Ketamine-aminophylline-induced decrease in seizure threshold

Provider-directed analgesia for dental pain

INTRODUCTION

Extraction of impacted molar teeth is a common procedure performed by oral surgeons and general dentists, with postoperative pain being a significant adverse event post-surgery. If mismanaged, pain can lead to complications that impact oral and systemic health. The current scourge of the opioid epidemic has ushered in a new era of provider-directed analgesic (PDA) therapy in dentistry.

AREAS COVERED

This article provides an in-depth review on the major pharmacological and therapeutic properties of established and alternative analgesics used to manage dental pain.

EXPERT OPINION

Substantial evidence-based literature shows combination of a non-steroidal anti-inflammatory drug (NSAID; e.g. ibuprofen) and acetaminophen provides superior pain relief than single-agent or combination opioid regimens. However, there are clinical scenarios (e.g. severe pain) when short-course opioid prescription is appropriate in select patients, in which a 2-3-day treatment duration is typically sufficient. Alternative agents (e.g. caffeine, gabapentin, phytotherapies), typically in combination with established agents, can mitigate postoperative dental pain. Some evidence suggests preemptive therapies (e.g. corticosteroids, NSAIDs) reduce amounts of postsurgical analgesic consumption and might lessen opioid prescription burden. In summary, this comprehensive review provides an opportune update on the evolving landscape of pharmacotherapy for acute postsurgical dental pain, informing best practices for PDA in the dental setting.

Consensus Guidelines on the Use of Intravenous Ketamine Infusions for Chronic Pain From the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists

BACKGROUND

Over the past 2 decades, the use of intravenous ketamine infusions as a treatment for chronic pain has increased dramatically, with wide variation in patient selection, dosing, and monitoring. This has led to a chorus of calls from various sources for the development of consensus guidelines.

METHODS

In November 2016, the charge for developing consensus guidelines was approved by the boards of directors of the American Society of Regional Anesthesia and Pain Medicine and, shortly thereafter, the American Academy of Pain Medicine. In late 2017, the completed document was sent to the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters, after which additional modifications were made. Panel members were selected by the committee chair and both boards of directors based on their expertise in evaluating clinical trials, past research experience, and clinical experience in developing protocols and treating patients with ketamine. Questions were developed and refined by the committee, and the groups responsible for addressing each question consisted of modules composed of 3 to 5 panel members in addition to the committee chair. Once a preliminary consensus was achieved, sections were sent to the entire panel, and further revisions were made. In addition to consensus guidelines, a comprehensive narrative review was performed, which formed part of the basis for guidelines.

RESULTS

Guidelines were prepared for the following areas: indications; contraindications; whether there was evidence for a dose-response relationship, or a minimum or therapeutic dose range; whether oral ketamine or another N-methyl-D-aspartate receptor antagonist was a reasonable treatment option as a follow-up to infusions; preinfusion testing requirements; settings and personnel necessary to administer and monitor treatment; the use of preemptive and rescue medications to address adverse effects; and what constitutes a positive treatment response. The group was able to reach consensus on all questions.

CONCLUSIONS

Evidence supports the use of ketamine for chronic pain, but the level of evidence varies by condition and dose range. Most studies evaluating the efficacy of ketamine were small and uncontrolled and were either unblinded or ineffectively blinded. Adverse effects were few and the rate of serious adverse effects was similar to placebo in most studies, with higher dosages and more frequent infusions associated with greater risks. Larger studies, evaluating a wider variety of conditions, are needed to better quantify efficacy, improve patient selection, refine the therapeutic dose range, determine the effectiveness of nonintravenous ketamine alternatives, and develop a greater understanding of the long-term risks of repeated treatments.

Anaesthesia for electroconvulsive therapy - new tricks for old drugs: a systematic review

OBJECTIVE

The objective of this review is to investigate existing literature in order to delineate whether the use of anaesthesia and timing of seizure induction in a new and optimised way may improve the efficacy of electroconvulsive therapy (ECT).

METHODS

PubMed/MEDLINE was searched for existing literature, last search on 24 June 2015. Relevant clinical studies on human subjects involving choice of anaesthetic, ventilation and bispectral index (BIS) monitoring in the ECT setting were considered. The references of relevant studies were likewise considered.

