Pharmacokinetic and pharmacodynamic study of intranasal and intravenous dexmedetomidine

Absorption pharmacokinetics and feasibility of intranasal dexmedetomidine in patients under general anaesthesia

BACKGROUND

The use of intranasal dexmedetomidine is hampered by a limited understanding of its absorption pharmacokinetics.

METHODS

We examined the pharmacokinetics and feasibility of intranasal dexmedetomidine administered in the supine position to adult patients undergoing general anaesthesia. Twenty-eight patients between 35 and 80 years of age, ASA 1-3 and weight between 50 and 100 kg, who underwent elective unilateral total hip or knee arthroplasty under general anaesthesia were recruited. All patients received 100 μg of intranasal dexmedetomidine after anaesthesia induction. Six venous blood samples (at 0, 5, 15, 45, 60, 240 min timepoints from dexmedetomidine administration) were collected from each patient and dexmedetomidine plasma concentrations were measured. Concentration-time profiles after nasal administration were pooled with earlier data from a population analysis of intravenous dexmedetomidine (n = 202) in order to estimate absorption parameters using nonlinear mixed effects. Peak concentration (CMAX) and time (TMAX) were estimated using simulation (n = 1000) with parameter estimates and their associated variability.

RESULTS

There were 28 adult patients with a mean (SD) age of 66 (8) years and weight of 83 (10) kg. The mean weight-adjusted dose of dexmedetomidine was 1.22 (0.15) μg kg-1. CMAX 0.273 μg L-1 was achieved at 98 min after intranasal administration (TMAX). The relative bioavailability of dexmedetomidine was 80% (95% CI 75-91%). The absorption half-time (TABS = 120 min; 95% CI 90-147 min) was slower than that in previous pharmacokinetic studies on adult patients. Perioperative haemodynamics of all patients remained stable.

CONCLUSIONS

Administration of intranasal dexmedetomidine in the supine position during general anaesthesia is feasible with good bioavailability. This administration method has slower absorption when compared to awake patients in upright position, with consequent concentrations attained after TMAX for several hours.

Dexmedetomidine for analgesia and sedation in newborn infants receiving mechanical ventilation

BACKGROUND

Dexmedetomidine is a selective alpha-2 agonist with minimal impact on the haemodynamic profile. It is thought to be safer than morphine or stronger opioids, which are drugs currently used for analgesia and sedation in newborn infants. Dexmedetomidine is increasingly being used in children and infants despite not being licenced for analgesia in this group.

OBJECTIVES

To determine the overall effectiveness and safety of dexmedetomidine for sedation and analgesia in newborn infants receiving mechanical ventilation compared with other non-opioids, opioids, or placebo.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and two trial registries in September 2023.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) and quasi-RCTs evaluating the effectiveness of dexmedetomidine compared with other non-opioids, opioids, or placebo for sedation and analgesia in neonates (aged under four weeks) requiring mechanical ventilation.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were level of sedation and level of analgesia. Our secondary outcomes included days on mechanical ventilation, number of infants requiring additional medication for sedation or analgesia (or both), hypotension, neonatal mortality, and neurodevelopmental outcomes. We planned to use GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified no eligible studies for inclusion. We identified four ongoing studies, two of which appear to be eligible for inclusion; they will compare dexmedetomidine with fentanyl in newborn infants requiring surgery. We listed the other two studies as awaiting classification pending assessment of full reports. One study will compare dexmedetomidine with morphine in asphyxiated newborns undergoing hypothermia, and the other (mixed population, age up to three years) will evaluate dexmedetomidine versus ketamine plus dexmedetomidine for echocardiography. The planned sample size of the four studies ranges from 40 to 200 neonates. Data from these studies may provide some evidence for dexmedetomidine efficacy and safety.

AUTHORS' CONCLUSIONS

Despite the increasing use of dexmedetomidine, there is insufficient evidence supporting its routine use for analgesia and sedation in newborn infants on mechanical ventilation. Furthermore, data on dexmedetomidine safety are scarce, and there are no data available on its long-term effects. Future studies should address the efficacy, safety, and long-term effects of dexmedetomidine as a single drug therapy for sedation and analgesia in newborn infants.

Pharmacokinetics of Intranasal Drugs, Still a Missed Opportunity?

The intranasal (IN) route of administration is important for topical drugs and drugs intended to act systemically. More recently, direct nose-to-brain input was considered to bypass the blood-brain barrier.Processes related to IN absorption and nose-to-brain distribution are complex and depend, sometimes in contrasting ways, on chemico-physical and structural parameters of the compounds, and on formulation options.Due to the intricacies of these processes and despite the large number of articles published on many different IN compounds, it appears that absorption after IN dosing is not yet fully understood. In particular, at variance of the understanding and modelling approaches that are available for predicting the pharmacokinetics (PK) following oral administration of xenobiotics, it appears that there is not a similar understanding of the chemico-physical and structural determinants influencing drug absorption and disposition of compounds after IN administration, which represents a missed opportunity for this research field. This is even more true regarding the understanding of the direct nose-to-brain input. Due to this, IN administrations may represent an interesting and open research field for scientists aiming to develop PK property predictions tools, mechanistic PK models describing rate and extent of IN absorption, and translational tools to anticipate the clinical PK following IN dosing based on in vitro and in vivo non clinical experiments.This review intends to provide: i) some basic knowledge related to the physiology of PK after IN dosing, ii) a non-exhaustive list of preclinical and clinical examples related to compounds explored for the potential nose-to-blood and nose-to-brain passage, and iii) the identification of some areas requiring improvements, the understanding of which may facilitate the development of IN drug candidates.

Opioid-free anaesthesia reduces postoperative nausea and vomiting after thoracoscopic lung resection: a randomised controlled trial

BACKGROUND

Intraoperative opioid use has a positive relationship with postoperative nausea and vomiting (PONV), and opioid-free anaesthesia (OFA) might reduce PONV. We investigated whether OFA compared with opioid-based anaesthesia would reduce PONV during the first 2 postoperative days among patients undergoing thoracoscopic lung resection.

METHODS

In this randomised controlled trial, 120 adult patients were randomly assigned (1:1, stratified by sex) to receive either OFA with esketamine, dexmedetomidine, and sevoflurane, or opioid-based anaesthesia with sufentanil and sevoflurane. A surgical pleth index (SPI) of 20-50 was applied for intraoperative analgesia provision. All subjects received PONV prophylaxis (dexamethasone and ondansetron) and multimodal analgesia (flurbiprofen axetil, ropivacaine wound infiltration, and patient-controlled sufentanil). The primary outcome was the occurrence of PONV during the first 48 h after surgery.

RESULTS

The median age was 53 yr and 66.7% were female. Compared with opioid-based anaesthesia, OFA significantly reduced the incidence of PONV (15% vs 31.7%; odds ratio [OR]=0.38, 95% confidence interval [CI], 0.16-0.91; number needed to treat, 6; P=0.031). Secondary and safety outcomes were comparable between groups, except that OFA led to a lower rate of vomiting (OR=0.23, 95% CI, 0.08-0.77) and a longer length of PACU stay (median difference=15.5 min, 95% CI, 10-20 min). The effects of OFA on PONV did not differ in the prespecified subgroups of sex, smoking status, and PONV risk scores.

CONCLUSIONS

In the context of PONV prophylaxis and multimodal analgesia, SPI-guided opioid-free anaesthesia halved the incidence of PONV after thoracoscopic lung resection, although it was associated with a longer stay in the PACU.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2200059710).

Comparative evaluation of nebulised dexmedetomidine vs fentanyl for the treatment of post-dural puncture headache (PDPH) in parturients after caesarean section under spinal anaesthesia: A randomised controlled study

Background and Aims

The incidence of post-dural puncture headache (PDPH) following spinal anaesthesia in the obstetric population is around 0.5%-2%. Hydration, bed rest, caffeine, paracetamol, non-steroid anti-inflammatory drugs, epidural blood patches, etc., are the various modalities used for its management. This study aims to compare nebulised dexmedetomidine versus fentanyl for the treatment of PDPH in parturients after caesarean section under spinal anaesthesia.

Methods

Ninety obstetric patients aged 18-35 years with American Society of Anesthesiologists (ASA) physical status II/III and suffering from PDPH as per the criteria of the International Headache Society after caesarean section under spinal anaesthesia were recruited in this double-blinded randomised study. Patients were randomised to Group D (dexmedetomidine 1 µg/kg nebulisation), Group F (fentanyl 1 µg/kg nebulisation), and Group S (saline nebulisation 4mL). The nebulisation was done 12 hourly for 72 hours. Assessment parameters included pain score and the requirement of additional treatment such as paracetamol, caffeine, and epidural blood patch. Analysis of variance test was used for continuous quantitative variables, and the Kruskal-Wallis test was used for quantitative discrete data.

Results

The pain scores at 1, 6, 12, 24, 48, and 72 hours following nebulisation were significantly lower in Group D in comparison to groups F and S (P < 0.001). The number of patients requiring additional analgesic therapy was lower in Group D in comparison to patients in other groups (P < 0.001).

Conclusion

Dexmedetomidine nebulisation resulted in effective reduction in PDPH symptoms and pain scores. Nebulisation with fentanyl did not alleviate PDPH symptoms when compared to the control group.

Clinical Use of Adrenergic Receptor Ligands in Acute Care Settings

In this chapter, we review how ligands, both agonists and antagonists, for the major classes of adrenoreceptors, are utilized in acute care clinical settings. Adrenergic ligands exert their effects by interacting with the three major classes of adrenoceptors. Adrenoceptor agonists and antagonists have important applications, ranging from treatment of hypotension to asthma, and have proven to be extremely useful in a variety of clinical settings of acute care from the operating room to the critical care environment. Continued research interpreting the mechanisms of adrenoreceptors may help the discovery of new drugs with more desirable clinical profiles.

