Evaluation of the abuse potential of difelikefalin,a selective kappa‐opioid receptor agonist,in recreational polydrug users

Difelikefalin, a selective kappa‐opioid receptor agonist with limited central nervous system penetration, is being developed for the treatment of chronic pruritic conditions. This randomized, double‐blind, active‐ and placebo‐controlled, four‐way crossover study was designed to evaluate the abuse potential of difelikefalin in healthy recreational polydrug users. Using a 4 × 4 Williams design, nondependent adult users of opioids and hallucinogens (N = 44) were randomized to receive single intravenous (i.v.) injections of difelikefalin at supratherapeutic doses (5 and 15 mcg/kg); pentazocine (0.5 mg/kg), a schedule IV mu‐opioid partial agonist and kappa‐opioid receptor agonist; and placebo. The abuse potential of difelikefalin was compared with pentazocine and placebo using the maximal score (maximum effect [E_max]) of the Drug Liking visual analog scale (VAS; primary end point), along with multiple secondary end points of subject‐rated measures and pupillometry. Difelikefalin produced significantly lower Drug Liking VAS E_max, and lower peak positive, sedative, and perceptual effects compared with pentazocine. These effects of difelikefalin were small, brief, and not dose‐dependent, although marginally greater than those observed with placebo. Neither dose of difelikefalin elicited significant negative or hallucinogenic effects. On end‐of‐session measures of overall drug liking and willingness to take the drug again, difelikefalin did not differ from placebo, indicating subjects neither liked nor disliked the effects overall and did not feel motivated to take the drug again. Consistent with its lack of mu agonist activity, difelikefalin did not induce miosis compared with pentazocine. All treatments were generally well‐tolerated. This study indicates that difelikefalin presents a low potential for abuse.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

Difelikefalin is a selective kappa‐opioid receptor agonist with limited central nervous system penetration being developed for the treatment of chronic pruritus. Difelikefalin has no affinity for other opioid receptors and therefore is different from opioid analgesics that predominantly bind to mu opioid receptors.

• WHAT QUESTION DID THIS STUDY ADDRESS?

This randomized, double‐blind, active‐ and placebo‐controlled, four‐way crossover study addressed whether difelikefalin has abuse potential in healthy recreational polydrug users.

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

Intravenous difelikefalin, at supratherapeutic doses, had an abuse potential profile that was significantly lower than the schedule IV opioid pentazocine, and not meaningfully different from placebo. Difelikefalin did not elicit significant negative or hallucinogenic effects.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

These findings suggest that difelikefalin should not be a target for diversion for recreational use. This has important clinical implications for patients who may require this treatment, and it demonstrates that peripherally restricted kappa‐opioid receptor exhibit fewer adverse effects and toxicities related to abuse over typical opioids.     

A randomized,double‐blind,placebo‐ and positive‐controlled crossover study of the effects of durlobactam on cardiac repolarization in healthy subjects

Durlobactam (formerly ETX2514) is a diazabicyclooctane β‐lactamase inhibitor that inhibits class A, C, and D β‐lactamases. Sulbactam combined with durlobactam has in vitro and in vivo activity against Acinetobacter baumannii including carbapenem‐ and colistin‐resistant isolates and is being developed for treating serious infections due to A. baumannii. The effect of a single supratherapeutic dose of durlobactam on the heart rate corrected QT interval (QTc) was evaluated in healthy subjects in a placebo‐ and active‐controlled, single‐infusion, three‐way crossover study. Subjects were randomized to 1 of 6 sequences that included a single 3‐h i.v. infusion of durlobactam 4 g (supratherapeutic dose), a single 3‐h i.v. infusion of placebo, and a single 3‐h i.v. infusion of placebo plus a single oral dose of moxifloxacin 400 mg given open‐label at the end of the i.v. infusion. In each treatment period, Holter electrocardiogram (ECG) measurements were obtained from predose through 24 h post‐start of infusion. For the primary ECG end point, placebo‐corrected change‐from‐baseline corrected QT Fridericia’s formula (ΔΔQTcF), no significant change was observed with durlobactam. A concentration‐QT analysis demonstrated no significant effect of durlobactam on ECG parameters, including QT interval prolongation. Thus, durlobactam has a low risk for prolonging the QT interval and is unlikely to produce any proarrhythmic effects.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

Drug‐induced prolongation of the QT interval has the potential to cause severe, potentially fatal ventricular arrhythmias. A number of antimicrobial agents, including fluoroquinolones and macrolides, are associated with a low, but clinically significant increased risk of QT prolongation.

• WHAT QUESTION DID THIS STUDY ADDRESS?

This study evaluated the effect of a single supratherapeutic dose of durlobactam on the heart rate corrected QT interval in healthy subjects to determine if there were any potentials for proarrhythmic effects.

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

This study found that durlobactam had a low risk for prolonging the QT interval and is unlikely to produce any proarrhythmic effects.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

Because durlobactam had a low risk for prolonging the QT interval alone and when co‐administered with sulbactam, clinicians should be confident in administering the combination without risk for proarrhythmic effects.     