RESULTS

Propofol yields the shortest seizures, etomidate and ketamine the longest. Etomidate and ketamine+propofol 1 : 1 seems to yield the seizures with best quality. Seizure quality is improved when induction of ECT is delayed until the effect of the anaesthetic has waned - possibly monitored with BIS values. Manual hyperventilation with 100% O2 may increase the pO2/pCO2-ratio, which may be correlated with better seizure quality.

CONCLUSION

Etomidate or a 1 : 1 ketamine and propofol combination may be the best method to achieve general anaesthesia in the ECT setting. There is a need for large randomised prospective studies comparing the effect of methohexital, thiopental, propofol, ketamine, propofol+ketamine 1 : 1 and etomidate in the ECT treatment of major depressed patients. These studies should investigate safety and side effects, and most importantly have antidepressant efficacy and cognitive side effects as outcome measures instead of seizure quality.

Anesthesia for Bedside Procedures

Within the past 10 years, numerous short-acting anesthetic drugs have been introduced for use in the operating room. This review article will discuss the role of these agents in critically ill patients undergoing bedside procedures.

After a brief historical update, the first part of the review will focus on issues related to the pathophysiology and pharmacology of critically ill patients in general, and of specific organ dysfunction in particular. In-appropriate dosing and improper selection of agents will be highlighted. The second part of the article will discuss specific classes of drugs, with reference to their advantages and disadvantages in the ICU population.

The article will conclude by emphasizing the potency, safety, and efficacy of these drugs in significantly reducing the pain and suffering experienced by patients with critical illness.

The NMDA receptor complex as a therapeutic target in epilepsy: a review

A substantial amount of research has shown that N-methyl-D-aspartate receptors (NMDARs) may play a key role in the pathophysiology of several neurological diseases, including epilepsy. Animal models of epilepsy and clinical studies demonstrate that NMDAR activity and expression can be altered in association with epilepsy and particularly in some specific seizure types. NMDAR antagonists have been shown to have antiepileptic effects in both clinical and preclinical studies. There is some evidence that conventional antiepileptic drugs may also affect NMDAR function. In this review, we describe the evidence for the involvement of NMDARs in the pathophysiology of epilepsy and provide an overview of NMDAR antagonists that have been investigated in clinical trials and animal models of epilepsy.

Spinal Myoclonus Developed during Cervical Epidural Drug Infusion in Postherpetic Neuralgia Patient

Postherpetic neuralgia is the most frequent complication of herpes zoster. Treatment of this neuropathic pain syndrome is difficult and often disappointing. Although postherpetic neuralgia is generally a self-limited condition, it can last indefinitely. Continuous epidural blockade for patients with acute zoster can shorten the duration of treatment. However, continuous epidural block has some complications such as infection, dural puncture, and total spinal and nerve damages. We report a case of myoclonus during continuous epidural block with ropivacaine, morphine, and ketamine in an acute zoster patient.

Induction of rat hepatic cytochrome P-450 by ketamine and its toxicological implications

