Prolonged sedation due to accumulation of conjugated metabolites of midazolam

Microdose Cocktail Study Reveals the Activity and Key Influencing Factors of OATP1B, P-Gp, BCRP, and CYP3A in End-Stage Renal Disease Patients

OATP1B, P-gp, BCRP, and CYP3A are the most contributing drug-metabolizing enzymes or transporters (DMETs) for commonly prescribed medication. Their activities may change in end-stage renal disease (ESRD) patients with large inter-individual variabilities (IIVs), leading to altered substrate drug exposure and ultimately elevated safety risk. However, the changing extent and indictive influencing factors are not quantified so far. Here, a microdose cocktail regimen containing five sensitive substrate drugs (pitavastatin, dabigatran etexilate, rosuvastatin, midazolam, and atorvastatin) for these DMETs was administrated to Chinese healthy volunteers and ESRD patients. Drug pharmacokinetics profiles were determined, together with physiological, pharmacogenetic, and gut microbiome signature. Population pharmacokinetic and machine learning model were established to identify key influencing factors and quantify their contribution to drug exposure change. The exposure of pitavastatin, dabigatran, rosuvastatin, and atorvastatin increased to 1.8-, 3.1-, 1.1-, and 1.3-fold, respectively, whereas midazolam exposure decreased by 72% in ESRD patients. Notably, in addition to disease state, the relative abundance of genus Veillonella and Clostridium_XIVb were firstly identified as significant influencing factors for PTV and RSV apparent clearance, respectively, suggesting their indicative role for OATP and BCRP activity evaluation. Moreover, several genera were found to strongly associate with drug clearance and reduce unexplained IIVs. Accordingly, it was estimated that OATP1B and intestine P-gp activity decreased by 35-75% and 29-44%, respectively, whereas BCRP and CYP3A4 activity may upregulate to some extent. Our study provides a quantitative and mechanistic understanding of individual DMET activity and could support precision medicine of substrate drugs in ESRD patients.

Remimazolam in neurosurgery

PURPOSE OF REVIEW

Remimazolam represents a novel intravenous anesthetic agent whose use began in 2020. As a new ultrashort-acting benzodiazepine, it has unique pharmacokinetic properties, such as remifentanil, designed to be active and easily transformed into inactive metabolites by tissue esterases. The purpose is to search the literature and evidences to use this new medication in neurosurgery.

RECENT FINDINGS

Currently, it is allowed for procedural sedation and general anesthesia in a few countries. More advantages of this new drug are predictable onset, short duration, rapid recovery profile, low liability for respiratory depression, cardiovascular depression, lack of injection pain, and known reversible agent, flumazenil. A literature search led to the conclusions that remimazolam may maintain better hemodynamic stability and reduce the episodes of hypotension during coil embolization of cerebral aneurysm and that general anesthesia with remimazolam does not alter cerebral metabolism, cerebral blood flow, and cerebral blood volume. Also, because it facilitates safe and quick arousal, it can be a suitable medication for awake craniotomy.

SUMMARY

With more desirable properties such as reduced risk of prolonged sedation and reliable safety margin, it is expected to increase the safety of sedation and general anesthesia in future.

Anaesthesia in chronic dialysis patients: A narrative review

The provision of anaesthesia for individuals receiving chronic dialysis can be challenging. Sedation and anaesthesia are frequently managed by critical care clinicians in the intensive care unit or operating room. This narrative review summarizes the important principles of sedation and anaesthesia for individuals on long-term dialysis, with reference to the best available evidence. Topics covered include the pharmacology of anaesthetic agents, the impacts of patient characteristics upon the pre-anaesthetic assessment and critical illness, and the fundamentals of dialysis access procedures.

Investigating the Relationship Between Midazolam Serum Concentrations and Paediatric Delirium in Critically Ill Children

OBJECTIVES

Intravenous midazolam is widely used for sedation in critically ill children. Sometimes, these children develop a paediatric delirium (PD). Our aim was to determine the relationship between midazolam serum concentration and the development of new PD in critically ill children.

DESIGN

Prospective observational pilot study.

SETTING

Paediatric Intensive Care Unit (PICU), Groningen, the Netherlands.

PATIENTS

All children admitted to the PICU from October-December 2019 who received continuous midazolam administration.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty-five percent (n = 7) of the included patients (n = 28) developed new PD. In most patients, PD occurred following midazolam dose reduction. The median cumulative midazolam dose was higher in patients who developed PD compared to those without PD. We analysed 104 blood samples to determine the midazolam concentrations. To determine whether patients had PD, the Sophia Observation withdrawal Symptoms-Paediatric Delirium (SOS-PD) score was used. Patients suffering PD (n = 7) had a lower median midazolam concentration on that day compared with the day prior to PD detection. Analysis of the active metabolites, 1-hydroxymidazolam and 1-hydroxymidazolam glucuronide, showed similar results.

CONCLUSIONS

PD may be linked to a sudden and significant reduction in the midazolam concentration in critically ill children. Further investigation in larger patient populations is necessary to validate our findings.

Impact of genetic polymorphisms and drug-drug interactions mediated by carboxylesterase 1 on remimazolam deactivation

Remimazolam (Byfavo, Acacia Pharma), a recent Food and Drug Administration-approved ester-linked benzodiazepine, offers advantages in sedation, such as rapid onset and predictable duration, making it suitable for broad anesthesia applications. Its favorable pharmacological profile is primarily attributed to rapid hydrolysis, the primary metabolism pathway for its deactivation. Thus, understanding remimazolam hydrolysis determinants is essential for optimizing its clinical use. This study aimed to identify the enzyme(s) and tissue(s) responsible for remimazolam hydrolysis and to evaluate the influence of genetic polymorphisms and drug-drug interactions on its hydrolysis in the human liver. An initial incubation study with remimazolam and PBS, human serum, and the S9 fractions of human liver and intestine demonstrated that remimazolam was exclusively hydrolyzed by human liver S9 fractions. Subsequent incubation studies utilizing a carboxylesterase inhibitor (bis(4-nitrophenyl) phosphate), recombinant human carboxylesterase 1 (CES1) and carboxylesterase 2 confirmed that remimazolam is specifically hydrolyzed by CES1 in human liver. Furthermore, in vitro studies with wild-type CES1 and CES1 variants transfected cells revealed that certain genetic polymorphisms significantly impair remimazolam deactivation. Notably, the impact of CES1 G143E was verified using individual human liver samples. Moreover, our evaluation of the drug-drug interactions between remimazolam and several other substrates/inhibitors of CES1-including simvastatin, enalapril, clopidogrel, and sacubitril-found that clopidogrel significantly inhibited remimazolam hydrolysis at clinically relevant concentrations, with CES1 genetic variants potentially influencing the interactions. In summary, CES1 genetic variants and its interacting drugs are crucial factors contributing to interindividual variability in remimazolam hepatic hydrolysis, holding the potential to serve as biomarkers for optimizing remimazolam use. SIGNIFICANCE STATEMENT: This investigation demonstrates that remimazolam is deactivated by carboxylesterase 1 (CES1) in the human liver, with CES1 genetic variants and drug-drug interactions significantly influencing its metabolism. These findings emphasize the need to consider CES1 genetic variability and potential drug-drug interactions in remimazolam use, especially in personalized pharmacotherapy to achieve optimal anesthetic outcomes.

Dental treatments under sedation-analgesia in patients who are unable to collaborate: a prospective observational study

Background

Excessive fear of dental procedures leads to disruptive behavior during dental examinations and treatments. Dental examinations and treatments of these patients usually require additional techniques, such as sedation. The most commonly used techniques are inhalation of nitrous oxide, infusion of propofol with fentanyl, and premedication and infusion of midazolam.

Methods

A prospective observational epidemiological study was conducted on patients who required sedoanalgesia techniques for dental exploration and procedures. The reasons for the inability of patients to cooperate (excessive fear or intellectual disability), age, sex, weight, systemic pathology, oral pathology, treatment performed, time of intervention, anesthetic technique performed, and occurrence of complications were recorded.

Results

In total, 218 patients were studied. Sixty-five patients came for fear of dental treatment and 153 for presenting with a diagnosis of intellectual disability and not collaborating in the treatment with local anesthesia. The average age of all patients was 30.54 ± 17.30 years. The most frequent oral pathologies found in patients with excessive fear were tartar (6.8%) and wisdom teeth (6.4%), followed by missing teeth (5%). In patients with disabilities, a combination of tartar and cavities appeared most frequently (41.3%), followed by cavities (15.6%). The most frequently used sedoanalgesia technique was the infusion of propofol with fentanyl in both groups of patients, followed by nitrous oxide.

Conclusion

The combination of propofol and fentanyl was the most frequently used alternative in patients who were unable to collaborate because of intellectual disability or carry out longer or more complex treatments. Inhaled nitrous oxide and midazolam were the sedative techniques of choice for simpler oral treatments, such as tartrectomies, shallow obturations, and shorter interventions, or in younger patients.

