Hydroxocobalamin as a Cyanide Antidote

Elevated methemoglobin levels in patients treated with high-dose hydroxocobalamin

OBJECTIVE

The aim of this study was to assess the impact of hydroxocobalamin (OHCbl) infusion on arterial blood gas and oximetry values in patients with vasoplegic syndrome.

METHODS

Blood samples collected from 95 patients receiving OHCbl infusion were assayed using the ABL90 FLEX Plus blood gas analyzer for the concentration of methemoglobin (MetHb), total hemoglobin (tHb), carboxyhemoglobin (COHb), arterial oxygen saturation (SaO2), arterial oxygen partial pressure (PaO2), and arterial carbon dioxide partial pressure (PaCO2). Interference of OHCbl on these variables was evaluated using the measured difference between the preinfusion and postinfusion samples.

RESULTS

Blood MetHb (%) measured after the infusion of OHCbl (5g) were significantly higher than the baseline levels, with a median of 4.8 (IQR, 3.0-6.5) versus 1.0 (IQR, 1.0-1.2) (P < .001). Blood COHb (%) increased from a median of 1.3 (IQR, 1.0-1.8) to 1.7 (IQR, 1.3-2.2) (P < .001) following the OHCbl infusion. No differences were seen in median levels of tHb, PaO2, PaCO2, and SaO2 between pre- and post-OHCbl treatment.

CONCLUSION

The presence of OHCbl in blood clearly interfered with the oximetry measurements of the hemoglobin component fractions by falsely increasing the levels of MetHb and COHb. Blood levels of MetHb and COHb cannot be reliably determined by the co-oximetry when OHCbl is known or suspected.

Hydroxocobalamin infusion in a patient monitored for plasma free hemoglobin levels

Hemolysis is one of the most common preanalytical concerns in the clinical laboratory. Hydroxocobalamin administration causes red pigmentation of plasma that may mimic hemolysis and may interfere with chemistry assays. A male patient in his sixties was placed on extracorporeal membrane oxygenation (ECMO) as a bridge to transplantation. Daily plasma free hemoglobin measurements were ordered to monitor for adverse ECMO events. An intensely red plasma specimen was inconsistent with modestly elevated hemoglobin levels and became pink on dilution. Follow-up with providers indicated that the red plasma could be attributed to hydroxocobalamin administration. Performance of scanning spectrophotometry and assessment of a sample spiked with hydroxocobalamin indicated that the red colored hydroxocobalamin did not interfere with our 3,3',5,5'-tetramethylbenzidine based methodology for free plasma hemoglobin measurement. It is important for the laboratory professionals to be aware of the possibility of interference in hemoglobin assays due to hydroxocobalamin.

Accidental Deaths Due to Toxic Industrial Cyanide Inhalation: An Autopsy Case Report

Autopsies of accidental deaths in industrial scenarios have always been a challenging job for a forensic pathologist. Industries that employ chemical agents pose a unique risk, especially when safety protocols are ignored. Exposure to cyanide salts creates an additional risk since death may occur quickly. We present one such incident of the accidental deaths of three industrial workers, which could have been prevented if proper safety measures had been followed. Four workers fell unconscious while cleaning the electroplating chamber of the handicraft industry. Three were declared dead on arrival at the emergency department, while one survived. Autopsy of all three victims showed similar findings of pink-colored post-mortem staining and multiple petechial hemorrhages over the heart and lungs. After histopathological and chemical analysis, the cause of death was opined to be due to complications of cyanide poisoning. In accidental industrial deaths, the forensic pathologist should consider the possibility of death due to toxic chemicals, such as cyanide, used in the manufacturing process. The industrial personnel should be educated about the risks involved, and proper use of safety equipment should be encouraged to avoid such hazardous outcomes. Additionally, the people employed in the autopsy of the deaths related to chemical disasters should ensure their personal safety and preventive measures.

Elevated methemoglobin levels in patients treated with hydroxocobalamin: a case series and in-vitro analysis

BACKGROUND

Historically, the first step in treating cyanide (CN^-) toxicity utilized antidotes to induce methemoglobinemia. This is concerning in patients who are already hypoxemic or have elevated carboxyhemoglobin. Hydroxocobalamin (OHCbl) is now the first-line antidote for CN^- toxicity and is not known to induce methemoglobinemia. We observed elevated methemoglobin (MetHb) levels in several patients treated with OHCbl and sought to investigate the incidence of MetHb formation following administration of OHCbl.

