Prevalence of autonomic signs and symptoms in antimuscarinic drug poisonings

An autopsy case of intoxication caused by drug interaction with multiple psychotropic drugs, fluvoxamine, levomepromazine, and trihexyphenidyl

A case of death due to combined use of multiple drugs is reported, and the pharmacokinetic interactions are discussed. A woman in her thirties was found dead in her home. A medico-legal autopsy found no findings suggestive of injury or natural disease. Toxicological analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) identified a toxic level of fluvoxamine (0.947 µg/mL), and concentrations greater than the therapeutic levels of levomepromazine (0.238 µg/mL) and trihexyphenidyl (0.225 µg/mL) were present, while bromazepam, haloperidol, sulpiride, and 7-aminoflunitrazepam were within or below their therapeutic ranges. Fluvoxamine is mainly metabolized by cytochrome P450 2D6 (CYP2D6), and levomepromazine is a potent CYP2D6 inhibitor. A high concentration of levomepromazine may increase the blood fluvoxamine level. Since the combined use of levomepromazine and fluvoxamine induces seizures, it may have been involved in causing the subject's death. In addition, combined use of trihexyphenidyl may potentiate anticholinergic effects of fluvoxamine overdose, including convulsions and coma. It was concluded that the cause of the subject's death was the interaction of multiple drugs.

Case report: asenapine and anticholinergic toxicity

While antipsychotic medications have long been associated with anticholinergic effects, asenapine has been purported to have no capacity for muscarinic cholinergic antagonism based on in vitro studies. Research in rat brain tissue has yielded different results, with one study finding more cholinergic M1-5 binding in the medial prefrontal cortex, dorsolateral frontal cortex and hippocampal CA1 and CA3 areas than would be predicted from in vitro findings. Moreover, it is structurally similar to other anticholinergic antipsychotics such as loxapine and, to a lesser degree, quetiapine, olanzapine and clozapine. This case report describes the anticholinergic toxidrome in a patient treated with benztropine and paroxetine at stable doses, with the emergence of the toxidrome after upward titration of asenapine. A broad differential was considered. With further consideration of the history, time-course, clinical features and physical examination, the presentation is most indicative of the anticholinergic toxidrome. Although not employed, physostigmine, the antidote for anticholinergic delirium, could help to differentiate this toxidrome and serve as a diagnostic and therapeutic intervention. We have presented this case to highlight the importance for clinicians to integrate history and bedside examination data with principles of pharmacology. In particular, asenapine should be added to the list of compounds with recognized anticholinergic potential.

A Critical Evaluation of Safety Signal Analysis Using Algorithmic Standardised MedDRA Queries

INTRODUCTION

Algorithmic Standardised MedDRA^® Queries (aSMQs) are increasingly used to enhance the efficiency of safety signal detection. The manner that aSMQs affect capture of potential safety cases is unclear.

OBJECTIVES

Our objective was to characterise the performance of aSMQs with respect to their potential for double counting, the likelihood of events in aSMQ positive cases being clinically related, how frequently terms are used for algorithmically positive cases, and the face validity of positive cases based on the drug inducing events. We were also interested in what effect requiring symptoms to overlap temporally would have on performance.

METHODS

We reviewed adverse event (AE) datasets of New Drug Applications and Biological License Applications and compiled a database including preferred terms and corresponding SMQs, SMQ term categories, AE start day, AE duration, drug name, and Anatomical Therapeutic Chemical class. Two reviewers independently determined if the algorithm was met and, if so, whether the broad terms overlapped temporally.

RESULTS

A total of 107 marketing applications were reviewed, including 103,928 patients and 277,430 AEs. Use of algorithms condensed the number of AEs to between 5 and 8% and the incidence to about 1.5% relative to when the SMQs are used without the algorithm. Certain aSMQs exhibited a potential for overcounting. Requiring symptoms to temporally overlap helped to eliminate irrelevant cases.

CONCLUSIONS

Our findings demonstrate that algorithmic and temporal assessment increased specificity of case retrieval, though the reduction in the number of terms or incidence seemed excessive for certain aSMQs. Evaluating the day of AE onset and duration improve specificity through identification of outlying events. Identification of drug classes known to cause the aSMQ's clinical condition provides face validity for this tool, yet detection of cases associated with novel classes may provide new understanding of these disorders. Improvements in some of the SMQ term lists may improve the performance of SMQs in general.

Two Cases of Anticholinergic Poisoning from Transdermal Scopolamine Patch

Scopolamine transdermal patch is a form of anticholinergic drug used to prevent motion sickness. We reported two cases of anticholinergic poisoning resulting from scopolamine transdermal patch. The first case experienced local toxicity and presented with right eye mydriasis for five days. The second case developed systemic anticholinergic toxidrome contributed by the scopolamine patch and presented with acute confusion. She was treated successfully by physostigmine, an anticholinergic antidote. The recommendation on physostigmine use was also discussed. We hope that these two case reports will raise the clinician awareness of the potential side effect of this kind of product.

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.

Neuroleptic malignant syndrome: mechanisms, interactions, and causality

This review focuses on new data from recent publications concerning how compounding interactions between different thermoregulatory pathways influence the development of hyperthermia and/or neuroleptic malignant syndrome (NMS), and the fundamental issue of the presumed causal role of antipsychotic drugs. The formal criteria for substantiating cause-effect relationships in medical science, established by Hill, are applied to NMS and, for comparison, also to malignant hyperthermia and serotonin toxicity. The risk of morbidities related to hyperthermia is reviewed from human and experimental data: temperatures in excess of 39.5°C cause physiological and cellular dysfunction and high mortality. The most temperature-sensitive elements of neural cells are mitochondrial and plasma membranes, in which irreversible changes occur around 40°C. Temperatures of up to 39°C are "normal" in mammals, so, the term hyperthermia should be reserved for temperatures of 39.5°C or greater. The implicitly accepted presumption that NMS is a hypermetabolic and hyperthermic syndrome is questionable and does not explain the extensive morbidity in the majority of cases, where the temperature is less than 39°C. The thermoregulatory effects of dopamine and acetylcholine are outlined, especially because they are probably the main pathways by which neuroleptic drugs might affect thermoregulation. It is notable that even potent antagonism of these mechanisms rarely causes temperature elevation and that multiple mechanisms, including the acute phase response, stress-induced hyperthermia, drugs effects, etc., involving compounding interactions, are required to precipitate hyperthermia. The application of the Hill criteria clearly supports causality for drugs inducing both MH and ST but do not support causality for NMS.

[Intentional Datura stramonium intoxication: an unknown etiology of mydriasis]

Two case reports of Datura stramonium intoxications are presented. The first one was a self poisoning, with a moderate anticholinergic syndrome and a spontaneous improvement. The second one was a recreational use of Datura stramonium for its hallucinogenic properties. The anticholinergic syndrome was marked and the improvement required orotracheal intubation, mechanical ventilation, intraveinous rehydratation, and active cooling to prevent organ failure.