Pharmacokinetics, Pharmacodynamics, and Side Effects of Midazolam: A Review and Case Example

Midazolam, a short-acting benzodiazepine, is widely used to alleviate patient anxiety, enhance compliance, and aid in anesthesia. While its side effects are typically dose-dependent and manageable with vigilant perioperative monitoring, serious cardiorespiratory complications, including fatalities and permanent neurological impairment, have been documented. Prolonged exposure to benzodiazepines, such as midazolam, has been associated with neurological changes in infants. Despite attempts to employ therapeutic drug monitoring for optimal sedation dosing, its efficacy has been limited. Consequently, efforts are underway to identify alternative predictive markers to guide individualized dosing and mitigate adverse effects. Understanding these factors is crucial for determining midazolam's suitability for future administration, particularly after a severe adverse reaction. This article aims to elucidate the factors influencing midazolam's pharmacokinetics and pharmacodynamics, potentially leading to adverse events. Finally, a case study is presented to exemplify the complex investigation into the causative factors of midazolam-related adverse events.

Ketamine in Critically Ill Patients: Use, Perceptions, and Potential Barriers

Objective: To evaluate practitioner use of ketamine and identify potential barriers to use in acutely and critically ill patients. To compare characteristics, beliefs, and practices of ketamine frequent users and non-users. Methods: An online survey developed by members of the Society of Critical Care Medicine (SCCM) Clinical Pharmacy and Pharmacology Section was distributed to physician, pharmacist, nurse practitioner, physician assistant and nurse members of SCCM. The online survey queried SCCM members on self-reported practices regarding ketamine use and potential barriers in acute and critically ill patients. Results: Respondents, 341 analyzed, were mostly adult physicians, practicing in the United States at academic medical centers. Clinicians were comfortable or very comfortable using ketamine to facilitate intubation (80.0%), for analgesia (77.9%), procedural sedation (79.4%), continuous ICU sedation (65.8%), dressing changes (62.4%), or for asthma exacerbation and status epilepticus (58.8% and 40.4%). Clinicians were least comfortable with ketamine use for alcohol withdrawal and opioid detoxification (24.7% and 23.2%). Most respondents reported "never" or "infrequently" using ketamine preferentially for continuous IV analgesia (55.6%) or sedation (61%). Responses were mixed across dosing ranges and duration. The most common barriers to ketamine use were adverse effects (42.6%), other practitioners not routinely using the medication (41.5%), lack of evidence (33.5%), lack of familiarity (33.1%), and hospital/institutional policy guiding the indication for use (32.3%). Conclusion: Although most critical care practitioners report feeling comfortable using ketamine, there are many inconsistencies in practice regarding dose, duration, and reasons to avoid or limit ketamine use. Further educational tools may be targeted at practitioners to improve appropriate ketamine use.

A Comparison of Midazolam and Propofol for Deep Sedation in Patients with Acute Respiratory Distress Syndrome Requiring Neuromuscular Blocking Agents

Purpose: The optimal agent for deep sedation in patients undergoing continuous infusion (CI) neuromuscular blocking agent (NMBA) use for acute respiratory distress syndrome (ARDS) is unknown. The purpose of this study is to compare the efficacy and safety of propofol and midazolam in ARDS patients requiring CI NMBA. Methods: A multi-center, retrospective study was performed in mechanically ventilated (MV) adult patients requiring CI NMBA for management of ARDS. The primary outcome was to compare the time to liberation from MV in patients sedated with propofol vs midazolam. Results: In the 109 patients included, there was no difference in time to MV liberation with propofol as compared to midazolam (121 hr [Interquartile range (IQR) 67 195] vs 98 hr [IQR 48, 292], P = .72). Median time to sedation emergence after NMBA discontinuation was shorter in patients receiving propofol (12.9 hr [IQR 19.8, 72.5] vs 31.5 hr [IQR 6.4, 34.6], P < .01). There were no significant differences in time to therapeutic sedation, ICU stay, mortality, and adverse events. Conclusion: Propofol may be an effective and safe alternative to midazolam for patients undergoing CI NMBA for ARDS. Additionally, patients receiving propofol may have a quicker return to light sedation after NMBA discontinuation.

Benefits of remimazolam as an anesthetic sedative for older patients: A review

Owing to the decreased levels of receptors in the peripheral and central nervous systems, the functions of various organ systems decline in older patients. When administering anesthesia to older patients, it is necessary to consider the effects of medication on the homeostatic balance. Remimazolam, a new benzodiazepine, was recently developed as an anesthetic drug that has shown promise in clinical anesthesia application owing to its molecular structure, targets, pharmacodynamics, and pharmacokinetic characteristics. Remimazolam exhibits a rapid onset and metabolism, with minor effects on liver and kidney functions. Moreover, the drug has a specific antagonist, flumazenil. It is safer to use in older patients than other anesthetic sedatives and has been widely used since its introduction. Comparisons of the pharmacokinetics, metabolic pathways, effects on target organs, and hemodynamics of different drugs with those of commonly used anesthetic sedative drugs are useful to inform clinical practice. This article elaborates on the benefits of remimazolam compared with those of other anesthetic sedatives for sedation in older patients to demonstrate how it offers a new option for anesthetics in older patients. In cases involving older patients with increased clinical complexities or very old patients requiring anesthesia, remimazolam can be selected as the preferred anesthetic sedative, as outlined in this review.

Top 25 Medications the Plastic and Reconstructive Surgery Trainee Should Know for an Emergency Medicine Department Consult

SUMMARY

Plastic surgery trainees are often called to render care in the emergency department (eg, for established patients, trauma, burns). Broad-based knowledge in pharmacotherapeutics during these encounters is critical. This includes an understanding of pain medications, anxiolytics, local anesthetics, antibiotics, anticoagulants, antidotes, and more to ensure optimal patient care. The purpose of this report is to describe 25 frequently used and other important medications that plastic surgery trainees should know for an adult emergency department encounter.

Trends in sedation-analgesia practices in pediatric liver transplant patients admitted postoperatively to the pediatric intensive care unit: An analysis of data from the pediatric health information system (PHIS) database

BACKGROUND

Children admitted to the pediatric intensive care unit (PICU), after liver transplantation, frequently require analgesia and sedation in the immediate postoperative period. Our objective was to assess trends and variations in sedation and analgesia used in this cohort.

METHODS

Multicenter retrospective cohort study using the Pediatric Health Information System from 2012 to 2022.

RESULTS

During the study period, 3963 patients with liver transplantation were admitted to the PICU from 32 US children's hospitals with a median age of 2 years [IQR: 0.00, 10.00]. 54 percent of patients received mechanical ventilation (MV). Compared with patients without MV, those with MV were more likely to receive morphine (57% vs 49%, p < .001), fentanyl (57% vs 44%), midazolam (45% vs 31%), lorazepam (39% vs. 24%), dexmedetomidine (38% vs 30%), and ketamine (25% vs 12%), all p < .001. Vasopressor usage was also higher in MV patients (22% vs. 35%, p < .001). During the study period, there was an increasing trend in the utilization of dexmedetomidine and ketamine, but the use of benzodiazepine decreased (p < .001).

CONCLUSION

About 50% of patients who undergo liver transplant are placed on MV in the PICU postoperatively and receive a greater amount of benzodiazepines in comparison with those without MV. The overall utilization of dexmedetomidine and ketamine was more frequent, whereas the administration of benzodiazepines was less during the study period. Pediatric intensivists have a distinctive opportunity to collaborate with the liver transplant team to develop comprehensive guidelines for sedation and analgesia, aimed at enhancing the quality of care provided to these patients.

Pharmacological Investigation of Hypoalbuminemia on the Prolonged and Potentiated Action of Midazolam in Rats

Midazolam (MDZ) is clinically used for its sedative and anticonvulsant properties. However, its prolonged or potentiated effects are sometimes concerning. The main binding protein of MDZ is albumin, and reduced serum albumin levels could lead to MDZ accumulation, thereby potentiating or prolonging its effects. Previous investigations have not thoroughly examined these phenomena from a behavioral pharmacology standpoint. Consequently, this study aimed to evaluate both the prolonged and potentiated effects of MDZ, as well as the effects of serum albumin levels on the action of MDZ in low-albumin rats. Male Wistar rats were classified into control (20% protein diet), low-protein (5% protein), and non-protein groups (0% protein diet) and were fed the protein-controlled diets for 30 d to obtain low-albumin rats. The locomotor activity and muscle relaxant effects of MDZ were evaluated using the rotarod, grip strength, and open-field tests conducted 10, 60, and 120 min after MDZ administration. Serum albumin levels decreased significantly in the low-protein and non-protein diet groups compared with those in the control group. Compared with the control rats, low-albumin rats demonstrated a significantly shorter time to fall, decreased muscle strength, and a significant decrease in the distance traveled after MDZ administration in the rotarod, grip strength, and open-field tests, respectively. Decreased serum albumin levels potentiated and prolonged the effects of MDZ. Hence, serum albumin level is a critical parameter associated with MDZ administration, which should be monitored, and any side effects related to decreased albumin levels should be investigated.

Finding the ideal sedative: a non-inferiority study of remimazolam vs propofol in endoscopic retrograde cholangiopancreatography

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) requires an ideal sedative that provides a predictable action duration and meets safety requirements. We compared the efficacies and safeties of remimazolam and propofol in patients who had undergone ERCP.

METHODS

In this prospective, randomized, single-blind, single-center study, we compared the performances of remimazolam and propofol for inpatient ERCP. Study medications were administered under the supervision of an endoscopist. One hundred and ten patients scheduled to undergo ERCP were randomly assigned to receive remimazolam or propofol. The primary endpoint was a composite of successful completion of the procedure and no requirement for rescue medication. Secondary endpoints included sedation efficacy, recovery time, and adverse events.

