Definition of and mechanism for opioid-induced sedation

Tropine exacerbates the ventilatory depressant actions of fentanyl in freely-moving rats

Our lab is investigating the efficacy profiles of tropine analogs against opioid-induced respiratory depression. The companion manuscript reports that the cell-permeant tropeine, tropine ester (Ibutropin), produces a rapid and sustained reversal of the deleterious actions of fentanyl on breathing, alveolar-arterial (A-a) gradient (i.e., index of alveolar gas exchange), and arterial blood-gas (ABG) chemistry in freely-moving male Sprague Dawley rats, while not compromising fentanyl analgesia. We report here that in contrast to Ibutropin, the injection of the parent molecule, tropine (200 μmol/kg, IV), worsens the adverse actions of fentanyl (75 μg/kg, IV) on ventilatory parameters (e.g., frequency of breathing, tidal volume, minute ventilation, peak inspiratory and expiratory flows, and inspiratory and expiratory drives), A-a gradient, ABG chemistry (e.g., pH, pCO2, pO2, and sO2), and sedation (i.e., the righting reflex), while not affecting fentanyl antinociception (i.e., the tail-flick latency) in freely-moving male Sprague Dawley rats. These data suggest that tropine augments opioid receptor-induced signaling events that mediate the actions of fentanyl on breathing and alveolar gas exchange. The opposite effects of Ibutropin and tropine may result from the ability of Ibutropin to readily enter peripheral and central cells. Of direct relevance is that tropine, resulting from the hydrolysis of Ibutropin, would combat the Ibutropin-induced reversal of the adverse effects of fentanyl. Because numerous drug classes, such as cocaine, atropine, and neuromuscular blocking drugs contain a tropine moiety, it is possible that their hydrolysis to tropine has unexpected/unintended consequences. Indeed, others have found that tropine exerts the same behavioral profile as cocaine upon central administration. Together, these data add valuable information about the pharmacological properties of tropine.

An insight review on the neuropharmacological effects, mechanisms of action, pharmacokinetics and toxicity of mitragynine

Mitragynine is one of the main psychoactive alkaloids in Mitragyna speciosa Korth. (kratom). It has opium-like effects by acting on μ-, δ-, and κ-opioid receptors in the brain. The compound also interacts with other receptors, such as adrenergic and serotonergic receptors and neuronal Ca2+ channels in the central nervous system to have its neuropharmacological effects. Mitragynine has the potential to treat diseases related to neurodegeneration such as Alzheimer's disease and Parkinson's disease, as its modulation on the opioid receptors has been reported extensively. This review aimed to provide an up-to-date and critical overview on the neuropharmacological effects, mechanisms of action, pharmacokinetics and safety of mitragynine as a prospective psychotropic agent. Its multiple neuropharmacological effects on the brain include antinociceptive, anti-inflammatory, antidepressant, sedative, stimulant, cognitive, and anxiolytic activities. The potential of mitragynine to manage opioid withdrawal symptoms related to opioid dependence, its pharmacokinetics and toxic effects were also discussed. The interaction of mitragynine with various receptors in the brain produce diverse neuropharmacological effects, which have beneficial properties in neurological disorders. However, further studies need to be carried out on mitragynine to uncover its complex mechanisms of action, pharmacokinetics, pharmacodynamic profiles, addictive potential, and safe dosage to prevent harmful side effects.

The effect of lavender on mothers sleep quality in the postpartum period: a systematic review and meta-analysis

Poor sleep quality in the postpartum period can have various negative effects on the health of mothers and infants such as anxiety, depression, low breastfeeding self-efficacy and disrupted child-mother attachment. Accordingly, intervention seems necessary to improve sleep quality. Given the probable effect of lavender on sleep problems, the present research intended to determine its effects on mothers' sleep quality during postpartum period. The PubMed, Embase, Cochrane Library, Scopus databases and the Persian language databases (Magiran and SID) were searched for all the articles they included at the end of February 2021. The risk of bias of the included studies was assessed using the Cochrane tool. The results of the meta-analysis were reported as the standardized mean difference (SMD). Heterogeneity of the studies was investigated using the I-squared test (I2). Three out of the 292 obtained studies entered the meta-analysis. The results indicated that sleep quality in the group receiving lavender improved compared to the control group, (SMD = -0.61; 95% CI: -1.07 to -015 p = 0.01) whereas the heterogeneity was higher. (I2 = 75%; Tau2 = 012; Chi2 = 7.905, p = 0.02). According to the results of this systematic review, use of lavender can improve postpartum maternal sleep quality. However, further randomized controlled trials using identical methodology, larger sample sizes and longer follow-up periods are needed.

Use and misuse of opioid after gynecologic surgery

Postoperative opioid use following gynecologic surgery may be necessary for effective treatment of pain; however, it can result in significant side effects, adverse reactions, and negative health consequences, including prolonged problematic use. Surgeons and healthcare providers of patients recovering from gynecologic procedures should be aware of effective strategies that can decrease the need for opioid use, while providing high-quality pain management. These include adherence to Enhanced Recovery After Surgery Protocols, particularly the use of multimodal analgesia management. When prescribing opioids, providers should adhere to responsible prescribing practices to minimize the risk of inappropriate and/or long-term opioid use.

Risk factors for opioid toxicity requiring naloxone rescue in adults: a case-control study

BACKGROUND

Opioid-induced sedation and respiratory depression (OSRD) is a potentially life-threatening side effect of opioid analgesia. However, little is known about the individual and clinical-related factors associated with OSRD in the New Zealand context.

AIM

To identify risk factors for OSRD in patients admitted to a large regional health board in New Zealand-Auckland District Health Board (ADHB).