METHODS

Chart review: A single-center, retrospective case series of patients who received 5 or 10 g of hydroxocobalamin from 01/01/2011 through 04/30/2019. Data was analyzed using descriptive statistics. In-vitro study: Discarded blood was separated into whole blood and plasma samples. OHCbl and normal saline was added to reach 0×, 1×, 2×, and 4× peak therapeutic concentrations and analyzed at times 0, 2, and 4 h after administration.

RESULTS

Chart review: Twenty-seven cases of OHCbl administration were identified. The median age was 53 years (IQR 38 - 64) and 20 (74.1%) were male. Exposure to a house fire or smoke inhalation was the reason for OHCbl administration in 21 (77.8%) patients. Five (18.5%) patients received 10 g of OHCbl while the rest received 5 g. Six (22.2%) patients developed methemoglobinemia, all after 5 g OHCbl administration; four had been exposed to fire and smoke, two received the medication for severe acidosis of unknown etiology not related to fire or smoke. The median peak level was 7.1% (IQR 2.2 - 16.4%) at a median time of 11.4 h post-administration. Two patients received methylene blue (MB), neither responded. Death occurred in 17 (63%) cases. In-vitro study: We observed a dose dependent elevation in total hemoglobin but did not detect any increase in MetHb.

CONCLUSION

We observed a noteworthy temporal association between the formation of methemoglobinemia and the administration of hydroxocobalamin. This does not appear to be an artifact of the CO-oximeters. This could have profound implications for patients who are already hypoxemic or have impaired oxygen carrying capacity from carboxyhemoglobin.

Glyoxylate protects against cyanide toxicity through metabolic modulation

Although cyanide's biological effects are pleiotropic, its most obvious effects are as a metabolic poison. Cyanide potently inhibits cytochrome c oxidase and potentially other metabolic enzymes, thereby unleashing a cascade of metabolic perturbations that are believed to cause lethality. From systematic screens of human metabolites using a zebrafish model of cyanide toxicity, we have identified the TCA-derived small molecule glyoxylate as a potential cyanide countermeasure. Following cyanide exposure, treatment with glyoxylate in both mammalian and non-mammalian animal models confers resistance to cyanide toxicity with greater efficacy and faster kinetics than known cyanide scavengers. Glyoxylate-mediated cyanide resistance is accompanied by rapid pyruvate consumption without an accompanying increase in lactate concentration. Lactate dehydrogenase is required for this effect which distinguishes the mechanism of glyoxylate rescue as distinct from countermeasures based solely on chemical cyanide scavenging. Our metabolic data together support the hypothesis that glyoxylate confers survival at least in part by reversing the cyanide-induced redox imbalances in the cytosol and mitochondria. The data presented herein represent the identification of a potential cyanide countermeasure operating through a novel mechanism of metabolic modulation.

Elevated Methemoglobin Levels in a Patient Treated with Hydroxocobalamin After Suspected Cyanide Exposure

BACKGROUND

Cyanide (CN) toxicity commonly occurs during enclosed-space fires. Historically, the first step in treating CN toxicity utilized amyl nitrite and sodium nitrite to induce methemoglobinemia, which can be dangerous in this population. Hydroxocobalamin (OHCob), which binds to CN to form the nontoxic metabolite cyanocobalamin, is now the first-line antidote for CN toxicity, and has the advantage of not inducing methemoglobinemia.

CASE REPORT

A 62-year-old man presented to the Emergency Department (ED) after a house fire. He was intubated for respiratory distress and hypoxia with an initial carboxyhemoglobin of 1.3%, methemoglobin 0.3%, and anion gap 19. Eleven hours after presentation, his serum lactic acid was 9 mmol/L. Given his continued deterioration, 14 h after arrival he received OHCob 5 g i.v. for presumed CN toxicity. Methemoglobin concentration 4 min prior to OHCob administration was 0.7%, and 2 h after administration was 4.2%. This subsequently increased to 14.3% (16 h after OHCob administration) and peaked at 16.3% (47 h after OHCob administration), at which time he was administered a dose of methylene blue 50 mg i.v., 60 h after ED arrival. His methemoglobin concentrations fluctuated until a consistent downward trend starting at 92 h from ED arrival. He continued to deteriorate and expired on hospital day 5 with a methemoglobin concentration of approximately 6.0%. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: CN toxicity requires immediate recognition and treatment. The antidote, OHCob, is believed to not induce methemoglobinemia. However, this potential side effect must be considered by emergency physicians when treating suspected CN toxicity, especially if the patient does not improve after antidotal therapy.