Preliminary pharmacokinetics and patient experience of jet-injected dexmedetomidine in healthy adults

Jet injection is a drug delivery system without a needle. A compressed liquid drug formulation pierces the skin, depositing the drug into the subcutaneous or intramuscular tissues. We investigated the pharmacokinetics and patient experience of dexmedetomidine administered using jet injection in six healthy adult study participants. This needleless jet injection device was used to administer dexmedetomidine 0.5 μg/kg to the subcutaneous tissues overlying the deltoid muscle. Serum concentrations of dexmedetomidine were assayed at approximately 5 minutes, 15 minutes, 30 minutes, 1 hour and 4 hours after administration. Pharmacokinetic interrogation of concentration time profiles estimated an absorption half time for jet-injected dexmedetomidine of 21 minutes (coefficient of variation 69.4%) with a relative bioavailability assumed unity. In our samples the measured median peak (range) concentration was 0.164 μg/l (0.011-0.325 μg/l), observed in the sample taken at a median (range) of 13.5 minutes (11-30 minutes). The Richmond agitation sedation scale was used to assess the sedative effect, and scored 0 (alert and calm) or -1 (drowsy) in all participants. Five of the six participants stated they would prefer jet injection to needle injection in the future and one had no preference. The findings suggest that the use of a larger dose (>2 μg/kg) would be required to achieve the clinically relevant target concentration of 1 μg/l necessary to achieve deeper sedation (Richmond agitation sedation scale ≤3).

Clinical observation of dexmedetomidine nasal spray in the treatment of sleep disorders on the first night after undergoing maxillofacial surgery: a single-center double-blind randomized controlled study

Purpose: Dexmedetomidine exerts a sedative effect by promoting the sleep pathway endogenously and producing a state similar to N2 sleep. This study aimed to study the efficacy and safety of dexmedetomidine nasal spray in the treatment of postoperative sleep disturbance. Methods: This study enrolled 120 participants [men and women; age, 18-40 years; American Society of Anesthesiologists grade, I or II] who underwent maxillofacial surgery under general anesthesia through nasotracheal intubation. The participants were randomly divided into three groups: blank control group (BC group), 1.0 μg/kg dexmedetomidine group (1.0 Dex group), and 1.5 μg/kg dexmedetomidine group (1.5 Dex group), with 40 patients allocated to each group. At 21:30 on the night after the operation, the intervention groups were administered their corresponding doses of dexmedetomidine nasal spray. The Pittsburgh Sleep Quality Index (PSQI) scale was used to evaluate the baseline sleep status of participants 1 month preoperatively and on the night after the operation. Polysomnography (PSG) was used to record the sleep status on the night after the operation. We recorded the rescue times of sedative and analgesic drugs on the first night after surgery, adverse reactions, total hospital stay duration, and total costs. Results: Compared with patients in the BC group, those in 1.0 Dex and 1.5 Dex groups had longer N2 sleep duration, were awake for a shorter time after dose administration, woke up less often, and had significantly improved sleep efficiency (p < 0.05). Compared with the BC group, the PSQI scores of 1.0 Dex and 1.5 Dex groups were significantly lower on the night after operation, and the proportion of PSQI > 5 was significantly lower (p < 0.05). Compared with patients in the BC group and the 1.0 Dex group, those in the 1.5 Dex group had significantly prolonged N3 sleep, reduced frequency of requiring sufentanil rescue, lower incidence of sore throat after surgery, and shorter average length of hospital stay (all, p < 0.05). Conclusion: The sleep quality of participants on the night after having undergone maxillofacial surgery was safely and effectively improved by 1.0-1.5 μg/kg dexmedetomidine atomized nasal sprays. Notably, only the latter could prolong N3 sleep. Level of Evidence II: Evidence was obtained from at least one properly designed randomized controlled trial.

Pharmacokinetic pharmacodynamic modeling of analgesics and sedatives in children

Pharmacokinetic pharmacodynamic modeling is an important tool which uses statistical methodology to provide a better understanding of the relationship between concentration and effect of drugs such as analgesics and sedatives. Pharmacokinetic pharmacodynamic models also describe between-subject variability that allows identification of subgroups and dose adjustment for optimal pain management in individual patients. This approach is particularly useful in the pediatric population, where most drugs have received limited evaluation and dosing is extrapolated from adult practice. In children, the covariates of weight and age are used to describe size- and maturation-related changes in pharmacokinetics. It is important to consider both size and maturation in order to develop an accurate model and determine the optimal dose for different age groups. An adequate assessment of analgesic and sedative effect using pain scales or brain activity measures is essential to build reliable pharmacokinetic pharmacodynamic models. This is often challenging in children due to the multidimensional nature of pain and the limited sensitivity and specificity of some measurement tools. This review provides a summary of the pharmacokinetic and pharmacodynamic methodology used to describe the dose-concentration-effect relationship of analgesics and sedation in children, with a focus on the different pharmacodynamic endpoints and the challenges of pharmacodynamic modeling.

Intranasal erythropoietin protects granular cells and reduces astrogliosis in the dentate gyrus after ischemic damage, an effect associated with molecular changes in erythropoietin and its receptor

Within the hippocampus, the CA1 and dentate gyrus (DG) regions are considered the most and the least susceptible to damage by cerebral ischemia, respectively. In addition, it has been tested that rHuEPO exhibits neuroprotective properties. This work investigates the effect of different intranasal doses of rHuEPO, applied in different ischemic post-damage times in the DG, and the effect of the rHuEPO on astroglial reactivity after cerebral ischemia. Additionally, an effective dose for neuroprotection and an administration time was used to evaluate gene and protein expression changes of EPO and EPOR in the DG region. We observed a considerable loss of cells on the granular layer and an increased number of GFAP immunoreactive cells in this region only 72 h after the onset of ischemia/damage. When rHuEPO was administered, the number of morphologically abnormal cells and immunoreactivity decreased. In the analysis of protein and gene expression, there is no correlation between expression level of these molecules, although the rHuEPO amplifies the response to ischemia of EPO and EPOR gene for each evaluated time; in the case of the protein only at 2 h this effect was observed. We demonstrated the susceptibility of the DG to ischemia; so granular cells damage was observed, moreover of the astrocytic response, which is accompanied by molecular changes in signaling mediated by rHuEPO intranasal administration.

Effect of Different Administration Routes of Dexmedetomidine on Postoperative Delirium in Elderly Patients Undergoing Elective Spinal Surgery: A Prospective Randomized Double-Blinded Controlled Trial

BACKGROUND

Intravenous dexmedetomidine has been reported to decrease the occurrence of postoperative delirium (POD) in elderly patients. Nevertheless, some previous studies have indicated that intratracheal dexmedetomidine and intranasal dexmedetomidine are also effective and convenient. The current study aimed to compare the effect of different administration routes of dexmedetomidine on POD in elderly patients.

METHODS

We randomly allocated 150 patients (aged 60 years or more) scheduled for spinal surgery to receive intravenous dexmedetomidine (0.6 μg/kg), intranasal dexmedetomidine (1 μg/kg) before anesthesia induction, or intratracheal dexmedetomidine (0.6 µg/kg) after anesthesia induction. The primary outcome was the frequency of delirium during the first 3 postoperative days. The secondary outcomes were the incidence of postoperative sore throat (POST) and sleep quality. Adverse events were recorded, and routine treatment was performed.

RESULTS

Compared with the intranasal group, the intravenous group had a significantly lower occurrence of POD within 3 days (3 of 49 [6.1%] vs 14 of 50 [28.0%]; odds ratio [OR], 0.17; 95% confidence intervals [CIs], 0.05-0.63; P < .017). Meanwhile, patients in the intratracheal group had a lower incidence of POD than those in the intranasal group (5 of 49 [10.2%] vs 14 of 50 [28.0%]; OR, 0.29; 95% CI, 0.10-0.89; P < .017). Whereas, there was no difference between the intratracheal and intravenous groups (5 of 49 [10.2%] vs 3 of 49 [6.1%]; OR, 1.74; 95% CI, 0.40-7.73; P > .017). The rate of POST was lower in the intratracheal group than that in the other 2 groups at 2 hours after surgery (7 of 49 [14.3%] vs 12 of 49 [24.5%] vs 18 of 50 [36.0%], P < .017, respectively). Intravenous dexmedetomidine had the lowest Pittsburgh Sleep Quality Index score on the second morning after surgery (median [interquartile range {IQR}]: 4 [3-5] vs 6 [4-7] vs 6 [4-7], P < .017, respectively). Compared with the intranasal group, the intravenous group had a higher rate of bradycardia and a lower incidence of postoperative nausea and vomiting ( P < .017). The intranasal group was associated with the highest incidence of hypertension ( P < .017).

CONCLUSIONS

For patients aged ≥60 years undergoing spinal surgery, compared with the intranasal route of dexmedetomidine, intravenous and intratracheal dexmedetomidine reduced the incidence of early POD. Meanwhile, intravenous dexmedetomidine was associated with better sleep quality after surgery, and intratracheal dexmedetomidine resulted in a lower incidence of POST. Adverse events were mild in all 3 administration routes of dexmedetomidine.

Low-dose intranasal dexmedetomidine premedication improves epidural labor analgesia onset and reduces procedural pain on epidural puncture: a prospective randomized double-blind clinical study

BACKGROUND

Epidural labor analgesia is a safe and effective method of pain management during labor with the drawbacks of delayed onset and maternal distress during epidural puncture. This study aimed to determine whether pretreatment with intranasal low-dose dexmedetomidine effectively shortens the onset of analgesia and reduces procedural pain.

METHODS

In this prospective, randomized double-blind trial, nulliparous patients were randomly assigned to either the intranasal dexmedetomidine group or the control group. The intranasal dexmedetomidine group received 0.5 μg/kg dexmedetomidine intranasally, and the control group received an equal volume of normal saline intranasally. Both groups were maintained with a programmed intermittent epidural bolus. The primary outcome was the onset time of analgesia and scores of pain related to the epidural puncture.

RESULTS

Seventy-nine patients were enrolled, and 60 completed the study and were included in the analysis. The time to achieve adequate analgesia was significantly shorter in the intranasal dexmedetomidine group than in the control group (hazard ratio = 2.069; 95% CI, 2.187 to 3.606; P = 0.010). The visual analogue scale pain scores during epidural puncture in the intranasal dexmedetomidine group were also significantly lower than those in the control group (2.0 (1.8-2.5) vs. 3.5 (3.3-4.5), P ≤ 0.001, Table 2). Pretreatment with intranasal dexmedetomidine before epidural labor analgesia was associated with improved visual analogue scale pain scores and Ramsay scores, less consumption of analgesics and higher maternal satisfaction (P < 0.05). No differences were observed for labor and neonatal outcomes or the incidence of adverse effects between the two groups.

