Clinical applications of commonly used contemporary antidotes. A US perspective

Aspiration von Aktivkohle: Organbefunde nach Fehllage einer Magensonde mit 18-tägiger Überlebenszeit

Laut Statistischem Bundesamt wurden 2016 in Deutschland 178.425 Vergiftungsfälle im Krankenhaus behandelt. Zu den klinischen Sofortmaßnahmen gehören Verfahren zur Verhinderung weiterer Giftresorption. Die Anwendung von Aktivkohle wird dabei als Dekontaminationsverfahren der ersten Wahl nach peroralen Vergiftungen angesehen. Ein 14 Jahre alt gewordenes Mädchen habe in fraglich suizidaler Absicht mehrere Tabletten Amitriptylin eingenommen. Im erstbehandelnden Krankenhaus sei ihr eine unbekannte Menge an Aktivkohle über eine Magensonde verabreicht worden. Aufgrund der Fehllage der Magensonde wurde die Aktivkohle jedoch endotracheal appliziert. Danach erfolgte die Verlegung an ein Krankenhaus der Maximalversorgung. Trotz intensivmedizinischer Therapie sei das Mädchen nach 18 Tagen an einem akutem Lungenversagen nach massiver Aspiration von Aktivkohle verstorben. Bei der gerichtlichen Obduktion und der anschließenden mikroskopischen Untersuchung fielen sowohl eine heterogene Verteilung der intraalveolär gelegenen, variabel dichten Ansammlungen der Aktivkohle in allen Lungenlappen als auch mehrzeitige, akute sowie chronische entzündliche Veränderungen im Lungenparenchym auf. Darüber hinaus konnte Aktivkohle innerhalb der Lebersinusoide sowie in den Tubuli des Nierenparenchyms nachgewiesen werden.

A review of pitfalls and progress in chelation treatment of metal poisonings

Most acute and chronic human metal poisonings are due to oral or inhalation exposure. Almost 80% of published animal experiments on chelation in metal poisoning used single or repeated intraperitoneal, intramuscular or intravenous administration of metal and chelator, impeding extrapolation to clinical settings. Intramuscular administration of dimercaptopropanol (BAL) has until now been used in acute arsenic, lead, and mercury poisonings, but repeated BAL administration increased the brain uptake of As, Pb and Hg in experimental animals. Also, diethyl dithiocarbamate (DDC) has been used as antidote in acute experimental animal parenteral Cd poisoning, and both DDC and tetraethylthiuram disulfide (TTD, disulfiram, Antabuse) have been used in nickel allergic patients. However, even one dose of DDC given immediately after oral Cd or Ni increased their brain uptake considerably. The calcium salt of ethylenediamminetetraacetic acid (CaEDTA) but not dimercaptosuccinic acid (DMSA) increased the brain uptake of Pb. In oral Cd or Hg poisoning, early oral administration of DMSA or dimercaptopropane sulfonate (DMPS) increased survival and reduced intestinal metal uptake. Oral administration of Prussian Blue or resins with fixed chelating groups that are not absorbed offer chelation approaches for decorporation after oral exposure to various metals. Diethylenetriaminepentaacetic acid (DTPA) nebulizers for pulmonary chelation after inhalation exposure need further development. Also, combined chelation with more than one compound may offer extensive advances. Solid knowledge on the chemistry of metal chelates together with relevant animal experiments should guide development of chelation procedures to alleviate and not aggravate the clinical status of poisoned patients.

Predicting the clinical efficacy and potential adverse effects of a humanized anticocaine monoclonal antibody

The effects of a humanized monoclonal antibody (mAb) having high affinity and specificity for cocaine in animal models are reviewed. The mAb reduced the concentration of cocaine in the brain of mice after intravenous injection of cocaine. In addition, the mAb increased the concentration of cocaine required to reinstate cocaine self-administration. These effects may predict clinical efficacy of a passive immunotherapy for reducing the probability of cocaine-induced relapse. However, in the presence of the mAb, once cocaine self-administration was reinstated, the consumption rate of cocaine was increased. This effect is hypothesized to result from a pharmacokinetic/pharmacodynamic interaction. A humanized mAb should minimize adverse events related to the immunogenicity of the mAb protein, and the specificity for cocaine should avoid adverse events related to interactions with physiologically relevant endogenous proteins.

