Management of calcium channel antagonist overdose

Intravenous Lipid Emulsion Treatment for Calcium-Channel Blocker Intoxication: Pediatric Case Series and Review of the Literature

BACKGROUND

Calcium-channel blocker (CCBs) intoxication remains the most lethal among all other drug overdoses (Arroyo and Kao. Pediatr Emerg Care 2009;25:533-538). This study aimed to describe the use and efficacy of intravenous lipid emulsion treatment in our CCB overdose patients in tandem with a comprehensive literature investigation.

CASE REPORTS

Hereby we report 4 adolescent patients who arrived to the pediatric emergency department after intentional CCB ingestions. All patients were hospitalized in pediatric intensive care unit because of hypotension, and they were initially treated with fluid boluses, glucagon, calcium infusion, vasopressors, inotropes and insulin. Intravenous lipid emulsion (dose: 20% lipid emulsion given as a 1.5-mL/kg bolus followed by 0.25-0.5 mL/kg/min for 30-60 minutes) treatment was given to all patients unresponsive to initial treatments. Hemodynamic instability improved immediately after intravenous lipid emulsion treatment. All patients were discharged with complete recovery at the sixth day of pediatric intensive care unit admission.

CONCLUSIONS

Intravenous lipid emulsion therapy stands as a salvage treatment for CCB intoxications with cardiovascular failure unresponsive to standard supportive treatments.

"Feeling the Blues": A Case of Calcium Channel Blocker Overdose Managed With Methylene Blue

Amlodipine is a dihydropyridine calcium channel blocker (CCB) commonly used to treat hypertension. In the United States, approximately 9,500 cases of CCB intoxication due to deliberate or inadvertent overdose were reported to poison centers in 2002. We present a case of a patient who presented with CCB overdose complicated by acute respiratory distress syndrome (ARDS) and recalcitrant shock all of which resolved with methylene blue therapy. We present a case of a 56-year-old African American woman who presented to the emergency department (ED) after intentional ingestion of large amounts of multiple pills likely consisting of cyclobenzaprine, amlodipine, losartan, and ibuprofen following an argument with her boyfriend. Treatment included insulin drip, 10% dextrose, and norepinephrine drip which was titrated up. First insulin drip and 10% dextrose were titrated up; however, vasopressor-resistant hypotension persisted, and the decision was made to administer methylene blue. Over 9,500 cases of CCB toxicity were reported to poison centers in the US in 2002. Although no definitive treatment is outlined, first-line therapy consists of IV calcium, high-dose insulin, and vasopressor support with either norepinephrine or epinephrine. Traditionally, methylene blue is used for methemoglobinemia and in cardiothoracic ICUs for post coronary artery bypass vasoplegia. It acts by selectively inhibiting nitric oxide-activated cyclic guanylate cyclase leading to decreased vasodilation of arteriolar smooth muscles improving vascular tone and systemic vascular resistance. In severe amlodipine overdose, experimental models demonstrate methylene blue improves HR and mean arterial pressure (MAP), improving survival rate. With few adverse side effects (green-tinged discoloration of urine, saliva, tears, and bodily fluids), methylene blue should be explored and implemented in the treatment of CCB overdose with refractory hypotension and ARDS.

Nifedipine toxicity is exacerbated by acetyl l-carnitine but alleviated by low-dose ketamine in zebrafish in vivo

Calcium channel blocker (CCB) poisoning is a common and sometimes life-threatening emergency. Our previous studies have shown that acetyl l-carnitine (ALCAR) prevents cardiotoxicity and developmental toxicity induced by verapamil, a CCB used to treat patients with hypertension. Here, we tested whether toxicities of nifedipine, a dihydropyridine CCB used to treat hypertension, can also be mitigated by co-treatment with ALCAR. In the zebrafish embryos at three different developmental stages, nifedipine induced developmental toxicity with pericardial sac edema in a dose-dependent manner, which were surprisingly exacerbated with ALCAR co-treatment. Even with low-dose nifedipine (5 μm), when the pericardial sac looked normal, ALCAR co-treatment showed pericardial sac edema. We hypothesized that toxicity by nifedipine, a vasodilator, may be prevented by ketamine, a known vasoconstrictor. Nifedipine toxicity in the embryos was effectively prevented by co-treatment with low (subanesthetic) doses (25-100 μm added to the water) of ketamine, although a high dose of ketamine (2 mm added to the water) partially prevented the toxicity.As expected of a CCB, nifedipine either in the presence or absence of ketamine-reduced metabolic reactive oxygen species (ROS), a downstream product of calcium signaling, in the rapidly developing digestive system. However, nifedipine induced ROS in the trunk region that showed significantly stunted growth indicating that the tissues under stress potentially produced pathologic ROS. To the best of our knowledge, these studies for the first time show that nifedipine and the dietary supplement ALCAR together induce adverse effects while providing evidence on the therapeutic efficacy of subanesthetic doses of ketamine against nifedipine toxicity in vivo.