CONCLUSIONS

Pretreatment with intranasal dexmedetomidine before epidural labor analgesia yielded a faster onset of analgesia and decreased epidural puncture pain without increasing adverse effects. Pretreatment with intranasal dexmedetomidine may be a useful adjunct for the initiation of epidural analgesia, and further investigation should be encouraged to determine its utility more fully.

TRIAL REGISTRATION

This trial was prospectively registered at Chictr.org.cn on 29/05/2020 with the registration number ChiCTR2000033356 ( http://www.chictr.org.cn/listbycreater.aspx ).

Intranasal Dexmedetomidine for Pain Management in Older Patients: A Cross-Over, Randomized, Double-Blinded, Active-Controlled Trial

BACKGROUND

Daily care procedures provoke breakthrough pain and anxiety in palliative situations. Dexmedetomidine may be an alternative to opioids during nursing procedures for older patients.

OBJECTIVE

We aimed to compare the efficacy of intranasal dexmedetomidine with subcutaneous opioids on the intensity of pain and anxiety during comfort management procedures.

METHODS

We conducted a randomized, active-controlled, double-blind, crossover trial (NCT03151863). Patients aged ≥ 65 years were randomized to receive, 45 min before nursing care, either intranasal dexmedetomidine together with subcutaneous placebo or intranasal placebo together with a subcutaneous opioid. Each of these two interventions were administered in a cross-over design and spaced out over a 24- or 48-h period. The primary outcome was the number of patients with an Elderly Caring Pain Assessment score > 5. Secondary outcomes included pain, sedation score, and vital signs.

RESULTS

Because of difficult recruitment, the trial was interrupted after the inclusion of 24 patients. Three patients withdrew after randomization, leaving 21 patients undergoing 42 complete sessions for descriptive analyses. Of the 21 patients, 12 (57.1%) were women, and their median age was 84 years, interquartile range (75-87 years). Nine (42.9%) patients presented an Elderly Caring Pain Assessment score > 5 when receiving subcutaneous opioids, and seven (33.3%) with intranasal dexmedetomidine. Hypoxemia occurred in a single patient receiving subcutaneous opioids. No episode of bradycardia was observed.

CONCLUSIONS

Intranasal dexmedetomidine is feasible in elderly patients and may be an alternative to opioids to ensure comfort during nursing care. Future studies are needed to confirm the efficacy and safety of this procedure.

Donepezil Brain and Blood Pharmacokinetic Modeling after Nasal Film and Oral Solution Administration in Mice

Intranasal delivery is a non-invasive mode of administration, gaining popularity due to its potential for targeted delivery to the brain. The anatomic connection of the nasal cavity with the central nervous system (CNS) is based on two nerves: olfactory and trigeminal. Moreover, the high vasculature of the respiratory area enables systemic absorption avoiding possible hepatic metabolism. Due to these physiological peculiarities of the nasal cavity, compartmental modeling for nasal formulation is considered a demanding process. For this purpose, intravenous models have been proposed, based on the fast absorption from the olfactory nerve. However, most of the sophisticated approaches are required to describe the different absorption events occurring in the nasal cavity. Donepezil was recently formulated in the form of nasal film ensuring drug delivery in both bloodstream and the brain. In this work, a three-compartment model was first developed to describe donepezil oral brain and blood pharmacokinetics. Subsequently, using parameters estimated by this model, an intranasal model was developed dividing the administered dose into three fractions, corresponding to absorption directly to the bloodstream and brain, as well as indirectly to the brain expressed through transit compartments. Hence, the models of this study aim to describe the drug flow on both occasions and quantify the direct nose-to-brain and systemic distribution.

Considerations for Intravenous Anesthesia Dose in Obese Children: Understanding PKPD

The intravenous induction or loading dose in children is commonly prescribed per kilogram. That dose recognizes the linear relationship between volume of distribution and total body weight. Total body weight comprises both fat and fat-free mass. Fat mass influences the volume of distribution and the use of total body weight fails to recognize the impact of fat mass on pharmacokinetics in children. Size metrics alternative to total body mass (e.g., fat-free and normal fat mass, ideal body weight and lean body weight) have been proposed to scale pharmacokinetic parameters (clearance, volume of distribution) for size. Clearance is the key parameter used to calculate infusion rates or maintenance dosing at steady state. Dosing schedules recognize the curvilinear relationship, described using allometric theory, between clearance and size. Fat mass also has an indirect influence on clearance through both metabolic and renal function that is independent of its effects due to increased body mass. Fat-free mass, lean body mass and ideal body mass are not drug specific and fail to recognize the variable impact of fat mass contributing to body composition in children, both lean and obese. Normal fat mass, used in conjunction with allometry, may prove a useful size metric but computation by clinicians for the individual child is not facile. Dosing is further complicated by the need for multicompartment models to describe intravenous drug pharmacokinetics and the concentration effect relationship, both beneficial and adverse, is often poorly understood. Obesity is also associated with other morbidity that may also influence pharmacokinetics. Dose is best determined using pharmacokinetic-pharmacodynamic (PKPD) models that account for these varied factors. These models, along with covariates (age, weight, body composition), can be incorporated into programmable target-controlled infusion pumps. The use of target-controlled infusion pumps, assuming practitioners have a sound understanding of the PKPD within programs, provide the best available guide to intravenous dose in obese children.

A comprehensive overview of clinical research on dexmedetomidine in the past 2 decades: A bibliometric analysis

Introduction: Dexmedetomidine is a potent, highly selective α-2 adrenoceptor agonist with sedative, analgesic, anxiolytic, and opioid-sparing properties. A large number of dexmedetomidine-related publications have sprung out in the last 2 decades. However, no bibliometric analysis for clinical research on dexmedetomidine has been published to analyze hot spots, trends, and frontiers in this field. Methods: The clinical articles and reviews related to dexmedetomidine, published from 2002 to 2021 in the Web of Science Core Collection, were retrieved on 19 May 2022, using relevant search terms. VOSviewer and CiteSpace were used to conduct this bibliometric study. Results: The results showed that a total of 2,299 publications were retrieved from 656 academic journals with 48,549 co-cited references by 2,335 institutions from 65 countries/regions. The United States had the most publications among all the countries (n = 870, 37.8%) and the Harvard University contributed the most among all institutions (n = 57, 2.48%). The most productive academic journal on dexmedetomidine was Pediatric Anesthesia and the first co-cited journal was Anesthesiology. Mika Scheinin is the most productive author and Pratik P Pandharipande is the most co-cited author. Co-cited reference analysis and keyword analysis illustrated hot spots in the dexmedetomidine field including pharmacokinetics and pharmacodynamics, intensive care unit sedation and outcome, pain management and nerve block, and premedication and use in children. The effect of dexmedetomidine sedation on the outcomes of critically ill patients, the analgesic effect of dexmedetomidine, and its organ protective property are the frontiers in future research. Conclusion: This bibliometric analysis provided us with concise information about the development trend and provided an important reference for researchers to guide future research.

Nurse-driven intranasal dexmedetomidine administration as sedation for non-invasive procedures in children: a single centre audit

The purpose of this study is to audit the efficacy and safety of intranasal dexmedetomidine sedation for non-invasive procedural sedation in children provided by nurses of the procedural sedation (PROSA) team in the University Hospitals Leuven. Efficacy (successful sedation as sole sedative) and safety (cardiorespiratory monitoring, saturation) were assessed. In this audit, prospectively recorded data were extracted from the medical files in 772 patients between 4 weeks to 18 years old, who underwent sedation with intranasal dexmedetomidine (2-4 µg/kg) by the nurse-driven PROSA team, following pre-screening on risk factors. Ninety-one percent of the patients were successfully sedated (single dose, monotherapy), 60 patients (7.8%) needed an additional intervention during sedation, 37 (4.8%) needed an extra dose of intranasal dexmedetomidine, and 14 (1.8%) received an additional other sedative. Successful sedation rates were higher in younger children, and medical imaging was the most common indication. Sedation failed in 12 (1.6%) patients, with 10 of them failed to fall asleep. Adverse events were limited in number (n = 13, 1.7%) and severity: 4 patients had a low heart rate (one received atropine), one had an irregular heart rate, and 7 desaturation events were described. Hypotension was treated with normal saline in one case.

CONCLUSIONS

In this nurse-driven PROSA setting, intranasal dexmedetomidine is effective and safe for non-invasive procedural sedation in an a priori low risk group of paediatric patients.

WHAT IS KNOWN

• Procedural sedation outside the operating theatre or intensive care units is increasingly used, including sedation performed by non-anaesthesiologists or nurses. This resulted in the development of procedural sedation and analgesia (PROSA) teams. • Off-label use of intranasal dexmedetomidine in children is increasing, with a limited number of audits on this practice, its safety and efficacy.

WHAT IS NEW

• In an audit on 772 procedures, nurse-driven intranasal dexmedetomidine administration as sedation for non-invasive procedures in children within a structured framework was safe and effective. • Imaging (CT, MRI) was the most common procedural indication in our study, but also nuclear imaging techniques were included.

Dose Escalation Pharmacokinetic Study of Intranasal Atomized Dexmedetomidine in Pediatric Patients With Congenital Heart Disease

BACKGROUND

Atomized intranasal dexmedetomidine is an attractive option when sedation is required for pediatric patients as either premedication or the sole agent for noninvasive, nonpainful procedures. While intranasal dexmedetomidine is used frequently in this population, it is still unclear what dose and time of administration relative to the procedure will result in the optimal effect. Knowledge regarding the maximum concentration (C max ) and time to reach maximum concentration (T max ) of intranasally administered dexmedetomidine is the first step toward this. The risk of hemodynamic instability caused by increasing doses of dexmedetomidine necessitates a greater understanding of the pharmacokinetics in children.

