The treatment of scopolamine-induced delirium with physostigmine

Determination of scopolamine and butylscopolamine in beverages, urine and Buscopan® tablets samples using electrophoresis microchip with integrated contactless conductivity detection

The number of cases in which scopolamine (SCO) was used for both recreational and predatory purposes has increased dramatically in recent decades. Linked to this, there is a concern about obtaining SCO through thermal degradation of butylscopolamine (BSCO) - an active ingredient of Buscopan® - a drug sold without a medical prescription. In this study, mixtures containing SCO and BSCO were separated and detected on a microchip electrophoresis (ME) device with integrated capacitively coupled contactless conductivity detection (C4D) using a running buffer composed of 40 mmol L-1 of butyric acid and 25 mmol L-1 of sodium hydroxide (pH 5.0). The separation was performed within ca. 115 s with a resolution of 1.3 and separation efficiency ranging from 1.4 × 105 to 1.5 × 105 theoretical plates m-1. A detection limit of 1.1 μmol L-1 was achieved for both species and the developed method revealed satisfactory repeatability with relative standard deviation (RSD) values for forty-eight injections between 4.8 and 9.4% for peak areas and lower than 3.3% for migration times. Furthermore, inter-day precision was evaluated for sixteen injections (a sequence of four injections performed over four days), and RSD values were less than 6.6% for peak areas and 2.2% for migration times. Satisfactory recovery values (95-114%) were obtained for all evaluated beverage samples (cachaça, vodka, whiskey, beer, Coca-Cola, and grape juice) as well as for artificial urine samples (95-107%). Finally, the conversion of BSCO into SCO was observed after simple heating procedure of Buscopan® sample (not subject to medical prescription), which was successfully confirmed through analysis by capillary electrophoresis coupled to the mass spectrometry (CE-MS). Based on the reported results, the use of ME-C4D devices has demonstrated a huge potential for applications in the forensic chemistry field.

Common Substances of Abuse

Adolescent substance abuse remains common, with almost a third of adolescents admitting to ethanol use, and a quarter admitting to illicit drug use. It is essential for pediatricians to regularly screen adolescent patients for substance use, because early initiation of drug use has been associated with physical, behavioral, and social health risks. Adolescents abuse what is common and readily available; this includes ethanol, over-the-counter products, marijuana, and inhalants. The most common and effective clinical treatments for significant toxicity from substances of abuse is symptomatic and supportive care including hemodynamic support, respiratory support, and sedation to control psychomotor agitation.

Cholinesterase inhibitors for the treatment of delirium in non-ICU settings

BACKGROUND

Delirium is a common clinical syndrome defined as alterations in attention with an additional disturbance in cognition or perception, which develop over a short period of time and tend to fluctuate during the course of the episode. Delirium is commonly treated in hospitals or community settings and is often associated with multiple adverse outcomes such as increased cost, morbidity, and even mortality. The first-line intervention involves a multicomponent non-pharmacological approach that includes ensuring effective communication and reorientation in addition to providing reassurance or a suitable care environment. There are currently no drugs approved specifically for the treatment of delirium. Clinically, however, various medications are employed to provide symptomatic relief, such as antipsychotic medications and cholinesterase inhibitors, among others.

OBJECTIVES

To evaluate the effectiveness and safety of cholinesterase inhibitors for treating people with established delirium in a non-intensive care unit (ICU) setting.

SEARCH METHODS

We searched ALOIS, which is the Cochrane Dementia and Cognitive Improvement Group's Specialised Register, on 26 October 2017. We also cross-checked the reference lists of included studies to identify any potentially eligible trials.

SELECTION CRITERIA

We included randomised controlled trials, published or unpublished, reported in English or Chinese, which compared cholinesterase inhibitors to placebo or other drugs intended to treat people with established delirium in a non-ICU setting.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. The primary outcomes were duration of delirium, severity of delirium, and adverse events. The secondary outcomes were use of rescue medications, persistent cognitive impairment, length of hospitalisation, institutionalisation, mortality, cost of intervention, leaving the study early, and quality of life. For dichotomous outcomes, we calculated the risk ratio (RR) with 95% confidence intervals (CIs); for continuous outcomes we calculated the mean difference (MD) with 95% CIs. We assessed the quality of evidence using GRADE to generate a 'Summary of findings' table.