Management of Calcium Channel Blocker Toxicity in the Pediatric Patient

Calcium channel blockers (CCBs) are commonly prescribed cardiovascular medications used in several disease states including hypertension, coronary artery disease, and atrial fibrillation. Inadvertent exposure or intentional overdose of CCBs may result in hypotension, bradycardia, dysrhythmias, conduction disturbances, and hyperglycemia. In the most severe cases, CCB toxicity can lead to rapid cardiovascular collapse. Given the risk of significant morbidity and mortality associated with CCB toxicity, it is important that health care professionals are able to recognize and treat patients who present with a potentially toxic ingestion. Due to the paucity of literature in managing pediatric patients with severe CCB toxicity, treatment strategies for pediatric patients are mostly limited to case reports and extrapolation from expert consensus recommendations for adults. All pediatric patients with a potentially toxic CCB ingestion should be evaluated in the emergency department. Activated charcoal may be considered for asymptomatic patients presenting within an hour of ingestion. Symptomatic patients should be placed under cardiac monitoring and treatments to stabilize the patient's hemodynamics should not be delayed. Traditional first-line IV therapies include small boluses of fluids, calcium, and vasopressors. High-dose insulin has been proposed to independently increase inotropy and improve CCB-induced hypoinsulinemia and insulin resistance that results from CCB inhibition of insulin release from pancreatic β-islet cells. High-dose insulin is recommended as first-line therapy for adults and shows promising efficacy and safety in several pediatric case reports. Intravenous lipid emulsion may be considered in patients who are refractory to first-line therapies, although the data for pediatric patients are extremely limited.

Calcium Channel Blocker Overdose Treated with Calcium Resulting in Pancreatitis: A Case Report

Calcium channel blockers (CCBs) are a mainstay for the treatment of hypertension. Here we report a case of a male who after intentionally ingesting amlodipine presented with overdose symptomology. His QTc (corrected QT) was 525 ms (millisecond) on admission, he was treated with calcium intravenous infusion and subsequently his QTc narrowed to 393 ms, but he also developed iatrogenic pancreatitis. His serum calcium levels were not checked during the infusion. He was treated with supportive care, which led to the normalization of serum calcium levels and a favorable outcome. Further studies are required regarding how frequently calcium levels should be checked during infusions.

Unresponsive shock due to amlodipine overdose: An unexpected cause

Amlodipine is a dihydropyridine calcium channel blocker which is widely used as an antihypertensive drug. Amlodipine overdose have been infrequently reported with occurrence of serious complications and even death in a few cases. We report an interesting case of a young lady who presented with refractory shock with acute kidney injury, which did not respond to therapy despite optimal fluid replacement and vasopressor support. The etiology of shock could not be ascertained and the patient was questioned again to elucidate the missing clue in the history. It was finally revealed that the patient had consumed 900 mg of amlodipine in a suicide bid, for her poor performance in academics. The targeted therapy in the form of IV calcium and hyperinsulinemia-euglycemia therapy (HIET) was started and the patient dramatically improved with shock reversal and improvement in renal function.

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.

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.

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.

Current Controversies in Gastrointestinal Decontamination

Most poisonings reported to American poison control centers occur in the home. The most common route of exposure is ingestion, which is responsible for most fatalities. The goal of gastrointestinal decontamination is to prevent absorption of the toxin. Trends in treating poisoned patients have changed over the past few decades in light of a move toward practicing evidence-based medicine. Efficacy and clinical outcome have come into question and have led to position papers published recently regarding syrup of ipecac, gastric lavage, activated charcoal, and whole-bowel irrigation. These different methods of decontamination and the scientific data supporting each one will be reviewed, and the current controversies surrounding each will be discussed.

