Population Pharmacokinetics of Esketamine Nasal Spray and its Metabolite Noresketamine in Healthy Subjects and Patients with Treatment-Resistant Depression

IN Esketamine and IV Ketamine: Results of a multi-site observational study assessing the effectiveness and tolerability of two novel therapies for treatment-resistant depression

Intravenous (IV) ketamine and intranasal (IN) esketamine are novel therapies to manage treatment resistant depression within major depressive disorder (MDD-TRD). This is a multi-site observational study aiming to assess the real-world effectiveness and tolerability of these novel therapies in the management of MDD-TRD. 53 patients were referred to receive IV ketamine (n = 26, 69.23 % female, 52.81 ± 14.33 years old) or IN esketamine (n = 27, 51.85 % female, 43.93 ± 13.57 years old). Treatment effectiveness was assessed using the Montgomery and Åsberg Depression Rating Scale (MADRS) for depression severity and item 10 of the MADRS for suicidal ideation (SI). Tolerability was assessed by systematically tracking side effects and depersonalization using the 6-item Clinician administered dissociative symptom scale (CADSS-6). The data was analyzed using descriptive statistics, risk ratio and effect size. Both IV ketamine and IN esketamine significantly reduced depressive symptoms and suicidal ideation by treatment endpoint. Patients receiving IN esketamine, and patients receiving IV ketamine had a similar risk of developing side effects. All side effects reported were mild and transient. These results suggested that both IV ketamine and IN esketamine are effective in the management of depressive symptoms and were well tolerated. Therefore, the results of this study could serve to inform clinical practice.

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.

Dose-response study of propofol combined with two different doses of esketamine for laryngeal mask airway insertion in women undergoing hysteroscopy

Objective

To prospectively determine the median effective dose (ED50) of propofol for inhibiting a response to laryngeal mask airway (LMA) insertion when combined with different doses of esketamine in female patients.

Methods

A total of 58 female patients (aged 20-60 years, ASAⅠ-Ⅱ) scheduled for elective hysteroscopy were enrolled and randomly divided into 2 groups, one of which was administered 0.2 mg/kg of esketamine (K1 group, n = 28) and the other 0.3 mg/kg of esketamine (K2 group, n = 30). The 2 groups received the corresponding doses of esketamine intravenously, followed by an intravenous injection of propofol (injection time was 30 s). The initial dose of propofol was 2 mg/kg, and the dose ratio of propofol in the adjacent patients was 0.9. If a positive reaction occurred due to LMA insertion, the dose ratio in the next patient was increased by 1 gradient; if not, the dose ratio was decreased by 1 gradient. The ED50, 95 % effective dose (ED95) and 95 % confidence interval (CI) of propofol for inhibiting a response to LMA insertion in the 2 esketamine groups were calculated using probit analysis.

Results

The ED50 of propofol for inhibiting a response to LMA insertion in female patients was 1.95 mg/kg (95 % CI, 1.82-2.08 mg/kg) in the K1 group and 1.60 mg/kg (95 % CI, 1.18-1.83 mg/kg) in the K2 group. The ED95 of propofol for inhibiting a response to LMA insertion in female patients was 2.22 mg/kg (95 % CI, 2.09-2.86 mg/kg) in the K1 group and 2.15 mg/kg (95 % CI, 1.88-3.09 mg/kg) in the K2 group.

Conclusion

Propofol combined with 0.3 mg/kg of esketamine has low ED50 and ED95 effective doses for inhibiting an LMA insertion response in female patients undergoing hysteroscopy and surgery. There were no significant adverse effects, but the additional dose of propofol and airway pressure were significantly higher than those in the group administered 0.2 mg/kg of esketamine. Based on the results, we recommend the combination of propofol with 0.2 mg/kg esketamine for optimal conditions during LMA insertion in women undergoing hysteroscopy.

The efficacy of nasal administration of esketamine in patients having moderate-to-severe pain after preoperative CT-guided needle localization: a randomized, double-blind, placebo-controlled trial

Background

Whether nasal administration of esketamine can provide effective analgesia is unclear in patients with acute pain after preoperative CT-guided needle localization.

Methods

In this double-blind, randomized, placebo-controlled trial, patients were assigned to receive either nasal administration of esketamine (0.3 mg/kg or 0.5 mg/kg) or saline (identical in appearance to esketamine) when they had visual analog scale (VAS) pain scores >3/10 during deep breathing after preoperative CT-guided needle localization. The primary outcome was the percentage of patients with satisfactory pain relief, which was defined as VAS pain scores ≤3/10 measured 15 min after intranasal of esketamine or saline. Secondary outcomes included VAS measured following esketamine or saline, the incidence and cumulative dose of rescue hydromorphone use, and related adverse events.

Results

A total of 90 patients were included in the final analysis. Following intranasal treatment, the percentage of patients with satisfactory pain relief was 16.7% (5/30) in the saline group, 56.7% (17/30) in the 0.3 mg/kg esketamine group, and 53.3% (16/30) in the 0.5 mg/kg esketamine group (p = 0.002). The median VAS during deep breathing was less after the intranasal administration of esketamine {median (IQR), 3 (3, 5) in 0.3 mg/kg or 0.5 mg/kg esketamine compared to the saline group [5 (4, 6)], p = 0.009}. The incidence of rescue hydromorphone use was detected less in the esketamine group compared to the saline group (43.3% in the 0.3 mg/kg esketamine group, 36.7% in the 0.5 mg/kg esketamine group, and 73.3% in the saline group, p = 0.010). The adverse events were similar among the three groups (p > 0.05).