MAIN RESULTS

We included one study involving 15 participants from the UK. The included participants were diagnosed with delirium based on the Confusion Assessment Method (CAM) criteria. Eight males and seven females were included, with a mean age of 82.5 years. Seven of the 15 participants had comorbid dementia at baseline. The risk of bias was low in all domains.The study compared rivastigmine with placebo. We did not find any clear differences between the two groups in terms of duration of delirium (MD -3.6, 95% CI -15.6 to 8.4), adverse events (nausea, RR 0.30, 95% CI 0.01 to 6.29), use of rescue medications (RR 0.13, 95% CI 0.01 to 2.1), mortality (RR 0.10, 95% CI 0.01 to 1.56), and leaving the study early (RR 0.88, 95% CI 0.07 to 11.54). Evidence was not available regarding the severity of delirium, persistent cognitive impairment, length of hospitalisation, cost of intervention, or other predefined secondary outcomes.The quality of evidence is low due to the very small sample size.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of cholinesterase inhibitors for the treatment of delirium in non-ICU settings. No clear benefits or harms associated with cholinesterase inhibitors were observed when compared with placebo due to the lack of data. More trials are required.

The Use of Physostigmine by Toxicologists in Anticholinergic Toxicity

The anticholinergic toxidrome is well described and relatively common. Despite controversy, studies have shown that physostigmine is relatively safe and effective in reversing this toxidrome. We would expect toxicologists would be liberal in its use. We retrospectively analyzed data in the Toxicology Investigators Consortium (ToxIC) registry, representing data from medical toxicologists in multiple institutions nationwide, searching for patients who exhibited an anticholinergic toxidrome, determining what treatment(s) they received, and classifying the treatments as physostigmine, benzodiazepines, physostigmine and benzodiazepines, antipsychotics, or no definitive treatment. The causal agents of the toxidrome were as reported by the treating toxicologist. Eight hundred fifteen consecutive patients with anticholinergic toxidromes were analyzed. Benzodiazepines alone were given in 28.7 %, 12.4 % were given physostigmine alone, 8.8 % received both physostigmine and benzodiazepines, 2.7 % were given antipsychotics, and 47.4 % were given no definitive treatment. In patients who received only physostigmine, there was a significant difference in the rate of intubation (1.9 vs. 8.4 %, OR 0.21, 95 % CI 0.05-0.87) versus other treatment groups. Physostigmine was given at varying rates based on causative agent with use in agents with mixed or unknown effects (15.1 %) being significantly lower than those with primarily anticholinergic effects (26.6 %) (p < 0.001). Patients with anticholinergic toxicity were more likely to receive benzodiazepines than physostigmine. Those patients who received only physostigmine had a significantly lower rate of intubation. Physostigmine was more likely to be used with agents exerting primarily anticholinergic toxicity than in those agents with multiple actions.

Treatment of opioid-induced delirium with acetylcholinesterase inhibitors: a case report

A 55-year-old woman with advanced ovarian cancer and severe pain developed hypoactive delirium after an increase in her opioid dosage. Myoclonus and delirium improved dramatically with the intravenous injection of the acetylcholinesterase inhibitor physostigmine, and this improvement was maintained during the administration of donepezil, an oral medication with similar pharmacodynamic properties. Evidence for a disorder of cholinergic neurotransmission in opioid-induced delirium is discussed, as is the rationale for treatment with acetylcholinesterase inhibitors and other cholinomimetic agents.

A comparison of physostigmine and benzodiazepines for the treatment of anticholinergic poisoning

STUDY OBJECTIVE

To compare the efficacy and safety of physostigmine with benzodiazepines for the treatment of agitation and delirium associated with anticholinergic poisoning.

METHODS

We conducted a retrospective study of 52 consecutive patients referred to a university hospital toxicology consultation service who were treated with physostigmine, benzo-diazepines, or both for anticholinergic agitation and delirium. Patients treated with physostigmine were compared with those treated with benzodiazepines with respect to demographics, severity of poisoning, response to treatment, side effects of treatment, and complications.

RESULTS

Physostigmine controlled agitation and reversed delirium in 96% and 87% of patients, respectively. Benzodiazepines controlled agitation in 24% of patients but were ineffective in reversing delirium. Initial treatment with physostigmine (n=30) resulted in a significant decrease in the incidence of agitation (P <.001) and level of central nervous system stimulation (P <.001), whereas initial treatment with benzodiazepines (n=22) did not (P =.03 and P =.05, respectively). Patients treated initially with physostigmine had a significantly lower incidence of complications (7% versus 46%; P <. 002) and a shorter time to recovery (median, 12 versus 24 hours; P =. 004) than those treated initially with benzodiazepines. There were no significant differences between these groups in the incidence of side effects (7% versus 14%; P =0.6) and length of stay (median, 32 versus 39 hours; P =.15).

CONCLUSION

Results suggest that physostigmine is more effective and safer than benzodiazepines for the treatment of anticholinergic agitation and delirium. A prospective controlled study is necessary to confirm such findings.