Behavioral sequelae following acute diisopropylfluorophosphate intoxication in rats: comparative effects of atropine and cannabinomimetics

The comparative effects of atropine and the indirect cannabinomimetics URB597 (a fatty acid amide hydrolase inhibitor) and URB602 (a monoacylglycerol lipase inhibitor) on functional and neurobehavioral endpoints following acute diisopropylfluorophosphate intoxication were studied. Male Sprague-Dawley rats were treated with vehicle or DFP (2.5mg/kg, sc), immediately post-treated with either vehicle, atropine (16mg/kg), URB597 (3mg/kg), URB602 (10mg/kg) or a combination of URB597 and URB602, and functional signs of toxicity as well as nocturnal motor activity were measured daily for seven consecutive days. Performance in the elevated plus maze (for anxiety-like behavior) and the forced swimming test (for depression-like behavior) was measured at days 6-8 and 27-29 after dosing. Twenty-four hours after dosing, DFP markedly reduced cholinesterase activity in selected brain regions and peripheral tissues (diaphragm and plasma). Substantial recovery of cholinesterase activity was noted at both 8 and 29days after dosing but significant inhibition was still noted in some brain regions at the latest time-point. DFP elicited body weight reductions and typical signs of cholinergic toxicity, and reduced nocturnal ambulation and rearing. Atropine and the cannabinomimetics (alone and in combination) partially attenuated DFP-induced functional signs of toxicity. None of the post-treatments reversed the DFP-induced reduction in ambulation or rearing, however. No significant treatment-related effects on elevated plus maze performance were noted. DFP-treated rats exhibited decreased swimming and increased immobility in the forced swimming test at both time-points. None of the post-treatments had any effect on DFP-induced changes in immobility or swimming at day 8. At day 29, atropine and the combination of URB597/URB602 significantly blocked DFP-induced changes in immobility, while URB597 and the combination reversed DFP-induced changes in swimming. The results suggest that early blockade of muscarinic receptors and enhancement of eCB signaling can attenuate both acute and delayed effects elicited by DFP.

Protective effects of mecamylamine and atropine against α(4)β(2) nicotinic receptor expression and functional toxicity in paraoxon-treated rats

Chronic and acute exposure to organophosphate pesticides or related nerve agents may lead to persistent neurological and neurobehavioral effects, which cannot be explained by acetylcholinesterase (AChE) inhibition alone. In the present study, the effects of mecamylamine (2mg/kg), or atropine (10mg/kg) alone, or in combination, on the expression of nicotinic acetylcholine receptors (nAChRs) subunits, functional signs of toxicity and lethality in paraoxon-treated rats were investigated. Surviving animals were sacrificed after 48h of paraoxon administration. Paraoxon, at dosage of 1× LD50, significantly reduced expression of α(4) and β(2) nAChR subunits mRNA and protein in rat brain homogenates. Mecamylamine, efficiently prevented reduction of the α(4) and β(2) nAChR mRNA and protein in paraoxon exposed rat brains, but atropine was not efficient. Concurrent treatment with mecamylamine and atropine restored nAChRs mRNA and protein level and prevented lethality and severe involuntary movements induced by paraoxon. Nicotinic receptors antagonists may be included in the cocktail of therapeutic agents targeting the various mechanisms for neuronal injury by organophosphates.

Sodium Thiosulfate or Hydroxocobalamin for the Empiric Treatment of Cyanide Poisoning?

Cyanide poisoning must be seriously considered in victims of smoke inhalation from enclosed space fires; it is also a credible terrorism threat agent. The treatment of cyanide poisoning is empiric because laboratory confirmation can take hours or days. Empiric treatment requires a safe and effective antidote that can be rapidly administered by either out-of-hospital or emergency department personnel. Among several cyanide antidotes available, sodium thiosulfate and hydroxocobalamin have been proposed for use in these circumstances. The evidence available to assess either sodium thiosulfate or hydroxocobalamin is incomplete. According to recent safety and efficacy studies in animals and human safety and uncontrolled efficacy studies, hydroxocobalamin seems to be an appropriate antidote for empiric treatment of smoke inhalation and other suspected cyanide poisoning victims in the out-of-hospital setting. Sodium thiosulfate can also be administered in the out-of-hospital setting. The efficacy of sodium thiosulfate is based on individual case studies, and there are contradictory conclusions about efficacy in animal models. The onset of antidotal action of sodium thiosulfate may be too slow for it to be the only cyanide antidote for emergency use. Hydroxocobalamin is being developed for potential introduction in the United States and may represent a new option for emergency personnel in cases of suspected or confirmed cyanide poisoning in the out-of-hospital setting.

Physostigmine for gamma-hydroxybutyrate coma: inefficacy, adverse events, and review

Physostigmine has been proposed as an antidote for gamma hydroxybutyrate (GHB) intoxication, based on associated awakenings in 1) patients anesthetized with GHB and 2) five of six patients administered physostigmine for GHB intoxication. However, there are neither well-supported mechanisms for physostigmine reversal of GHB effects, supportive animal studies, nor randomized, placebo-controlled trials demonstrating safety, efficacy, or improved outcomes. We sought to determine the outcomes of patients with GHB-induced coma after a physostigmine treatment protocol was instituted in an urban Emergency Department and ambulance service. Our search of medical records located five cases of GHB toxicity, all with co-intoxicants, who received physostigmine. None demonstrated response and, further, there were associated adverse events, including atrial fibrillation (2), pulmonary infiltrates (1) and significant bradycardia (1), and hypotension (1). We also reviewed 18 published GHB toxicity case series for incidence of adverse effects, stimulant co-intoxicants (which may heighten risk of physostigmine), complications, and outcomes of supportive care for GHB toxicity. We conclude that physostigmine is not indicated for reversal of GHB-induced alteration of consciousness; it is not efficacious, it may be unsafe, particularly in the setting of recreational polydrug use; and supportive care results in universally good outcomes.