METHODS

Sixteen pediatric patients 2 to 6 years of age undergoing elective cardiac catheterization received 2 or 4 μg/kg dexmedetomidine intranasally. Plasma concentrations were determined by liquid chromatography-tandem mass spectrometry with a validated assay. Descriptive noncompartmental analysis provided estimates of peak concentrations and time to reach peak concentrations. A population pharmacokinetic model was developed using nonlinear mixed-effects modeling. Simulations were performed using the final model to assess dose concentrations with an alternative dosing regimen of 3 µg/kg.

RESULTS

A median peak plasma concentration of 413 pg/mL was achieved 91 minutes after 2 μg/kg dosing, and a median peak plasma concentration of 1000 pg/mL was achieved 54 minutes after 4 μg/kg dosing. A 1-compartment pharmacokinetic model adequately described the data. Three subjects in the 4 μg/kg dosing cohort achieved a dose-limiting toxicity (DLT), defined as a plasma dexmedetomidine concentration >1000 pg/mL. None of these subjects had any significant hemodynamic consequences. Simulations showed that no subjects would experience a level >1000 pg/mL when using a dose of 3 µg/kg.

CONCLUSIONS

Concentrations associated with adequate sedation can be achieved with intranasal dexmedetomidine doses of 2 to 4 µg/kg in children 2 to 6 years of age. However, 50% of our evaluable subjects in this cohort reached a plasma concentration >1000 pg/mL. Doses of 3 µg/kg may be optimal in this population, with simulated concentrations remaining below this previously established toxicity threshold. Further studies correlating concentrations with efficacy and adverse effects are needed.

Parental presence and intranasal dexmedetomidine for the prevention of anxiety during anesthesia induction in children undergoing tonsillectomy and/or adenoidectomy surgery: A randomized controlled trial

Background: During the perioperative period of pediatric surgery, it is extremely stressful for children and parents to enter the operating room and receive the anesthesia induction. This study was designed to evaluate the perioperative outcomes with parental presence at induction of anesthesia (PPIA), intranasal dexmedetomidine, and combined use of PPIA and intranasal dexmedetomidine. Methods: In this prospective study, 124 children were randomly divided into four groups: control (no parental presence or intranasal dexmedetomidine), PPIA (parental presence), DEX (intranasal dexmedetomidine (1.0 μg/kg)), and PPIA + DEX (parental presence and intranasal dexmedetomidine (1.0 μg/kg)). The anxiety of children was mainly evaluated by the modified Yale Preoperative Anxiety Scale-Short Form (mYPAS-SF). Secondary evaluation methods were, for example, the Induction Compliance Checklist (ICC), the Pediatric Anesthesia Emergence Delirium Scale (PAED), the COMFORT Behavior Scale (COMFORT-B Scale), the State-Trait Anxiety Inventory (STAI), and the Visual Analog Scale (VAS). Results: Children in the PPIA + DEX group exhibited significantly lower mYPAS-SF and ICC scores compared with all three other groups (p < 0.001), and children in that group exhibited significantly lower mYPAS-SF and ICC scores compared with the PPIA and DEX groups (p < 0.05). The children's PAED scores in the PPIA, DEX, and PPIA + DEX groups were significantly lower than the control group (p < 0.001).The STAI-S scores of the PPIA, DEX, and PPIA + DEX groups were significantly lower than the score of the control group (p < 0.001). The VAS scores of the PPIA, DEX, and PPIA + DEX groups were significantly higher than that of the control group (p < 0.001), while the score of the PPIA + DEX group was significantly higher than those of the PPIA and DEX groups (p < 0.05). Conclusion: The combined use of PPIA and intranasal dexmedetomidine is more effective than PPIA or intranasal dexmedetomidine for alleviating the preoperative anxiety of children, improving children's induction compliance and parental satisfaction.

Could dexmedetomidine be repurposed as a glymphatic enhancer?

Cerebrospinal fluid (CSF) flows through the central nervous system (CNS) via the glymphatic pathway to clear the interstitium of metabolic waste. In preclinical studies, glymphatic fluid flow rate increases with low central noradrenergic tone and slow-wave activity during natural sleep and general anesthesia. By contrast, sleep deprivation reduces glymphatic clearance and leads to intracerebral accumulation of metabolic waste, suggesting an underlying mechanism linking sleep disturbances with neurodegenerative diseases. The selective α₂-adrenergic agonist dexmedetomidine is a sedative drug that induces slow waves in the electroencephalogram, suppresses central noradrenergic tone, and preserves glymphatic outflow. As recently developed dexmedetomidine formulations enable self-administration, we suggest that dexmedetomidine could serve as a sedative-hypnotic drug to enhance clearance of harmful waste from the brain of those vulnerable to neurodegeneration.

Justification Of Empiric Methodology to Determine Dexmedetomidine Dose for the TREX Study

INTRODUCTION

Dexmedetomidine is the sedative agent administered in combination with remifentanil and low dose of sevoflurane in the interventional arm of the ongoing TREX trial (Trial Remifentanil DExmedetomidine). The TREX pilot study (published in Paediatr Anaesth 2019;29:59-67) established infusion rates higher than those initially proposed. This could be attributed to an inappropriate target concentration for sedation or incorrect initial pharmacokinetic parameter estimates.

METHODS

The TREX study is a Phase III, randomized, active controlled, parallel group, blinded evaluator, multicentre, superiority trial comparing neurological outcome after standard sevoflurane anaesthesia with dexmedetomidine/remifentanil and low dose sevoflurane anaesthesia in children aged less than 2 years undergoing anaesthesia of 2 hours or longer. In this report, dexmedetomidine pharmacokinetics were analysed in the interventional arm of the Italian population.

RESULTS

There were 162 blood samples from 32 infants (22 male and 10 female). The median (IQR) age was 12 (5.2-15.5) months, weight 9.9 (7.3-10.8) kg. Duration of anaesthesia ranged from 2-6 hours. None of the children were born premature (median postnatal age 39 weeks, IQR 38-40 weeks). A 3-compartment PK model that incorporated allometric scaling and a maturation function demonstrated plasma concentration observations from the current Italian arm of the TREX study were consistent with those predicted by a "universal" model using pooled data obtained from neonates to adults.

CONCLUSIONS

This current PK analysis from the Italian arm of the TREX study confirms that plasma concentration of dexmedetomidine is predictable using known covariates such as age and size. The initial target concentration (0.6 μg.L-1 ) used to sedate children cared for in the intensive care after cardiac surgery was inadequate for infants in the current TREX study. A target concentration 1 mcg.L-1 , corresponding to a loading dose of 1 mcg.kg-1 followed by an infusion of 1 mcg.kg-1 .hour-1 , provided adequate sedation.

Atomised intranasal dexmedetomidine versus oral melatonin in prevention of emergence delirium in children undergoing ophthalmic surgery with sevoflurane: A randomised double-blind study

BACKGROUND

Melatonin and dexmedetomidine have both been used as a premedication to decrease emergence delirium in children. The effectiveness of oral melatonin, compared with atomised intranasal dexmedetomidine, in this role is not well studied.

OBJECTIVE

To study the efficacy of pre-operative atomised intranasal dexmedetomidine versus oral melatonin in children scheduled for ophthalmic surgery under sevoflurane.

DESIGN

A prospective, randomised, double-blind trial.

SETTING

Ophthalmic surgery in a university teaching hospital, April 2021 to October 2021.

PATIENTS

A total of 120 children undergoing ophthalmic surgery with sevoflurane anaesthesia.

INTERVENTION

Children were randomised to receive pre-operative intranasal dexmedetomidine 2 μg/kg via an atomiser device (dexmedetomidine group) or oral melatonin 0.5 mg kg -1 (melatonin group), 45 min before surgery.

OUTCOMES MEASURED

The primary outcome was the incidence of emergence delirium assessed by the Paediatric Anaesthesia Emergence Delirium scale. Secondary outcomes included pre-operative sedation, quality of inhalational induction, postoperative sedation and pain.

RESULTS

The incidence of emergence delirium was lower in the dexmedetomidine group than in the melatonin group (17 versus 37%, relative risk 0.45, 95% CI: 0.24 to 0.88; P  = 0.01). Children in the dexmedetomidine group were more sedated following premedication and in the postanaesthesia care unit ( P  < 0.05). Postoperative pain scores were lower in the dexmedetomidine group than in the melatonin group: 0 [0 to 3] versus 2.5 [0-4], ( P  = 0.01). The requirement for and dose of rescue fentanyl analgesia postoperatively was comparable between the two groups.

CONCLUSION

Atomised intranasal dexmedetomidine significantly reduced emergence delirium in paediatric opthalmic procedures under sevoflurane anaesthesia compared to oral melatonin.

TRIAL REGISTRATION

Clinical Trials Registry of India CTRI/2021/03/032388 ( www.ctri.nic.in ).

Dexmedetomidine decreases the 50% effective dose (ED50) of intravenous propofol required to prevent tracheal intubation response in Beagles

OBJECTIVE

To determine the 50% effective dose (ED50) of intravenous propofol required for successfully preventing tracheal intubation response in Beagles co-induced with dexmedetomidine.

ANIMALS

36 adult male Beagles.

PROCEDURES

The dogs were randomly assigned to either group D1, group D2, or group C (received 1 µg/kg, 2 µg/kg dexmedetomidine intravenously, or the same amount of normal saline as dexmedetomidine, 10 mL). The first dog in each group received 6 mg/kg of propofol for induction. The pump speed of propofol was 600 mL/h. The dosage varied with increments or decrements of 0.5 mg/kg based on the Dixon up-and-down method. The duration of eye-opening after propofol administration was recorded. Changes in heart rate (HR) and respiratory rate (RR) were recorded at 5 timepoints: after entering the operation room and prior to propofol administration (T1), 1 and 3 min after propofol administration (T2 and T3), 3 and 5 min after intubation (T4 and T5).