Conclusion

Intranasal administration of esketamine is easier and more effective in alleviating acute pain in patients after preoperative CT-guided needle localization without significant adverse effects.

The rapid antidepressant effectiveness of repeated dose of intravenous ketamine and intranasal esketamine: A post-hoc analysis of pooled real-world data

INTRODUCTION

Intravenous ketamine (KET-IV) and intranasal esketamine (ESK-NS) are effective in the acute treatment of Treatment-Resistant Depression (TRD). Studies comparing KET-IV and ESK-NS concerning their action, safety, and tolerability are currently lacking.

MATERIALS AND METHODS

We combined patients' data from two unipolar TRD cohorts that received KET-IV (n = 171) at the Canadian Rapid Treatment Center of Excellence in Toronto, Canada, or ESK-NS (n = 140) at several TRD clinics in Italy. The Quick Inventory for Depression Symptomatology-Self-Report-16/QIDS-SR16 in the KET-IV group and Montgomery-Åsberg Depression Rating Scale/MADRS in the ESK-NS group measured depressive symptoms at baseline (T0) and after the acute treatment phase (T1) (i.e., four infusions of KET-IV and eight administrations of ESK-NS). As different scales were used, the primary outcome was to compare the improvement in depression severity in the two cohorts by measuring effect sizes, response and remission rates. Finally, we compare side effects and discontinuation rates.

RESULTS

At T1, KET-IV and ESK-NS significantly reduced depressive symptoms (respectively: QIDS-SR16 mean reduction = 5.65, p < 0.001; MADRS mean reduction = 11.41, p = 0.025). KET-IV showed larger effect sizes compared to ESK-NS (1.666 vs. 1.244). KET-IV had higher response rates (36 % vs. 25 %; p = 0.042) but not superior remission rates (13 % vs. 12 %; p = 0.845) than ESK-NS at T1. Despite more reported side effects, KET-IV did not cause more discontinuations for adverse events (4.6 % vs. 2.12 %; p = 0.228) than ESK-NS.

CONCLUSION

KET-IV showed a higher short-term antidepressant effect, whereas ESK-NS exhibited lower side effects. Both were generally well tolerated. Future head-to-head studies should consider the long-term efficacy of these treatments.

Effect of esketamine on postpartum depression after labor analgesia and potential mechanisms: a randomized, double-blinded controlled trial

BACKGROUND

To evaluate the effect of esketamine combined with ropivacaine hydrochloride on the occurrence of postpartum depression (PPD) after labor analgesia under epidural analgesia pump and explore the possible mechanisms.

METHODS

A total of 120 women aged 24 to 36 years old who underwent labor analgesia by epidural analgesia pump, with American Society of Anesthesiologists (ASA) physical status II were enrolled. According to the formula of epidural analgesia pump, all participants were randomly divided into two groups: esketamine group (Group E) and control group (Group C). Epidural anaesthesia were operated in all women between L2 and L3 after cervical dilation up to 2 ~ 3 cm. After successful puncture, the epidural catheter was placed 3.5 cm toward the head and 1% lidocaine was injected for 3 ml. The epidural analgesia pump was connected. Esketamine (0.2 mg/kg) combined with 0.75% ropivacaine hydrochloride (20 ml) were diluted by normal saline up to 100 ml in Group E, when only the equal dose of ropivacaine hydrochloride was used in Group C. The visual analogue scale (VAS) before analgesia (T1), 5 (T2), 10 (T3) and 20 (T4) minutes after analgesia were measured. The duration of the first and second stage of labor, the Apgar score of fetus at delivery, postpartum hemorrhage, consumption of esketamine and ropivacaine were recorded. The incidence of PPD was recorded at 1 week and 6 weeks after delivering. The occurrence of side effects such as nausea and vomiting, dizziness, and nightmares were also recorded for 48 h after delivering. The levels of leptin, norepinephrine(NE), and epinephrine(E) in the peripheral venous blood were measured before labor analgesia and at 24 h, 1 week, and 6 weeks after delivering.

RESULTS

Compared with Group C, the VAS score at T2, T3 and T4 were significantly lower in Group E (P < 0.01). Compared with Group C, the incidence of PPD was significantly lower at 1 week and 6 weeks after delivering in Group E (P < 0.01). Compared with Group C, the levels of leptin were significantly higher at 24 h and 1 week after delivering in Group E (P < 0.01), while NE and E (P < 0.01) were lower at the same time (P < 0.01). There were no significant difference of the duration of the first and second stage of labor, the Apgar score of fetus at delivery, postpartum hemorrhage, consumption of ropivacaine and the side effects for 48 h after delivering between the two groups.

CONCLUSION

Esketamine combined with ropivacaine hydrochloride used in labor analgesia can significantly reduce the incidence of postpartum depression after delivering without increasing related side effects, which may be related to the regulation of leptin, norepinephrine, and epinephrine in the serum.

TRIAL REGISTRATION

The trial was registered at the Chinese Clinical Trial Registry on 30/05/2022 (CTRI registration number-ChiCTR2200060387). URL of registry: https://www.chictr.org.cn/bin/home .