Fab antibody fragments: some applications in clinical toxicology

This review provides current information on the use of antigen-binding fragments (Fab) from cleaved antibodies to treat poisoning with digoxin and other potent, low formula mass poisons, such as colchicine and tricyclic antidepressants. Anti-digoxin Fab fragments have been used successfully for many years in the management of severe poisoning with digoxin, digitoxin, and a range of other structurally related compounds, including cardiotoxins from Nerium and Thevetia sp. (oleander) and Bufo sp. (toads). However, their main use remains treating digoxin poisoning. Equimolar doses of anti-digoxin Fab fragments completely bind digoxin in vivo. The approximate dose of Fab fragments (mg) is 80 times the digoxin body burden (mg). If neither the dose ingested nor the plasma digoxin/digitoxin concentration is known, in an adult 380 mg of anti-digoxin Fab fragments should be given. The dose for elderly patients or those with renal impairment should be similar to that for those with normal renal function. Fab fragments have a plasma half-life of 12-20 hours, but this can be prolonged in patients with renal impairment. Analysis of serum ultrafiltrate using an immunoassay shown not to have matrix bias remains the most accurate approach to measuring free digoxin in the presence of anti-digoxin Fab fragments. The antibody fragments are given intravenously over 15-30 minutes after dilution to at least 250 mL with plasma protein solution, 0.9% (w/v) sodium chloride, or deionised water, except in infants where the volume infused can be reduced. Factors limiting the efficacy of Fab fragments are the dose, the duration of the infusion and any delay in administration. Guidelines for Fab fragment administration in children include (i) dilution to a final Fab concentration of 10 g/L in either 5% (w/v) dextrose or 0.9% (w/v) sodium chloride; (ii) infusion through a 0.22 microm filter; (iii) administration of the total dose over a minimum of 30 minutes; and (iv) avoiding coadministration of other drugs and/or electrolyte solutions. Fab fragments are generally well tolerated. Adverse effects attributable to Fab treatment include hypokalaemia and exacerbation of congestive cardiac failure; renal function could be impaired in some patients. Fab fragment preparations for treating acute colchicine and tricyclic antidepressant poisoning have been developed, but are not available commercially. Colchicine poisoning is rare in Western countries, and pharmacological management together with supportive care is usually effective even in severe tricyclic antidepressant overdosage. Attempts have been made to produce anti-paraquat antibodies capable of enhancing paraquat elimination from the lung, but thus far all such attempts have proved unsuccessful.

Activated charcoal forms non-IgE binding complexes with peanut proteins

BACKGROUND

Conventional management of peanut-induced anaphylaxis is composed of administration of epinephrine, antihistamine, and steroid and stabilization of airway, ventilatory, and circulatory function. Therapies directed toward slowing or preventing further absorption of peanut protein from the gastrointestinal tract after accidental ingestion have not been a routine part of management.

OBJECTIVE

The purpose of this study was to determine the ability of activated charcoal to complex with peanut protein, thereby preventing its binding to either peanut-specific IgE or peanut-specific IgG.

METHODS

Peanut protein was coincubated with micronized activated charcoal suspension at pH 3.5 or 7.4. Peanut protein complexed with charcoal was removed by centrifugation. Binding of residual peanut protein to peanut-specific IgG was measured by a sandwich ELISA assay. Also, ability of uncomplexed peanut protein to bind to peanut-specific IgE was determined by Western blot and by skin prick testing in subjects with peanut allergy.

RESULTS

Activated charcoal (AC) formed complexes with peanut protein, effectively competing for binding with peanut-specific IgG in a sandwich ELISA assay. AC complexed efficiently with peanut protein at both neutral and acidic pH in as little as 60 seconds. AC was also able to remove IgE-binding peanut allergens from solution as determined by Western blot and by skin prick testing in subjects with peanut allergy. A ratio of 200 mg of AC to 1 mg peanut protein was required for complete removal of peanut protein from solution. AC was able to complex with peanut protein within food matrices such as ice cream and chocolate.

CONCLUSION

The data presented herein show that AC removes both IgE-binding and IgG-binding peanut proteins from solution rapidly at both neutral and acidic pH. These data suggest that administration of AC may be useful as an adjunct to slow or to prevent further absorption of peanut protein from the gastrointestinal tract after accidental ingestion by individuals with peanut allergy.