Unexpected Complication of Hydroxocobalamin Administration for Refractory Vasoplegia in Orthotopic Liver Transplant: A Case Report

A 40-year-old male with alcoholic cirrhosis and end-stage renal disease presented for simultaneous liver and kidney transplantation. Hemodialysis was utilized intraoperatively during liver transplantation. During the procedure, the patient developed refractory hypotension and ultimately received hydroxocobalamin for vasoplegia. Shortly after administration, the hemodialysis machine ceased working after a "blood leak" alarm developed. Without the ability to continue intraoperative dialysis, the kidney transplantation portion of his surgery was postponed. The patient was transferred to the intensive care unit, where he underwent continuous renal replacement therapy overnight, and his kidney transplant proceeded the following morning.

Behavioral toxicity of sodium cyanide following oral ingestion in rats: Dose-dependent onset, severity, survival, and recovery

Sodium cyanide (NaCN) is a commonly and widely used industrial and laboratory chemical reagent that is highly toxic. Its availability and rapid harmful/lethal effects combine to make cyanide a potential foodborne/waterborne intentional-poisoning hazard. Thus, laboratory studies are needed to understand the dose-dependent progression of toxicity/lethality following ingestion of cyanide-poisoned foods/liquids. We developed an oral-dosing method in which a standard pipette was used to dispense a sodium cyanide solution into the cheek, and the rat then swallowed the solution. Following poisoning (4-128 mg/kg), overt toxic signs were recorded and survival was evaluated periodically up to 30 hours thereafter. Toxic signs for NaCN doses higher than 16 mg/kg progressed quickly from head burial and mastication, to lethargy, convulsions, gasping/respiratory distress, and death. In a follow-on study, trained operant-behavioral performance was assessed immediately following cyanide exposure (4-64 mg/kg) continuously for 5 h and again the following day. Onset of behavioral intoxication (i.e., behavioral suppression) occurred more rapidly and lasted longer as the NaCN dose increased. This oral-consumption method with concomitant operantbehavioral assessment allowed for accurate dosing and quantification of intoxication onset, severity, and recovery, and will also be valuable in characterizing similar outcomes following varying medical countermeasure drugs and doses.

Hemodialysis failure secondary to hydroxocobalamin exposure

Hydroxocobalamin is a recently approved antidote for the treatment of cyanide poisoning. The case presented involves a young patient administered empiric hydroxocobalamin due to suspected cyanide overdose. Due to the development of acute kidney injury and severe metabolic derangement, emergent hemodialysis was initiated. Unfortunately, hemodialysis was confounded by a recurrent "blood leak" alarm. This unforeseen effect was secondary to interference from hydroxocobalamin. Hydroxocobalamin causes orange/red discoloration of bodily fluids and permeates the dialysate. This leads to defraction of light in the effluent path of the blood leak detector from discolored dialysate, which can result in activation of the blood leak alarm and an inability to continue hemodialysis treatment. This case highlights several new and emerging critical concerns with this medication, including the potential consequence of delayed initiation of emergent renal replacement therapy with empiric administration, the need for increased awareness among clinicians of various disciplines, and the need for multidisciplinary communication.

Utility and outcomes of hydroxocobalamin use in smoke inhalation patients

INTRODUCTION

Hydroxocobalamin has been available for use for suspected cyanide toxicity in smoke inhalation patients in the United States since 2006. Our study compares outcomes of patients who received hydroxocobalamin to historical controls who did not.

METHODS

In this retrospective review, patients administered hydroxocobalamin (2008-2014) were compared to historical controls (2002-2008). Patients <18 years, patients who received an alternate antidote, and patients without suspicion of smoke inhalation injury were excluded. Mortality was the primary outcome. Secondary outcomes evaluated were 7-day change in creatinine, culture-proven pneumonia, days on mechanical ventilation, ventilator- free days (VFD), ICU length of stay (ICU LOS), and hospital length of stay (HLOS).