RESULTS

The required ED50 of propofol that prevented tracheal intubation response in D1, D2, and C groups were 6.4 mg/kg (95% CI, 6.1 to 6.7 mg/kg), 5.8 mg/kg (95% CI, 5.67 to 6 mg/kg), and 8.3 mg/kg (95% CI, 8 to 8.5 mg/kg), respectively. The recovery time of group D2 was significantly longer than that of groups D1 and C (P < .05). The differences in HR among the 3 groups were significant from T2 up to T5 timepoint (P < .05). The differences in RR among the 3 groups were significant at T2 and T3 timepoints (P < .05).

CLINICAL RELEVANCE

Dexmedetomidine pre-injection reduces the amount of propofol required for endotracheal intubation response in Beagles, thereby reducing the respiratory inhibition induced by propofol.

Comparison of intranasal and nebulized dexmedetomidine for premedication in pediatric patients: A non-inferiority randomized controlled trial

Background and Aims

Dexmedetomidine is a highly selective α-2 adrenoreceptor agonist and has been found to be an effective premedication agent when administered via the intranasal route. We aimed to compare the efficacy of dexmedetomidine premedication administered via intranasal route and through nebulization in pediatric patients.

Material and Methods

This non-inferiority randomized controlled trial was conducted after getting approval from institutes ethics committee and informed written parental consent. Sixty-four children aged 2-8 years scheduled for elective surgery under general anesthesia were enrolled and were divided into two groups. Group I (Intranasal, n = 33) received 2 mcg/kg dexmedetomidine via intranasal route and group N (Nebulized, n = 31) received 2 mcg/kg dexmedetomidine through nebulization. The primary outcome was number of patients with satisfactory sedation 30 minutes after premedication at separation from parent. The secondary outcome included ease of medication acceptance, anxiety at parental separation, acceptance of anesthesia mask, perioperative hemodynamics, emergence agitation during recovery and adverse effects. Data collected was analyzed using Chi-square test, Student "t" test and Mann-Whitney U test with the help of SPSS 22. A one tailed P value < 0.025 was considered significant.

Results

Demographic profile was comparable between groups. On arrival in OR 27 (81.8%) patients in group I and 21 (67.7%) patients in group N had satisfactory sedation score (P = 0.19). The median (IQR) sedation score was comparable between group I and group N (P = 0.057). Patients in Group I showed significantly better medication and mask acceptance scores (P < 0.0001, P = 0.001 respectively), parental separation anxiety score (P < 0.0001) and emergence agitation score (P = 0.001). There were no significant differences in hemodynamic parameters and adverse effects between the groups.

Conclusion

Although nebulized dexmedetomidine is non-inferior to intranasal dexmedetomidine in providing desired level of sedation but intranasal administration had better acceptance of medication and anesthesia mask with lesser anxiety at parental separation and postoperative emergence agitation.

Population Pharmacokinetics of Intranasal Dexmedetomidine in Infants and Young Children

BACKGROUND

Intranasal dexmedetomidine provides noninvasive, effective procedural sedation for pediatric patients, and has been widely used in clinical practice. However, the dosage applied has varied fourfold in pediatric clinical studies. To validate an appropriate dosing regimen, this study investigated the pharmacokinetics of intranasal dexmedetomidine in Chinese children under 3 yr old.

METHODS

Intranasal dexmedetomidine 2 µg · kg-1 was administered to children with simple vascular malformations undergoing interventional radiological procedures. A population pharmacokinetic analysis with data from an optimized sparse-sampling design was performed using nonlinear mixed-effects modeling. Clearance was modeled using allometric scaling and a sigmoid postmenstrual age maturation model. Monte Carlo simulations were performed to assess the different dosing regimens.

RESULTS

A total of 586 samples from 137 children aged 3 to 36 months were included in the trial. The data were adequately described by a two-compartment model with first-order elimination. Body weight with allometric scaling and maturation function were significant covariates of dexmedetomidine clearance. The pharmacokinetic parameters for the median subjects (weight 10 kg and postmenstrual age 101 weeks) in the authors' study were apparent central volume of distribution 7.55 l, apparent clearance of central compartment 9.92 l · h-1, apparent peripheral volume of distribution 7.80 l, and apparent intercompartmental clearance 61.7 l · h-1. The simulation indicated that at the dose of 2 µg · kg-1, 95% of simulated individuals could achieve a target therapeutic concentration of 0.3 ng · ml-1 within 20 min, and the average peak concentration of 0.563 ng · ml-1 could be attained at 61 min.

CONCLUSIONS

The pharmacokinetic characteristics of intranasal dexmedetomidine were evaluated in Chinese pediatric patients aged between 3 and 36 months. An evidence-based dosing regimen at 2 µg · kg-1 could achieve a preset therapeutic threshold of mild to moderate sedation that lasted for up to 2 h.

EDITOR’S PERSPECTIVE

Effects of intranasal and intramuscular dexmedetomidine in cats receiving total intravenous propofol anesthesia

Background and Aim:

The efficacy of intranasal (IN) dexmedetomidine in cats as a premedication remains elusive. Thus, this study aimed to compare the perioperative and sparing effects of IN and intramuscular (IM) dexmedetomidine administration on propofol requirements for anesthetic induction in cats.

Materials and Methods:

This study randomly assigned 16 cats into two groups of IN or IM dexmedetomidine at 20 μg/kg. Sedation scores and side effects were recorded at time points of 0, 5, 10, 15, and 20 min after the dexmedetomidine administration. Anesthesia was induced with intravenous (IV) 1% propofol by titrating a bolus of 2 mg every 45 s and the total dose of the administered IV propofol to achieve endotracheal intubation was recorded.

Results:

Cats receiving IM dexmedetomidine were significantly associated with higher sedation scores. All cats were sedated at 20 min after premedication; however, the average composite sedation scores in the IN group were significantly lower than those in the IM group during premedication. Pre-operative side effects, including vomiting, were more frequently observed in the IN group (5 cats, 62.5%) than in the IM group (3 cats, 37.5%; p < 0.05). Higher body temperature (>1°F compared to baseline) was more frequently observed in the IN group (6 cats, 75.0%) than in the IM group (1 cat, 12.5%; p < 0.05). The dosage of required propofol in the IN group was significantly higher (1.1 ± 0.3 mg/kg) than that in the IM group (0.7 ± 0.2 mg/kg; p < 0.05). The duration of general anesthesia was comparable between the groups.

Conclusion:

IN dexmedetomidine produces moderate sedation and cats may have side effects, including vomiting and higher body temperature. Higher sparing effects of propofol were identified in the IM group compared with the IN group. Nonetheless, IN administration of dexmedetomidine provides a noninvasive alternative to the IM route.

Seeking the Light in Intensive Care Unit Sedation: The Optimal Sedation Strategy for Critically Ill Patients

The clinical approach to sedation in critically ill patients has changed dramatically over the last two decades, moving to a regimen of light or non-sedation associated with adequate analgesia to guarantee the patient’s comfort, active interaction with the environment and family, and early mobilization and assessment of delirium. Although deep sedation (DS) may still be necessary for certain clinical scenarios, it should be limited to strict indications, such as mechanically ventilated patients with Acute Respiratory Distress Syndrome (ARDS), status epilepticus, intracranial hypertension, or those requiring target temperature management. DS, if not indicated, is associated with prolonged duration of mechanical ventilation and ICU stay, and increased mortality. Therefore, continuous monitoring of the level of sedation, especially when associated with the raw EEG data, is important to avoid unnecessary oversedation and to convert a DS strategy to light sedation as soon as possible. The approach to the management of critically ill patients is multidimensional, so targeted sedation should be considered in the context of the ABCDEF bundle, a holistic patient approach. Sedation may interfere with early mobilization and family engagement and may have an impact on delirium assessment and risk. If adequately applied, the ABCDEF bundle allows for a patient-centered, multidimensional, and multi-professional ICU care model to be achieved, with a positive impact on appropriate sedation and patient comfort, along with other important determinants of long-term patient outcomes.

What's New in Intravenous Anaesthesia? New Hypnotics, New Models and New Applications

New anaesthetic drugs and new methods to administer anaesthetic drugs are continually becoming available, and the development of new PK-PD models furthers the possibilities of using arget controlled infusion (TCI) for anaesthesia. Additionally, new applications of existing anaesthetic drugs are being investigated. This review describes the current situation of anaesthetic drug development and methods of administration, and what can be expected in the near future.

Pharmacokinetic Pharmacodynamic Modelling Contributions to Improve Paediatric Anaesthesia Practice

The use of pharmacokinetic-pharmacodynamic models has improved anaesthesia practice in children through a better understanding of dose-concentration-response relationships, developmental pharmacokinetic changes, quantification of drug interactions and insights into how covariates (e.g., age, size, organ dysfunction, pharmacogenomics) impact drug prescription. Simulation using information from these models has enabled the prediction and learning of beneficial and adverse effects and decision-making around clinical scenarios. Covariate information, including the use of allometric size scaling, age and consideration of fat mass, has reduced population parameter variability. The target concentration approach has rationalised dose calculation. Paediatric pharmacokinetic-pharmacodynamic insights have led to better drug delivery systems for total intravenous anaesthesia and an expectation about drug offset when delivery is stopped. Understanding concentration-dependent adverse effects have tempered dose regimens. Quantification of drug interactions has improved the understanding of the effects of drug combinations. Repurposed drugs (e.g., antiviral drugs used for COVID-19) within the community can have important effects on drugs used in paediatric anaesthesia, and the use of simulation educates about these drug vagaries.

Safety, Pharmacokinetics/Pharmacodynamics, and Absolute Bioavailability of Dexmedetomidine Hydrochloride Nasal Spray in Healthy Subjects: A Randomized, Parallel, Escalating Dose Study

Background: The present study evaluated the safety, pharmacokinetics/pharmacodynamics (PK/PD), and absolute bioavailability (Fabs) of Dex nasal spray in healthy adult subjects, which serves as a bridge for the subsequent study in children.

Methods: Part 1: a double-blind, placebo-controlled, single ascending dose study was performed on 48 subjects. For 20-/40-μg groups, every 6/2 subjects received either Dex/placebo nasal spray or Dex/placebo injection in two periods. In total, 12/4 subjects each received 100 μg Dex/placebo nasal spray. Part 2: a randomized, double-blind, placebo-controlled study; 12/4 subjects received 150 μg Dex/placebo nasal spray. Part 3: a randomized, open, self-crossover study; 12 subjects received 20 μg and 100 μg Dex nasal spray in two periods alternately. The method of administration was optimized in Part 2 and Part 3.