RESULTS

Of the 110 patients randomized, 108 underwent sedation, and ERCP (53 received remimazolam and 55 propofol). The primary endpoint was met for remimazolam and propofol in 100% of patients in both arms. Incidences and frequencies of emergent adverse events, including desaturation, requiring treatment were comparable in both arms. However, ERCP was started sooner in the propofol arm (mean, 63.18 ± 16.56 s) than in the remimazolam arm (75.23 ± 32.27 s; P-value = 0.02). Time to full alertness after ERCP was also significantly shorter in the propofol arm (304.18 ± 146.25 vs 448.34 ± 224.09 s; P-value <0.001).

CONCLUSION

Remimazolam is not inferior to propofol in achieving successful ERCP completion without rescue medication. Incidences of adverse events were comparable. Remimazolam is a safe and effective alternative to propofol for ERCP sedation, expanding options for clinicians and improving patient outcomes.

Sedation for Patients with Sepsis: Towards a Personalised Approach

This article looks at the challenges of sedoanalgesia for sepsis patients, and argues for a personalised approach. Sedation is a necessary part of treatment for patients in intensive care to reduce stress and anxiety and improve long-term prognoses. Sepsis patients present particular difficulties as they are at increased risk of a wide range of complications, such as multiple organ failure, neurological dysfunction, septic shock, ARDS, abdominal compartment syndrome, vasoplegic syndrome, and myocardial dysfunction. The development of any one of these complications can cause the patient's rapid deterioration, and each has distinct implications in terms of appropriate and safe forms of sedation. In this way, the present article reviews the sedative and analgesic drugs commonly used in the ICU and, placing special emphasis on their strategic administration in sepsis patients, develops a set of proposals for sedoanalgesia aimed at improving outcomes for this group of patients. These proposals represent a move away from simplistic approaches like avoiding benzodiazepines to more "objective-guided sedation" that accounts for a patient's principal pathology, as well as any comorbidities, and takes full advantage of the therapeutic arsenal currently available to achieve personalised, patient-centred treatment goals.

The Clearance of Midazolam and Metabolites during Continuous Renal Replacement Therapy in Critically Ill Patients with COVID-19

INTRODUCTION

Midazolam-based continuous intravenous sedation in patients admitted to the intensive care unit (ICU) was a necessity during the COVID-19 pandemic. However, benzodiazepine-based sedation is associated with a high incidence of benzodiazepine-related delirium and additional days on mechanical ventilation. Due to the requirement of high midazolam doses in combination with the impaired renal clearance (CL) of the pharmacological active metabolite 1-OH-midazolam-glucuronide (10% compared to midazolam), ICU patients with COVID-19 and continuous renal replacement therapy (CRRT) were at risk of unintended prolonged sedation. Several CRRT-related factors may have influenced the delivered CL of midazolam and its metabolites. Therefore, the aim of the study was to identify and describe these CRRT-related factors.

METHODS

Pre-filter blood samples and ultrafiltrate samples were collected simultaneously. Midazolam, 1-OH-midazolam, and 1-OH-midazolam-glucuronide plasma samples were analyzed using an UPLC-MS/MS method. The prescribed CRRT dose was corrected for downtime and filter integrity using the urea ratio (urea concentration in effluent/urea concentration plasma). CL of midazolam and its metabolites were calculated with the delivered CRRT dose (corrected for downtime and saturation coefficient [SD]).

RESULTS

Three patients on continuous venovenous hemodialysis (CVVHD) and 2 patients on continuous venovenous hemodiafiltration (CVVHDF) were included. Midazolam, 1-OH-midazolam, and 1-OH-midazolam-glucuronide concentrations were 2,849 (0-6,700) μg/L, 153 (0-295) μg/L, and 27,297 (1,727-39,000) μg/L, respectively. The SD was 0.03 (0.02-0.03) for midazolam, 0.05 (0.05-0.06) for 1-OH-midazolam, and 0.33 (0.23-0.43) for 1-OH-midazolam-glucuronide. The delivered CRRT CL was 1.4 (0-1.7) mL/min for midazolam, 2.7 (0-3.5) mL/min for 1-OH-midazolam, and 15.7 (4.0-27.7) mL/min for 1-OH-midazolam-glucuronide.

CONCLUSIONS

Midazolam and 1-OH-midazolam were not removed during CVVHD and CVVHDF. However, 1-OH-midazolam-glucuronide was removed reasonably, approximately up to 43%. CRRT modality, filter integrity, and downtime affect this removal. These data imply a personalized titration of midazolam in critically ill patients with renal failure and awareness for the additional sedative effects of its active metabolites.

General Anesthesia With Remimazolam and Peripheral Nerve Blocks Is Useful for Femoral Surgery in Patients With Severe Aortic Stenosis: A Case Report

Traditional intravenous anesthetics and opioid analgesics are susceptible to inducing hemodynamic instability. Herein, we describe a case of open reduction and internal fixation of a femoral neck fracture in a patient with severe aortic stenosis. General anesthesia was accomplished using remimazolam, an intravenous anesthetic devoid of hemodynamic instability properties, in combination with a peripheral nerve block. During the surgical procedure, the need for circulatory agonist was reduced to a single dose, and satisfactory pain management was achieved. This approach represents an alternative method for patients with circulatory risk undergoing femoral surgery.

Pharmacokinetics in Critically Ill Children with Acute Kidney Injury

Acute kidney injury (AKI) is a commonly encountered comorbidity in critically ill children. The coexistence of AKI disturbs drug pharmacokinetics and pharmacodynamics, leading to clinically significant consequences. This can complicate an already critical clinical scenario by causing potential underdosing or overdosing giving way to possible therapeutic failures and adverse reactions. Current available studies offer little guidance to help maneuver such complex dosing regimens and decision-making in pediatric patients as most of them are done on heterogeneous groups of adult populations. Though there are some studies on drug dosing during continuous renal replacement therapy (CRRT), their utility is in question because of the recent advances in CRRT technology. Our review aims to discuss the principles of pharmacokinetics pertinent for honing the existing practices of drug dosing in critically ill children with AKI, and the various complexities and intricate challenges involved. This in turn will provide a framework to help enable caretakers to tailor dosing regimens in complex clinical setups with further ease and precision.

The Impact of Suboptimal 25-Hydroxyvitamin D Levels and Cholecalciferol Replacement on the Pharmacokinetics of Oral Midazolam in Control Subjects and Patients With Chronic Kidney Disease

The aim of this study was to investigate the impact of suboptimal 25-hydroxyvitamin D (25-VitD) and cholecalciferol (VitD3 ) supplementation on the pharmacokinetics of oral midazolam (MDZ) in control subjects and subjects with chronic kidney disease (CKD). Subjects with CKD (n = 14) and controls (n = 5) with suboptimal 25-VitD levels (<30 ng/mL) were enrolled in a 2-phase study. In phase 1 (suboptimal), subjects were administered a single oral dose of VitD3 (5000 IU) and MDZ (2 mg). In phase 2 (replete) subjects who achieved 25-VitD repletion after receiving up to 16 weeks of daily cholecalciferol were given the identical single oral doses of VitD3 and MDZ as in phase 1. Concentrations of MDZ and metabolites, 1'-hydroxymidazolam (1'-OHMDZ), and 1'-OHMDZ glucuronide (1'-OHMDZ-G) were measured by liquid chromatography-tandem mass spectrometry and pharmacokinetic analysis was performed. Under suboptimal 25-VitD, reductions in MDZ clearance and renal clearance of 47% and 87%, respectively, and a 72% reduction in renal clearance of 1'-OHMDZ-G were observed in CKD vs controls. In phase 1 versus phase 2, MDZ clearance increased in all control subjects, with a median (interquartile range) increase of 10.5 (0.62-16.7) L/h. No changes in MDZ pharmacokinetics were observed in subjects with CKD between phases 1 and 2. The effects of 25-VitD repletion on MDZ disposition was largely observed in subjects without kidney disease. Impaired MDZ metabolism and/or excretion alterations due to CKD in a suboptimal 25-VitD state may not be reversed by cholecalciferol therapy. Suboptimal 25-VitD may augment the reductions in MDZ and 1'-OHMDZ-G clearance values observed in patients with CKD.

Machine learning and structure-based modeling for the prediction of UDP-glucuronosyltransferase inhibition

UDP-glucuronosyltransferases (UGTs) are responsible for 35% of the phase II drug metabolism. In this study, we focused on UGT1A1, which is a key UGT isoform. Strong inhibition of UGT1A1 may trigger adverse drug/herb-drug interactions, or result in disorders of endobiotic metabolism. Most of the current machine learning methods predicting the inhibition of drug metabolizing enzymes neglect protein structure and dynamics, both being essential for the recognition of various substrates and inhibitors. We performed molecular dynamics simulations on a homology model of the human UGT1A1 structure containing both the cofactor- (UDP-glucuronic acid) and substrate-binding domains to explore UGT conformational changes. Then, we created models for the prediction of UGT1A1 inhibitors by integrating information on UGT1A1 structure and dynamics, interactions with diverse ligands, and machine learning. These models can be helpful for further prediction of drug-drug interactions of drug candidates and safety treatments.