METHOD

A retrospective matched case-control study design was undertaken among adults who were admitted to ADHB and prescribed opioids in hospital between August 2015 and April 2020. Those who were prescribed opioids and received naloxone for OSRD were defined as cases, whereas those who received opioids but did not experience OSRD were identified as controls. Cases and controls were matched on a 1:1 basis by age (± 10 years). Data were retrieved from the electronic medical records of ADHB. A conditional logistic regression model was used to identify the risk factors for OSRD.

RESULTS

We identified 51 cases, and these were matched with 51 control patients. The odds of experiencing OSRD were four times higher among opioid-naïve patients compared to those exposed to opioids prior to hospital admission (OR  4.113; 95% CI 1.14-14.89). Increased risk of OSRD was also associated with higher serum creatinine level prior to OSRD episode (OR 1.015; 95% CI 1.01-1.03) and a higher oral morphine milligram equivalent (OME) (OR 1.023; 95% CI 1.01-1.04).

CONCLUSION

Increased risk of OSRD was associated with a higher OME, a higher serum creatinine level prior to OSRD episode, and opioid naivety. Our findings can inform policies that aim to prevent serious adverse effects related to opioids.

Opioids and Falls Risk in Older Adults: A Narrative Review

Pain treatment is important in older adults but may result in adverse events such as falls. Opioids are effective for nociceptive pain but the evidence for neuropathic pain is weak. Nevertheless, both pain and opioids may increase the risk of falls. This narrative literature review aims to summarize the existing knowledge on the opioid-related fall risk in older adults, including the pharmacokinetics and pharmacodynamics, and assist clinicians in prescribing and deprescribing opioids in older persons. We systematically searched relevant literature on opioid-related fall risk in older adults in PubMed and Scopus in December 2020. We reviewed the literature and evaluated fall-related adverse effects of opioids, explaining how to optimally approach deprescribing of opioids in older adults. Opioid use increases fall risk through drowsiness, (orthostatic) hypotension and also through hyponatremia caused by weak opioids. When prescribing, opioids should be started with low dosages if possible, keeping in mind their metabolic genetic variation. Falls are clinically significant adverse effects of all opioids, and the risk may be dose dependent and highest with strong opioids. The risk is most prominent in older adults prone to falls. To reduce the risk of falls, both pain and the need for opioids should be assessed on a regular basis, and deprescribing or changing to a lower dosage or safer alternative should be considered if the clinical condition allows. Deprescribing should be done by reducing the dosage gradually and by assessing and monitoring the pain and withdrawal symptoms at the same time. Weighing the risks and benefits is necessary before prescribing opioids, especially to older persons at high risk of falls. Clinical decision tools assist prescribers in clinical decisions regarding (de-) prescribing.

Sleep dysregulation in binge eating disorder and "food addiction": the orexin (hypocretin) system as a potential neurobiological link

It has been proposed that binge eating reflects a pathological compulsion driven by the "addictive" properties of foods. Proponents of this argument highlight the large degree of phenomenological and diagnostic overlap between binge eating disorder (BED) and substance use disorders (SUDs), including loss of control over how much is consumed and repeated unsuccessful attempts to abstain from consumption, as well as commonalities in brain structures involved in food and drug craving. To date, very little attention has been given to an additional behavioral symptom that BED shares with SUDs-sleep dysregulation-and the extent to which this may contribute to the pathophysiology of BED. Here, we review studies examining sleep outcomes in patients with BED, which collectively point to a heightened incidence of sleep abnormalities in BED. We identify the orexin (hypocretin) system as a potential neurobiological link between compulsive eating and sleep dysregulation in BED, and provide a comprehensive update on the evidence linking this system to these processes. Finally, drawing on evidence from the SUD literature indicating that the orexin system exhibits significant plasticity in response to drugs of abuse, we hypothesize that chronic palatable food consumption likewise increases orexin system activity, resulting in dysregulated sleep/wake patterns. Poor sleep, in turn, is predicted to exacerbate binge eating, contributing to a cycle of uncontrolled food consumption. By extension, we suggest that pharmacotherapies normalizing orexin signaling, which are currently being trialed for the treatment of SUDs, might also have utility in the clinical management of BED.

Advantages and disadvantages of disulfiram coadministered with popular addictive substances

Disulfiram (DSF) is a well-known anti-alcohol agent that inhibits aldehyde dehydrogenase and results in extreme 'hangover' symptoms when consumed with alcohol. This drug, however, has been suggested as useful in other forms of drug addiction due to its beneficial potential in both drug abuse reduction and withdrawal. However, among other drugs used in alcohol dependence, it carries the greatest risk of pharmacological interactions. Concomitant use of DSF and central nervous system stimulants usually leads to harmful, undesirable effects. To date, there is still limited data regarding the detailed safety profile of DSF as a concomitant drug. In this review article, we outline the current state of knowledge about DSF, its broad pharmacological action, as well as therapeutic effects, with a particular emphasis on the molecular understanding of its potential pharmacodynamic interactions with common addictive substances (e.g., alcohol, cocaine, cannabinoids, opioids) supported by relevant examples.

Dexmedetomidine - Commonly Used in Functional Imaging Studies - Increases Susceptibility to Seizures in Rats But Not in Wild Type Mice