Results: In part 1, Dex nasal spray was well tolerated up to the maximum dose of 100 μg, whereas the Fabs was tolerated to only 28.9%–32.3%. In Part 2 and Part 3, the optimized nasal spray method was adopted to promote the Fabs of Dex nasal spray to 74.1%–89.0%. A severe adverse event was found in Part 2. In Part 3 (100 μg), the Ramsay score increased the most and lasted the longest, whereas the BIS score decreased most significantly.

Conclusion: Using the optimized nasal spray method, a single dose of 20/100 μg of the test drug was safe and tolerable, and 100 μg may have approached or reached the plateau of sedation. In addition, it is found that the optimized method can greatly improve the bioavailability of the test drug, leading to its higher reference value.

Effect of intratracheal dexmedetomidine combined with ropivacaine on postoperative sore throat: a prospective randomised double-blinded controlled trial

Background

The present study aimed to investigate whether intratracheal dexmedetomidine combined with ropivacaine reduces the severity and incidence of postoperative sore throat after tracheal intubation under general anaesthesia.

Methods

Two hundred patients with American Society of Anaesthesiologists physical status I-II who were subjected to general anaesthesia were randomly divided into four groups, namely, Group D, Group R, Group DR and Group S; these groups received intratracheal dexmedetomidine (1 µg/kg), 0.8% ropivacaine (40 mg), dexmedetomidine (1 µg/kg) combined with 0.8% ropivacaine (40 mg) and normal saline before endotracheal intubation, respectively. The primary outcomes were the incidence and grade of sore throat and hoarseness at 2 h and 24 h after surgery. Moreover, the modified Observer's Assessment of Alertness/Sedation Scale results were recorded at each time point. The secondary outcomes were intraoperative haemodynamic fluctuations, intraoperative anaesthetic drug requirements, and adverse reactions during and after surgery. The patients’ vital signs before induction, before superficial anaesthesia, after superficial anaesthesia, before intubation, after intubation, and 1 min after intubation were recorded. The use of anaesthetic drugs and occurrence of adverse effects were also recorded.

Results

The incidence and severity of sore throat were significantly lower in Group DR than in the other three groups 2 h after the operation, but they were only significantly lower in Group DR than in the control group 24 h after the operation. Moreover, compared with Group S and Group D, Group DR exhibited more stable haemodynamics during intubation. The doses of remifentanil and propofol were significantly lower in Group DR than in the other groups.

Conclusion

The combined use of dexmedetomidine and ropivacaine for surface anaesthesia before intubation significantly reduced the incidence and severity of postoperative sore throat. This treatment also decreased anaesthetic drug requirements and intraoperative haemodynamic fluctuations and caused no adverse effects.

Trial registration

This clinical research was registered at the Chinese Clinical Trial Registry (ChiCTR1900022907, Registration date 30/04/2019).

Determination of the ED95 of intranasal sufentanil combined with intranasal dexmedetomidine for moderate sedation during endoscopic ultrasonography

BACKGROUND

Sedation during endoscopic ultrasonography (EUS) poses many challenges and moderate-to-deep sedation are often required. The conventional method to preform moderate-to-deep sedation is generally intravenous benzodiazepine alone or in combination with opioids. However, this combination has some limitations. Intranasal medication delivery may be an alternative to this sedation regimen.

AIM

To determine, by continual reassessment method (CRM), the minimal effective dose of intranasal sufentanil (SUF) when combined with intranasal dexmedetomidine (DEX) for moderate sedation of EUS in at least 95% of patients (ED₉₅).

METHODS

Thirty patients aged 18-65 and scheduled for EUS were recruited in this study. Subjects received intranasal DEX and SUF for sedation. The dose of DEX (1 μg/kg) was fixed, while the dose of SUF was assigned sequentially to the subjects using CRM to determine ED₉₅. The sedation status was assessed by modified observer’s assessment of alertness/sedation (MOAA/S) score. The adverse events and the satisfaction scores of patients and endoscopists were recorded.

RESULTS

The ED₉₅ was intranasal 0.3 μg/kg SUF when combined with intranasal 1 μg/kg DEX, with an estimated probability of successful moderate sedation for EUS of 94.9% (95% confidence interval: 88.1%-98.9%). When combined with intranasal 1 μg/kg DEX, probabilities of successful moderate sedation at each dose level of intranasal SUF were as follows: 0 μg/kg SUF, 52.8%; 0.1 μg/kg SUF, 75.4%; 0.2 μg/kg SUF, 89.9%; 0.3 μg/kg SUF, 94.9%; 0.4 μg/kg SUF, 98.0%; 0.5 μg/kg SUF, 99.0%.

CONCLUSION

The ED₉₅ needed for moderate sedation for EUS is intranasal 0.3 μg/kg SUF when combined with intranasal 1 μg/kg DEX, based on CRM.

Perioperative Low Dose Dexmedetomidine and Its Effect on the Visibility of the Surgical Field for Middle Ear Microsurgery: A Randomised Controlled Trial

Background and Purpose: There are many benefits of administering dexmedetomidine perioperatively. The pharmacokinetics (PK) and pharmacodynamics (PD) of intravenous, intranasal and oral dexmedetomidine that was administered before anesthesia were compared in this study, and the effects of dexmedetomidine on the surgical field visibility in tympanoplasty was evaluated. Methods: A single-blind, randomized controlled trial was conducted in a university-affiliated hospital where 45 patients who underwent tympanoplasty under general anesthesia were randomly allocated into three groups. Dexmedetomidine was administered by intravenous infusion at 0.8 μg.kg^-1 for 10 min, intranasal instillation at a drop rate of 1 μg.kg^-1 and oral intake at 4 μg.kg^-1 ten minutes before the induction of anesthesia. The PK and PD of dexmedetomidine after a single low dose administration and its effect on the surgical field in tympanoplasty were analysed. Results: A plasma concentration of dexmedetomidine of 220 pg/ml was achieved immediately after intravenous infusion and at 13.2 and 70.3 min for intranasal and oral administration, respectively. Dexmedetomidine decreased the heart rate (HR) and mean arterial pressure (MAP) in all three groups, although these values remained higher in the oral dexmedetomidine group at all eight time points. Intravenous dexmedetomidine provided the best visualization of the surgical field for opening of the tympanic sinus, 30 min after the start of the infusion (p < 0.05). Intranasal dexmedetomidine provided a significantly better visual field than oral dexmedetomidine for the repair of a tympanic membrane perforation using the fascia temporal muscle (p < 0.05). Conclusion: A single low dose of dexmedetomidine administered intravenously or intranasally could decrease HR and MAP, improve surgical field visibility and be appropriate for deliberate hypotension for surgical procedures of 1-2 h in length. Trial registration: Clinicaltrials.gov identifier: NCT03800641.

Dexmedetomidine sedation vs. inhaled general anesthesia for pediatric MRI: A retrospective cohort study: Dexmedetomidine sedation vs. inhaled general anesthesia for MRI

OBJECTIVES

The objective of this study was to evaluate the feasibility and the efficacy of a dexmedetomidine-based protocol followed by anesthesiologists unaccustomed to using dexmedetomidine during pediatric magnetic resonance imaging (MRI) examinations compared to conventional halogenated general anesthesia.

METHODS

This was a single-center retrospective cohort study including patients younger than 18 years who underwent sedation for MRI between August 1, 2018 and March 31, 2019. Patients who received dexmedetomidine were included in the DEX group and patients who had general anesthesia formed the GA group. Patients were matched with a ratio of 2 GA:1 DEX, based on age and type of MRI examination.

RESULTS

Overall, 78 patients were included (DEX=26; GA=52). Dexmedetomidine was significantly associated with a decrease in invasive ventilation (p<0.001) with no impact on image quality. The sedation failure rate was 42% with dexmedetomidine vs. 0% with general anesthesia (p<0.001). All cases of failure followed the intranasal administration of dexmedetomidine.

CONCLUSION

Dexmedetomidine seems to be a suitable sedation option for pediatric MRI. It provides an alternative to halogenated general anesthesia with the aim of limiting exposure to conventional anesthetic agents and invasive ventilation.

Recent Advances in the Clinical Value and Potential of Dexmedetomidine

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has sedative, anxiolytic, analgesic, sympatholytic, and opioid-sparing properties and induces a unique sedative response which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Recent studies indicate several emerging clinical applications via different routes. We review recent data on dexmedetomidine studies, particularly exploring the varying routes of administration, experimental implications, clinical effects, and comparative advantages over other drugs. A search was conducted on the PubMed and Web of Science libraries for recent studies using different combinations of the words “dexmedetomidine”, “route of administration”, and pharmacological effect. The current routes, pharmacological effects, and application categories of dexmedetomidine are presented. It functions by stimulating pre- and post-synaptic α2-adrenoreceptors within the central nervous system, leading to hyperpolarization of noradrenergic neurons, induction of an inhibitory feedback loop, and reduction of norepinephrine secretion, causing a sympatholytic effect, in addition to its anti-inflammation, sleep induction, bowel recovery, and sore throat reduction effects. Compared with similar α2-adrenoceptor agonists, dexmedetomidine has both pharmacodynamics advantage of a significantly greater α2:α1-adrenoceptor affinity ratio and a pharmacokinetic advantage of having a significantly shorter elimination half-life. In its clinical application, dexmedetomidine has been reported to present a significant number of benefits including safe sedation for various surgical interventions, improvement of intraoperative and postoperative analgesia, sedation for compromised airways without respiratory depression, nephroprotection and stability of hypotensive hemodynamics, reduction of postoperative nausea and vomiting and postoperative shivering incidence, and decrease of intraoperative blood loss. Although the clinical application of dexmedetomidine is promising, it is still limited and further research is required to enhance understanding of its pharmacological properties, patient selection, dosage, and adverse effects.

The Sedative Effects of Inhaled Nebulized Dexmedetomidine on Children: A Systematic Review and Meta-Analysis

BACKGROUND

Children that need surgery and medical examinations are often uncooperative, and preoperative sedation is necessary. We aimed to assess the safety and efficacy of inhaled nebulized dexmedetomidine in children for sedation that underwent medical examinations or surgery.