Antidote Use in the Critically Ill Poisoned Patient

The proper use of antidotes in the intensive care setting when combined with appropriate general supportive care may reduce the morbidity and mortality associated with severe poisonings. The more commonly used antidotes that may be encountered in the intensive care unit ( N-acetylcysteine, ethanol, fomepizole, physostigmine, naloxone, flumazenil, sodium bicarbonate, octreotide, pyridoxine, cyanide antidote kit, pralidoxime, atropine, digoxin immune Fab, glucagon, calcium gluconate and chloride, deferoxamine, phytonadione, botulism antitoxin, methylene blue, and Crotaline snake antivenom) are reviewed. Proper indications for their use and knowledge of the possible adverse effects accompanying antidotal therapy will allow the physician to appropriately manage the severely poisoned patient.

Atenolol and amlodipine combination overdose managed with continuous venovenous hemodiafiltration: A case report

We present a patient of who ingested large dose of of atenolol and amlodipine and was treated successfully with continuous venovenous hemodiafiltration. Early recognition of indications for renal support and early initiation of the same is the key to successful management.

Management of a mixed overdose of calcium channel blockers, β-blockers and statins

We describe a case of extreme mixed overdose of calcium channel blockers, β-blockers and statins. The patient was successfully treated with aggressive resuscitation including cardiac pacing and multiorgan support, glucagon and high-dose insulin for toxicity related to calcium channel blockade and β-blockade, and ubiquinone for treating severe presumed statin-induced rhabdomyolysis and muscle weakness.

High-dose insulin and intravenous lipid emulsion therapy for cardiogenic shock induced by intentional calcium-channel blocker and Beta-blocker overdose: a case series

BACKGROUND

Recently, high-dose insulin (HDI) and intravenous lipid emulsion (ILE) have emerged as treatment options for severe toxicity from calcium-channel blocker (CCB) and beta blocker (BB).

OBJECTIVE

Our aim was to describe the use and effectiveness of HDI and ILE for the treatment of CCB and BB overdose.

CASE REPORTS

We describe 2 patients presenting to the emergency department after intentional ingestions of CCBs and BBs. A 35-year-old man presented in pulseless electrical activity after ingesting amlodopine, verapamil, and metoprolol. A 59-year-old man presented with cardiogenic shock (CS) after ingesting amlodopine, simvastatin, lisinopril, and metformin. Both patients were initially treated with glucagon, calcium, and vasopressors. Shortly after arrival, HDI (1 unit/kg × 1; 1 unit/kg/h infusion) and ILE 20% (1.5 mL/kg × 1; 0.25 mL/kg/min × 60 min) were initiated. This led to hemodynamic improvement and resolution of shock. At the time of hospital discharge, both patients had achieved full neurologic recovery.

CONCLUSIONS

HDI effectively reverses CS induced by CCBs and BBs due to its inotropic effects, uptake of glucose into cardiac muscle, and peripheral vasodilatation. ILE is theorized to sequester agents dependent on lipid solubility from the plasma, preventing further toxicity. To our knowledge, these are the first two successful cases reported using the combination of HDI and ILE for reversing CS induced by intentional ingestions of CCBs and BBs.

Rate-dependent Ca2+ signalling underlying the force-frequency response in rat ventricular myocytes: a coupled electromechanical modeling study

BACKGROUND

Rate-dependent effects on the Ca2+ sub-system in a rat ventricular myocyte are investigated. Here, we employ a deterministic mathematical model describing various Ca2+ signalling pathways under voltage clamp (VC) conditions, to better understand the important role of calmodulin (CaM) in modulating the key control variables Ca2+/calmodulin-dependent protein kinase-II (CaMKII), calcineurin (CaN), and cyclic adenosine monophosphate (cAMP) as they affect various intracellular targets. In particular, we study the frequency dependence of the peak force generated by the myofilaments, the force-frequency response (FFR).

METHODS

Our cell model incorporates frequency-dependent CaM-mediated spatially heterogenous interaction of CaMKII and CaN with their principal targets (dihydropyridine (DHPR) and ryanodine (RyR) receptors and the SERCA pump). It also accounts for the rate-dependent effects of phospholamban (PLB) on the SERCA pump; the rate-dependent role of cAMP in up-regulation of the L-type Ca2+ channel (ICa,L); and the enhancement in SERCA pump activity via phosphorylation of PLB.