The Efficacy and Safety of Intranasal Formulations of Ketamine and Esketamine for the Treatment of Major Depressive Disorder: A Systematic Review

Ketamine and its enantiomers represent an innovative glutamatergic agent as a treatment for individuals with treatment-resistant depression (TRD) and major depressive disorder (MDD) with suicidal ideation and behavior. Intranasal (IN) formulations could allow for quick onset of action on depressive symptoms as well as a reduction in side effects by bypassing the blood-brain barrier compared with administration via the intravenous route. The aim of this review was to provide an up-to-date analysis of the data on the efficacy and safety of IN ketamine and IN esketamine for the treatment of MDD. A systematic review following PRISMA guidelines was conducted. Databases (PubMed, Embase, MEDLINE, PsycINFO, and Google Scholar) were searched to capture articles about IN ketamine or IN esketamine for MDD. This systematic review highlighted the interest in IN routes of ketamine and esketamine for MDD patients with TRD or active suicidal ideation. They provide a rapid onset of antidepressant action within the first hours after administration. Nevertheless, the evidence of efficacy is stronger for IN esketamine than for IN ketamine in MDD patients. The safety profile appears to be acceptable for IN esketamine but requires further studies, and a more accurate IN delivery device is required for ketamine.

Pharmacokinetics of Nasal Esketamine in Patients with Allergic Rhinitis with and Without Nasal Decongestant Pretreatment and in Healthy Subjects with and Without Nasal Corticosteroid Pretreatment

BACKGROUND AND OBJECTIVES

Nasal esketamine is indicated for the treatment of adults with treatment-resistant depression and depressive symptoms in adults with major depressive disorder with acute suicidal ideation or behavior. Primary objectives of this study were to evaluate the effect of nasal decongestant pretreatment in patients with allergic rhinitis and the impact of daily nasal corticosteroid administration by healthy subjects on nasal esketamine pharmacokinetics.

METHODS

Patients with allergic rhinitis self-administered 56 mg of nasal esketamine after pretreatment with nasal oxymetazoline (0.05%) at 1 h before esketamine and without oxymetazoline pretreatment. They were exposed to grass pollen in an allergen challenge chamber to induce allergic rhinitis symptoms at approximately 2 h before each esketamine administration until 1 h after. Healthy subjects self-administered esketamine (56 mg) before and after administration for 16 consecutive days of mometasone (200 µg), with the second esketamine dose administered 1 h after the last mometasone dose. The plasma pharmacokinetics of esketamine and noresketamine were assessed after each esketamine administration. The tolerability of esketamine, including effects on dissociative and potential psychotomimetic symptoms and level of sedation and suicidal ideation and behavior, was evaluated.

RESULTS

The rate of esketamine absorption was slightly greater in patients exhibiting symptoms of allergic rhinitis (decrease in median tmax from 32 min to 22 min). Increases in esketamine Cmax and AUC were also small (mean, ≤ 21%). The pharmacokinetics of esketamine was not affected by oxymetazoline or mometasone pretreatment. Esketamine was well tolerated when it was administered with or without pretreatment of oxymetazoline or mometasone.

CONCLUSIONS

Patients exhibiting symptoms of rhinitis may receive nasal esketamine spray without dose adjustment. In addition, esketamine may be administered 1 h after using a nasal decongestant or corticosteroid.

TRIAL REGISTRATION

The study was registered in the Clinical Trials (NCT02154334) and EudraCT (2014-000534-38) registries.

The application of iliac fascia space block combined with esketamine intravenous general anesthesia in PFNA surgery of the elderly: A prospective, single-center, controlled trial

To observe the effect of iliac fascia space block combined with esketamine intravenous general anesthesia in proximal femoral nail antirotation (PFNA) of the elderly. Eighty elderly patients who underwent PFNA were randomly divided into experimental group and control group. In the experimental group, iliac fascial block combined with esketamine and propofol intravenous general anesthesia was used to keep spontaneous breathing. The control group used iliac fascia block combined with remifentanil and propofol intravenous general anesthesia to maintain spontaneous breathing. Record important indexes such as heart rate (HR), mean arterial pressure (MAP), pulse oxygen saturation (SpO2), visual analogue score (VAS) scores, etc. at different moment during the operation. Trial data showed that there were significant differences in HR, MAP, and SpO2 between the two groups at the beginning of operation, and there was no significant difference in VAS scores between the two groups at each moment after surgery, and there were significant differences in the number of vasopressor applications, length of hospital stay, and QoR-15 scores between the two groups, and there were significant differences in the incidence of total adverse reactions and the incidence of hypotension. The trial indicated that patients in the experimental group have more stable hemodynamics and lower stress response, which is conducive to rapid recovery after surgery.

Effect of pre-administration of esketamine intraoperatively on postpartum depression after cesarean section: A randomized, double-blinded controlled trial

BACKGROUND

To evaluate the effect of pre-administration of esketamine intraoperatively on the occurrence of postpartum depression after cesarean section under combined spinal-epidural anesthesia.

METHODS

A total of 120 women aged 24 to 36 years undergoing cesarean section by spinal-epidural anesthesia with American Society of Anesthesiologists physical status II were enrolled. According to the intraoperative use of esketamine, all participants were randomly divided into 2 groups: test group (group E) and control group (group C). Esketamine was administered intravenously at a dose of 0.2 mg/kg after the infant was delivered in group E and equal volume of normal saline was given in group C. The incidence of postpartum depression was recorded at 1 week and 6 weeks after the operation. The occurrence of adverse reactions such as postpartum bleeding, nausea and vomiting, drowsiness, and nightmares were also recorded at 48 hours after surgery.

RESULTS

Compared with group C, the incidence of postpartum depression was significantly lower at 1 week and 6 weeks after surgery in group E (P < .01). There was no significant difference of the adverse effects at 48 hours after the operation between the 2 groups.

CONCLUSION

Intravenous infusion of 0.2 mg/kg esketamine in women during cesarean section can significantly reduce the incidence of postpartum depression at 1 week and 6 weeks after surgery without increasing related adverse effects.