Neurological and psychiatric adverse effects of anaesthetics: epidemiology and treatment

The practice of anaesthesia has changed considerably over the past 20 to 30 years owing largely to technological advances in patient monitoring and an expanded and improved pharmacological repertoire. While patient safety in anaesthesia has greatly improved, the risk of neurological and psychiatric adverse effects of anaesthetics remains and is the focus of continued investigation. For example, a great deal of attention has recently been directed at intraoperative awareness. This adverse event can be caused by delivering an inappropriate amount or type of anaesthetic. Another risk of anaesthesia involves drug-induced unpleasant subjective states in patients. Those drugs most frequently associated with these states include ketamine, droperidol and scopolamine. This risk can often be attenuated by careful adjustment of drug dose and the use of adjunctive agents such as benzodiazepines which may produce amnesia of the unpleasant subjective state. While it is well established that modern anaesthetic drugs cause acute impairment of cognition and psychomotor functioning, there is little evidence that these drugs have long term impairing effects. Finally, a particular kind of surgery, cardiac surgery requiring cardiopulmonary bypass, can be associated with adverse neurological and psychiatric sequelae which, while not directly related to anaesthesia, are of intense interest to anaesthesiologists.

The effect of the muscarinic antagonist scopolamine on regional cerebral blood flow during the performance of a memory task

Scopolamine, a muscarinic antagonist, impairs memory performance in both humans and animals. In this study, repeated measurements of regional cerebral blood flow (rCBF) were made in normal volunteers whilst performing auditory verbal memory tasks, before and after the administration of scopolamine (0.4 mg s.c.) or placebo. Compared to placebo, scopolamine increased blood flow in the lateral occipital cortex bilaterally and the left orbitofrontal region. Scopolamine decreased rCBF in the region of the right thalamus, the precuneus and the right and left lateral premotor areas. Scopolamine attenuated memory-task-induced increases of rCBF in the left and right prefrontal cortex and the right anterior cingulate region. These data suggest that acute blockade of cholinergic neurotransmission affects diverse brain areas, including components of the visual and motor systems, and, in addition, modulates memory task activations at distinct points in a distributed network for memory function.

Disinhibitory reactions to benzodiazepines: a review

This article reviews some of the important aspects of benzodiazepine-induced disinhibitory reactions. Although reactions of this type are relatively rare, they may sometimes manifest themselves in aggressive behavior accompanied by suicidal or homicidal tendencies. It appears that these reactions occur more commonly in younger patients, although the elderly (above 65 years) may also be at risk. Many mechanisms have been postulated, but none truly explain how these reactions arise. The concept that central cholinergic mechanisms may play a role, however, remains attractive and stems primarily from physostigmine's ability to successfully reverse this type of reaction. The potential role of the benzodiazepine antagonists, eg, flumazenil, in reversing disinhibitory reactions is also discussed. Apart from patients who previously exhibited poor impulse control, there are no reliable indicators for recognizing potential candidates for this type of reaction. To minimize the occurrence of disinhibitory reactions, some guidelines, which include the avoidance of certain drug combinations, the use of low doses of benzodiazepines, slow incremental intravenous administration, and good rapport with patients, are presented.

Physostigmine reversal of drug-induced paradoxical excitement

Paradoxical excitement associated with intravenous conscious-sedation in a patient undergoing dental surgery was successfully reversed with 1.0 mg physostigmine. Physostigmine is felt to have exerted this effect by 2 mechanisms: the re-establishment of homeostasis in the CNS via augmented cholinergic pathways with the net result being thalamacocortical excitation, and cholinergically-mediated increase in cerebral blood flow increasing the rate of redistribution of the intravenous sedative agents used. The most commonly encountered side-effects of physostigmine used to reverse parodoxical excitement, emergence delirium, or prolonged narcosis are bradycardia, nausea, and/or vomiting. The incidence of these side-effects is low in doses, below 2.0 mg/70 kg. body weight.

Use of scopolamine for dental anesthesia and analgesia techniques

A review of the English literature on the pharmacologic effects of scopolamine is presented and indications for the current use of the drug in dental anesthesia and analgesia are evaluated. The authors conclude that the role of scopolamine in the production of conscious sedation for outpatient dental surgery should be reevaluated in the light of contemporary findings.

Scopolamine intoxications

Pure scopolamine intoxications are extremely rare. We treated a series of severe intoxications exclusively caused by scopolamine and due to the intentional mixing of pure scopolamine into drinks. The clinical course and therapy are reported. On the basis of our experience and a survey of literature, we found physostigmine to be an excellent antidote. The symptomatology of the patients confirms that scopolamine has a dose-related stimulant effect on the central nervous system.