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UGTs are responsible for 35% of the phase II drug metabolism reactions

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We created machine learning models for prediction of UGT1A1 inhibitors

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Our simulations suggested key residues of UGT1A1 involved in the substrate binding

Acute Kidney Injury Predictors and Outcomes after Cardiac Surgery in Children with Congenital Heart Disease: An Observational Cohort Study

Acute Kidney Injury (AKI) commonly complicates cardiac surgery in children with congenital heart disease (CHD). In this study we assessed incidence, risk factors, and outcomes of postoperative AKI, while testing the hypothesis that, depending on the underlying diagnosis, there would be significant differences in AKI incidence among different diagnostic groups. We conducted an observational cohort study of children with CHD undergoing cardiac surgery in a single tertiary center between January 2019 and August 2021 (n = 362). Kidney Disease Improving Global Outcome (KDIGO) criteria were used to determine the incidence of postoperative AKI. Diagnosis was incorporated into multivariate models using an anatomic-based CHD classification system. Overall survival was estimated using Kaplan−Meier curves. Log-rank test and adjusted Cox proportional hazard modelling were used to test for differences in survival distributions and determine AKI effect on survival function, respectively. AKI occurred in 70 (19.3%), with 21.4% in-hospital mortality for AKI group. Younger age, lower weight, longer cardiopulmonary bypass time, preoperative mechanical ventilation and diagnostic category were associated with postoperative AKI. Resolution rate was 92.7% prior to hospital discharge for survivors. AKI was associated with longer duration of mechanical ventilation, ICU and hospital length of stay. AKI patients had significantly higher probability of all-cause mortality postoperatively when compared to the non-AKI group (log-rank test, p < 0.001). Adjusted hazard ratio for AKI versus non-AKI group was 11.08 (95% CI 2.45−50.01; p = 0.002). Diagnostic category was associated with cardiac surgery-related AKI in children with CHD, a finding supporting the development of lesion specific models for risk stratification. Postoperative AKI had detrimental impact on clinical outcomes and was associated with decreased survival to hospital discharge.

Construction of a prediction model for drug removal rate in hemodialysis based on chemical structures

In designing drug dosing for hemodialysis patients, the removal rate (RR) of the drug by hemodialysis is important. However, acquiring the RR is difficult, and there is a need for an estimation method that can be used in clinical settings. In this study, the RR predictive model was constructed using the RR of known drugs by quantitative structure-activity relationship (QSAR) analysis. Drugs were divided into a model construction drug set (75%) and a model validation drug set (25%). The RR was collected from 143 medicines. The objective variable (RR) and chemical structural characteristics (descriptors) of the drug (explanatory variable) were used to construct a prediction model using partial least squares (PLS) regression and artificial neural network (ANN) analyses. The determination coefficients in the PLS and ANN methods were 0.586 and 0.721 for the model validation drug set, respectively. QSAR analysis successfully constructed dialysis RR prediction models that were comparable or superior to those using pharmacokinetic parameters. Considering that the RR dataset contains potential errors, we believe that this study has achieved the most reliable RR prediction accuracy currently available. These predictive RR models can be achieved using only the chemical structure of the drug. This model is expected to be applied at the time of hemodialysis.

New Insight Concerning Therapeutic Drug Monitoring-The Importance of the Concept of Psychonephrology

Recently, the concept of psychonephrology was developed and has been recognized as a field of study that focuses on nephrology and mental health fields, such as psychiatry and psychosomatic medicine. Indeed, patients with chronic kidney disease frequently suffer from mental problems as the disease stage progresses. Most psychotropic drugs are hepatically metabolized, but some are unmetabolized and eliminated renally. However, renal disease may affect the pharmacokinetics of many psychotropic drugs, as the decreased renal function not only delays the urinary excretion of the drug and its metabolites but also alters various pharmacokinetic factors, such as protein-binding, enterohepatic circulation, and activity of drug-metabolizing enzymes. Therefore, when prescribing drug therapy for patients with both renal disease and mental issues, we should consider reducing the dosage of psychotropic drugs that are eliminated mainly via the kidney and also carefully monitor the blood drug concentrations of other drugs with a high extrarenal clearance, such as those that are largely metabolized in the liver. Furthermore, we should carefully consider the dialyzability of each psychotropic drug, as the dialyzability impacts the drug clearance in patients with end-stage renal failure undergoing dialysis. Therapeutic drug monitoring (TDM) may be a useful tool for adjusting the dosage of psychotropic drugs appropriately in patients with renal disease. We herein review the pharmacokinetic considerations for psychotropic drugs in patients with renal disease as well as those undergoing dialysis and offer new insight concerning TDM in the field of psychonephrology.

Hyperinflammation Reduces Midazolam Metabolism in Critically Ill Adults with COVID-19

BACKGROUND AND OBJECTIVE

Many patients treated for COVID-19 related acute respiratory distress syndrome in the intensive care unit are sedated with the benzodiazepine midazolam. Midazolam undergoes extensive metabolism by CYP3A enzymes, which may be inhibited by hyperinflammation. Therefore, an exaggerated proinflammatory response, as often observed in COVID-19, may decrease midazolam clearance. To develop a population pharmacokinetic model for midazolam in adult intensive care unit patients infected with COVID-19 and to assess the effect of inflammation, reflected by IL-6, on the pharmacokinetics of midazolam.

METHODS

Midazolam blood samples were collected once a week between March 31 and April 30 2020. Patients were excluded if they concomitantly received CYP3A4 inhibitors, CYP3A4 inducers and/or continuous renal replacement therapy. Midazolam and metabolites were analyzed with an ultra-performance liquid chromatography-tandem mass spectrometry method. A population pharmacokinetic model was developed, using nonlinear mixed effects modelling. IL-6 and CRP, markers of inflammation, were analyzed as covariates.

RESULTS

The data were described by a one-compartment model for midazolam and the metabolites 1-OH-midazolam and 1-OH-midazolam-glucuronide. The population mean estimate for midazolam clearance was 6.7 L/h (4.8-8.5 L/h). Midazolam clearance was reduced by increased IL-6 and IL-6 explained more of the variability within our patients than CRP. The midazolam clearance was reduced by 24% (6.7-5.1 L/h) when IL-6 increases from population median 116 to 300 pg/mL.

CONCLUSIONS

Inflammation, reflected by high IL-6, reduces midazolam clearance in critically ill patients with COVID-19. This knowledge may help avoid oversedation, but further research is warranted.

Review of remimazolam and sedatives in the intensive care unit

Remimazolam is a novel intravenous ultra-short acting benzodiazepine that has the potential of being a safe and effective new sedative for use in intensive care unit (ICU) settings. Because remimazolam metabolizes rapidly by being hydrolyzed to an inactive metabolite (CNS 7054) through non-specific tissue esterase activity, specific dosing adjustment for older adults and for patients with renal or hepatic impairment patients (except for those with severe hepatic impairment) is not required. In addition, research has shown that remimazolam may be reversed by administration of flumazenil, as its half time was sufficiently short compared to flumazenil. It shows a lower incidence of cardiorespiratory depression, less injection pain, and no fatal complications such as propofol infusion syndrome and malignant hyperthermia of inhalational anesthetics. Future studies to study the suitability of remimazolam for managing the sedation of ICU patients who need sedation for a long time over several days is required.

Sequential use of midazolam and dexmedetomidine for long-term sedation may reduce weaning time in selected critically ill, mechanically ventilated patients: a randomized controlled study

Background

Current sedatives have different side effects in long-term sedation. The sequential use of midazolam and dexmedetomidine for prolonged sedation may have distinct advantages. We aimed to evaluate the efficacy and safety of the sequential use of midazolam and either dexmedetomidine or propofol, and the use of midazolam alone in selected critically ill, mechanically ventilated patients.

Methods

This single-center, randomized controlled study was conducted in medical and surgical ICUs in a tertiary, academic medical center. Patients enrolled in this study were critically ill, mechanically ventilated adult patients receiving midazolam, with anticipated mechanical ventilation for ≥ 72 h. They passed the spontaneous breathing trial (SBT) safety screen, underwent a 30-min-SBT without indication for extubation and continued to require sedation. Patients were randomized into group M-D (midazolam was switched to dexmedetomidine), group M-P (midazolam was switched to propofol), and group M (sedation with midazolam alone), and sedatives were titrated to achieve the targeted sedation range (RASS − 2 to 0).

Results

Total 252 patients were enrolled. Patients in group M-D had an earlier recovery, faster extubation, and more percentage of time at the target sedation level than those in group M-P and group M (all P < 0.001). They also experienced less weaning time (25.0 h vs. 49.0 h; HR1.47, 95% CI 1.05 to 2.06; P = 0.025), and a lower incidence of delirium (19.5% vs. 43.8%, P = 0.002) than patients in group M. Recovery (P < 0.001), extubation (P < 0.001), and weaning time (P = 0.048) in group M-P were shorter than in group M, while the acquisition cost of sedative drug was more expensive than other groups (both P < 0.001). There was no significant difference in adverse events among these groups (all P > 0.05).

Conclusions

The sequential use of midazolam and dexmedetomidine was an effective and safe sedation strategy for long-term sedation and could provide clinically relevant benefits for selected critically ill, mechanically ventilated patients.

Trial registration

NCT02528513. Registered August 19, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03967-5.

Sedation level with midazolam: a pediatric surgery approach

Midazolam (MDZ) is a short-acting benzodiazepine that is widely used to induce and maintain general anesthesia during diagnostic and therapeutic procedures in pediatric patients due to its sedative properties. The aim of this study was to perform a systematic review without a meta-analysis to identify scientific articles and clinical assays concerning MDZ-induced sedation for a pediatric surgery approach. One hundred and twenty-eight results were obtained. After critical reading, 37 articles were eliminated, yielding 91 publications. Additional items were identified, and the final review was performed with a total of 106 publications.