Determining the effective dose of esketamine for mitigating pain during propofol injection by Dixon's up-and-down method: a double-blind, prospective clinical study of drug dose response

BACKGROUND

Propofol is an intravenous (IV) anesthetic medication widely used for procedural sedation, operative anesthesia, and in intensive care unit (ICU), but the incidence of pain during IV infusion can reach 28-90%. Ketamine can attenuate pain associated with IV propofol injection through local and central analgesic effects. Ketamine is gradually being transitioned to its S-enantiomer, esketamine, which has a similar mechanism of action. The purpose of our study is to determine the half effective dose (ED₅₀), 95% effective dose (ED₉₅), and 99% effective dose (ED₉₉) of esketamine for attenuating propofol injection pain using Dixon's up-and-down method to provide a reference for optimal dose selection for surgeries and procedures.

METHODS

Thirty gynecological patients undergoing hysteroscopic surgery were enrolled in a sequential method to determine the effective dose of esticketamine for analgesic propofol injection in order of operation. This study was based on the sequential allocation up-and-down rule designed by Dixon, and each patient was induced by esticketamine combined with propofol. During induction, the target dose of esketamine was first given via venous access in the left hand of the patient, and 30 s later, a fixed dose of 2 mg/kg (1 ml/s) of propofol was given. Patient perception of pain was scored with the verbal rating scale (VRS) every 5 s after the start of the propofol infusion, and the evaluation was stopped once the patient became unresponsive. The dosage of esketamine was increased or decreased up or down according to the patient's pain response. The initial dose of esketamine was 0.2 mg/kg, and the gradient of adjacent dose was 0.02 mg/kg. If the pain response assessment of the upper patient was positive (+), the dose of esselketamine in the next patient was increased by 0.02 mg/kg; if the pain response assessment of the upper patient was negative (-), the dose of esselketamine in the next patient was decreased by 0.02 mg/kg. The tests were carried out sequentially, with the pain response changing from positive to negative or from negative to positive, and the tests were stopped after at least 6 crossover points, and the effective dose of esticketamine was calculated using probit probability regression analysis.

RESULTS

The ineffective group comprised patients with a positive pain response and the effective group comprised patients with a negative pain response. The 95% CI was set as the confidence interval of effective dose ED value，and we found esketamine's ED₅₀ = 0.143 mg/kg (0.120, 0.162 mg/kg), ED₉₅ = 0.176 mg/kg (0.159, 0.320 mg/kg), and ED₉₉ = 0.189 mg/kg (0.167, 0.394 mg/kg). The esketamine dose and VRS score during propofol injection were significantly different between the two groups (P < 0.05), whereas surgical duration, emergence time, visual analogue scale (VAS) score of postoperative uterine contraction pain, and Riker sedation/anxiety scale (SAS) score were not significantly different. Bradycardia occurred in only one patient during anesthesia induction, while hemodynamics was stable in the rest of the patients without obvious adverse reactions.

CONCLUSION

Small doses of esketamine combined with propofol can be safely and effectively used for hysteroscopic surgery. We recommended a dose of 0.2 mg/kg IV esketamine before induction of anesthesia to reduce the pain of propofol injection.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100048951. Date of registration: July 19, 2021.

Evidence for the beneficial effect of ketamine in the treatment of patients with post-traumatic stress disorder: A systematic review and meta-analysis

Post-traumatic stress disorder (PTSD) is an anxiety disorder with manifestations somatic resulting from reliving the trauma. The therapy for the treatment of PTSD has limitations, between reduced efficacy and "PTSD pharmacotherapeutic crisis". Scientific evidence has shown that the use of ketamine has benefits for the treatment of depressive disorders and other symptoms present in PTSD compared to other conventional therapies. Therefore, this study aims to analyze the available evidence on the effect of ketamine in the treatment of post-traumatic stress. The systematic review and the meta-analysis were conducted following PRISMA guidelines and RevManager software, using randomized controlled trials and eligible studies of quality criteria for data extraction and analysis. The sample design evaluated included the last ten years, whose search resulted in 594 articles. After applying the exclusion criteria, 35 articles were selected, of which 14 articles were part of the sample, however, only six articles were selected the meta-analysis. The results showed that the ketamine is a promising drug in the management of PTSD with effect more evident performed after 24 h evaluated by MADRS scale. However, the main limitations of the present review demonstrate that more high-quality studies are needed to investigate the influence of therapy, safety, and efficacy.

Effects of esketamine on analgesia and postpartum depression after cesarean section: A randomized, double-blinded controlled trial

BACKGROUND

The aim of this randomized double-blind placebo controlled clinical trial was to investigate the effects of different doses of esketamine combined with sufentanil for postoperative intravenous controlled analgesia after cesarean section and the incidence of postpartum depression.

METHODS

One hundred and sixty patients undergoing elective cesarean section, with a singleton term pregnancy and American Society of Anesthesiologists physical status II were selected. All patients were treated by a combined epidural with spinal anesthesia. They were randomly divided into 4 groups according to patient controlled intravenous analgesia formula. The consumption of sufentanil, times of effective press and remediate analgesia at 48 hours after cesarean section, incidence of postpartum depression (PPD) at 1 week and 6 weeks after the operation were recorded.

RESULTS

Comparison of cumulated dosage of sufentanil, times of effective press and rescue analgesia at 48 hours after operation: Group H was significantly lower than Group M, Group L, and Group C (P < .05), Group M significantly lower than group L and Group C (P < .05), and Group L significantly lower than Group C (P < .05). Comparison of the incidence of PPD at 1 week and 6 weeks later: Group H was significantly lower than Group M, Group L, and Group C (P < .01), Group M significantly lower than Group L and Group C (P < .01) and Group L significantly lower than Group C (P < .01). Compared with Group C, the incidence of nausea and vomiting was significantly reduced in Group H, Group M, and Group L (P < .05).