RESULTS

Our model reproduces positive peak FFR observed in rat ventricular myocytes during voltage-clamp studies both in the presence/absence of cAMP mediated β-adrenergic stimulation. This study provides quantitative insight into the rate-dependence of Ca2+-induced Ca2+-release (CICR) by investigating the frequency-dependence of the trigger current (ICa,L) and RyR-release. It also highlights the relative role of the sodium-calcium exchanger (NCX) and the SERCA pump at higher frequencies, as well as the rate-dependence of sarcoplasmic reticulum (SR) Ca2+ content. A rigorous Ca2+ balance imposed on our investigation of these Ca2+ signalling pathways clarifies their individual roles. Here, we present a coupled electromechanical study emphasizing the rate-dependence of isometric force developed and also investigate the temperature-dependence of FFR.

CONCLUSIONS

Our model provides mechanistic biophysically based explanations for the rate-dependence of CICR, generating useful and testable hypotheses. Although rat ventricular myocytes exhibit a positive peak FFR in the presence/absence of beta-adrenergic stimulation, they show a characteristic increase in the positive slope in FFR due to the presence of Norepinephrine or Isoproterenol. Our study identifies cAMP-mediated stimulation, and rate-dependent CaMKII-mediated up-regulation of ICa,L as the key mechanisms underlying the aforementioned positive FFR.

Near fatal case of amlodipine poisoning in an infant

An 11-mo-old infant received 12.5 times the maximum therapeutic dose of amlodipine as a result of a medication error in lieu of amoxicillin. He presented with vomiting, lethargy, breathlessness, muffled heart sounds and progressed to hypotensive shock within three hours of admission. He received mechanical ventilation, fluid therapy with normal saline and inotropes. But his parameters improved rapidly only after initiating him on insulin and dextrose infusion therapy (for 15 h) along with glucagon and calcium gluconate infusion (for 72 h). Calcium channel blockers (CCB) cause impaired insulin secretion causing hyperglycemia. High levels of blood sugar are of prognostic value rather than hemodynamic variables in CCB poisoning. A continuous infusion of 0.5 to 1 unit per kg body weight per hour of insulin along with supportive therapy including peritoneal dialysis (for deranged renal function) was used with success in managing amlodipine poisoning.

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.

The use of extracorporeal life support in adolescent amlodipine overdose

Calcium channel blocker (CCB) toxicity is associated with refractory hypotension and can be fatal. A 13 year old young woman presented to the emergency department(ED) six hours after an intentional overdose of amlodipine, barbiturates, and alcohol. She remained extremely hypotensive despite the administration of normal saline and calcium chloride and despite infusions of norepinephrine, epinephrine, insulin, and dextrose. Due to increasing evidence of end organ dysfunction, Extracorporeal Life Support (ECLS) was initiated 9 hours after presentation to the ED. The patient's blood pressure and end organ function immediately improved after cannulation. She was successfully decannulated after 57 hours of ECLS and was neurologically intact. Patients with calcium channel blocker overdose who are resistant to medical interventions may respond favorably to early ECLS.

Amlodipine fatality in an infant with postmortem blood levels

INTRODUCTION

Amlodipine is a dihydropyridine calcium channel blocker used in the treatment of hypertension and angina pectoris. Toxic effects reported from amlodipine include hypotension, reflex tachycardia, metabolic acidosis, and pulmonary edema. We report a rare fatality in an infant after ingestion of amlodipine with benazepril, with postmortem blood concentrations.

CASE REPORT

An 11-month-old, 10.88-kg boy ingested 10 to 45 mg amlodipine with 40 to 180 mg benazepril. No action was taken initially because the parents believed only one or two capsules had been ingested. A later count revealed a maximum of nine capsules missing. The child was observed at home and vomited once with possible capsule fragments. Forty-five minutes post-ingestion, the child was noted to be suddenly unresponsive and was brought the local emergency department by a private vehicle. Upon arrival (90 min post-ingestion), the child was unresponsive with the following vital signs HR 133 bpm, BP 67/42 mmHg, respiratory rate 40/min, and temperature 97.5°F. Pertinent abnormal laboratory values were HCO(3) 13 mmol/l and glucose 302 mg/dl. The child was placed on oxygen via a non-rebreather mask and was intubated 45 min post-arrival. The patient became progressively bradycardic, and 55 min after arrival, the patient was in asystole with no palpable blood pressure. Resuscitation measures included chest compressions, epinephrine atropine, sodium bicarbonate, and calcium gluconate. Rescue insulin therapy was begun with 4 units IVP followed by 10 units per hour. Resuscitation efforts persisted for 1 h without success. An autopsy revealed pulmonary edema and no gross or microscopic evidence of natural disease. Stomach contents revealed food matter with small white fragments. Analysis of postmortem heart blood showed amlodipine 1,300 ng/ml (therapeutic <20 ng/ml). Benazepril levels were not available.