In conclusion, to use MDZ accurately, individual patient characteristics, the base disease state, comorbidities, the treatment burden and other drugs with possible pharmacological interactions or adverse reactions must be considered to avoid direct alterations in the pharmacokinetics and pharmacodynamics of MDZ to obtain the desired effects and avoid overdosing in the pediatric population.

Pre-hospital and emergency department treatment of convulsive status epilepticus in adults: an evidence synthesis

BACKGROUND

Convulsive status epilepticus is defined as ≥ 5 minutes of either continuous seizure activity or repetitive seizures without regaining consciousness. It is regarded as an emergency condition that requires prompt treatment to avoid hospitalisation and to reduce morbidity and mortality. Rapid pre-hospital first-line treatment of convulsive status epilepticus is currently benzodiazepines, administered either by trained caregivers in the community (e.g. buccal midazolam, rectal diazepam) or by trained health professionals via intramuscular or intravenous routes (e.g. midazolam, lorazepam). There is a lack of clarity about the optimal treatment for convulsive status epilepticus in the pre-hospital setting.

OBJECTIVES

To assess the current evidence on the clinical effectiveness and cost-effectiveness of treatments for adults with convulsive status epilepticus in the pre-hospital setting.

DATA SOURCES

We searched major electronic databases, including MEDLINE, EMBASE, PsycInfo®, CINAHL, CENTRAL, NHS Economic Evaluation Database, Health Technology Assessment Database, Research Papers in Economics, and the ISPOR Scientific Presentations Database, with no restrictions on publication date or language of publication. Final searches were carried out on 21 July 2020.

REVIEW METHODS

Systematic review of randomised controlled trials assessing adults with convulsive status epilepticus who received treatment before or on arrival at the emergency department. Eligible treatments were any antiepileptic drugs offered as first-line treatments, regardless of their route of administration. Primary outcomes were seizure cessation, seizure recurrence and adverse events. Two reviewers independently screened all citations identified by the search strategy, retrieved full-text articles, extracted data and assessed the risk of bias of the included trials. Results were described narratively.

RESULTS

Four trials (1345 randomised participants, of whom 1234 were adults) assessed the intravenous or intramuscular use of benzodiazepines or other antiepileptic drugs for the pre-hospital treatment of convulsive status epilepticus in adults. Three trials at a low risk of bias showed that benzodiazepines were effective in stopping seizures. In particular, intramuscular midazolam was non-inferior to intravenous lorazepam. The addition of levetiracetam to clonazepam did not show clear advantages over clonazepam alone. One trial at a high risk of bias showed that phenobarbital plus optional phenytoin was more effective in terminating seizures than diazepam plus phenytoin. The median time to seizure cessation from drug administration varied from 1.6 minutes to 15 minutes. The proportion of people with recurrence of seizures ranged from 10.4% to 19.1% in two trials reporting this outcome. Across trials, the rates of respiratory depression among participants receiving active treatments were generally low (from 6.4% to 10.6%). The mortality rate ranged from 2% to 7.6% in active treatment groups and from 6.2% to 15.5% in control groups. Only one study based on retrospective observational data met the criteria for economic evaluation; therefore, it was not possible to draw any robust conclusions on cost-effectiveness.

LIMITATIONS

The limited number of identified trials and their differences in terms of treatment comparisons and outcomes hindered any meaningful pooling of data. None of the included trials was conducted in the UK and none assessed the use of buccal midazolam or rectal diazepam. The review of economic evaluations was hampered by lack of suitable data.

CONCLUSIONS

Both intravenous lorazepam and intravenous diazepam administered by paramedics are more effective than a placebo in the treatments of adults with convulsive status epilepticus, and intramuscular midazolam is non-inferior to intravenous lorazepam. Large well-designed clinical trials are needed to establish which benzodiazepines are more effective and preferable in the pre-hospital setting.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42020201953.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 26, No. 20. See the NIHR Journals Library website for further project information.

Associated Factors of High Sedative Requirements within Patients with Moderate to Severe COVID-19 ARDS

The coronavirus pandemic continues to challenge global healthcare. Severely affected patients are often in need of high doses of analgesics and sedatives. The latter was studied in critically ill coronavirus disease 2019 (COVID-19) patients in this prospective monocentric analysis. COVID-19 acute respiratory distress syndrome (ARDS) patients admitted between 1 April and 1 December 2020 were enrolled in the study. A statistical analysis of impeded sedation using mixed-effect linear regression models was performed. Overall, 114 patients were enrolled, requiring unusual high levels of sedatives. During 67.9% of the observation period, a combination of sedatives was required in addition to continuous analgesia. During ARDS therapy, 85.1% (n = 97) underwent prone positioning. Veno-venous extracorporeal membrane oxygenation (vv-ECMO) was required in 20.2% (n = 23) of all patients. vv-ECMO patients showed significantly higher sedation needs (p < 0.001). Patients with hepatic (p = 0.01) or renal (p = 0.01) dysfunction showed significantly lower sedation requirements. Except for patient age (p = 0.01), we could not find any significant influence of pre-existing conditions. Age, vv-ECMO therapy and additional organ failure could be demonstrated as factors influencing sedation needs. Young patients and those receiving vv-ECMO usually require increased sedation for intensive care therapy. However, further studies are needed to elucidate the causes and mechanisms of impeded sedation.

Outcomes in Critically Ill Patients Sedated with Intravenous Lormetazepam or Midazolam: A Retrospective Cohort Study

The benzodiazepine, midazolam, is one of the most frequently used sedatives in intensive care medicine, but it has an unfavorable pharmacokinetic profile when continuously applied. As a consequence, patients are frequently prolonged and more deeply sedated than intended. Due to its distinct pharmacological features, including a cytochrome P450-independent metabolization, intravenous lormetazepam might be clinically advantageous compared to midazolam. In this retrospective cohort study, we compared patients who received either intravenous lormetazepam or midazolam with respect to their survival and sedation characteristics. The cohort included 3314 mechanically ventilated, critically ill patients that received one of the two drugs in a tertiary medical center in Germany between 2006 and 2018. A Cox proportional hazards model with mortality as outcome and APACHE II, age, gender, and admission mode as covariates revealed a hazard ratio of 1.75 [95% CI 1.46–2.09; p < 0.001] for in-hospital mortality associated with the use of midazolam. After additionally adjusting for sedation intensity, the HR became 1.04 [95% CI 0.83–1.31; p = 0.97]. Thus, we concluded that excessive sedation occurs more frequently in critically ill patients treated with midazolam than in patients treated with lormetazepam. These findings require further investigation in prospective trials to assess if lormetazepam, due to its ability to maintain light sedation, might be favorable over other benzodiazepines for sedation in the ICU.

Review of the Physiology and Anesthetic Considerations for Pleuroscopy/Medical Thoracoscopy

Pleuroscopy or medical thoracoscopy is the second most common utilized procedure after bronchoscopy in the promising field of interventional pulmonology. Its main application is for the diagnosis and management of benign or malignant pleural effusions. Entry into the hemithorax is associated with pain and patient discomfort, whereas concurrently, notable pathophysiologic alterations occur. Therefore, frequently procedural sedation and analgesia is needed, not only to alleviate the patient's emotional stress and discomfort by mitigating the anxiety and minimizing the pain but also for yielding better procedural conditions for the operator. The scope of this review is to present the physiologic derangements occurring in pleuroscopy and compare the various anesthetic techniques and sedative agents that are currently being used in this context.

Remimazolam: Non-Clinical and Clinical Profile of a New Sedative/Anesthetic Agent

A program to identify novel intravenous sedatives with a short and predictable duration of action was initiated in the late 1990's by Glaxo Wellcome. The program focussed on the identification of ester-based benzodiazepine derivatives that are rapidly broken down by esterases. Remimazolam was identified as one of the lead compounds. The project at Glaxo was shelved for strategic reasons at the late lead optimization stage. Via the GSK ventures initiative, the program was acquired by the small biotechnology company, TheraSci, and, through successive acquisitions, developed as the besylate salt at CeNeS and PAION. The development of remimazolam besylate has been slow by industry standards, primarily because of the resource limitations of these small companies. It has, however, recently been approved for anesthesia in Japan and South Korea, procedural sedation in the United States, China, and Europe, and for compassionate use in intensive care unit sedation in Belgium. A second development program of remimazolam was later initiated in China, using a slightly different salt form, remimazolam tosylate. This salt form of the compound has also recently been approved for procedural sedation in China. Remimazolam has the pharmacological profile of a classical benzodiazepine, such as midazolam, but is differentiated from other intravenous benzodiazepines by its rapid conversion to an inactive metabolite resulting in a short onset/offset profile. It is differentiated from other intravenous hypnotic agents, such as propofol, by its low liability for cardiovascular depression, respiratory depression, and injection pain. The benzodiazepine antagonist flumazenil can reverse the effects of remimazolam in case of adverse events and further shorten recovery times. The aim of this review is to provide an analysis of, and perspective on, published non-clinical and clinical information on 1) the pharmacology, metabolism, pharmacokinetics, and pharmacodynamic profile of remimazolam, 2) the profile of remimazolam compared with established agents, 3) gaps in the current understanding of remimazolam, 4) the compound's discovery and development process and 5) likely future developments in the clinical use of remimazolam.