CONCLUSION

Esketamine combined with sufentanil used for patient controlled intravenous analgesia after elective cesarean section can reduce the consumption of sufentanil, improve postoperative analgesia, decrease the incidence of PPD at 1 week and 6 weeks and postoperative nausea and vomiting.

Effective dose of propofol combined with a low-dose esketamine for gastroscopy in elderly patients: A dose finding study using dixon’s up-and-down method

Objective: This study aimed to determine the optimal dose of propofol combined with esketamine to inhibit the response to gastroscope insertion in elderly patients.

Methods: This is a prospective, non-controlled, non-randomized, single-center study. Elderly patients aged 65–80 years were enrolled in the study with the American society of anesthesiologists (ASA) physical status I or II undergoing elective gastroscopy. All patients were administered propofol after an intravenous esketamine at the dosage of 0.3 mg/kg 30 s, the subsequent dose of propofol was determined by the response of the previous patient to gastroscope insertion (choking, body movement, etc.) using Dixon’s up-and-down method. The initial dose of propofol administered to the first elderly patient was 3.0 mg/kg, and the standard ratio of propofol dose in adjacent patients was 0.9. At least six crossover points were obtained before the conclusion of the study. By using Probit analysis the median effective dose (ED₅₀), 95% effective dose (ED₉₅), and the corresponding 95% confidence interval (CI) for propofol were determined.

Results: The study continued until we obtained seven crossover points and 32 elderly patients (17 males and 15 females) were collected. The ED₅₀ of propofol combined with esketamine inhibiting response to gastroscope insertion in elderly patients were found to be 1.479 mg/kg (95% CI 1.331–1.592 mg/kg), and ED₉₅ was found to be 1.738 mg/kg (95% CI 1.614–2.487 mg/kg).

Conclusion: According to the present study, propofol combined with 0.3 mg/kg esketamine is safe and effective for elderly patients undergoing gastroscopy. The ED₅₀ and ED₉₅ doses of propofol inhibiting response to gastroscope insertion in elderly patients when combined with 0.3 mg/kg esketamine were 1.479 and 1.738 mg/kg, respectively, without apparent adverse effects.

S-Ketamine Oral Thin Film—Part 1: Population Pharmacokinetics of S-Ketamine, S-Norketamine and S-Hydroxynorketamine

Ketamine is administered predominantly via the intravenous route for the various indications, including anesthesia, pain relief and treatment of depression. Here we report on the pharmacokinetics of sublingual and buccal fast-dissolving oral-thin-films that contain 50 mg of S-ketamine in a population of healthy male and female volunteers. Twenty volunteers received one or two oral thin films on separate occasions in a randomized crossover design. The oral thin films were placed sublingually (n = 15) or buccally (n = 5) and left to dissolve for 10 min in the mouth during which the subjects were not allowed to swallow. For 6 subsequent hours, pharmacokinetic blood samples were obtained after which 20 mg S-ketamine was infused intravenously and blood sampling continued for another 2-hours. A population pharmacokinetic analysis was performed in NONMEM pharmacokinetic model of S-ketamine and its metabolites S-norketamine and S-hydroxynorketamine; p < 0.01 were considered significant. S-ketamine bioavailability was 26 ± 1% (estimate ± standard error of the estimate) with a 20% lower bioavailability of the 100 mg oral thin film relative to the 50 mg film, although this difference did not reach the level of significance. Due to the large first pass-effect, 80% of S-ketamine was metabolized into S-norketamine leading to high plasma levels of S-norketamine following the oral thin film application with 56% of S-ketamine finally metabolized into S-hydroxynorketamine. No differences in pharmacokinetics were observed for the sublingual and buccal administration routes. The S-ketamine oral thin film is a safe and practical alternative to intravenous S-ketamine administration that results in relatively high plasma levels of S-ketamine and its two metabolites.

Targeting Affective Mood Disorders With Ketamine to Prevent Chronic Postsurgical Pain

The phencyclidine-derivative ketamine [2-(2-chlorophenyl)-2-(methylamino)cyclohexan-1-one] was added to the World Health Organization's Model List of Essential Medicines in 1985 and is also on the Model List of Essential Medicines for Children due to its efficacy and safety as an intravenous anesthetic. In sub-anesthetic doses, ketamine is an effective analgesic for the treatment of acute pain (such as may occur in the perioperative setting). Additionally, ketamine may have efficacy in relieving some forms of chronic pain. In 2019, Janssen Pharmaceuticals received regulatory-approval in both the United States and Europe for use of the S-enantiomer of ketamine in adults living with treatment-resistant major depressive disorder. Pre-existing anxiety/depression and the severity of postoperative pain are risk factors for development of chronic postsurgical pain. An important question is whether short-term administration of ketamine can prevent the conversion of acute postsurgical pain to chronic postsurgical pain. Here, we have reviewed ketamine's effects on the biopsychological processes underlying pain perception and affective mood disorders, focusing on non-NMDA receptor-mediated effects, with an emphasis on results from human trials where available.