Hydroxocobalamin: improved public health readiness for cyanide disasters

The United States is under the constant threat of a mass casualty cyanide disaster from industrial accidents, hazardous material transportation incidents, and deliberate terrorist attacks. The current readiness for cyanide disaster by the emergency medical system in the United States is abysmal. We, as a nation, are simply not prepared for a significant cyanide-related event. The standard of care for cyanide intoxication is the cyanide antidote kit, which is based on the use of nitrites to induce methemoglobinemia. This kit is both expensive and ill suited for out-of-hospital use. It also has its own inherent toxicity that prevents rapid administration. Furthermore, our hospitals frequently fail to stock this life-saving antidote or decline to stock more than one. Hydroxocobalamin is well recognized as an efficacious, safe, and easily administered cyanide antidote. Because of its extremely low adverse effect profile, it is ideal for out-of-hospital use in suspected cyanide intoxication. To effectively prepare for a cyanide disaster, the United States must investigate, adopt, manufacture, and stockpile hydroxocobalamin to prevent needless morbidity and mortality.

Inadequate stocking of antidotes in Taiwan: is it a serious problem?

OBJECTIVE

Insufficient hospital stock of a variety of poisoning antidotes is a worldwide problem. In an attempt to establish an antidote storage and distribution system for the response of the various poisoning accidents, we conducted a nationwide survey to characterize the current availability of selected antidotes and their anticipated need in Taiwan.

MATERIALS AND METHODS

A questionnaire was mailed to 834 hospitals to gather information on the availability, anticipated need, and preferred purchase policy of 20 selected antidotes. A survey on the availability of cyanide antidote in 523 cyanide-handling facilities and their neighboring hospitals was also conducted.

RESULTS

Hospitals of different size and service levels had a statistically significant difference in response rates. Except for pyridoxine, the availability and anticipated need for antidotes also varied significantly among different hospital groups. We found that physostigmine, cyanide antidote kit, BAL, EDTA, methylene blue, Vipera Russell formosensis antivenin, and botulism antitoxin were not available in most (>90%) hospitals. Interestingly, these antidotes are also among the most needed antidotes. Most hospitals preferred a government-ordered purchase of antidotes. In the survey of cyanide-processing facilities, a response rate of 24.1% was obtained and only 9.3% of these 107 facilities that both replied to the questionnaire and continued handling cyanide products had stocked cyanide antidote. It is noteworthy that cyanide antidote was also frequently lacking in the neighboring hospitals.

CONCLUSIONS

The appropriate storage of antidotes in hospitals or workplaces in rural areas is instrumental in the timely treatment of certain poisonings, while nationwide unavailability is the critical problem. Raising awareness of the importance of antidotes by education, regular review of antidote storage, distribution plans, and appropriate legislation might provide solutions.

Capillary electrophoretic separation of N-acetylcysteine and its impurities as a method for quality control of pharmaceuticals

Capillary electrophoresis has been applied to separate and determine N-acetylcysteine (NAC) and related impurities. Determination conditions were found to be optimum with 100 mmol/l borate as the buffer, pH 8.40. The limit of detection was established for each substance examined. The method has been validated by examining linearity ranges, precision and repeatability. The method was used to determine the content of NAC in, and purity of, pharmaceutical preparations. The major impurities (N,N-diacetylcystine, N,S-diacetylcysteine and cystine) were determined at levels of 0.1%.

Mechanism of action and value of N-acetylcysteine in the treatment of early and late acetaminophen poisoning: a critical review

INTRODUCTION

The mechanism of action of N-acetylcysteine in early acetaminophen poisoning is well understood, but much remains to be learned of the mechanism of its possible benefit in acetaminophen poisoning presenting beyond 15 hours.

METHODS

Selective review of medical literature. N-acetylcysteine should be used in all cases of early acetaminophen poisoning where the plasma acetaminophen concentration lies "above the line;" which line is chosen depends on individual preference and whether enzyme induction is suspected. Particular care should be taken with the use of the nomogram for patients with chronic excess ingestion of acetaminophen or for those who have taken slow-release formulations.

CONCLUSIONS

While there is a trend suggesting a beneficial effect of N-acetylcysteine in some patients presenting beyond 15 hours, further research is necessary to establish just how effective N-acetylcysteine is, particularly in patients presenting with fulminant hepatic failure. Candidate mechanisms for a beneficial effect in-clude improvement of liver blood flow, glutathione replenishment, modification of cytokine production, and free radical or oxygen scavenging. Hemody-namic and oxygen delivery and utilization parameters must be monitored carefully during delayed N-acetylcysteine treatment of patients with fulminant hepatic failure, as unwanted vasodilation may be deleterious to the maintenance of mean arterial blood pressure.