DISCUSSION

We believe this is the first reported fatality in an infant from amlodipine. While benazepril may have contributed, ACE inhibitors have not been previously associated with rapid cardiovascular collapse.

CONCLUSION

Small doses of amlodipine (0.9 to 4.1 mg/kg) may produce rapid and fatal cardiovascular collapse in an infant.

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.

Management of calcium channel antagonist overdose with hyperinsulinemia-euglycemia therapy: case series and review of the literature

Calcium channel antagonists (CCAs) are commonly involved in drug overdoses. Standard approaches to the management of CCA overdoses, including fluid resuscitation, gut decontamination, administration of calcium, glucagon, and atropine, as well as supportive care, are often ineffective. We report on two patients who improved after addition of hyperinsulinemia-euglycemia (HIE) therapy. We conclude with a literature review on hyperinsulinemia-euglycemia therapy with an exploration of the physiology behind its potential use.

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.

Prevalence and long-term glucose metabolism evolution of post-transplant diabetes mellitus in Chinese renal recipients

AIM

To assess the prevalence and predictors of post-transplant diabetes mellitus (PTDM) in Chinese renal recipients and describe their long-term evolution of glucose metabolism.

METHODS

887 non-diabetic Chinese adult renal recipients were studied retrospectively, with a median follow-up of 7 years. PTDM patients were categorized into transient PTDM and permanent PTDM. The cumulative incidence and risk factors of PTDM were estimated by Kaplan-Meier and Cox regression.

RESULTS

The cumulative incidence of PTDM at 3 months, 1, 3, 5, 10, 15 and 20 years post-transplant was 10.4%, 11.4%, 13.4%, 15.2%, 22.7%, 27.9% and 38.3%, respectively. 61.9% of PTDM cases were diagnosed within the first three months and 61.6% of them developed persistent diabetes in the future. Risk factors for all PTDM included older age, body mass index (BMI)≥25 kg/m(2), triglycerides≥1.5 mmol/L, rejection, the use of tacrolimus and diltiazem. The predictors of permanent PTDM included age >50 years (RR=2.322, 95% CI 1.255-4.296, P=0.007), BMI≥25 kg/m(2) (RR=1.699, 95% CI 1.014-2.846, P=0.044) and the use of tacrolimus (RR=1.835, 95% CI 1.181-2.851, P=0.007).

CONCLUSIONS

Patients were most susceptible to PTDM within the first three months post-transplant and more than half of them developed persistent diabetes in the future. Age >50 years, overweight and tacrolimus application were risk factors for both PTDM and permanent PTDM.

Predictors of mortality in verapamil overdose: usefulness of serum verapamil concentrations

Verapamil poisoning may result in life-threatening cardiovascular morbidities and fatalities. To date, prognosticators of mortality have been poorly investigated and the use of serum verapamil concentration for prognosis remains unclear. We aimed to evaluate the ability of usual clinical and laboratory parameters including serum verapamil concentrations measured on admission to predict outcome (survival versus death) in verapamil poisoning. We reviewed the medical records of all intentional and symptomatic verapamil poisonings admitted over 8 years to two medical intensive care units. Clinical and laboratory parameters were measured in 65 patients, and final outcomes of survival or death recorded. A multivariable analysis was conducted to evaluate the prognostic values of recorded parameters. Life-threatening complications of verapamil poisonings included shock (62%), atrioventricular blocks (24%), sinoatrial blocks (20%), acute respiratory distress syndrome (19%) and cardiac arrest (11%) resulting in death (8%). Verapamil concentration measured on intensive care unit admission was the only independent factor associated with mortality (p = 0.01). The optimal verapamil cut-off point was 5.0 μM (100% sensitivity, 91% specificity), which conferred a 2.76-times increase in odds of fatality. In conclusion, cardiovascular monitoring and assessment of organ failure are vital in symptomatic verapamil poisonings. The serum verapamil concentration has excellent prognostic ability for predicting fatality in verapamil overdose.