Midazolam Attenuates Esketamine-Induced Overactive Behaviors in Mice Before the Sedation, but Not During the Recovery

Esketamine showed more potency, more rapid recovery from anesthesia, and less psychotomimetic side effects when compared with ketamine. However, the patients still experience psychotomimetic side effects of esketamine. In order to investigate whether midazolam can attenuate the esketamine-induced overactive behaviors and neuronal hyperactivities, midazolam 0, 40, 80, and 120 mg/kg combined with esketamine 50 mg/kg were administrated on Kunming mice to assess the behaviors changes during anesthesia. The indicators, including action time, duration of agitation before the sedation, duration of sedation, duration of loss of pedal withdrawal reaction (PWR), duration of loss of righting reaction (RR), duration of agitation during the recovery, and recovery time, were monitored for up to 3–4 h after intraperitoneal administration. The results demonstrated that midazolam 40, 80, and 120 mg/kg efficiently decreased the esketamine-induced overactive behaviors including ataxia, excitation, and catalepsy before sedation. Midazolam and esketamine synergically improved the anesthesia quality assessed by PWR and RR. However, even high doses of midazolam were not able to suppress the esketamine-induced psychotomimetic effects during the recovery.

Research advances in the clinical application of esketamine

Esketamine is dextrorotatory ketamine, which is an enantiomer of ketamine. Compared with ketamine, it has the advantages of a fast metabolism, fewer side effects, and strong pharmacological effects, so it is more suitable for clinical use. Esketamine has a powerful analgesic effect and has little effect on breathing. It has a wide range of applications in the fields of pediatric anesthesia, conscious sedation anesthesia, and emergency analgesia. In addition, it is also used for pain that is difficult to relieve with conventional drugs and to prevent postoperative pain. Various routes of administration are also suitable for patients who need short-term analgesia and sedation. As a drug, esketamine inevitably brings some side effects when it is used clinically. In this article, by introducing the mechanism of action and pharmacological characteristics of esketamine, its clinical application is reviewed, and it provides a reference for the more reasonable and safe clinical application of esketamine.

Response to intravenous racemic ketamine after switch from intranasal (S)-ketamine on symptoms of treatment-resistant depression and post-traumatic stress disorder in Veterans: A retrospective case series

BACKGROUND

Racemic (R,S)-ketamine is a glutamatergic drug with potent and rapid acting antidepressant effects. An intranasal formulation of (S)-ketamine was recently approved by the US Food and Drug Administration (FDA) to be used in individuals with treatment-resistant depression (TRD). There are no data directly comparing outcomes on depression or other comorbidities between these two formulations of ketamine. However, recent meta-analyses have suggested that IV racemic ketamine may be more potent than IN-(S)-ketamine.

METHODS

We retrospectively analyzed clinical outcomes in 15 Veterans with comorbid TRD and post-traumatic stress disorder (PTSD) who underwent ketamine treatment at the VA San Diego Neuromodulation Clinic. All Veterans included in this analysis were given at least 6 intranasal (IN)-(S)-ketamine treatments prior to switching to treatment with IV racemic ketamine.

RESULTS

Veterans receiving ketamine treatment ( across both IN-(S)-ketamine and IV-(R,S)-ketamine) showed significant reductions in both the Patient Health Questionnaire-9 (PHQ-9), a self-report scale measuring depression symptoms (rm ANOVA F(14,42) = 12.6, p < 0.0001), and in the PTSD checklist for DSM-5 (PCL-5), a self-report scale measuring PSTD symptoms (rm ANOVA F(13,39) = 5.9, p = 0.006). Post hoc testing revealed that PHQ-9 scores were reduced by an average of 2.4 ± 1.2 compared to baseline after (S)-ketamine treatments (p = 0.1) and by an average of 5.6 ± 1 after IV-ketamine treatments (p = 0.0003) compared to pretreatment baseline scores. PCL-5 scores were reduced by an average of 4.3 ± 3.3 after IN (S)-ketamine treatments (p = 0.6) and 11.8 ± 3.5 after IV-ketamine treatments (p = 0.03) compared to pretreatment baseline scores.

CONCLUSIONS

This work suggests that off-label IV-(R,S)-ketamine could be considered a reasonable next step in patients who do not respond adequately to the FDA-approved IN-(S)-ketamine. Further double-blinded, randomized controlled trials are warranted to assess whether IV racemic ketamine is more effective than IN-(S)-ketamine.

Long-term Safety and Efficacy of Esketamine Nasal Spray Plus an Oral Antidepressant in Patients with Treatment-resistant Depression- an Asian Sub-group Analysis from the SUSTAIN-2 Study

Objective

To evaluate the long-term safety and efficacy of intranasal esketamine in patients with treatment-resistant depression from the Asian subgroup of the SUSTAIN-2 study.

Methods

SUSTAIN-2 was a phase 3, open-label, single-arm, multicenter study comprising a 4-week screening, 4-week induction, 48-week optimization/maintenance, and 4-week follow-up (upon esketamine discontinuation) phase. Patients with treatment-resistant depression received esketamine plus an oral antidepressant during the treatment period.

Results

The incidence of ≥ 1 serious treatment-emergent adverse event (TEAE) among the 78 subjects from the Asian subgroup (Taiwan 33, Korea 26, Malaysia 19) was 11.5% (n = 9); with no fatal TEAE. 13 Asian patients (16.7%) discontinued esketamine due to TEAEs. The most common TEAEs were dizziness (37.2%), nausea (29.5%), dissociation (28.2%), and headache (21.8%). Most TEAEs were mild to moderate in severity, transient and resolved on the same day. Upon discontinuation of esketamine, no trend in withdrawal symptoms was observed to associate long-term use of esketamine with withdrawal syndrome. There were no reports of drug seeking, abuse, or overdose. Improvements in symptoms, functioning and quality of life, occurred during in the induction phase and were generally maintained through the optimization/maintenance phases of the study.