RESULTS

A total of 138 patients in the hydroxocobalamin group and 135 in the control group were identified. Mortality rate was similar between both groups (29% vs. 28%, p=0.90). Hydroxocobalamin was associated with lower pneumonia rate (23% vs. 49%, p<0.01), less ventilator days (4 days vs. 7 days, p<0.01), and increased VFD (20 days vs. 11 days, p=0.01) compared to controls. Shorter ICU LOS (6 days vs. 10 days, p=0.03) and a trend toward lower HLOS (7 day vs. 11 days, p=0.06) were also found in patients who received hydroxocobalamin.

CONCLUSIONS

Routine administration was associated with lower rate of pneumonia, faster liberation from the ventilator, and reductions in intensive care unit stay. Burn centers should consider its empiric use in suspected smoke inhalation patients.

Concentrations of cyanide in blood samples of corpses after smoke inhalation of varying origin

Cyanide (CN) blood concentration is hardly considered during routine when evaluating smoke gas intoxications and fire victims, although some inflammable materials release a considerable amount of hydrogen cyanide. CN can be significant for the capacity to act and can in the end even be the cause of death. Systematic data concerning the influence of different fire conditions, especially those of various inflammable materials, on the CN-blood concentration of deceased persons do not exist. This study measured the CN level in 92 blood samples of corpses. All persons concerned were found dead in connection with fires and/or smoke gases. At the same time, the carboxyhemoglobin (COHb) level was determined, and the corpses were examined to detect pharmaceutical substances, alcohol and drugs. Furthermore, we analysed autopsy findings and the investigation files to determine the inflammable materials and other circumstances of the fires. Due to the inflammable materials, the highest concentration of CN in the victims was found after enclosed-space fires (n = 45) and after motor-vehicle fires (n = 8). The CN levels in these two groups (n = 53) were in 47 % of the cases toxic and in 13 % of the cases lethal. In victims of charcoal grills (n = 17) and exhaust gases (n = 6), no or only traces of CN were found. Only one case of the self-immolations (n = 12) displayed a toxic CN level. The results show that CN can have considerable significance when evaluating action ability and cause of death with enclosed-space fires and with motor-vehicle fires.

Determination of 3-mercaptopyruvate in rabbit plasma by high performance liquid chromatography tandem mass spectrometry

Accidental or intentional cyanide poisoning is a serious health risk. The current suite of FDA approved antidotes, including hydroxocobalamin, sodium nitrite, and sodium thiosulfate is effective, but each antidote has specific major limitations, such as large effective dosage or delayed onset of action. Therefore, next generation cyanide antidotes are being investigated to mitigate these limitations. One such antidote, 3-mercaptopyruvate (3-MP), detoxifies cyanide by acting as a sulfur donor to convert cyanide into thiocyanate, a relatively nontoxic cyanide metabolite. An analytical method capable of detecting 3-MP in biological fluids is essential for the development of 3-MP as a potential antidote. Therefore, a high performance liquid chromatography tandem mass spectrometry (HPLC-MS-MS) method was established to analyze 3-MP from rabbit plasma. Sample preparation consisted of spiking the plasma with an internal standard ((13)C3-3-MP), precipitation of plasma proteins, and reaction with monobromobimane to inhibit the characteristic dimerization of 3-MP. The method produced a limit of detection of 0.1μM, a linear dynamic range of 0.5-100μM, along with excellent linearity (R(2)≥0.999), accuracy (±9% of the nominal concentration) and precision (<7% relative standard deviation). The optimized HPLC-MS-MS method was capable of detecting 3-MP in rabbits that were administered sulfanegen, a prodrug of 3-MP, following cyanide exposure. Considering the excellent performance of this method, it will be utilized for further investigations of this promising cyanide antidote.

Review article: management of cyanide poisoning

Cyanide poisoning is uncommon, but generates interest because of the presumed utility of an antidote immediately available in those areas with a high risk of cyanide exposure. As part of its regular review of guidelines, the Australian Resuscitation Council conducted a systematic review of the human evidence for the use of various proposed cyanide antidotes, and a narrative review of the relevant pharmacological and animal studies. There have been no relevant comparative or placebo-controlled human trials. Nine case series were identified. Treatment with hydroxocobalamin was reported in a total of 361 cases. No serious adverse effects of hydroxocobalamin were reported, and many patients with otherwise presumably fatal poisoning survived. Sodium thiosulphate use was reported in two case series, similarly with no adverse effects. Treatment with a combination of sodium nitrite, amyl nitrite and sodium thiosulphate was reported in 74 patients, with results indistinguishable from those of hydroxocobalamin and sodium thiosulphate. No case series using dicobalt edetate or 4-dimethylaminophenol were identified, but successful use in single cases has been reported. Hydroxocobalamin and sodium thiosulphate differ from alternatives in having negligible adverse effects, and on the basis of current evidence are the antidotes of choice. The indications for the use of an antidote, the requirements for supportive care and a recommended approach for workplaces where there is a risk of cyanide poisoning are presented.