Transmembrane pH-gradient liposomes to treat cardiovascular drug intoxication

Injectable scavenging nanocarriers have been proposed as detoxifying agents when there are no specific antidotes to treat pharmacological overdoses. They act by capturing the drug in situ, thereby restricting distribution in tissues. In the clinic, the only systems used for that purpose are parenteral lipid emulsions, which are relatively inefficient in terms of uptake capacity. In this study, we investigated long-circulating liposomes with a transmembrane pH gradient as treatment for diltiazem intoxication. The unique ion-trapping properties of the vesicles toward ionizable compounds were exploited to sequester the drug in the bloodstream and limit its pharmacological effect. After in vitro optimization of the formulation, the in vivo scavenging properties of the liposomes were demonstrated by examining the drug's pharmacokinetics. The reduced volume of distribution and increased area under the plasma concentration versus time curve in animals treated with liposomes indicated limited tissue distribution. The vesicles exerted a similar but more pronounced effect on deacetyl-diltiazem, the principal active metabolite of the drug. This in vivo uptake of both drug and metabolite altered the overall pharmacological outcome. In rats receiving an intravenous bolus of diltiazem, the liposomes tempered the hypotensive decline and maintained higher average blood pressure for 1 h. The detoxifying action of liposomes was even stronger when the rats received higher doses of the drug via perfusion. In conclusion, the present work provided clear evidence that liposomes with a transmembrane pH gradient are able to change the pharmacokinetics and pharmacodynamics of diltiazem and its metabolite and confirmed their potential as efficient detoxifying nanocarriers.

Cardiac ion channel safety profiling on the IonWorks Quattro automated patch clamp system

The normal electrophysiologic behavior of the heart is determined by the integrated activity of specific cardiac ionic currents. Mutations in genes encoding the molecular components of individual cardiac ion currents have been shown to result in multiple cardiac arrhythmia syndromes. Presently, 12 genes associated with inherited long QT syndrome (LQTS) have been identified, and the most common mutations are in the hKCNQ1 (LQT1, Jervell and Lange-Nielson syndrome), hKCNH2 (LQT2), and hSCN5A (LQT3, Brugada syndrome) genes. Several drugs have been withdrawn from the market or received black box labeling due to clinical cases of QT interval prolongation, ventricular arrhythmias, and sudden death. Other drugs have been denied regulatory approval owing to their potential for QT interval prolongation. Further, off-target activity of drugs on cardiac ion channels has been shown to be associated with increased mortality in patients with underlying cardiovascular diseases. Since clinical arrhythmia risk is a major cause for compound termination, preclinical profiling for off-target cardiac ion channel interactions early in the drug discovery process has become common practice in the pharmaceutical industry. In the present study, we report assay development for three cardiac ion channels (hKCNQ1/minK, hCa(v)1.2, and hNa(v)1.5) on the IonWorks Quattro™ system. We demonstrate that these assays can be used as reliable pharmacological profiling tools for cardiac ion channel inhibition to assess compounds for cardiac liability during drug discovery.

Addition of phenylephrine to high-dose insulin in dihydropyridine overdose does not improve outcome

INTRODUCTION

Vasopressors are commonly used for calcium channel blocker (CCB)-induced cardiogenic shock after calcium and high-dose insulin (HDI). Vasopressor therapy is frequently used in combination with HDI to increase blood pressure and improve outcome. However, no studies have compared the efficacy of HDI to the combination of a vasopressor and HDI in dihydropyridine overdose. We conducted a study to compare the efficacy of HDI to phenylephrine (PE) plus HDI in a porcine model of dihydropyridine toxicity.

METHODS

Cardiogenic shock was induced by administering a nifedipine (NP) infusion of 0.0125 mcg/kg/min until a point of toxicity, defined as a 25% decrease in the baseline product of mean arterial pressure (MAP) × cardiac output (CO). Each arm was resuscitated with 20 mL/kg of saline (NS). The nifedipine infusion continued throughout a 4-h resuscitation protocol. The HDI group was titrated up to 10 units/kg/h of insulin and the HDI/PE group was titrated up to a dose of HDI 10 units/kg/h plus PE 3.6 mcg/kg/min.

RESULTS

No baseline differences were found among groups including time to toxicity. Survival was not different between the HDI and HDI/PE arms. When comparing the HDI to the HDI/PE arm no differences were found for cardiac index (CI) (p = 0.06), systemic vascular resistance (p = 0.34), heart rate (HR) (p = 0.95), mean arterial pressure (p = 0.99), pulmonary vascular resistance (PVR) (p = 0.07), or base excess (p = 0.36).

CONCLUSION

In this model of nifedipine-induced cardiogenic shock, the addition of PE to HDI therapy did not improve mortality, cardiac output, blood pressure, systemic vascular resistance (SVR), or base excess.