METHODS

We systematically searched PubMed, Web of science, Embase, and Cochrane library, for randomized controlled trials of Intranasal dexmedetomidine using a spray or a mucosal atomization device in children undergoing examination or elective surgery. We included all studies that analyzed the sedation efficiency of intranasal dexmedetomidine in children.

RESULTS

Ten studies with 1,233pediatric patients were included. Compared to other sedation treatments, inhaled nebulized dexmedetomidine showed similar sedation satisfaction [risk ratio RR: 1.02; 95% confidence interval (CI): 0.87-1.18; P = 0.83; I² = 72%]. there was also no statistical difference in the success rate of separation from parents (RR: 0.96; 95% CI: 0.82-1.12; P = 0.58; I² = 67%), and mask acceptability (RR: 1; 95% CI: 0.83-1.20; P = 0.99; I² = 35%). But it is worth mentioning that nebulized dexmedetomidine combined with ketamine provided better sedation satisfaction (RR: 0.69; 95% CI: 0.49-0.96; I² = 49%) and more satisfactory separation from parents (RR: 0.85; 95% CI: 0.74-0.97; I² = 0%). Moreover, nebulized dexmedetomidine reduced the occurrences of nausea and vomiting (RR: 0.28; 95% CI: 0.15-0.51; P < 0.01; I² = 10%) and emergence agitation (RR: 0.30; 95% CI: 0.18-0.49; P < 0.01; I² = 0%). There are no hypotension or arrhythmia reported that required intervention in all articles.

CONCLUSION

Compared to other premedication treatments, inhaled nebulized dexmedetomidine provided equivalent sedation satisfaction for the examination or preoperative sedation of children, but it reduced the occurrences of emergence agitation and postoperative nausea and vomiting.

Intranasal Dexmedetomidine for the Treatment of Pre-operative Anxiety and Insomnia: A Prospective, Randomized, Controlled, and Clinical Trial

BACKGROUND AND OBJECTIVE

Several patients with pre-operative anxiety and insomnia refuse to take sleeping pills because of the side effects of sleeping pills. This study aimed to evaluate the applicability of intranasal dexmedetomidine (DEX) in the treatment of pre-operative anxiety and insomnia.

METHODS

A total of 72 patients with insomnia and anxiety were randomly divided into two groups of intranasal DEX (n = 36) and intranasal normal saline (NS, n = 36). The primary outcomes included patients' time to fall asleep, total sleep time, insomnia severity index (ISI) after treatment, and satisfaction with the treatment effect. The secondary outcomes were mean arterial pressure (MAP), oxygen saturation (SPO₂), heart rate (HR), Narcotrend index (NI) in the first 2 h of treatment, and the incidence of adverse events within 12 h after treatment.

RESULTS

The time to fall asleep (22.08 ± 3.95 min) and total sleep time (400.06 ± 28.84 min) in the DEX group were significantly different from those in the NS group [time to fall asleep, 89.31 ± 54.56 min; total sleep time (295.19 ± 73.51 min; P < 0.001)]. ISI after treatment in the DEX group was lower than that in the NS group (P < 0.001). Satisfaction with the treatment effect was better in the DEX group than that in the NS group (P < 0.001). The general vital signs in the two groups were stable during the treatment. The drowsiness rate in the NS group was higher than that in the DEX group (P < 0.001).

CONCLUSION

Intranasal DEX can significantly improve pre-operative anxiety and insomnia.

CLINICAL TRIAL REGISTRATION

This study was registered on Chinese Clinical Trial Registry (http://www.chictr.org.cn/searchproj.aspx, ChiCTR2100044747).

Efficacy and Safety of Intranasal Dexmedetomidine vs. Oral Chloral Hydrate for Sedation in Children Undergoing Computed Tomography/Magnetic Resonance Imaging: A Meta-Analysis

OBJECTIVE

This meta-analysis aims to evaluate the sedative efficacy and safety of intranasal administration of dexmedetomidine (DEX) compared with oral chloral hydrate for Computed tomography (CT) or Magnetic Resonance Imaging (MRI) examination in Children.

METHODS

Cochrane Library, PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), and China WanFang Databases were searched to collect randomized controlled trials (RCTs) investigating intranasal DEX (test group) vs. oral chloral hydrate (control group) in pediatric CT/MRI examinations up to December 30, 2021. The data were analyzed using Stata 15.0 software.

RESULTS

Seven RCTs with 1,846 children were identified. The meta-analysis results showed that the success rate of sedation (RR = 1.14, 95% CI: 1.03-1.26, P = 0.011), sedation onset time [weighted mean difference (WMD) = -0.87, 95% CI: -1.42 to -0.31, P = 0.002], sedation duration (WMD = -9.05, 95% CI:-14.69 to -3.42, P = 0.002), time to awakening (WMD = -9.75, 95% CI:-17.57 to -1.94, P = 0.014), and incidence of nausea and vomiting [relative risk (RR) = 0.09, 95% CI:0.04-0.23, P < 0.001) of the test group were significantly better than those of the control group. However, no significant differences were identified in incidence of hypotension (RR = 1.18, 95% CI: 0.51-2.74) and bradycardia (RR = 1.17, 95% CI: 0.13-22.11) between the two groups.

CONCLUSION

Intranasal administration of DEX is superior to oral chloral hydrate for sedation during pediatric CT/MRI examinations and has a better safety profile.

Effects of different sedatives/analgesics on stress responses in patients undergoing craniotomy and bone flap decompression

Objective

To explore the effects of sedation and analgesia with dexmedetomidine and other drugs on the stress response in patients with cerebral hemorrhage after craniotomy hematoma removal and bone flap decompression and insertion of an indwelling endotracheal catheter.

Methods

A total of 180 patients with cerebral hemorrhage with consciousness disturbance who underwent emergency surgery were included in this study. They were divided into six groups treated with propofol, dexmedetomidine, lidocaine, sufentanil, dezocine, and remifentanil, respectively. Intravenous medication was given after recovery of spontaneous respiration, and stress responses were compared among the group.

Results

Serum concentrations of norepinephrine, epinephrine, and cortisol and systolic blood pressure were significantly correlated with drug treatment. Serum norepinephrine concentrations differed significantly among the groups, except between the sufentanil and propofol groups. There were significant differences in serum epinephrine concentrations among all groups, and significant differences in serum cortisol concentrations among all groups, except the propofol, dexmedetomidine, and lidocaine groups.

Conclusion

Dexmedetomidine can reduce the stress response in patients with intracerebral hemorrhage undergoing emergency craniotomy and bone flap decompression, and can reduce adverse events from an indwelling endotracheal catheter 3 hours post-operation.

Dexmedetomidine-soaked nasal packing can reduce pain and improve sleep quality after nasal endoscopic surgery: a double-blind, randomized, controlled clinical trial

STUDY OBJECTIVE

Bilateral endoscopic nasal surgery is usually associated with pain and sleep disturbance. The aim of this study was to evaluate the effects of dexmedetomidine-soaked nasal packing on analgesia and improvement of sleep quality in patients undergoing this surgery.

METHOD

Eighty patients were enrolled and randomly allocated into 4 groups. At the end of surgery, dexmedetomidine-soaked nasal packings were applied to three groups with a dosage of 1 μg kg^-1 (D1), 2μg kg^-1 (D2), 4 μg kg^-1 (D4) and normal saline-soaked nasal packing (NS) was applied to a fourth group. The primary outcome was postoperative pain scores using a visual analog scale (VAS) recorded at six time points: before the surgery (T1); 2 h (T2), 8 h (T3), 24 h (T4), 48 h (T5) after surgery; and at the moment of nasal packing removal (T6). Secondary outcomes were postoperative sleep status evaluated by the Pittsburgh sleep quality index (PSQI) and subjective sleep quality value (SSQV). Factors affecting sleep, hemodynamic changes, and adverse events were also recorded.

RESULTS

Compared with the NS group, dexmedetomidine-soaked nasal packing significantly relieved postoperative pain and improved sleep quality. The effect was similar between D2 and D4, which was greater than in D1. However, D2 was associated with fewer adverse events.

CONCLUSIONS

Dexmedetomidine-soaked nasal packing not only offers effective analgesia but also improves postoperative sleep quality in patients undergoing bilateral endoscopic nasal surgery. Taking effect and adverse events into consideration, a dosage of 2μg kg^-1 may be optimal.

TRIAL REGISTRATION

www.chictr.org.cn/index.aspx (ChiCTR1900025692) Retrospectively registered 5 September 2019.

Dexmedetomidine vs. lidocaine for postoperative analgesia in pediatric patients undergoing craniotomy: a protocol for a prospective, randomized, double-blinded, placebo-controlled trial

Background

Postoperative pain is a common problem that occurs in pediatric patients following neurosurgery which may lead to severe complications. Dexmedetomidine is a commonly used adjuvant medicine in craniotomy owing to its sedative, amnestic, analgesic, and neuroprotective properties. Besides, studies suggest that lidocaine has similar effects on sedation, analgesia, and neuroprotection. Both two adjuvants can reduce postoperative pain after neurosurgery in adults. However, it is still unknown whether dexmedetomidine or lidocaine can reduce postoperative pain in children undergoing craniotomy, and if yes, which is a better medicine choice. Therefore, we aimed to compare the effect of dexmedetomidine vs. lidocaine on postoperative pain in pediatric patients after craniotomy.

Methods/design

We will perform a randomized (1:1:1), double-blind, placebo-controlled, single-center trial. Children aged 1–12 years scheduled for craniotomy will be eligible for inclusion. The 255 recruited participants will be stratified by age in two strata (1–6 years and 7–12 years), and then each stratum will be equally randomized to three groups: group D (infusion of dexmedetomidine [intervention group]), group L (infusion of lidocaine [intervention group]), and group C (infusion of normal saline [control group]). Patients will be followed up at 1 h, 2 h, 4 h, 24 h, and 48 h after surgery. The primary outcome will be total sufentanil consumption within 24 h after surgery.