Functional MRI (fMRI) utilizes changes in metabolic and hemodynamic signals to indirectly infer the underlying local changes in neuronal activity. To investigate the mechanisms of fMRI responses, spontaneous fluctuations, and functional connectivity in the resting-state, it is important to pursue fMRI in animal models. Animal studies commonly use dexmedetomidine sedation. It has been demonstrated that potent sensory stimuli administered under dexmedetomidine are prone to inducing seizures in Sprague-Dawley (SD) rats. Here we combined optical imaging of intrinsic signals and cerebral blood flow with neurophysiological recordings to measure responses in rat area S1FL to electrical forepaw stimulation administered at 8 Hz. We show that the increased susceptibility to seizures starts no later than 1 h and ends no sooner than 3 h after initiating a continuous administration of dexmedetomidine. By administering different combinations of anesthetic and sedative agents, we demonstrate that dexmedetomidine is the sole agent necessary for the increased susceptibility to seizures. The increased susceptibility to seizures prevails under a combination of 0.3–0.5% isoflurane and dexmedetomidine anesthesia. The blood-oxygenation and cerebral blood flow responses to seizures induced by forepaw stimulation have a higher amplitude and a larger spatial extent relative to physiological responses to the same stimuli. The epileptic activity and the associated blood oxygenation and cerebral blood flow responses stretched beyond the stimulation period. We observed seizures in response to forepaw stimulation with 1–2 mA pulses administered at 8 Hz. In contrast, responses to stimuli administered at 4 Hz were seizure-free. We demonstrate that such seizures are generated not only in SD rats but also in Long-Evans rats, but not in C57BL6 mice stimulated with similar potent stimuli under dexmedetomidine sedation. We conclude that high-amplitude hemodynamic functional imaging responses evoked by peripheral stimulation in rats sedated with dexmedetomidine are possibly due to the induction of epileptic activity. Therefore, caution should be practiced in experiments that combine the administration of potent stimuli with dexmedetomidine sedation. We propose stimulation paradigms that elicit seizure-free, well detectable neurophysiological and hemodynamic responses in rats. We further conclude that the increased susceptibility to seizures under dexmedetomidine sedation is species dependent.

Ultrasound-guided Modified Parasternal Intercostal Nerve Block: Role of Preemptive Analgesic Adjunct for Mitigating Poststernotomy Pain

Background and Aim

To assess the quality and effectiveness of postoperative pain relief after fast-tracking tracheal extubation in cardiac surgery intensive care unit, effected by a single-shot modified parasternal intercostal nerve block compared with routine in-hospital analgesic protocol, when administered before sternotomy.

Design

A prospective, randomized, double-blinded interventional study.

Setting

Single-center tertiary teaching hospital.

Participants

Ninety adult patients undergoing elective coronary artery bypass grafting surgery under cardiopulmonary bypass.

Materials and Methods

Patients were randomized into two groups. Patients in the parasternal intercostal block group (PIB) (n = 45) received ultrasound-guided modified parasternal intercostal nerve block with 0.5% levobupivacaine after anesthesia induction at 2^nd-6^th intercostal space along postinduction using standardized anesthesia drugs with routine postoperative hospital analgesic protocol with intravenous morphine. Patients in the group following routine hospital analgesia protocol (HAP) (n = 45) served as controls, with standardized anesthesia drugs and routine hospital postoperative analgesic protocol with intravenous morphine. The primary study outcome aimed to evaluate pain at rest and when doing deep breathing exercises with spirometry, coughing expectorations using a 11-point numerical rating scale.

Results

The postoperative pain score at rest and during breathing exercises was compared between the two groups at different time durations (15 min after extubation and every 4^th hourly for 24 h). Patients in the PIB group had significantly lower pain scores and better quality of analgesia during the entire study period at rest and during breathing exercise (P < 0.0001). Furthermore, the side effect profile and need of rescue analgesics were better in the PIB group than the HAP group at different time intervals.

Conclusion

PIB is safe for presternotomy administration and provided significant quality of pain relief postoperatively, as seen after tracheal extubation for a period of 24 h, on rest as well as with deep breathing, coughing, and chest physiotherapy exercises when compared to intravenous morphine alone after sternotomy. This study further emphasizes the role of preemptive analgesia in mitigating postoperative sternotomy pain and it's role as a plausible safe analgesic adjunct facilitating fast tracking with sternotomies on systemic heparinization.

Opioids and alpha-2-agonists for analgesia and sedation in newborn infants: protocol of a systematic review

BACKGROUND

Hospitalized newborn infants may require analgesia and sedation either for the management of procedural pain, during or after surgery, and other painful conditions. The benefits and harms of opioids administered at different doses and routes of administration have been reported in numerous trials and systematic reviews. The use of alpha-2-agonists such as clonidine and dexmedetomidine in newborn infants is more recent, and they might be prescribed to reduce the total amount of opioids which are thought to have more side effects. Moreover, alpha-2-agonists might play an important role in the management of agitation and discomfort.

METHODS

We will conduct a systematic review and meta-analysis on the use of opioids, alpha-2-agonists, or the combination of both drugs. We will include randomized controlled trials to assess benefits and harms and observational studies to assess adverse events and pharmacokinetics; preterm and term infants; studies on any opioids or alpha-2-agonists administered for any indication and by any route except spinal, intraosseous, or administration for nerve blocks and wound infusions. The use of opioids or alpha-2-agonists will be compared to no intervention; placebo with normal saline or other non-sedative, non-analgesic drug; control with oral sugar solution or non-pharmacological intervention; same drug of different dose or route; or a different drug (not limiting to opioids and alpha-2-agonists) or combinations of such drugs. The primary outcomes for this review will be all-cause mortality during initial hospitalization and hypotension requiring medical therapy. We will conduct a search in the following databases: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, Embase, and CINAHL. Two review authors will independently screen records for inclusion, undertake data abstraction using a data extraction form and assess the risk of bias of all included trials using the Cochrane "Risk of bias" tool.

DISCUSSION

This systematic review will summarize and update our knowledge about neonatal analgesia and sedation including pharmacokinetics/pharmacodynamics, and provide a platform for developing evidence-based guidelines that we can immediately apply to our clinical practice.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2020 CRD42020170852.

Gender Differences in Sleep Problems Among Drug Users

BACKGROUND

Illicit drug use has been recognized as a major problem. Clinical studies demonstrated that poor sleep quality was associated with increased frequency of drug use and relapse. However, few studies addressed the issue of sleep quality and gender differences in illicit drug dependent subjects. The present study aimed to explore the gender differences in sleep problems in drug users.