Levosimendan as treatment option in severe verapamil intoxication: a case report and review of the literature

Cardiovascular shock due to verapamil intoxication is often refractory to standard resuscitation methods. Recommended therapy includes prevention of further absorption of the drug, inotropic therapy, calcium gluconate, and hyperinsulinemia/euglycemia therapy. Often further measures are needed such as ventricular pacing or mechanical circulatory support. Still, mortality remains high. Levosimendan, an inotropic agent, that enhances myofilament response to calcium, increases myocardial contraction and could therefore be beneficial in verapamil intoxication. Here, we report the case of a 60-year-old patient with clinically severe verapamil poisoning who presented with shock, bradycardia, and sopor. Standard therapy including high-dose inotropes failed to ameliorate the signs of intoxication. But additional therapy with levosimendan led to rapid improvement. Based on this observation, the literature is reviewed focusing on utilization of levosimendan in the treatment of calcium channel blocker overdose. We suggest to consider levosimendan as additional treatment option in patients with cardiovascular shock due to verapamil intoxication that are refractory to standard management.

A case of torsades de pointes induced by severe QT prolongation after an overdose of eperisone and triazolam in a patient receiving nifedipine

INTRODUCTION

Eperisone hydrochloride is a centrally acting muscle relaxant, and triazolam is a short-acting benzodiazepine. Although commonly prescribed, cardiotoxicity induced by a single overdose of either drug is comparatively rare. A patient receiving nifedipine developed torsades de pointes (TdP) because of prolongation of the corrected QT (QTc) interval after an overdose of eperisone hydrochloride and triazolam.

CASE REPORT

A 60-year-old man receiving nifedipine was admitted in a comatose condition 3 h after ingesting 5,000 mg of eperisone and 2.5 mg of triazolam. Electrocardiogram showed sinus rhythm with prolongation of the QTc interval (820 ms). The serum electrolyte levels were as follows: potassium, 3.8 mEq/L; magnesium, 2.4 mg/dL. The serum drug concentrations were high: eperisone, 15,360 ng/mL; triazolam, 110.8 ng/mL. A temporary cardiac pacemaker was implanted immediately after the development of TdP, 11 h after the ingestion. The serum triazolam concentration normalized on day 2. The QTc interval and eperisone concentration normalized on day 6.

CONCLUSION

Eperisone and triazolam overdose can cause life-threatening cardiotoxicity. Electrocardiographic monitoring and serial determination of QTc interval are likely the best way to observe these patients and evaluate the risk of cardiotoxicity.

Drugs and pharmaceuticals: management of intoxication and antidotes

The treatment of patients poisoned with drugs and pharmaceuticals can be quite challenging. Diverse exposure circumstances, varied clinical presentations, unique patient-specific factors, and inconsistent diagnostic and therapeutic infrastructure support, coupled with relatively few definitive antidotes, may complicate evaluation and management. The historical approach to poisoned patients (patient arousal, toxin elimination, and toxin identification) has given way to rigorous attention to the fundamental aspects of basic life support--airway management, oxygenation and ventilation, circulatory competence, thermoregulation, and substrate availability. Selected patients may benefit from methods to alter toxin pharmacokinetics to minimize systemic, target organ, or tissue compartment exposure (either by decreasing absorption or increasing elimination). These may include syrup of ipecac, orogastric lavage, activated single- or multi-dose charcoal, whole bowel irrigation, endoscopy and surgery, urinary alkalinization, saline diuresis, or extracorporeal methods (hemodialysis, charcoal hemoperfusion, continuous venovenous hemofiltration, and exchange transfusion). Pharmaceutical adjuncts and antidotes may be useful in toxicant-induced hyperthermias. In the context of analgesic, anti-inflammatory, anticholinergic, anticonvulsant, antihyperglycemic, antimicrobial, antineoplastic, cardiovascular, opioid, or sedative-hypnotic agents overdose, N-acetylcysteine, physostigmine, L-carnitine, dextrose, octreotide, pyridoxine, dexrazoxane, leucovorin, glucarpidase, atropine, calcium, digoxin-specific antibody fragments, glucagon, high-dose insulin euglycemia therapy, lipid emulsion, magnesium, sodium bicarbonate, naloxone, and flumazenil are specifically reviewed. In summary, patients generally benefit from aggressive support of vital functions, careful history and physical examination, specific laboratory analyses, a thoughtful consideration of the risks and benefits of decontamination and enhanced elimination, and the use of specific antidotes where warranted. Data supporting antidotes effectiveness vary considerably. Clinicians are encouraged to utilize consultation with regional poison centers or those with toxicology training to assist with diagnosis, management, and administration of antidotes, particularly in unfamiliar cases.