Discussion

In this clinical trial, we expect to clarify and compare the postoperative analgesic effect of dexmedetomidine vs. lidocaine infusion on pediatric patients undergoing craniotomy. We believe that the results of this trial will provide more choices for postoperative analgesia for the pediatric population.

Trial registration

Chinese ClinicalTrials.gov ChiCTR1800019411. Registered on 10 November 2018

Intranasal Dexmedetomidine Accompanied by Cartoon Video Preoperation for Reducing Emergence Delirium in Children Undergoing Strabismus Surgery: A Prospective Randomized Trial

Background: After general anesthesia, many pediatric patients present with emergence delirium (ED). The aim of this study was to determine whether dexmedetomidine intranasal premedication accompanied by a cartoon video 30 min before general anesthesia would have an effect on reducing emergence delirium in preschool children.

Methods: One hundred and forty children aged 3–6 year undergoing elective strabismus surgery were randomly to be premedicated with 2 μg kg⁻¹ intranasal dexmedetomidine accompanied by the viewing of a cartoon video (Group DV) or without any premedication as usual (Group C). The primary outcome was the incidence of emergence delirium at the postanesthesia care unit (PACU), evaluated by the Pediatric Anesthesia Emergence Delirium (PAED) scale. The secondary outcomes included: the Modified Yale Preoperative Anxiety Scale (mYPAS) upon separation from parents; the Induction Compliance Checklist score (ICC); the PACU discharge time; the parental satisfaction score; the incidences of the side effects and the Post-Hospital Behavior Questionnaire (PHBQ) score during the first day after surgery.

Results: The incidence of emergence agitation (PAED score ≥ 10) was reduced in Group DV compared with Group C [8 (11.4%) vs. 24 (34.3%); P = 0.001]. None of the patients in the DV group experienced severe emergence agitation (PAED score ≥ 15), as compared with the C group (P = 0.006). The mYPAS score upon separation from parents (P < 0.001) and the incidence of poor coordination (ICC ≥ 4) during induction (P < 0.001) were significantly lower in Group DV than in Group C. In Group DV, the PACU discharge time was longer (P < 0.001), and the parental satisfaction score was higher (P < 0.001). However, during the first day after surgery, the PHBQ score was lower in Group DV compared with Group C (P = 0.001).

Conclusions: Premedication with 2 μg kg⁻¹ intranasal dexmedetomidine accompanied by cartoon video viewing can dramatically reduce emergence delirium in preschool children undergoing strabismus surgery, relieve preoperative anxiety and improve the parental satisfaction and the postoperative behavior changes during the first day after surgery.

Clinical Trial Registration: ChiCTR2000030678.

Intranasal Dexmedetomidine in Elderly Patients (Aged > 65 Years) During Maxillofacial Surgery: Sedative Properties and Safety Analysis

PURPOSE

Light sedation rather than intravenous sedation is preferred when patients have a low heart rate and blood pressure during maxillofacial surgery. Intranasal administration of dexmedetomidine is reported to be efficacious and safe in adults. However, dexmedetomidine could be unsuitable for routine clinical use in elderly patients because many of these patients take β-blockers, which increase the cardiovascular effects of dexmedetomidine. The objectives of the study were to evaluate the sedative properties and safety of intranasal dexmedetomidine, regardless of concurrent β-blocker treatment, in elderly patients who underwent maxillofacial surgery.

METHODS

This study was a retrospective analysis of 535 patients aged > 65 years (American Society of Anesthesiologists physical status I or II) who were undergoing maxillofacial surgery. Very anxious patients and those with hypertension received intranasal 1 µg/kg dexmedetomidine through an intranasal mucosal atomization device before anesthesia (local ropivacaine).

RESULTS

Intranasal administration of dexmedetomidine decreased the requirement for midazolam before surgery (18 of 252 vs 63 of 283, P < .0001), but increased the requirement for norepinephrine (102 of 252 vs 8 of 283, P < .0001) during or after the surgery. A combination of a β-blocker and intranasal administration of dexmedetomidine reduced the hemodynamic parameters for an extended period. Intranasal administration of dexmedetomidine resulted in bradycardia and hypotension, regardless of concurrent β-blocker treatment.

CONCLUSIONS

Intranasal 1 µg/kg dexmedetomidine was associated with a high sedation score during the operation, but also with bradycardia and hypotension.

Population Modelling of Dexmedetomidine Pharmacokinetics and Haemodynamic Effects After Intravenous and Subcutaneous Administration

Background and Objective

Dexmedetomidine is a potent agonist of α₂-adrenoceptors causing dose-dependent sedation in humans. Intravenous dexmedetomidine is commonly used perioperatively, but an extravascular route of administration would be favoured in palliative care. Subcutaneous infusions provide desired therapeutic plasma concentrations with fewer unwanted effects as compared with intravenous dosing. We aimed to develop semi-mechanistic population models for predicting pharmacokinetic and pharmacodynamic profiles of dexmedetomidine after intravenous and subcutaneous dosing.

Methods

Non-linear mixed-effects modelling was performed using previously collected concentration and haemodynamic effects data from ten (eight in the intravenous phase) healthy human subjects, aged 19–27 years, receiving 1 µg/kg of intravenous or subcutaneous dexmedetomidine during a 10-min infusion.

Results

The absorption of dexmedetomidine from the subcutaneous injection site, and distribution to local subcutaneous fat tissue was modelled using a semi-physiological approach consisting of a depot and fat compartment, while a two-compartment mammillary model explained further disposition. Dexmedetomidine-induced reductions in plasma norepinephrine concentrations were accurately described by an indirect response model. For blood pressure models, the net effect was specified as hyper- and hypotensive effects of dexmedetomidine due to vasoconstriction on peripheral arteries and sympatholysis mediated via the central nervous system, respectively. A heart rate model combined the dexmedetomidine-induced sympatholytic effect, and input from the central nervous system, predicted from arterial blood pressure levels. Internal evaluation confirmed the predictive performance of the final models, as well as the accuracy of the parameter estimates with narrow confidence intervals.

Conclusions

Our final model precisely describes dexmedetomidine pharmacokinetics and accurately predicts dexmedetomidine-induced sympatholysis and other pharmacodynamic effects. After subcutaneous dosing, dexmedetomidine is taken up into subcutaneous fat tissue, but our simulations indicate that accumulation of dexmedetomidine in this compartment is insignificant.

ClinicalTrials.org

NCT02724098 and EudraCT 2015-004698-34

Electronic supplementary material

The online version of this article (10.1007/s40262-020-00900-3) contains supplementary material, which is available to authorized users.

Intranasal dexmedetomidine: Procedural sedation in palliative care: A case report

BACKGROUND

This report describes the use of intranasal dexmedetomidine to control incident pain and facilitate daily change of dressing in a patient with cutaneous breast cancer.

CASE PRESENTATION

A 45-year-old woman with extensive thoracic cutaneous metastatic bilateral breast cancer requiring daily 2-hour dressing changes to manage significant exudate. Pain during change of dressing was severe and unresponsive to usual analgesics. Deeper sedation was not an option as the patient was required to change position 1 hour into dressing change.

CASE MANAGEMENT

Intranasal dexmedetomidine was administered 40 minutes prior to dressing change and provided effective rousable sedation and analgesia for the duration of the procedure.

CASE OUTCOME

Dexmedetomidine provided rousable sedation, allowing the patient to follow commands and mobilise during the procedure. Pain was controlled. No adverse cardiovascular effects were noted with the use of intranasal dexmedetomidine.

CONCLUSION

Intranasal dexmedetomidine is a potentially useful medication for procedural sedation in the management of complex wound dressings. It provides rousable short-term sedation, anxiolysis and analgesia. Further research into the role of intranasal dexmedetomidine to facilitate challenging dressing changes in a community setting is warranted.

Pharmacokinetic concepts for dexmedetomidine target-controlled infusion pumps in children

Pharmacokinetic parameter estimates are used in mathematical equations (pharmacokinetic models) to describe concentration changes with time in a population and are specific to that population. Simulation using these models and their parameter estimates can enrich understanding of drug behavior and serve as a basis for study design. Pharmacokinetic concepts are presented pertaining to future designs of dexmedetomidine target-controlled infusion pumps in children. This manuscript provides the pediatric anesthesiologist with an understanding of the nuances that should be considered when using target-controlled infusion pumps; how the central volume may differ between populations, how clearance changes with age, and the impact of adverse effects on dose. In addition, the ideal loading dose and rate of delivery to achieve target concentration without adverse cardiovascular effects are reviewed, and finally, dose considerations for obese children, based on contact-sensitive half-time, are introduced. An understanding of context-sensitive half-time changes with age enables anesthetic practitioners to better estimate duration of effect after cessation of dexmedetomidine infusion. Use of these known pharmacokinetic parameters and covariate information for the pediatric patient could readily be incorporated into commercial target-controlled infusion pumps to allow effective and safe open-loop administration of dexmedetomidine in children.

A comprehensive review of integrative pharmacology-based investigation: A paradigm shift in traditional Chinese medicine

Over the past decade, traditional Chinese medicine (TCM) has widely embraced systems biology and its various data integration approaches to promote its modernization. Thus, integrative pharmacology-based traditional Chinese medicine (TCMIP) was proposed as a paradigm shift in TCM. This review focuses on the presentation of this novel concept and the main research contents, methodologies and applications of TCMIP. First, TCMIP is an interdisciplinary science that can establish qualitative and quantitative pharmacokinetics-pharmacodynamics (PK-PD) correlations through the integration of knowledge from multiple disciplines and techniques and from different PK-PD processes in vivo. Then, the main research contents of TCMIP are introduced as follows: chemical and ADME/PK profiles of TCM formulas; confirming the three forms of active substances and the three action modes; establishing the qualitative PK-PD correlation; and building the quantitative PK-PD correlations, etc. After that, we summarize the existing data resources, computational models and experimental methods of TCMIP and highlight the urgent establishment of mathematical modeling and experimental methods. Finally, we further discuss the applications of TCMIP for the improvement of TCM quality control, clarification of the molecular mechanisms underlying the actions of TCMs and discovery of potential new drugs, especially TCM-related combination drug discovery.