. The authors discuss the other management options available for patients presenting with amlodipine overdose.

Lipid rescue of massive verapamil overdose: a case report

Introduction

Massive intentional verapamil overdose is a toxic ingestion which can cause multiorgan system failure and has no currently known antidote.

Case Presentation

The patient is a 41-year-old Caucasian woman who ingested 19.2 g of sustained release verapamil in a suicide attempt. Our patient became hypotensive requiring three high-dose vasopressors to maintain arterial pressure. She also developed acute respiratory failure, bradycardic ventricular rhythm necessitating continuous transvenous pacing, and anuric renal failure. Our patient was treated with intravenous calcium, bicarbonate, hyperinsulinemic euglycemic therapy and continuous venovenous hemodialysis without success. On the fourth day after hospital admission continuous intravenous lipid therapy was initiated. Within three hours of beginning lipid therapy, our patient's vasopressor requirement decreased by half. Within 24 hours, she was on minimal vasopressor support and regained an underlying junctional rhythm. After three days of lipid infusion, she no longer required inotropic agents to maintain blood pressure or pacing to maintain stable hemodynamics.

Conclusions

Intravenous fat emulsion therapy may be an effective antidote for massive verapamil toxicity.

Successful treatment of refractory hypotension, noncardiogenic pulmonary edema and acute kidney injury after an overdose of amlodipine

Treatment of patients with amlodipine overdose remains challenging. We describe a case of successful treatment of refractory hypotension, noncardiogenic pulmonary edema and acute kidney injury after an intoxication with 250 mg of amlodipine. Marked improvement in all hemodynamic parameters was noted with combination of fluids, inotropes, low-dose calcium, low dose insulin, mechanical ventilation and hemodialysis. All available information on overdose of amlodipine is limited to case reports and series. Prospective trial on the use of these agents is required to define its role as the first-line treatment in amlodipine, a calcium channel blockers overdose.

Phosphodiesterases Inhibition Enhances the Effect of Glucagon on Cardiac Automaticity in the Isolated Right Ventricle of the Rat

We evaluated the effect of glucagon on cardiac automaticity as well as the possible role of cyclic nucleotide phosphodiesterases (PDE) in regulating this effect. Concentration response curves for glucagon in the absence and in the presence of the non-selective PDE inhibitor IBMX were performed in the isolated right ventricle of the rat. We found that glucagon produces only a minor increase of ventricular automaticity (11.0±4.1, n=5) when compared to the full agonist of β-adrenoceptor isoproterenol (182.2±25.3, n=7). However, IBMX enhances the maximal efficacy of glucagon on cardiac automaticity (11.0±4.1, in the absence and 45.3±3.2 in the presence of IBMX, n=5, P<0.05). These results indicate that PDE blunts proarrhythmic effects of glucagon in rat myocardium.