METHODS

In this cross-sectional study, a total of 2,178 illicit drug users, including 1,875 male users [884 methamphetamine (MA) users and 991 heroin or other drug users] and 303 female users (78 MA users and 225 heroin or other drug users, 13.9%), from drug rehabilitation centers in Changsha, and 2,236 non-drug-using subjects, including 1,910 males and 326 females (14.6%) completed the self-report Pittsburgh Sleep Quality Index (PSQI).

RESULTS

We found that the prevalence of suggestive sleep problems (PSQI>5) between male and female was 67.4 and 75.2% in overall illicit drug use sample (p<0.001), 52.4 and 75.6% in MA users (<0.001), 80.8 and 75.1% in heroin or other drugs users (p=0.054), 26.0 and 28.8% in healthy controls (p=0.287). For sleep quality, the mean of PSQI total score (M±SD) between male and female was 7.8±4.42 and 8.9±4.15 in overall illicit drug users (p<0.001), 6.4±4.45 and 9.1±4.00 in MA users (<0.001), 9.1±3.96 and 8.9±4.21 in heroin or other drugs users (p=0.394), 4.2±2.46 and 4.4±2.51 in healthy control sample (p=0.090). These results indicated that only MA users, rather than heroin or other drugs users and healthy controls, showed gender differences in sleep problems.

CONCLUSIONS

In this study, female users reported higher frequency of sleep problems and poorer sleep quality than male users in MA users' group, but not in heroin or other drug users group. Future studies aim at quantifying the benefits of treatment interventions should not neglect the influence of sleeping problems and its gender differences.

Cebranopadol reduces cocaine self-administration in male rats: Dose, treatment and safety consideration

As a novel first-in-class potent analgesic acting as an agonist of multiple opioid receptors, cebranopadol showed high efficacy and good tolerability in a broad range of preclinical models and clinical trials related to pain. In the present study, to evaluate the efficacy and safety of cebranopadol as a potential treatment of cocaine dependence, we tested the effects of cebranopadol with single and repeated doses (25, 50, 75, or 100 μg/kg, oral gavage) using rat models of cocaine fixed-ratio (FR) self-administration (SA), cocaine progressive-ratio (PR) SA, and sucrose pellet SA. In single-dosing treatment paradigm, cebranopadol significantly and dose-dependently reduced cocaine SA under FR and PR schedules and suppressed food intake under FR schedule without causing apparent side effects. In repeated-dosing treatment scheme, i.e. daily administration of 25, 50, 75, or 100 μg/kg cebranopadol for a week, the similar reduction in cocaine intake was detected, while non-negligible complications/side effects were observed at repeated high doses (75 and 100 μg/kg). The observed side effects were similar to the common toxic signs elicited by heroin at high doses, although cebranopadol did not fully substitute heroin's discriminative stimulant effects in our drug discriminative tests. These results demonstrated that the most appropriate oral dose of cebranopadol to balance the efficacy and safety is 50 μg/kg. Collectively, although cebranopadol may serve as a new treatment for cocaine dependence, more consideration, cautiousness, and a clear optimal dose window to dissociate its therapeutic effects from opioid side effects/complications in male and female subjects will be necessary to increase its practical clinical utility.

[Characteristics of sleep disturbances related to substance use disorders]

Sleep disturbances are frequently observed in patients with substance use disorders during active use as well as in withdrawal period and in remission. However, there is limited information about the association between sleep disturbances and substance use disorders. This review summarizes results of the studies on specific characteristics of sleep disturbances related to alcohol, opioids and psychostimulants (cocaine) use. Data on objective and subjective measurements of sleep characteristics at different stages of the course of an addiction disorder (active use, withdrawal, remission) are presented.

Effectiveness of complementary and alternative medicine interventions for sleep quality in adult intensive care patients: A systematic review

BACKGROUND

Pharmacological interventions for sleep (analgesic, sedative and hypnotic agents) can both disrupt and induce sleep and have many negative side effects within the intensive care population. The use of complementary and alternative medicine therapies to assist with sleep has been studied but given the variety of modalities and methodological limitations no reliable conclusions have been drawn.

OBJECTIVE

To synthesise research findings regarding the effectiveness of using complementary and alternative medicine interventions within the domains of mind and body practices (relaxation techniques, acupuncture) and natural biologically based products (herbs, vitamins, minerals, probiotics) on sleep quality and quantity in adult intensive care patients.

REVIEW METHOD USED

Systematic review.

DATA SOURCES

Five databases were searched in August 2018 and updated in February 2019 and 2020.

REVIEW METHODS

Searches were limited to peer reviewed randomised controlled trials, published in English involving adult populations in intensive care units. Interventions were related to the complementary and alternative medicine domains of mind and body practices and natural products. Included studies were assessed using Cochrane's risk of bias tool.

RESULTS

Seventeen studies were included. The interventions used varied: 4 investigated melatonin; 4 music +/- another therapy; 3 acupressure; 2 aromatherapy and 1 each for relaxation and imagery, reflexology, bright light exposure and inspiratory muscle training. Measurement of sleep quantity and quality was also varied: 5 studies used objective measures such as Polysomnography and Bispectral index with the remaining using subjective patient or clinician assessment (for example, Richards-Campbell Sleep Questionnaire, Pittsburgh Sleep Quality Index, observation). Given the different interventions, outcomes and measures used in the studies a meta-analysis was not possible. Generally, the results support the use of complementary and alternative medicine for assisting with sleep with 11 out of 17 trials reporting significant results for the interventions examined.

CONCLUSIONS

Complementary and alternative medicine interventions, in particular, melatonin and music, have shown promise for improving sleep in adults with critical conditions; however, further research that addresses the limitations of small sample sizes and improved techniques for measuring sleep is needed.