Effects of Propofol on Hemodynamic Profile in Adults Receiving Targeted Temperature Management

Background: Propofol is a key component for the management of sedation and shivering during targeted temperature management (TTM) following cardiac arrest. The cardiac depressant effects of propofol have not been described during TTM and may be especially relevant given the stress to the myocardium following cardiac arrest. The purpose of this study is to describe hemodynamic changes associated with propofol administration during TTM. Methods: This single center, retrospective cohort study evaluated adult patients who received a propofol infusion for at least 30 minutes during TTM. The primary outcome was the change in cardiovascular Sequential Organ Failure Assessment (cvSOFA) score 30 minutes after propofol initiation. Secondary outcomes included change in systolic blood pressure (SBP), mean arterial pressure (MAP), heart rate (HR), and vasopressor requirements (VR) expressed as norepinephrine equivalents at 30, 60, 120, 180, and 240 minutes after propofol initiation. A multivariate regression was performed to assess the influence of propofol and body temperature on MAP, while controlling for vasopressor dose and cardiac arrest hospital prognosis (CAHP) score. Results: The cohort included 40 patients with a median CAHP score of 197. The goal temperature of 33°C was achieved for all patients. The median cvSOFA score was 1 at baseline and 0.5 at 30 minutes, with a non-significant change after propofol initiation ( P = .96). SBP and MAP reductions were the greatest at 60 minutes (17 and 8 mmHg; P < .05 for both). The median change in HR at 120 minutes was −9 beats/minute from baseline. This reduction was sustained through 240 minutes ( P < .05). No change in VR were seen at any time point. In multivariate regression, body temperature was the only characteristic independently associated with changes in MAP (coefficient 4.95, 95% CI 1.6-8.3). Conclusion: Administration of propofol during TTM did not affect cvSOFA score. The reductions in SBP, MAP, and HR did not have a corresponding change in vasopressor requirements and are likely not clinically meaningful. Propofol appears to be a safe choice for sedation in patients receiving targeted temperature management after cardiac arrest.

Current State of Analgesia and Sedation in the Pediatric Intensive Care Unit

Critically ill pediatric patients often require complex medical procedures as well as invasive testing and monitoring which tend to be painful and anxiety-provoking, necessitating the provision of analgesia and sedation to reduce stress response. Achieving the optimal combination of adequate analgesia and appropriate sedation can be quite challenging in a patient population with a wide spectrum of ages, sizes, and developmental stages. The added complexities of critical illness in the pediatric population such as evolving pathophysiology, impaired organ function, as well as altered pharmacodynamics and pharmacokinetics must be considered. Undersedation leaves patients at risk of physical and psychological stress which may have significant long term consequences. Oversedation, on the other hand, leaves the patient at risk of needing prolonged respiratory, specifically mechanical ventilator, support, prolonged ICU stay and hospital admission, and higher risk of untoward effects of analgosedative agents. Both undersedation and oversedation put critically ill pediatric patients at high risk of developing PICU-acquired complications (PACs) like delirium, withdrawal syndrome, neuromuscular atrophy and weakness, post-traumatic stress disorder, and poor rehabilitation. Optimal analgesia and sedation is dependent on continuous patient assessment with appropriately validated tools that help guide the titration of analgosedative agents to effect. Bundled interventions that emphasize minimizing benzodiazepines, screening for delirium frequently, avoiding physical and chemical restraints thereby allowing for greater mobility, and promoting adequate and proper sleep will disrupt the PICU culture of immobility and reduce the incidence of PACs.

The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study

Midazolam is metabolized by the developmentally regulated intestinal and hepatic drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5. It is frequently administered orally to children, yet knowledge is lacking on the oral bioavailability in term neonates up until 1 year of age. Furthermore, the dispositions of the major metabolites 1-OH-midazolam (OHM) and 1-OH-midazolam-glucuronide (OHMG) after oral administration are largely unknown for the entire pediatric age span. We aimed to fill these knowledge gaps with a pediatric [14 C]midazolam microtracer population pharmacokinetic study. Forty-six stable, critically ill children (median age 9.8 (range 0.3-276.4) weeks) received a single oral [14 C]midazolam microtracer (58 (40-67) Bq/kg) when they received a therapeutic continuous intravenous midazolam infusion and had an arterial line in place enabling blood sampling. For midazolam, in a one-compartment model, bodyweight was a significant predictor for clearance (0.98 L/hour) and volume of distribution (8.7 L) (values for a typical individual of 5 kg). The typical oral bioavailability in the population was 66% (range 25-85%). The exposures of OHM and OHMG were highest for the youngest age groups and significantly decreased with postnatal age. The oral bioavailability of midazolam, largely reflective of intestinal and hepatic CYP3A activity, was on average lower than the reported 49-92% for preterm neonates, and higher than the reported 21% for children> 1 year of age and 30% for adults. As midazolam oral bioavailability varied widely, systemic exposure of other CYP3A-substrate drugs after oral dosing in this population may also be unpredictable, with risk of therapy failure or toxicity.

Escalate and De-Escalate Therapies for Intracranial Pressure Control in Traumatic Brain Injury

Severe traumatic brain injury (TBI) is frequently associated with an elevation of intracranial pressure (ICP), followed by cerebral perfusion pressure (CPP) reduction. Invasive monitoring of ICP is recommended to guide a step-by-step “staircase approach” which aims to normalize ICP values and reduce the risks of secondary damage. However, if such monitoring is not available clinical examination and radiological criteria should be used. A major concern is how to taper the therapies employed for ICP control. The aim of this manuscript is to review the criteria for escalating and withdrawing therapies in TBI patients. Each step of the staircase approach carries a risk of adverse effects related to the duration of treatment. Tapering of barbiturates should start once ICP control has been achieved for at least 24 h, although a period of 2–12 days is often required. Administration of hyperosmolar fluids should be avoided if ICP is normal. Sedation should be reduced after at least 24 h of controlled ICP to allow neurological examination. Removal of invasive ICP monitoring is suggested after 72 h of normal ICP. For patients who have undergone surgical decompression, cranioplasty represents the final step, and an earlier cranioplasty (15–90 days after decompression) seems to reduce the rate of infection, seizures, and hydrocephalus.

A fast and simple method for the simultaneous analysis of midazolam, 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, plasma and urine

For the quantification of the sedative and anesthetic drug midazolam and its main (active) metabolites 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, human EDTA plasma, human heparin plasma and human urine a single accurate method by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed. Protein precipitation as sample preparation, without the need of a time-consuming deglucuronidation step for the quantification of 1-hydroxymidazolam glucuronide, resulted in a simple and rapid assay suitable for clinical practice with a total runtime of only 1.1  min. The four components and the isotope-labeled internal standards were separated on a C₁₈ column and detection was performed with a triple-stage quadrupole mass spectrometer operating in positive ionization mode. The method was validated based on the "Guidance for Industry Bioanalytical Method Validation" (Food and Drug Administration, FDA) and the "Guideline on bioanalytical method validation" of the European Medicines Agency (EMA). Linearity was proven over the ranges of 5-1500 μg/L for midazolam, 1-hydroxymidazolam and 4-hydroxymidazolam and 25-5000 μg/L for 1-hydroxymidazolam glucuronide, using a sample volume of 100 μL. Matrix comparison indicated that the assay is also applicable to other human matrices like EDTA and heparin plasma and urine. Stability experiments showed good results for the stability of midazolam, 1-hydroxymidazolam and 1-hydroxymidazolam glucuronide in serum, EDTA and heparin plasma and urine stored for 7 days under different conditions. At room temperature, 4-hydroxymidazo-lam is stable for 7 days in EDTA plasma, but stable for only 3 days in serum and heparin plasma and less than 24 h in urine. All four compounds were found to be stable in serum, EDTA plasma, heparin plasma and urine for 7 days after sample preparation and for 3 freeze-thaw cycles. The assay has been applied in therapeutic drug monitoring of midazolam for (pediatric) intensive care patients.

Impact of concurrent remifentanil on the sedative effects of remimazolam, midazolam and propofol in cynomolgus monkeys

Drug-drug interactions can substantially change pharmacological effects of the individual substances involved. For the use of sedatives or anaesthetics, having knowledge of the extent and characteristics of such interactions is crucial for ensuring the proper protection of patients undergoing any kind of sedation. Remimazolam is a new ultra-short acting benzodiazepine that is currently under development for intravenous use in procedural sedation and general anaesthesia. It exhibits a fast onset and fast offset which enables a more rapid recovery than currently available drugs in that class, such as midazolam. The purpose of this study was to more closely investigate the sedative properties and pharmacodynamic drug-drug interaction potential of remimazolam with the opioid analgesic remifentanil and compare it with other commonly used sedatives - midazolam and propofol. For this purpose, six Cynomolgus monkeys received escalating doses of remimazolam, propofol, and midazolam intravenously without or with concurrent remifentanil. Sedation was evaluated using a general sedation scale that included monitoring exploratory and avoidance behaviour, responses to sensory stimuli, posture and gait, and eyelid position as endpoints. Based on the results, sedative doses were calculated to allow evaluation of pharmacological drug-drug interaction with remifentanil. Remimazolam induced dose-dependent and consistent sedative effects in each endpoint tested and showed a high degree of synergism with remifentanil. Midazolam showed a comparable synergism while the interaction between propofol and remifentanil was less pronounced.