Early use of high-dose insulin euglycaemic therapy for verapamil toxicity

A 49-year-old man presented with verapamil toxicity complicated by hypotension and a junctional rhythm, in the context of deliberate self-poisoning with multiple drugs. The patient's hypotension normalised following the early use of high-dose insulin euglycaemic therapy (HIET), without the need for additional vasopressors; it recurred when HIET was prematurely stopped, and again stabilised when HIET was recommenced. Consideration should be given to the early use of HIET in treating severe calcium channel blocker toxicity, rather than as a last resort after other therapies have failed.

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).

Determining Triage Guidelines for Unintentional Overdoses with Calcium Channel Antagonists

BACKGROUND

Calcium channel antagonists (CCAs) are known to cause significant toxicity in overdose. Determining triage guidelines for CCAs is an important but difficult task. This study was designed to determine if an unintentional overdose of a patient's CCA could result in clinically significant cardiovascular (CV) symptoms (hypotension, bradycardia, conduction disturbances).

METHODS

Poison center records over a 3-year period were reviewed for adults ingesting at least double their prescribed dose of CCAs and who were evaluated in an emergency department (ED). Cases were reviewed for: patient age and gender, co-ingestants, CCA involved, dosage form, dose taken, usual dose, symptoms, available vital signs, and medical outcomes.

RESULTS

225 cases were identified; 161 cases met study criteria. There were 51 cases involving co-ingestants and 13 in which the usual dose was unknown. These were excluded. One hundred twenty-two patients (76%) were female and the mean age of all patients was 64 years. One hundred and four (65%) cases involved ingestions equal to double the usual dose (DD), 57 (35%) involved more than a DD. For DD cases, nine (9%) developed clinically significant CV signs or symptoms; while in cases with more than DD, eight (14%) did.

CONCLUSIONS

This retrospective review demonstrated that the toxicity of CCAs following a therapeutic overdose can be highly variable and that the dose producing a toxic effect on the cardiovascular system may be within the maximum range of therapeutic doses. This may be the result of a number of factors, including the broad range of therapeutic doses as well as the pre-existing conditions in patients taking these medications. This variability makes home management of these cases difficult and therefore, poison centers should be conservative in their evaluation of these cases.

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.

Severe amlodipine intoxication treated by hyperinsulinemia euglycemia therapy

The objective of this study was to report a use of hyperinsulinemia euglycemia therapy in severe amlodipine intoxication. Intoxication with 420 mg of amlodipine caused severe hypotension in a 20-year-old female patient. The patient was initially treated with fluids, calcium gluconate, and epinephrine without effect. She was then given hyperinsulinemia euglycemia therapy. We observed a rise in blood pressure (BP) approximately 30 min after insulin was given and the BP was subsequently responsive to epinephrine. The patient was weaned from pressors 5 h after insulin therapy. The trachea was extubated 24 h after ingesting amlodipine, and the patient was transferred for psychiatric treatment 3 days later. This possible positive inotropic effect of insulin therapy in patients with calcium channel blocker intoxication supports previous findings. It is suggested that hyperinsulinemia euglycemia therapy may be considered as a first-line therapy in amlodipine intoxication.

Lessons learnt in the pharmacokinetic analysis of the effect of haemoperfusion for acute overdose with sustained-release diltiazem

The effect of charcoal haemoperfusion on the pharmacokinetics of diltiazem is described in a patient with severe clinical toxicity following acute overdose. The patient presented within 3 h following acute ingestion of multiple medications including sustained-release diltiazem. Routine resuscitation and supportive care were administered, but hypotension did not resolve despite intravenous fluids and infusions of calcium, adrenaline, noradrenaline and vasopressin. Multiple-doses of activated charcoal, haemodialysis and charcoal haemoperfusion were prescribed to expedite the elimination of diltiazem. The maximum diltiazem concentration (577 microg.l(-1)) was recorded 7 h post ingestion which was followed by an erratic and prolonged elimination phase. The maximum clearance of diltiazem due to haemoperfusion was calculated to be 19.4 and 15.1 ml.min(-1) at different times, equating to removal of approximately 1.5 mg diltiazem during 4 h of haemoperfusion. Haemoperfusion did not appear to remove sufficient diltiazem to recommend its routine use in the treatment of patients with acute diltiazem overdose.