A randomized evaluation of the reversal of ketamine by physostigmine

One hundred and eleven patients undergoing ketamine anaesthesia for therapeutic abortion were studied in a double-blind trial of the reversal of ketamine by physostigmine administered postoperatively. The results demonstrate that physostigmine does not shorten recovery time or reduce the occurrence of ketamine emergence phenomena such as hallucinations, restlessness and dreams. In fact, the recovery course was prolonged in patients given physostigmine immediately upon termination of anaesthesia as compared with controls. By contrast, when physostigmine was given 30 minutes after the last dose of ketamine, the recovery was not prolonged as compared with that of the placebo-treated controls. These findings suggest some synergism between the effects of ketamine and physostigmine and should discourage the use of physostigmine as a ketamine antidote.

Atropine and hyoscine

The drugs atropine and hyoscine are reviewed in the context of their use by anaesthetists. The results of recent studies are stressed and guidelines given for use of these drugs in modern anaesthetic practice.

Effects of physostigmine, scopolamine, and mecamylamine on the sleeping time induced by ketamine in the rat

Male Sprague-Dawley rats weighing 116--241 g were injected i.p. with ketamine hydrochloride, 80 mg per kilo of body weight. Immediately after loss of righting reflex, scopolamine, physostigmine, and mecamylamine were administered i.p. to different groups of rats. Control animals received sterile saline by the same route. The ketamine-induced sleeping time was significantly prolonged by physostigmine and scopolamine, but not by mecamylamine. After the delayed injection of physostigmine, the ketamine sleeping time was longer. These results, although too preliminary for a mechanistic interpretation, suggest that multiple neurotransmitter systems, probably including the cholinergic system, are involved in the mechanism of action of ketamine-induced narcosis.

Discriminable effects of antimuscarinics: dose response and substitution test studies

In a shock escape T-maze task, rats were trained to turn right following one drug treatment and left following a second drug treatment. The specific drug and dose conditions were the only discriminative cues available to the animals. The number of training sessions before criterion performance indicated the discriminability of the two training conditions. Drug vs no drug training showed that discriminability was proportional to dosage for low doses, but was constant over a range of higher doses. Such an asymptote of discriminability was observed with scopolamine, atropine, benactyzine and Ditran (JB 329), and was shown not to result from tolerance. High dose vs low dose discriminations involving scopolamine were learned very slowly if both doses were within the asymptotic range; this indicates that similar discriminable effects were produced by high and low doses. To compare various drugs, substitution tests were administered to trained rats. The four antimuscarinic drugs generally substituted for one another but did not mimic and were not mimicked by drugs in other pharmacological classes. Some exceptions to this pattern were noted. The discriminable effects of scopolamine were partially antagonized by physostigmine. The results indicate that the antimuscarinic drugs share discriminable actions probably produced by their anticholinergic actions. The asymptote of action at high doses appears genuine, possibly reflecting receptor saturation.

Studies on human memory: the interactions of diazepam, scopolamine, and physostigmine

Seventy volunteers were injected with diazepam (0.3 mg/kg), scopolamine (8 mug/kg), or placebo, followed 70 min later by another injection of physostigmine, physostigmine and methscopolamine (in case of diazepam treatment), or placebo. Physostigmine was given in two doses, 16 and 32 mug/kg; methscopolamine, 8 and 16 mug/kg. Subjects (Ss) were tested in groups of 5 in a double blind procedure with treatments distributed according to a Latin square design. Prior to treatment, Ss heard a series of lists of words, followed by an immediate recall test. Following the first injection, delayed free recall and recognition tests were given. The second drug was then injected, followed by a presentation of another two sets of lists which were tested similarly. Subjective feelings were also evaluated with a rating questionnaire. Diazepam and scopolamine did not affect recall of information which had been learned prior to drug injection. However, both drugs impaired the learning or acquisition of new information. Physostigmine, especially in its high dose, antagonized most of the memory deficits produced by scopolamine while those of diazepam remained. This is a strong indication that scopolamine acts centrally through an anticholinergic mechanism while diazepam may act through a different system.

Quantitative assay of physostigmine in human whole blood

A quantitative assay for measuring physostigmine in human whole blood is described. Blood samples are maintained at 37 degrees, and cholinesterase activity is measured periodically. The time required for enzyme reactivation is related to physostigmine concentration. The precision of the method is within +/- 4% over a physostigmine concentration range of 0.5-5.0 x 10(-7) M.

Experiences with physostigmine in the reversal of adverse post-anaesthetic effects

Physostigmine salicylate has proved to be a very useful agent for use in the recovery room. All but two of our first 110 patients receiving it were returned to full consciousness, whether they had been comatose or agitated. In our hands it has been used to reverse the adverse central effects of tranquilizers, antihistamines and belladonna alkaloids.