Conclusion

The safety and efficacy of esketamine in the Asian subgroup was generally consistent with the total SUSTAIN-2 population. There was no new safety signal and no indication of a high potential for abuse with the long-term (up to one year) use of esketamine in the Asian subgroup. Most of the benefits of esketamine occurred early during the induction phase.

Using the Intranasal Route to Administer Drugs to Treat Neurological and Psychiatric Illnesses: Rationale, Successes, and Future Needs

While the intranasal administration of drugs to the brain has been gaining both research attention and regulatory success over the past several years, key fundamental and translational challenges remain to fully leveraging the promise of this drug delivery pathway for improving the treatment of various neurological and psychiatric illnesses. In response, this review highlights the current state of understanding of the nose-to-brain drug delivery pathway and how both biological and clinical barriers to drug transport using the pathway can been addressed, as illustrated by demonstrations of how currently approved intranasal sprays leverage these pathways to enable the design of successful therapies. Moving forward, aiming to better exploit the understanding of this fundamental pathway, we also outline the development of nanoparticle systems that show improvement in delivering approved drugs to the brain and how engineered nanoparticle formulations could aid in breakthroughs in terms of delivering emerging drugs and therapeutics while avoiding systemic adverse effects.

CYP 450 enzymes influence (R,S)-ketamine brain delivery and its antidepressant activity

Esketamine, the S-stereoisomer of (R,S)-ketamine was recently approved by drug agencies (FDA, EMA), as an antidepressant drug with a new mechanism of action. (R,S)-ketamine is a N-methyl-d-aspartate receptor (NMDA-R) antagonist putatively acting on GABAergic inhibitory synapses to increase excitatory synaptic glutamatergic neurotransmission. Unlike monoamine-based antidepressants, (R,S)-ketamine exhibits rapid and persistent antidepressant activity at subanesthetic doses in preclinical rodent models and in treatment-resistant depressed patients. Its major brain metabolite, (2R,6R)-hydroxynorketamine (HNK) is formed following (R,S)-ketamine metabolism by various cytochrome P450 enzymes (CYP) mainly activated in the liver depending on routes of administration [e.g., intravenous (largely used for a better bioavailability), intranasal spray, intracerebral, subcutaneous, intramuscular or oral]. Experimental or clinical studies suggest that (2R,6R)-HNK could be an antidepressant drug candidate. However, questions still remain regarding its molecular and cellular targets in the brain and its role in (R,S)-ketamine's fast-acting antidepressant effects. The purpose of the present review is: 1) to review (R,S)-ketamine pharmacokinetic properties in humans and rodents and its metabolism by CYP enzymes to form norketamine and HNK metabolites; 2) to provide a summary of preclinical strategies challenging the role of these metabolites by modifying (R,S)-ketamine metabolism, e.g., by administering a pre-treatment CYP inducers or inhibitors; 3) to analyze the influence of sex and age on CYP expression and (R,S)-ketamine metabolism. Importantly, this review describes (R,S)-ketamine pharmacodynamics and pharmacokinetics to alert clinicians about possible drug-drug interactions during a concomitant administration of (R,S)-ketamine and CYP inducers/inhibitors that could enhance or blunt, respectively, (R,S)-ketamine's therapeutic antidepressant efficacy in patients.

Safety concerns on the abuse potential of esketamine: Multidimensional analysis of a new anti-depressive drug on the market

Prominent features of esketamine (e.g., similar mechanism of action as ketamine and target population) require to be vigilant regarding its benefits/risks balance and its risks of abuse in real-life settings. The aim of this study was to review all available pharmacological and clinical data to assess the abuse potential of esketamine shortly after its marketing. This multidimensional study is a quantitative and qualitative analysis of complementary data sources, ranging from preauthorization data (i.e., fundamental pharmacology and clinical trials) to real-life settings data (i.e., pharmacovigilance databases and web forums). According to esketamine pharmacology, its psychoactive effects play a role both in its therapeutic effect and its abuse potential. Only one out of the three short-term efficacy trials found a significant difference between esketamine and placebo in treatment-resistant depression. Beside adverse events that may be sought for abuse purpose (e.g., dissociation, sedation, euphoric mood, hallucination, feeling drunk, and derealization), clinical signs related to substance use disorder (e.g., tolerance, withdrawal syndrome, and drug dependence) and misuse (e.g., off-label use) were also identified in pharmacovigilance databases. Analysis of pharmacovigilance narratives and web forums showed that esketamine psychoactive effects are appreciated by some patients, while they are badly experienced by others. Strict compliance with the market authorization, close monitoring of patients by psychiatrists, and surveillance of any signs of misuse, abuse, or dependence must be part of any treatment course.

Ready for a "breakthrough" with ketamine? A look at recent pharmacological insights!

PURPOSE OF REVIEW

To update pharmacological insights on ketamine integrating information from different disciplines for developing steps to "breakthrough" approaches in clinical challenges.

RECENT FINDINGS

Pharmacokinetic/pharmacodynamic (PK/PD) models have incorporated recirculation, ketamine metabolites, drug-drug interaction, and covariates such as age. Ketamine-induced relief from treatment-resistant depression has been explained by "disinhibition" of gamma-aminobutyric acid-ergic interneurons and synaptogenic mechanisms requiring neurotrophic signals. Neuroimaging/electroencephalographic investigations have shown an increase in gamma spectral power in healthy volunteers and patients with depression, but also opposite changes in functional network connectivity after subanesthetic ketamine. Volunteer data may not be transferable to clinical conditions. Altered states of consciousness induced by subanesthetic ketamine have been described by disruption of resisting-state functional networks and frontoparietal connectivity with preservation of multisensory and sensor-motor networks. This has been interpreted as a "disconnected consciousness".