Ketamine is a common intravenous anesthetic and a frequent drug of abuse, alone or in combination with cocaine. However, the pharmacokinetic effects of ketamine have not been fully investigated. This study determined the effects of ketamine on cytochrome P-450 (P-450)-dependent catalytic activities, protein levels, and hepatotoxicity using male Wistar rats treated with 10, 20, 40, or 80 mg/kg ketamine intraperitoneally twice daily for 4 d. Treatment with ketamine produced a dose-dependent increase of pentoxyresorufin O-dealkylation activity of liver microsomes. Treatment with 80 mg/kg ketamine resulted in 14-, 3-, and 2-fold rise in O-dealkylation of pentoxyresorufin, ethoxyresorufin, and methoxyresorufin of rat liver microsomes, respectively. The treatment produced 31% and 86% increases in 7-ethoxycoumarin O-deethylation and erythromycin N-demethylation, respectively. In addition, aniline hydroxylation activity was elevated by 62%. Protein blot analysis of liver microsomal proteins revealed that 80 mg/kg ketamine induced P-450 1A, 2B, 2E1, and 3A proteins by 2-, 13-, 2-, and 2-fold, respectively. In reversibility study, ketamine-induced pentoxyresorufin O-dealkylation, 7-ethoxycoumarin O-deethylation, erythromycin N-demethylation, and methoxyresorufin O-demethylation activities of liver microsomes prepared from rats 4 d after ketamine treatment were 75%, 48%, 29%, and 38% lower than the respective activities of liver microsomes prepared from rats 1 d after treatment. Protein blot analysis showed that ketamine-induced P-450 2B1/2 proteins also decreased in a time-dependent manner in 4 d. In hepatotoxicity study, treatment of rats with 1 ml/kg CCl4 produced a 7-fold increase in serum alanine aminotransferase activity level and a 17-fold rise in rats pretreated with 80 mg/kg ketamine for 4 d. Treatment of ICR mice with 120 mg/kg cocaine produced a 17% mortality, whereas the same dose of cocaine produced a 50% mortality in mice pretreated with ketamine. Treatment of mice with 100 mg/kg cocaine produced a 76-fold increase in serum alanine aminotransferase activity level and a 260-fold rise in mice pretreated with 80 mg/kg ketamine for 4 d. The present study shows that ketamine induces the expression of multiple forms of P-450 in rat liver microsomes and increases CCl4-induced liver toxicity and cocaine-mediated acute toxicity. Other potential pharmacological or toxicological events related to ketamine use need to be further explored.

Strategies in the patient with compromised respiratory function

Respiratory diseases are commonly divided into restrictive or obstructive lung diseases. For anaesthesiological considerations restrictive lung diseases appear as a static condition with minimal short-term development. Overall, restrictive lung diseases don't lead to acute exacerbations due to the choice of anaesthetic techniques or the choice of anaesthesia-specific agents. Compared to restrictive lung diseases, obstructive lung diseases such as asthma or chronic obstructive lung diseases have a high prevalence and are one of the four most frequent causes of death. Obstructive lung diseases can be significantly influenced by the choice of anaesthetic technique and anaesthetic agent. Basically, the severity of the chronic obstructive pulmonary disease (COPD) and the degree of bronchial hyperreactivity will determine the perioperative anaesthetic risk. This risk has to be assessed by a thorough preoperative evaluation and will provide the rationale on which to decide the adequate anaesthetic technique. In particular, airway instrumentation can cause severe reflex bronchoconstriction. The use of regional anaesthesia alone or in combination with general anaesthesia can help to avoid airway irritation and even leads to reduced postoperative complications. Prophylactic anti-obstructive treatment, volatile anaesthetics, propofol, opioids, and an adequate choice of muscle relaxants minimize the anaesthetic risk when general anaesthesia is required. If intraoperative bronchospasm occurs, despite all precautions, deepening of anaesthesia, repeated administration of beta2-adrenergic agents and parasympatholytics, and a single systemic dose of corticosteroids are the main treatment options.

[Epileptogenic drugs in anesthesia]

Most anaesthetics and analgesics have both pro- and anticonvulsant activity. The data in the literature should be analysed with respect to the patient population, the recording of epileptic activity and the method of EEG analysis. Among inhaled anaesthetics, isoflurane has strong anticonvulsant properties. In some circumstances, sevoflurane may induce an epileptic activity. With the exception of ketamine and etomidate, all intravenous hypnotics may be used for anesthesia of the epileptic patient. Midazolam is a potent anticonvulsant. Among narcotics, fentanyl and alfentanil may induce clinical or electroencephalographic seizures. Considering the large number of patients treated with these agents without any neurological adverse effect, the clinical relevance of these data is unclear. Neuromuscular blocking agents do not possess pro- or anticonvulsant properties.

Drug interactions during anesthesia. General principles

Anesthesia for most procedures in small animal practice involves administration of more than one drug. In addition, many patients concurrently receive a number of other drugs related to their surgical condition or disease. The probability of a drug interaction increases exponentially with the number of drugs a patient receives; therefore, the potential for drug interactions may be greater in anesthesia than for any other area of medicine. This article describes potentially harmful drug interactions that may occur in the anesthetic setting.