Effects of an intrathecal TRPV1 antagonist, SB366791, on morphine-induced itch, body temperature, and antinociception in mice

Purpose

Transient receptor potential vanilloid 1 (TRPV1) not only is activated by multiple stimuli but also is involved with histamine-induced itch. The effects of TRPV1 on morphine-induced itch are unknown. We examined the effects of intrathecal administration of TRPV1 antagonist on morphine-induced itch, body temperature, and antinociception for mice.

Methods

Each C57/BL6j mouse was intrathecally administered with one of the following solutions: morphine, SB366791 (as the TRPV1 antagonist), morphine + SB366791, saline, or vehicle. For each mouse, each instance of observed scratching behavior was counted, the body temperature was measured, and the nociceptive threshold was determined using the tail-immersion test.

Results

SB366791 dose-dependently reduced the scratching behavior induced by the administration of morphine. SB366791 and the morphine + SB366791 groups did not manifest an increase in body temperature. Antinociceptive effects were observed to occur dose-dependently for morphine but not for SB366791. Compared with morphine alone, the administration of morphine + SB366791 did not reduce significant antinociceptive effects.

Conclusion

We propose that an intrathecal TRPV1 antagonist, SB366791, reduced morphine-induced itch without causing hyperthermia and did not suppress morphine-induced antinociception for mice.

Opioid-Induced Sedation and Respiratory Depression: Are Sedation Scales Enough to Prevent Adverse Drug Events Postoperatively?

OBJECTIVES

Nurses who care for hospitalized patients are responsible for ensuring adequate pain management is provided in a safe manner. The clinical challenge is balancing the effective control of the patient's pain with the side effects of administering opioids. The aim of this literature review is to explore the evidence on how nurses assess for opioid-induced sedation and advancing respiratory depression and how they integrate those data in their critical thinking skills when deciding to administer opioids for pain.

DESIGN

A matrix method was used to guide the review and synthesis of the evidence. Tables with column headings (citation, purpose of study, design/measurements, outcomes, and results) were constructed to record data extracted from each study.

DATA SOURCES

Primary source research articles were examined using the MESH terms sedation, sedation scale, respiratory depression, opioid, pain, pain assessment, adverse events, naloxone and postoperative.

REVIEW/ANALYSIS METHODS

Original studies such as retrospective case-control studies and descriptive studies were included. The final studies that met the inclusion criteria and were independently reviewed by the authors. The two main areas of interest were the evidence for how nurses assess for advancing sedation and excessive respiratory depression and how nurses integrate their assessment data in their critical thinking skills when deciding to administer opioids for pain.

RESULTS

Results indicated a lack of evidence examining the relationships among sedation, respiratory depression, and adverse events and the overall impact of managing these variables on patients' pain.

CONCLUSIONS

This review revealed a lack of evidence between how nurses assess for opioid induced advancing sedation and excessive respiratory depression, and the impact, including the adverse events associate with acute pain management.

Sedation scales: Do they capture the concept of opioid-induced sedation?

AIM

The purpose of this study was to explore the concept of opioid-induced sedation and how nurses define and measure sedation in the hospital setting.

BACKGROUND

Opioid medications are the primary treatment for acute pain in the postoperative setting. One of the most serious side effects of opioid therapy is excessive sedation and respiratory depression. Nurses have the responsibility of providing effective pain management, while keeping the patient safe from adverse sedation and respiratory depression. Thus, the assessment of sedation becomes an integral part of the nurses' responsibilities.

REVIEW METHOD

A review of the literature on the concept of opioid-induced sedation, and how it is measured by nurses in the hospital setting was performed using the Walker and Avant's (2011) framework.

RESULTS

Sedation is an ambiguous concept that challenges nurse's critical thinking skills. The linear sedation scales can assist with the measurement of sedation, but may lack sensitivity and specificity in detecting the small changes on the continuum of levels of consciousness. Additionally, the scales may not capture the entire aspects of the concept of sedation.

CONCLUSIONS

Sedation, as defined by the linear sedation scales is limiting nurses' appreciation of the small changes in level of cognition as well as consciousness that occurs as an adverse and potentially dangerous side effect of opioid medications used for acute pain management. Through developing a better understanding of sedation as a clinical concept, nurses may enhance their clinical skillset in safer postoperative pain management. Additionally, linear sedation scales could be further developed to better capture all aspects of sedation.

The common meanings and shared practices of sedation assessment in the context of managing patients with an opioid: A phenomenological study

AIMS AND OBJECTIVES

To examine the common meanings of opioid-induced sedation and shared practices in the context of post-operative pain management in expert Post-Anesthesia Care Unit nurses during patient's pain management with opioids.

BACKGROUND

Within the clinical setting, linear pain and sedation scales are not enough to support clinical judgement with acute pain management. Because sedation measurement rests along a fluctuating continuum, it is possible for a patient to be sedated and then shift to increasing alertness, and then to drift back to a sedated state. This potential for acute clinical transition can be challenging to nurses of all levels, even for expert nurses.

DESIGN

Interpretive phenomenology.

METHODS

Twenty expert Post-Anesthetic Care Unit nurses, with more than 7 years of nursing experience, participated in qualitative interviews regarding their lived experiences. Interviews were analysed using a modified seven-stage process for interpretation by Diekelmann, Allen and Tanner. The manuscript was developed utilising the COREQ guidelines for reporting qualitative studies.

RESULTS

Four themes identified through the participant's stories were recognising every patient is different, engaging in iterative knowing, walking a fine line, and looking beyond and anticipating. This study identified a constitutive pattern of interpreting sedation by integrating practical understanding and anticipating beyond.

CONCLUSIONS

This study indicates a deeper complexity in the way opioid-induced sedation is assessed and balanced with pain management by nurses in the Post-Anesthetic Care Unit.

RELEVANCE TO PRACTICE

Nurses in the study adapted their practices around pain management with opioids, in response to their patient's level of sedation; incorporating practices such as giving small, incremental doses and changing the drug. Nurses valued the importance of having "eyeballs on everybody" and being ready to meet the needs of their patient. They appreciate the time to watch and wait for their patient to respond, to better judge the result of their interventions.