SUMMARY

More precise PK/PD models may improve the ketamine use regimen. The findings from research on depression are an important discovery because ketamine's impact on neuronal plasticity and synaptogenesis in human brain disease has directly been documented. Psychic adverse effects with subanesthetic ketamine are related to a "disconnected consciousness". Overall, progress has been made, but the "breakthrough" still has to come.

The pharmacokinetic interaction between nasally administered naloxone and the opioid remifentanil in human volunteers

Purpose

Remifentanil has been shown to increase the bioavailability of nasally administered naloxone. The aim of this study was to explore the nature of this observation.

Methods

We analysed samples from three pharmacokinetic studies to determine the serum concentrations of naloxone-3-glucuronide (N3G), the main metabolite of naloxone, with or without exposure to remifentanil. To enable direct comparison of the three studies, the data are presented as metabolic ratios (ratio of metabolite to mother substance, N3G/naloxone) and dose-corrected values of the area under the curve and maximum concentration (Cmax).

Results

Under remifentanil exposure, the time to maximum concentration (Tmax) for N3G was significantly higher for intranasal administration of 71 min compared to intramuscular administration of 40 min. The dose-corrected Cmax of N3G after intranasal administration of naloxone under remifentanil exposure was significantly lower (4.5 ng/mL) than in subjects not exposed to remifentanil (7.8–8.4 ng/mL). The metabolic ratios after intranasal administration rose quickly after 30–90 min and were 2–3 times higher at 360 min compared to intravenous and intramuscular administration. Remifentanil exposure resulted in a much slower increase of the N3G/naloxone ratio after intranasal administration compared to intranasal administration with the absence of remifentanil. After remifentanil infusion was discontinued, this effect gradually diminished. From 240 min there was no significant difference between the ratios observed after intranasal naloxone administration.

Conclusion

Remifentanil increases the bioavailability of naloxone after nasal administration by reducing the pre-systemic metabolism of the swallowed part of the nasal dose.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-021-03190-1.

Fluoroethylnormemantine, A Novel Derivative of Memantine, Facilitates Extinction Learning Without Sensorimotor Deficits

BACKGROUND

Memantine, a noncompetitive N-methyl-D-aspartate receptor antagonist, has been approved for use in Alzheimer's disease, but an increasing number of studies have investigated its utility for neuropsychiatric disorders. Here, we characterized a novel compound, fluoroethylnormemtantine (FENM), which was derived from memantine with an extra Fluor in an optimized position for in vivo biomarker labeling. We sought to determine if FENM produced similar behavioral effects as memantine and/or if FENM has beneficial effects against fear, avoidance, and behavioral despair.

METHODS

We administered saline, FENM, or memantine prior to a number of behavioral assays, including paired-pulse inhibition, open field, light dark test, forced swim test, and cued fear conditioning in male Wistar rats.

RESULTS

Unlike memantine, FENM did not produce nonspecific side effects and did not alter sensorimotor gating or locomotion. FENM decreased immobility in the forced swim test. Moreover, FENM robustly facilitated fear extinction learning when administered prior to either cued fear conditioning training or tone reexposure.

CONCLUSIONS

These results suggest that FENM is a promising, novel compound that robustly reduces fear behavior and may be useful for further preclinical testing.

CYP2B6 Functional Variability in Drug Metabolism and Exposure Across Populations-Implication for Drug Safety, Dosing, and Individualized Therapy

Adverse drug reactions (ADRs) are one of the major causes of morbidity and mortality worldwide. It is well-known that individual genetic make-up is one of the causative factors of ADRs. Approximately 14 million single nucleotide polymorphisms (SNPs) are distributed throughout the entire human genome and every patient has a distinct genetic make-up which influences their response to drug therapy. Cytochrome P450 2B6 (CYP2B6) is involved in the metabolism of antiretroviral, antimalarial, anticancer, and antidepressant drugs. These drug classes are commonly in use worldwide and face specific population variability in side effects and dosing. Parts of this variability may be caused by single nucleotide polymorphisms (SNPs) in the CYP2B6 gene that are associated with altered protein expression and catalytic function. Population variability in the CYP2B6 gene leads to changes in drug metabolism which may result in adverse drug reactions or therapeutic failure. So far more than 30 non-synonymous variants in CYP2B6 gene have been reported. The occurrence of these variants show intra and interpopulation variability, thus affecting drug efficacy at individual and population level. Differences in disease conditions and affordability of drug therapy further explain why some individuals or populations are more exposed to CYP2B6 pharmacogenomics associated ADRs than others. Variabilities in drug efficacy associated with the pharmacogenomics of CYP2B6 have been reported in various populations. The aim of this review is to highlight reports from various ethnicities that emphasize on the relationship between CYP2B6 pharmacogenomics variability and the occurrence of adverse drug reactions. In vitro and in vivo studies evaluating the catalytic activity of CYP2B6 variants using various substrates will also be discussed. While implementation of pharmacogenomic testing for personalized drug therapy has made big progress, less data on pharmacogenetics of drug safety has been gained in terms of CYP2B6 substrates. Therefore, reviewing the existing evidence on population variability in CYP2B6 and ADR risk profiles suggests that, in addition to other factors, the knowledge on pharmacogenomics of CYP2B6 in patient treatment may be useful for the development of personalized medicine with regards to genotype-based prescription.