Drug interactions with intravenous and local anaesthetics

Relatively few clinically significant drug interactions with anaesthetics have been documented in the literature. The following should be stressed since these interactions are not readily predictable or are potentially fatal. Pethidine should never be administered to patients who have received monamine oxidase inhibiting drugs within the last fortnight, since a fatal hyperpyrexia and/or hypertension may result. Thiopentone induction seems to make the heart more susceptible to arrhythmias caused by adrenergic drugs, and may cause severe arterial hypotension in patients treated with diazoxide. Midazolam orally should possibly be avoided as premedication in patients treated with erythromycin since anaesthetic concentrations of midazolam may result. Patients for whom bupivacaine analgesia is planned could preferentially be premedicated with other drugs than diazepam, which causes the serum level of bupivacaine to increase. Bradycardia and hypotension not attributable to sympathetic blockade have been reported following bupivacaine extradurally in verapamil-treated patients. Sulfonamides and the ester group of local anaesthetics, such as prilocaine in combination, may result in severe methaemoglobinaemia in infants. Epinephrine added to local anaesthetics may cause local vasodilation if administered to patients concurrently being treated with cyclic antidepressants, and the combination imposes the risk of severe hypertension and arrhythmias.

Perioperative complications of anesthesia

An overview of several perioperative complications and their management strategies is presented. Operative hypothermia, malignant hyperthermia, bronchospasm, and side effects of spinal opioid agents are discussed. Ramifications of these complications may extend well beyond the operative period and influence patient outcome. Therefore, it is necessary that the surgeon have a fundamental understanding of the pathophysiology and modalities of treatment in the context of anesthesia and surgery.

Evaluation of theophylline overdoses and toxicities

Patients presenting with elevated theophylline concentrations and manifestations of toxicity may be categorized as being either overdose or iatrogenic toxic. In addition to severe cardiac and neurologic toxicities, such as arrhythmias and seizures, OD patients probably require monitoring for manifestation of gastrointestinal hemorrhage, electrolyte abnormalities, and hypotension. The possibility of a delayed peak theophylline concentration after sustained release product ingestion must be considered. Patients with initial serum concentrations of less than 60 mg/L may receive a single dose of oral activated charcoal and have repeat concentrations drawn to ensure the avoidance of continued absorption. The presence of a serum concentration exceeding 60 mg/L in OD patients warrants initiation of elimination-enhancing modalities. Oral activated charcoal is the fastest and most readily available. Multiple-dose oral activated charcoal should be given until serum theophylline concentrations of 60 mg/L or less are reached. Cardiac monitoring and seizure precautions are recommended. Admission to the intensive care unit should be considered when serum concentrations do not decline after several hours of charcoal therapy or when seizures and severe cardiovascular manifestations occur. Patients having initial concentrations exceeding 100 mg/L and/or rapidly rising concentrations 100 mg/L over baseline values should be considered as candidates for CHP or RHP if available. If both CHP and RHP are unavailable or will be excessively delayed, HD is a reasonable alternative. Patients on chronic theophylline therapy (IA patients) presenting with symptoms of toxicity must be evaluated carefully. If serum concentrations are less than 20 mg/L, short-term observation or a reduction in dose should be sufficient. Patients with concentrations between 20 and 60 mg/L should be candidates for seizure precautions and cardiac monitoring. Oral activated charcoal may be started and continued until levels are below 20 mg/mL. Patients with concentrations in excess of 60 mg/L require intensive monitoring (including seizure precautions and cardiac monitoring) as well as initiation of MOAC or CHP/RHP as situation, availability, and patient tolerance dictate. Again, HD may be a reasonable alternative if the others are unavailable or contraindicated.

Aminophylline toxicity

Aminophylline therapy has undergone change in the past decade. With the changes in usage and dosage forms, the frequency of toxicity in the pediatric population, especially in adolescents, has increased dramatically. Two distinct patterns, chronic and acute, have been recognized and treatment methods for both are changing. Table 4 summarizes the emerging state-of-the-art therapy for aminophylline toxicity. Judging from the activity seen in the literature, investigation into aminophylline toxicity will continue to be a priority. We will see a greater understanding of the disease process and a refining of the therapeutic process. The ultimate goal is the elimination of mortality and the minimization of morbidity from aminophylline toxicity.