Chemical characterization, pharmacological effects, and toxicity of an ethanol extract of Celtis pallida Torr. (Cannabaceae) aerial parts

ETHNOPHARMACOLOGICAL RELEVANCE

Celtis pallida Torr (Cannabaceae) is employed as a folk medicine for the treatment of inflammation, pain, skin infections, and diarrhea, among other diseases.

AIM OF THE STUDY

The purpose of this work was to assess the chemical composition, the in vitro and in vivo toxicity, the antimicrobial, anti-inflammatory, antidiarrheal, antinociceptive, locomotor, and sedative effects of an ethanolic extract obtained from Celtis pallida aerial parts (CPE).

MATERIALS AND METHODS

The composition of CPE was carried out by GC-MS. The in vitro and in vivo toxic activity of CPE was estimated with the comet assay (10-1000 µg/ml) for 5 h in peripheral blood mononuclear cells, and the acute toxicity test (500-5000 mg/kg p.o.), for 14 days, respectively. The antimicrobial effect of CPE was evaluated using the minimum inhibitory concentration (MIC) assay, whereas the antidiarrheal activity (10-200 mg/kg p.o.) was calculated using the castor oil test. The antinociceptive effects of CPE (50-200 mg/kg p.o.) were estimated with the acetic acid and formalin tests, as well as the hot plate test. The sedative and locomotor activities of CPE (50-200 mg/kg p.o.) were assessed with the pentobarbital-induced sleeping time test and the rotarod test, respectively.

RESULTS

The main compound found in CPE was the triterpene ursolic acid (22% of the extract). CPE at concentrations of 100 µg/ml or higher induced genotoxicity in vitro and showed low in vivo toxicity (LD₅₀ > 5000 mg/kg p.o.). Additionally, CPE lacked (MIC > 400 µg/ml) antimicrobial activity but exerts antinociceptive (ED₅₀ = 12.5 ± 1.5 mg/kg) and antidiarrheal effects (ED₅₀ = 2.8 mg/kg), without inducing sedative effects or altering the locomotor activity. The antinociceptive activity of CPE suggests the participation of adrenoceptors, as well as the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

CONCLUSION

C. pallida exerts its antinociceptive effects probably mediated by the nitric oxide/cyclic guanosine monophosphate (cGMP) pathway.

Antipyretic therapy: clinical pharmacology

Fever depends on a complex physiologic response to infectious agents and other conditions. To alleviate fever, many medicinal agents have been developed over a century of trying to improve upon aspirin, which was determined to work by inhibiting prostaglandin synthesis. We present the process of fever induction through prostaglandin synthesis and discuss the development of pharmaceuticals that target enzymes and receptors involved in prostaglandin-mediated signal transduction, including prostaglandin H₂ synthase (also known as cyclooxygenase), phospholipase A₂, microsomal prostaglandin E₂ synthase-1, EP receptors, and transient potential cation channel subfamily V member 1. Clinical use of established antipyretics will be discussed as well as medicinal agents under clinical trials and future research.

Effects of Intrathecal κ-Opioid Receptor Agonist on Morphine-Induced Itch and Antinociception in Mice

The μ-opioid receptor (MOR) agonist-induced itch is a significant issue associated with analgesic therapies. Research suggested that systemically administered κ-opioid receptor (KOR) agonists inhibit intrathecal morphine-induced itch in primates. However, serious adverse effects induced by systemically administered KOR agonists may restrict their usefulness in humans. We investigated the effects of intrathecal KOR agonists on intrathecal morphine-mediated itch and antinociception in mice.Mice received intrathecal injections of one of the following drugs: morphine (0.1-1.0 nmol), the selective KOR agonist TRK-820 100 pmol, the combination of morphine 0.3 nmol + TRK-820 (10-100 pmol), and 5 μL of saline. One hour after intraperitoneal administration of the selective KOR antagonist nor-binaltorphimine 1.0 μmol, the effect of TRK-820 100 pmol on intrathecal morphine 0.3 nmol-induced scratching was tested. Total numbers of scratches after intrathecal injection were analyzed. After observing scratching behavior, sedation level was evaluated subjectively. Nociceptive threshold was determined by tail immersion test with intrathecal injections of the following agents: morphine (0.1-1.0 nmol), TRK-820 (10-100 pmol), morphine 0.1 nmol + TRK-820 10 pmol, and 5 μL of saline.Intrathecal TRK-820 dose-dependently inhibited intrathecal morphine-induced scratching compared with that in the saline group. Intraperitoneal nor-binaltorphimine completely inhibited the antiscratching effect of intrathecal TRK-820 100 pmol. The combination of morphine 0.3 nmol and TRK-820 did not alter the sedation score compared with that in the morphine 0.3 nmol group. Morphine 0.1 nmol + TRK-820 10 pmol significantly produced greater thermal antinociceptive effects than morphine 0.1 nmol.We demonstrated that intrathecal KOR agonists exert antipruritic effects on intrathecal morphine-induced itch without affecting sedation. The combination of intrathecal morphine and intrathecal KOR agonists produces more potent antinociceptive effects against a thermal stimulus compared with morphine alone.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

The Large Role of Prescription Drugs in Accidental Drug Deaths

Drug abuse may involve illicit drugs, prescription drugs, or the combination of illicit and prescription drugs, with or without the use of alcohol. Historically, illicit drugs have been responsible for many of the drug-related deaths investigated by medical examiner and coroner offices. However, in more recent years, deaths resulting from prescription drugs have become increasingly more common. This study reviewed all accidental (unintentional) drug deaths that were investigated at a medical examiner's office over a one-year time frame. The study revealed that prescription drugs made up the largest category of drug deaths, followed by prescription drug/illicit drug combinations, followed by illicit drugs. Drugs capable of causing or contributing to significant respiratory insufficiency such as opioids, benzodiazepines, relaxants (defined as muscle relaxants or sleep medications), and alcohol, or some combination thereof, were detected in 197 out of 256 (77%) of all accidental drug deaths, and were detected in 132 out of 138 (95%) of all prescription drug deaths (cases without any illicit drugs detected). These prescription drugs were most often found in combination, and their similar respiratory depressant effects can be cumulative and deadly.