Optimal Sedation and Pain Management: A Patient- and Symptom-Oriented Paradigm

In the critically ill patient, optimal pain and sedation management remains the cornerstone of achieving comfort, safety, and to facilitate complex life support interventions. Pain relief, using multimodal analgesia, is an integral component of any orchestrated approach to achieve clinically appropriate goals in critically ill patients. Sedative management, however, remains a significant challenge. Subsequent studies including most recent randomized trials have failed to provide strong evidence in favor of a sedative agent, a mode of sedation or ancillary protocols such as sedative interruption and sedative minimization. In addition, clinical practice guidelines, despite a comprehensive evaluation of relevant literature, have limitations when applied to individual patients. These limitations have been most apparent during the coronavirus disease 2019 pandemic. As such, there is a need for a mindset shift to a practical and achievable sedation strategy, driven by patients' characteristics and individual patient needs, rather than one cocktail for all patients. In this review, we present key principles to achieve patient-and symptom-oriented optimal analgesia and sedation in the critically ill patients. Sedative intensity should be proportionate to care complexity with due consideration to an individual patient's modifiers. The use of multimodal analgesics, sedatives, and antipsychotics agents-that are easily titratable-reduces the overall quantum of sedatives and opioids, and reduces the risk of adverse events while maximizing clinical benefits. In addition, critical considerations regarding the choice of sedative agents should be given to factors such as age, medical versus operative diagnosis, and cardiovascular status. Specific populations such as trauma, neurological injury, and pregnancy should also be taken into account to maximize efficacy and reduce adverse events.

Treatment of Refractory Convulsive Status Epilepticus: A Comprehensive Review by the American Epilepsy Society Treatments Committee

Purpose:

Established tonic–clonic status epilepticus (SE) does not stop in one-third of patients when treated with an intravenous (IV) benzodiazepine bolus followed by a loading dose of a second antiseizure medication (ASM). These patients have refractory status epilepticus (RSE) and a high risk of morbidity and death. For patients with convulsive refractory status epilepticus (CRSE), we sought to determine the strength of evidence for 8 parenteral ASMs used as third-line treatment in stopping clinical CRSE.

Methods:

A structured literature search (MEDLINE, Embase, CENTRAL, CINAHL) was performed to identify original studies on the treatment of CRSE in children and adults using IV brivaracetam, ketamine, lacosamide, levetiracetam (LEV), midazolam (MDZ), pentobarbital (PTB; and thiopental), propofol (PRO), and valproic acid (VPA). Adrenocorticotropic hormone (ACTH), corticosteroids, intravenous immunoglobulin (IVIg), magnesium sulfate, and pyridoxine were added to determine the effectiveness in treating hard-to-control seizures in special circumstances. Studies were evaluated by predefined criteria and were classified by strength of evidence in stopping clinical CRSE (either as the last ASM added or compared to another ASM) according to the 2017 American Academy of Neurology process.

Results:

No studies exist on the use of ACTH, corticosteroids, or IVIg for the treatment of CRSE. Small series and case reports exist on the use of these agents in the treatment of RSE of suspected immune etiology, severe epileptic encephalopathies, and rare epilepsy syndromes. For adults with CRSE, insufficient evidence exists on the effectiveness of brivaracetam (level U; 4 class IV studies). For children and adults with CRSE, insufficient evidence exists on the effectiveness of ketamine (level U; 25 class IV studies). For children and adults with CRSE, it is possible that lacosamide is effective at stopping RSE (level C; 2 class III, 14 class IV studies). For children with CRSE, insufficient evidence exists that LEV and VPA are equally effective (level U, 1 class III study). For adults with CRSE, insufficient evidence exists to support the effectiveness of LEV (level U; 2 class IV studies). Magnesium sulfate may be effective in the treatment of eclampsia, but there are only case reports of its use for CRSE. For children with CRSE, insufficient evidence exists to support either that MDZ and diazepam infusions are equally effective (level U; 1 class III study) or that MDZ infusion and PTB are equally effective (level U; 1 class III study). For adults with CRSE, insufficient evidence exists to support either that MDZ infusion and PRO are equally effective (level U; 1 class III study) or that low-dose and high-dose MDZ infusions are equally effective (level U; 1 class III study). For children and adults with CRSE, insufficient evidence exists to support that MDZ is effective as the last drug added (level U; 29 class IV studies). For adults with CRSE, insufficient evidence exists to support that PTB and PRO are equally effective (level U; 1 class III study). For adults and children with CRSE, insufficient evidence exists to support that PTB is effective as the last ASM added (level U; 42 class IV studies). For CRSE, insufficient evidence exists to support that PRO is effective as the last ASM used (level U; 26 class IV studies). No pediatric-only studies exist on the use of PRO for CRSE, and many guidelines do not recommend its use in children aged <16 years. Pyridoxine-dependent and pyridoxine-responsive epilepsies should be considered in children presenting between birth and age 3 years with refractory seizures and no imaging lesion or other acquired cause of seizures. For children with CRSE, insufficient evidence exists that VPA and diazepam infusion are equally effective (level U, 1 class III study). No class I to III studies have been reported in adults treated with VPA for CRSE. In comparison, for children and adults with established convulsive SE (ie, not RSE), after an initial benzodiazepine, it is likely that loading doses of LEV 60 mg/kg, VPA 40 mg/kg, and fosphenytoin 20 mg PE/kg are equally effective at stopping SE (level B, 1 class I study).

Conclusions:

Mostly insufficient evidence exists on the efficacy of stopping clinical CRSE using brivaracetam, lacosamide, LEV, valproate, ketamine, MDZ, PTB, and PRO either as the last ASM or compared to others of these drugs. Adrenocorticotropic hormone, IVIg, corticosteroids, magnesium sulfate, and pyridoxine have been used in special situations but have not been studied for CRSE. For the treatment of established convulsive SE (ie, not RSE), LEV, VPA, and fosphenytoin are likely equally effective, but whether this is also true for CRSE is unknown. Triple-masked, randomized controlled trials are needed to compare the effectiveness of parenteral anesthetizing and nonanesthetizing ASMs in the treatment of CRSE.

Effect of acute kidney injury on weaning from mechanical ventilation in chronic obstructive pulmonary diseases patients with respiratory failure

Background

Acute kidney injury (AKI) worsens the outcome in mechanically ventilated patients. The occurrence of AKI may have an effect on weaning from mechanical ventilation (MV). The purpose of this work is to study the effect of AKI on weaning from MV for chronic obstructive pulmonary disease (COPD) patients with respiratory failure (RF). The study included 100 mechanically ventilated COPD patients with RF. Patients were classified into group 1, mechanically ventilated COPD patients with type 2 RF who developed AKI, and group 2, mechanically ventilated COPD patients with type 2 RF, who did not develop AKI.

Results

The age of the studied group ranged between 46 and 80 years, and serum creatinine on admission was within normal. There is a significant difference in a serum creatinine level after 2 days and after 1 week of MV in an intensive care unit (ICU) among AKI cases. There is a significant difference in weaning success between AKI and non-AKI patients with much higher weaning success in non-AKI group. Also, there is a significant reduction in glomerular filtration rate (GFR) in AKI patients after 48 h of admission.

Conclusions

AKI is frequent in COPD patients within 48 h of ICU admission and MV increases the risk of AKI in COPD patients.

Financial impact of an analgosedation protocol for mechanically ventilated patients in a cardiovascular intensive care unit

PURPOSE

The primary objective was to evaluate the impact of an analgosedation protocol in a cardiac intensive care unit (CICU) on daily doses and costs of analgesic, sedative, and antipsychotic medications.

METHODS

We conducted a single-center quasi-experimental study in 363 mechanically ventilated patients admitted to our CICU from March 1, 2011, to April 13, 2013. On March 1, 2012, an analgosedation protocol was implemented. Patients in the pre-implementation group were managed at the cardiologist's discretion, which consisted of a continuous sedative-hypnotic approach and opioids as needed. Patients in the implementation group were managed using this protocol.

RESULTS

The mean ± S.D. per-patient doses (mg/day) of propofol, lorazepam, and clonazepam decreased with the use of an analgosedation protocol (propofol 132,265.7 ± 12,951 versus 87,980.5 ± 10,564 [p = 0.03]; lorazepam 10.5 ± 7.3 versus 3.3 ± 4.0 [p < 0.001]; clonazepam 9.9 ± 8.3 versus 1.1 ± 0.5 [p = 0.03]). The mean daily cost of propofol and lorazepam also significantly decreased (33.5% reduction in propofol cost [p = 0.03]; 69.0% reduction in lorazepam cost [p < 0.001]). The per-patient dose and cost of fentanyl (mcg/day) declined with analgosedation protocol use (fentanyl 2,274.2 ± 2317.4 versus 1,026.7 ± 981.4 [p < 0.001]; 54.8% decrease in fentanyl cost [p < 0.001]).

CONCLUSION

The implementation of an analgosedation protocol significantly decreased both the use and cost of propofol, lorazepam, and fentanyl. Further investigation of the clinical impact and cost-effectiveness of a critical care consultation service with implementation of an analgosedation protocol is warranted in the CICU.

Midazolam Dose Optimization in Critically Ill Pediatric Patients With Acute Respiratory Failure: A Population Pharmacokinetic-Pharmacogenomic Study

OBJECTIVES

To develop a pharmacokinetic-pharmacogenomic population model of midazolam in critically ill children with primary respiratory failure.

DESIGN

Prospective pharmacokinetic-pharmacogenomic observational study.

SETTING

Thirteen PICUs across the United States.

PATIENTS

Pediatric subjects mechanically ventilated for acute respiratory failure, weight greater than or equal to 7 kg, receiving morphine and/or midazolam continuous infusions.