A review of acute cyanide poisoning with a treatment update

Cyanide causes intracellular hypoxia by reversibly binding to mitochondrial cytochrome oxidase a(3). Signs and symptoms of cyanide poisoning usually occur less than 1 minute after inhalation and within a few minutes after ingestion. Early manifestations include anxiety, headache, giddiness, inability to focus the eyes, and mydriasis. As hypoxia progresses, progressively lower levels of consciousness, seizures, and coma can occur. Skin may look normal or slightly ashen, and arterial oxygen saturation may be normal. Early respiratory signs include transient rapid and deep respirations. As poisoning progresses, hemodynamic status may become unstable. The key treatment is early administration of 1 of the 2 antidotes currently available in the United States: the well-known cyanide antidote kit and hydroxocobalamin. Hydroxocobalamin detoxifies cyanide by binding with it to form the renally excreted, non-toxic cyanocobalamin. Because it binds with cyanide without forming methemoglobin, hydroxocobalamin can be used to treat patients without compromising the oxygen-carrying capacity of hemoglobin.

Development of nano alpha-ketoglutarate nebulization formulation and its pharmacokinetic and safety evaluation in healthy human volunteers for cyanide poisoning

Development of nano alpha-ketoglutarate (A-KG) nebulization formulation for neutralization of inhaled cyanide ion toxicity. Objectives of the present study were to (a) develop a novel A-KG nebulization formulation against cyanide poisoning, particularly hydrogen cyanide gas (b) validate its respiratory fraction in vitro and in vivo, and (c) create its pharmacokinetic data in human volunteers. The formulation was optimized on the basis of particle size of aerosolized droplets after nebulization in 6 volunteers. Gamma scintigraphy was used to quantify total and regional lung deposition of nebulized A-KG after radiolabeling it with Technetium-99m. The formulation was optimized using 30% ethanol-saline with particle size in the range of 300-500 nm. In vitro and in vivo studies showed that drug nebulization resulted in a significant respirable fraction of 65 ± 0.6% with whole lung deposition of 13 ± 1%. Human pharmacokinetic data was derived in 6 healthy human volunteers with peak serum concentration (C(max)) of 39 ± 3 μg/ml, while the area under curve (AUC) after inhalation was 376 ± 23 μg × h/ml indicating that the drug was rapidly and completely absorbed when targeted directly to lungs. Significant lung deposition of A-KG was achieved with the developed formulation. The formulation appears to have several advantages, including the potential of neutralizing inhaled CN(-) ions in the lungs themselves. It is a safe and efficacious procedure, suitable for hospital or ambulance use in accidental cyanide poisoning cases, or as a preventive approach for fire-rescue teams.

Does amyl nitrite have a role in the management of pre-hospital mass casualty cyanide poisoning?

CONTEXT

Amyl nitrite has been recommended as a cyanide antidote for several decades. Its antidotal properties were initially attributed to induction of methemoglobin and later to a nitric oxide mediated hemodynamic effect. The ease of administration and alleged rapid clinical effect would recommend its wide use in the pre-hospital management of mass casualty cyanide poisoning; yet there are concerns regarding the use of amyl nitrite for this indication.

OBJECTIVE

Review the data on amyl nitrite in cyanide poisoning and evaluate its efficacy and safety in mass casualty cyanide poisoning.

METHODS

A literature search utilizing PubMed, Toxnet, textbooks in toxicology and pharmacology, and the bibliographies of the articles retrieved identified 17 experimental studies and human reports on the use of amyl nitrite in cyanide poisoning, and 40 additional articles on amyl nitrite's properties and adverse effects. One paper was excluded as it was a conference abstract with limited data.

MECHANISMS OF ACTION

The antidotal properties of amyl nitrite were attributed initially to induction of methemoglobinemia and later to nitric oxide mediated vasodilation.