Aspiration pneumonitis caused by delayed respiratory depression following intrathecal morphine administration

Opioid analgesia is the primary pharmacologic intervention for managing pain. However, opioids can cause various adverse effects including pruritus, nausea, constipation, and sedation. Respiratory depression is the most fatal side effect. Therefore, cautious monitoring of respiratory status must be done after opioid administration. Here, we report a patient who suffered from respiratory depression with deep sedation and aspiration pneumonitis after intrathecal morphine administration.

Sedative load among community-dwelling people aged 75 years or older: association with balance and mobility

Drugs with sedative properties are frequently used among older people. Sedative load is a measure of the cumulative effect of taking multiple drugs with sedative properties. The objective of this study was to investigate the association between sedative load and balance and mobility. A random sample of 1000 people 75 years or older was invited to participate. Seven hundred community-dwelling participants (mean age, 81.3 years; 69% women) were included in the present study. Demographic, diagnostic, and drug use data were elicited during nurse interviews in 2004. Balance and mobility were tested by physiotherapists. Sedative load was calculated using a previously published model for each participant by summing the sedative ratings of primary sedatives (rating 2) and drugs with sedation as a prominent adverse effect (rating 1). Analyses of covariance and logistic regression analyses were used to assess the association between sedative load and balance and mobility. Of the 700 participants, 21% (n = 147) had a sedative load of 1-2, and 8% (n = 58) had sedative load of 3 or greater. After adjusting for covariates, exposure to higher sedative load ranges was associated with slower walking speed (P = 0.0003), longer time to perform Timed Up and Go test (P = 0.005), and lower scores on Berg Balance Scale (P = 0.005), but not with self-reported ability to walk 400 m. In conclusion, having a higher sedative load was associated with impaired balance and mobility among community-dwelling older people. Clinicians should remain cognizant of this association and regularly reevaluate drug therapy prescribed to older people.

Muscle strength and sedative load in community-dwelling people aged 75 years and older: a population-based study

BACKGROUND

Use of psychotropic and sedative drugs has been associated with impaired muscle strength. Muscle weakness predicts important outcomes for older people including functional disability and mortality. The objective of this study was to investigate if the use of drugs with sedative properties is associated with poorer muscle strength.

METHODS

Seven-hundred community-dwelling participants, aged 75 years and older, enrolled in the population-based Geriatric Multidisciplinary Strategy for the Good Care of the Elderly (GeMS) study in 2004 were included in the present analyses. Data on demographics, diagnostics, and drug use were collected during standardized interviews, conducted by trained nurses and verified through medical records. Physiotherapists conducted objective tests of handgrip strength, knee extension strength, and the five repeated chair stands test. Sedative load was calculated using a previously published model for each participant.

RESULTS

Twenty-one percent of the participants (n = 147) had a sedative load of 1-2 and 8% (n = 58) had a sedative load 3 or more. After adjusting for covariates, participants with sedative load more than 0 had poorer performance on grip strength (p = .009), knee extension strength (p = .02), and five chair stands (p = .003) than nonusers of drugs with sedative properties. Increasing sedative load was associated with poorer grip strength.

CONCLUSIONS

Use of drugs with sedative properties was associated with impaired muscle strength. Although we adjusted for diagnoses affecting physical function, the possibility of confounding by indication cannot be entirely excluded. Given that muscle strength is predictive of functional disability and mortality, further attention should be directed toward conducting regular reviews of drug therapy and reducing use of sedative drugs.

Opioids, Ventilation and Acute Pain Management

Despite the increasing use of a variety of different analgesic strategies, opioids continue as the mainstay for management of moderate to severe acute pain. However, concerns remain about their potential adverse effects on ventilation. The most commonly used term, respiratory depression, only describes part of that risk. Opioid-induced ventilatory impairment (OIVI) is a more complete term encompassing opioid-induced central respiratory depression (decreased respiratory drive), decreased level of consciousness (sedation) and upper airway obstruction, all of which, alone or in combination, may result in decreased alveolar ventilation and increased arterial carbon dioxide levels.

Concerns about OIVI are warranted, as deaths related to opioid administration in the acute pain setting continue to be reported. Risks are often said to be higher in patients with obstructive sleep apnoea. However, the tendency to use the term ‘obstructive sleep apnoea’ to encompass the much broader spectrum of sleep- and obesity-related hypoventilation syndromes and the related misuse of terminology in papers relating to obstructive sleep apnoea and sleep-disordered breathing remain significant problems in discussions of opioid-related effects.

Opioids given for management of acute pain must be titrated to effect for each patient. However, strategies aiming for better pain scores alone, without highlighting the need for appropriate monitoring of OIVI, can and will lead to an increase in adverse events. Therefore, all patients must be monitored appropriately for OIVI (at the very least using sedation scores as a ‘6th vital sign’) so that it can be detected at an early stage and appropriate interventions triggered.