INTERVENTIONS

Serial blood sampling for drug quantification and a single blood collection for genomic evaluation.

MEASUREMENTS AND MAIN RESULTS

Concentrations of midazolam, the 1' (1`-hydroxymidazolam metabolite) and 4' (4`-hydroxymidazolam metabolite) hydroxyl, and the 1' and 4' glucuronide metabolites were measured. Subjects were genotyped using the Illumina HumanOmniExpress genome-wide single nucleotide polymorphism chip. Nonlinear mixed effects modeling was performed to develop the pharmacokinetic-pharmacogenomic model. Body weight, age, hepatic and renal functions, and the UGT2B7 rs62298861 polymorphism are relevant predictors of midazolam pharmacokinetic variables. The estimated midazolam clearance was 0.61 L/min/70kg. Time to reach 50% complete mature midazolam and 1`-hydroxymidazolam metabolite/4`-hydroxymidazolam metabolite clearances was 1.0 and 0.97 years postmenstrual age. The final model suggested a decrease in midazolam clearance with increase in alanine transaminase and a lower clearance of the glucuronide metabolites with a renal dysfunction. In the pharmacogenomic analysis, rs62298861 and rs28365062 in the UGT2B7 gene were in high linkage disequilibrium. Minor alleles were associated with a higher 1`-hydroxymidazolam metabolite clearance in Caucasians. In the pharmacokinetic-pharmacogenomic model, clearance was expected to increase by 10% in heterozygous and 20% in homozygous for the minor allele with respect to homozygous for the major allele.

CONCLUSIONS

This work leveraged available knowledge on nonheritable and heritable factors affecting midazolam pharmacokinetic in pediatric subjects with primary respiratory failure requiring mechanical ventilation, providing the basis for a future implementation of an individual-based approach to sedation.

Midazolam: an essential palliative care drug

Midazolam is a commonly used benzodiazepine in palliative care and is considered one of the four essential drugs needed for the promotion of quality care in dying patients. Acting on the benzodiazepine receptor, it promotes the action of gamma-aminobutyric acid. Gamma-aminobutyric acid action promotes sedative, anxiolytic, and anticonvulsant properties. Midazolam has a faster onset and shorter duration of action than other benzodiazepines such as diazepam and lorazepam lending itself to greater flexibility in dosing than other benzodiazepines. The kidneys excrete midazolam and its active metabolite. Metabolism occurs in the liver by the P450 system. This article examines the pharmacology, pharmacodynamics, and clinical uses of midazolam in palliative care.

Pharmacokinetics of midazolam in sevoflurane-anesthetized cats

OBJECTIVE

To estimate the pharmacokinetics of midazolam and 1-hydroxymidazolam after midazolam administration as an intravenous bolus in sevoflurane-anesthetized cats.

STUDY DESIGN

Prospective pharmacokinetic study.

ANIMALS

A group of six healthy adult, female domestic cats.

METHODS

Anesthesia was induced and maintained with sevoflurane. After 30 minutes of anesthetic equilibration, cats were administered midazolam (0.3 mg kg^-1) over 15 seconds. Venous blood was collected at 0, 1, 2, 4, 8, 15, 30, 45, 90, 180 and 360 minutes after administration. Plasma concentrations for midazolam and 1-hydroxymidazolam were measured using high-pressure liquid chromatography. The heart rate (HR), respiratory rate (f_R), rectal temperature, noninvasive mean arterial pressure (MAP) and end-tidal carbon dioxide (Pe'CO₂) were recorded at 5 minute intervals. Population compartment models were fitted to the time-plasma midazolam and 1-hydroxymidazolam concentrations using nonlinear mixed effect modeling.

RESULTS

The pharmacokinetic model was fitted to the data from five cats, as 1-hydroxymidazolam was not detected in one cat. A five-compartment model best fitted the data. Typical values (% interindividual variability where estimated) for the volumes of distribution for midazolam (three compartments) and hydroxymidazolam (two compartments) were 117 (14), 286 (10), 705 (14), 53 (36) and 334 mL kg^-1, respectively. Midazolam clearance to 1-hydroxymidazolam, midazolam fast and slow intercompartmental clearances, 1-hydroxymidazolam clearance and 1-hydroxymidazolam intercompartment clearance were 18.3, 63.5 (15), 22.1 (8), 1.7 (67) and 3.8 mL minute^-1 kg^-1, respectively. No significant changes in HR, MAP, f_R or Pe'CO₂ were observed following midazolam administration.

CONCLUSION AND CLINICAL RELEVANCE

In sevoflurane-anesthetized cats, a five-compartment model best fitted the midazolam pharamacokinetic profile. There was a high interindividual variability in the plasma 1-hydroxymidazolam concentrations, and this metabolite had a low clearance and persisted in the plasma for longer than the parent drug. Midazolam administration did not result in clinically significant changes in physiologic variables.

Monitored Anesthesia Care for Cardiovascular Interventions

The interventional cardiology is growing and evolving. Many complex procedures are now performed outside the operating room to manage cardiovascular pathologies which had been traditionally treated with cardiac surgery. Appropriate sedation strategy is crucial for improved patient comfort and successful procedure while ensuring safety. Sedation for cardiovascular intervention is frequently challenging, especially in critically-ill, high-risk patients. This review addresses pre-procedure evaluation and preparation of patients, proper monitoring, commonly used sedatives and analgesics, and considerations for specific procedures. Appropriate depth of sedation and analgesia should be balanced with patient, procedural and institutional factors. Understanding of the pharmacology of sedatives/analgesics, vigilant monitoring, ability and proper preparation for management of potential complications may improve outcomes in patients undergoing sedation for cardiovascular procedures.

Drug Disposition and Pharmacotherapy in Neonatal ECMO: From Fragmented Data to Integrated Knowledge

Extracorporeal membrane oxygenation (ECMO) is a lifesaving support technology for potentially reversible neonatal cardiac and/or respiratory failure. As the survival and the overall outcome of patients rely on the treatment and reversal of the underlying disease, effective and preferentially evidence-based pharmacotherapy is crucial to target recovery. Currently limited data exist to support the clinicians in their every-day intensive care prescribing practice with the contemporary ECMO technology. Indeed, drug dosing to optimize pharmacotherapy during neonatal ECMO is a major challenge. The impact of the maturational changes of the organ function on both pharmacokinetics (PK) and pharmacodynamics (PD) has been widely established over the last decades. Next to the developmental pharmacology, additional non-maturational factors have been recognized as key-determinants of PK/PD variability. The dynamically changing state of critical illness during the ECMO course impairs the achievement of optimal drug exposure, as a result of single or multi-organ failure, capillary leak, altered protein binding, and sometimes a hyperdynamic state, with a variable effect on both the volume of distribution (Vd) and the clearance (Cl) of drugs. Extracorporeal membrane oxygenation introduces further PK/PD perturbation due to drug sequestration and hemodilution, thus increasing the Vd and clearance (sequestration). Drug disposition depends on the characteristics of the compounds (hydrophilic vs. lipophilic, protein binding), patients (age, comorbidities, surgery, co-medications, genetic variations), and circuits (roller vs. centrifugal-based systems; silicone vs. hollow-fiber oxygenators; renal replacement therapy). Based on the potential combination of the above-mentioned drug PK/PD determinants, an integrated approach in clinical drug prescription is pivotal to limit the risks of over- and under-dosing. The understanding of the dose-exposure-response relationship in critically-ill neonates on ECMO will enable the optimization of dosing strategies to ensure safety and efficacy for the individual patient. Next to in vitro and clinical PK data collection, physiologically-based pharmacokinetic modeling (PBPK) are emerging as alternative approaches to provide bedside dosing guidance. This article provides an overview of the available evidence in the field of neonatal pharmacology during ECMO. We will identify the main determinants of altered PK and PD, elaborate on evidence-based recommendations on pharmacotherapy and highlight areas for further research.

Pharmacokinetics of midazolam and its major metabolite 1-hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations

Midazolam is a benzodiazepine with sedative, muscle relaxant, anxiolytic, and anticonvulsant effects. Twelve ball pythons (Python regius) were used in a parallel study evaluating the pharmacokinetics of 1 mg/kg midazolam following a single intracardiac (IC) or intramuscular (IM) administration. Blood was collected from a central venous catheter placed 7 days prior, or by cardiocentesis, at 15 time points starting just prior to and up to 72 hr after drug administration. Plasma concentrations of midazolam and 1-hydroxymidazolam were determined by the use of high-performance liquid chromatography tandem-mass spectrometry and pharmacokinetic parameters were estimated using noncompartmental analysis. The mean ± SD terminal half-lives of IC and IM midazolam were 12.04 ± 3.25 hr and 16.54 ± 7.10 hr, respectively. The area under the concentration-time curve extrapolated to infinity, clearance, and apparent volume of distribution in steady-state of IC midazolam were 19,112.3 ± 3,095.9 ng*hr/ml, 0.053 ± 0.008 L hr^-1  kg^-1 , and 0.865 ± 0.289 L/kg, respectively. The bioavailability of IM midazolam was estimated at 89%. Maximum plasma concentrations following an IM administration were reached 2.33 ± 0.98 hr and 24.00 ± 14.12 hr postinjection for midazolam and 1-hydroxymidazolam, respectively, and 22.33 ± 20.26 hr postinjection for 1-hydroxymidazolam following IC administration.