EFFICACY

EXPERIMENTAL STUDIES

Animal studies on the use of amyl nitrite in cyanide poisoning are limited, and their results are inconsistent, which makes their extrapolation to humans questionable.

EFFICACY

HUMAN STUDIES

Clinical reports are limited in number and the part played by amyl nitrite relative to the other treatments administered (e.g. life support, sodium nitrite, and sodium thiosulfate) is unclear.

ADVERSE EFFECTS

Amyl nitrite can be associated with potentially serious adverse reactions such as hypotension, syncope, excessive methemoglobinemia, and hemolysis in G6PD deficient patients. These effects are more pronounced in young children, in the elderly, and in patients with cardiac and pulmonary disorders. Dose regimen. The method of administration of amyl nitrite (breaking pearls into gauze or a handkerchief and applying it intermittently to the victim's nose and mouth for a few minutes) is not easily controlled, might result in under- or over-dosing, can prevent the caregiver from administering life support, and possibly expose him/her to amyl nitrite's adverse effects.

CONCLUSIONS

Administration of amyl nitrite in mass casualty cyanide poisoning can result in unnecessary morbidity and may interfere with the proper management of the incident and the required supportive treatment and rapid evacuation. In the authors' opinion these drawbacks make the use of amyl nitrite in pre-hospital mass casualty cyanide poisoning unwarranted.

Hemodialysis complications of hydroxocobalamin: a case report

Hydroxocobalamin is a new antidote approved by the FDA for the treatment of cyanide poisoning. Our report describes a patient with cyanide poisoning who survived after treatment with hydroxocobalamin and complications we encountered with hemodialysis. A 34-year-old female presented to the emergency department after a syncopal event and seizures. Her systolic blood pressure was 75 mmHg, her QRS complex progressively widened, and pulses were lost. She was intubated and resuscitated with fluids, sodium bicarbonate for her QRS widening and vasopressors. Venous blood gas demonstrated a pH of 6.36 with an O₂ saturation of 99%. Due to the acidemia with a normal pulse oximetry, simultaneous venous and arterial blood gases were obtained. Venous gas demonstrated a pH of 6.80 with a PO₂ of 222 mmHg, an O₂ saturation of 99%. The arterial blood gas showed a pH of 6.82, a PO₂ 518 mmHg, an O₂ saturation of 100%. Cyanide was suspected and hydroxocobalamin and sodium thiosulfate were given. Within 40 min of hydroxocobalamin administration, vasopressors were discontinued. Initially, nephrology attempted dialysis for metabolic acidosis; however, the dialysis machine repeatedly shut down due to a "blood leak". This was an unforeseen effect attributed to hydroxocobalamin. Cyanide level, drawn 20 min after the antidote was completed, was elevated at 22 mcg/dL. Her urinary thiocyanate level could not be analyzed due to an "interfering substance". Hydroxocobalamin is an effective antidote. However, clinicians must be aware of its effects on hemodialysis machines which could delay the initiation of this important treatment modality in the severely acidemic patient.

Critical care toxicology

Emergency physicians are regularly called on to care for critically poisoned patients. This article reviews the general approach and management of the critically poisoned patient. Specific clinical characteristics are identified that may clue the clinician into a specific toxin class as a diagnosis. Appropriate testing in the poisoned patient is reviewed. Complications of poisoning that may bring a rapid demise of the critically ill poisoned patient are highlighted and the management of those complications is discussed.

Novel, orally effective cyanide antidotes

A series of prodrugs of 3-mercaptopyruvate (3-MP), the substrate for the enzyme 3-mercaptopyruvate/cyanide sulfurtransferase (3-MPST) that converts cyanide to the nontoxic thiocyanate, which are highly effective cyanide antidotes, have been developed. These prodrugs of 3-MP are unique in being not only orally bioavailable, but may be administered up to an hour prior to cyanide as a prophylactic agent and are both rapid- or slow-acting when given parenterally.

Chemical Terrorism Attacks: Update on Antidotes

There is well-founded concern that a chemical or radioactive agent will at some point be used as a weapon of terror. There are several antidotes that, if used correctly in a timely fashion, can help lessen the harm caused by these agents. This article is meant to introduce the clinician to several such agents, along with the antidotes useful in the management of exposure to these. It covers the indications, administration, and precautions for using these antidotes.