Utility of saccadic eye movement analysis as an objective biomarker to detect the sedative interaction between opioids and sleep deprivation in opioid-naive and opioid-tolerant populations

Analysis of saccadic eye movements (SEMs) has previously been used to detect drug- and sleep-deprivation-induced sedation, but never in combination. We compared the effects of sleep deprivation and opioids on 10 opioid-naive with nine opioid-tolerant participants. The naive-participant study evaluated the effects of sleep deprivation alone, morphine alone and the combination; the tolerant-participant study compared day-to-day effects of alternate-daily-dosed buprenorphine and the combination of buprenorphine on the dosing day with sleep deprivation. Psychomotor impairment was measured using SEMs, a 5-minute pupil adaptation test (PAT), pupil light reflex (PLR) and alertness visual analogue scale (AVAS). The PAT and PLR did not detect sleep deprivation, in contrast to previous studies. Whilst consistently detecting sleep deprivation, the AVAS also detected buprenorphine in the tolerant study, but not morphine in the naive study. SEMs detected morphine alone and sleep deprivation alone as well as an additive interaction in the naive study and the effect of sleep deprivation in the tolerant study. The alternate-day buprenorphine dosing did not alter SEMs. The current study revealed greater SEMs, but not AVAS impairment in tolerant versus naive participants. The current study demonstrates that objective measures provide additional information to subjective measures and thus should be used in combination.

The role of sedation tests in identifying sedative drug effects in healthy volunteers and their power to dissociate sedative-related impairments from memory dysfunctions

The study investigated whether four specified drugs would show similar patterns on tests considered to measure sedation. In addition, their drug-effect patterns on sedation and memory performance were compared to determine whether the sedative effects could be differentiated from the memory effects. Two double-blind, placebo-controlled, crossover studies, each with 16 healthy volunteers, were performed, one testing lorazepam (2.5 mg) and mirtazapine (15 mg) and the other olanzapine (10 mg) and haloperidol (2.5 mg). Subjective sedation was assessed by means of visual analogue scales (VAS) and objective sedation using a simple-reaction-time (SRT) task and a choice-reaction-time (CRT) task, code substitution (symbol digit substitution test (SDST)) and the peak velocity of saccadic eye movements (SEM). A verbal memory test (VMT) was administered to evaluate memory capacity. Apart from haloperidol, all drugs proved to impair performance on all five sedation indices. Contrary to the VAS, the objective measures yielded different response profiles. Two types of drug-effect patterns emerged: one for greater impairments in response speed (SRT, SEM) and one for greater impairments in information processing (CRT, SDST). Lorazepam and olanzapine impeded memory performance, whereas mirtazapine did not. With the use of standardized scores it proved possible to differentiate between the size of the effects of the drugs on the sedation and memory tests. To accurately assess the level and nature of sedation and to differentiate sedation from memory impairments different types of sedation measures are required. Besides studying the subjective effects, it is recommended to also test psychomotor responses and information processing speed.

Management of opioid-induced sedation in patients with cancer

Opioid-induced sedation is a common dose-limiting side effect of opioid therapy that can be very distressing and sometimes is more difficult to manage than pain. Opioid-induced sedation may prohibit patients from participating in certain activities of daily living, which can be a source of considerable distress for patients and their families. The issue presents a therapeutic dilemma for healthcare professionals caring for patients experiencing the side effect. Currently, several therapeutic approaches are used to counteract or minimize the severity of opioid-induced sedation, including reduction of the opioid dose, the addition of other drugs, opioid rotation, and the use of invasive routes of administration. This article will address the management of opioid-induced sedation.

Pharmacologic Treatment of Opioid-Induced Sedation in Chronic Pain

OBJECTIVE:

To review the literature for pharmacologic management of opioid-induced sedation (OIS) in patients with chronic pain.

DATA SOURCES:

A search of MEDLINE (1966–October 2004) for English-language literature and selected bibliographies was completed. Search terms included pain, opioid, sedation, psychostimulants, amphetamines, modafinil, and donepezil.

DATA SYNTHESIS:

Amphetamines and amphetamine-like agents, caffeine, donepezil, and modafinil have been evaluated for OIS. Available literature is limited by numbers of subjects, duration, and trial design; however, there is limited support for the use of methylphenidate, donepezil, and modafinil.

CONCLUSIONS:

Pharmacologic treatment of OIS should be utilized selectively, given the available literature. Methylphenidate, donepezil, and modafinil may be considered in appropriate patients.

Respiratory Depression in Adult Patients With Intravenous Patient-Controlled Analgesia

Patient-controlled analgesia (PCA) has been widely implemented to provide better pain relief and increased patient satisfaction with relatively few side effects. However, patients using intravenous (i.v.) PCA are at increased risk for specific adverse effects, especially respiratory depression. A review of the literature from 1990 to present was done to identify the incidence and risk factors for respiratory depression and recommendations for care. Several studies have documented the incidence of respiratory depression with i.v. PCA; rates ranged from 0.19% to 5.2%. Variation in incidence existed because authors defined respiratory depression differently. Methods for monitoring oxygenation include sedation; respiratory rate, depth, and rhythm, and oxygen saturation using pulse oximetry. No single parameter is the single indicator for respiratory depression. Risk factors for respiratory depression with i.v. PCA include age greater than 70 years; basal infusion with i.v. PCA; renal, hepatic, pulmonary, or cardiac impairment; sleep apnea (suspected or history); concurrent central nervous system depressants; obesity; upper abdominal or thoracic surgery; and i.v. PCA bolus > 1 mg. Structures and processes should be in place to guide appropriate dosing, identify risk factors, and activate pertinent monitoring and frequency. Finally, respiratory depression occurs infrequently in comparison to the 10% of patients who are undertreated for pain.

Measurement of opioid-induced sedation

One of the major side effects of opioid analgesics is sedation. Despite the fact that neither a universal definition nor a gold standard for the measurement of opioid-induced sedation exists, various neurophysiologic and psychomotor measures are used to quantify the sedative effects of opioids. This report reviews the strengths and weaknesses of various approaches that are used to measure opioid-induced sedation. The first section summarizes various neurophysiologic measures (i.e., electroencephalogram, autonomic reflexes, and evoked responses), and the second section reviews psychomotor measures (i.e., visual analog scales, observer assessments, motor performance tests, tests of perceptual processes, tests of information processing, tests of memory, and composite tests) that are used to evaluate the sedative effects of opioids. Implications for future research on opioid-induced sedation are discussed.