Topiramate for the management of methamphetamine dependence: a pilot randomized,double‐blind,placebo‐controlled trial

To date, no medication has been approved as an effective treatment for methamphetamine dependence. Topiramate has attracted considerable attention as a treatment for the dependence on alcohol and stimulants. Therefore, this study aimed to evaluate the effect of topiramate for methamphetamine dependence. This study was a double‐blind, randomized, placebo‐controlled trial. In the present investigation, 62 methamphetamine‐dependent adults were enrolled and randomized into two groups, and received topiramate or a placebo for 10 weeks in escalating doses from 50 mg/day to the target maintenance dose of 200 mg/day. Addiction severity index (ASI) and craving scores were registered every week. The Beck questionnaire was also given to each participant at baseline and every 2 weeks during the treatment. Urine samples were collected at baseline and every 2 weeks during the treatment. Fifty‐seven patients completed 10 weeks of the trial. There was no significant difference between both groups in the mean percentage of prescribed capsules taken by the participants. At week six, the topiramate group showed a significantly lower proportion of methamphetamine‐positive urine tests in comparison with the placebo group (P = 0.01). In addition, there were significantly lower scores in the topiramate group in comparison with the placebo group in two domains of ASI: drug use severity (P < 0.001) and drug need (P < 0.001). Furthermore, the craving score (duration) significantly declined in the topiramate patients compared to those receiving the placebo. In conclusion, the results of this trial suggest that topiramate may be beneficial for the treatment of methamphetamine dependence.     

Muscle velocity recovery cycles as pharmacodynamic biomarker: Effects of mexiletine in a randomized double‐blind placebo‐controlled cross‐over study

Measuring muscle velocity recovery cycles (MVRCs) is a method to obtain information on muscle cell excitability, independent of neuromuscular transmission. The goal was to validate MVRC as a pharmacodynamic (PD) biomarker for drugs targeting muscle excitability. As proof‐of‐concept, sensitivity of MVRC to detect effects of mexiletine, a voltage‐gated sodium channel (Na_v) blocker, was assessed. In a randomized, double‐blind, two‐way crossover study, effects of a single pharmacologically active oral dose of 333 mg mexiletine was compared to placebo in 15 healthy male subjects. MVRC was performed predose, and 3‐ and 5‐h postdose using QTrac. Effects of mexiletine versus placebo were calculated using a mixed effects model with baseline as covariate. Mexiletine had significant effects on MVRC when compared to placebo. Early supernormality after five conditioning stimuli was decreased by mexiletine (estimated difference −2.78% [95% confidence interval: −4.16, −1.40]; p value = 0.0003). Moreover, mexiletine decreased the difference in late supernormality after five versus one conditioning stimuli (5XLSN; ED −1.46% [−2.26, −0.65]; p = 0.001). These results indicate that mexiletine decreases the percentage increase in velocity of the muscle fiber action potential after five conditioning stimuli, at long and short interstimulus intervals, which corresponds to a decrease in muscle membrane excitability. This is in line with the pharmacological activity of mexiletine, which leads to use‐dependent Na_V1.4 blockade affecting muscle membrane potentials. This study shows that effects of mexiletine can be detected using MVRC in healthy subjects, thereby indicating that MVRC can be used as a tool to demonstrate PD effects of drugs targeting muscle excitability in early phase drug development.

Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Muscle velocity recovery cycles (MVRC) is a method to obtain information on muscle excitability, independent of neuromuscular transmission. MVRC has been used to distinguish various neuromuscular diseases from healthy controls. WHAT QUESTION DID THIS STUDY ADDRESS? Can MVRC be a valuable pharmacodynamic (PD) biomarker for drugs targeting muscle excitability? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? As proof‐of‐concept, we evaluated effects of mexiletine—a sodium channel blocker expected to decrease muscle excitability—on MVRC in a double‐blind, placebo‐controlled study in healthy subjects. We demonstrated significant effects of mexiletine on MVRC, indicating reduced muscle excitability, in line with the pharmacological mechanism of action. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? Our results encourage use of MVRC as a tool to demonstrate PD effects in the development of drugs targeting muscle excitability. This biomarker may be used to demonstrate target engagement in early clinical drug development. Furthermore, it could be of interest as a biomarker in the translation from preclinical to clinical studies, and from healthy subjects to patients with neuromuscular disease.     

First‐in‐human,randomized, double‐blind,placebo‐controlled,dose escalation trial of the anti‐herpes simplex virus monoclonal antibody HDIT101 in healthy volunteers

HDIT101 is a first‐in‐class humanized monoclonal antibody recognizing a conserved epitope in glycoprotein B, a target present on the surface of herpes simplex virus 1 (HSV‐1) and HSV‐2 particles as well as on virus‐infected cells. This was a first‐in‐human, single‐center, double‐blind, placebo‐controlled trial in 24 healthy volunteers, randomized 3:1 (placebo:active) in each of the six dose levels with escalating doses up to 12,150 mg HDIT101. HDIT101 was administered intravenously, to study safety, pharmacokinetics (PKs), and immunogenicity. HDIT101 was well‐tolerated in all recipients and no serious or severe adverse events, no infusion‐related reactions, and no events suggestive of dose limiting off‐target toxicity occurred. The mean serum exposure (area under the curve from zero to infinity [AUC_0‐∞]) of HDIT101 showed a linear increase from 4340 h*μg/ml at a dose of 50 mg to 1,122,247 h*μg/ml at a dose of 12,150 mg. No immunogenic effects following HDIT101 exposure were observed at any of the applied doses. HDIT101 demonstrated the expected PK properties of a monoclonal antibody was well‐tolerated, and could be safely administered even at excessively high doses that may be required for treatment of patients with septical HSV spread.

Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Herpes simplex virus (HSV‐1) and HSV‐2 are a global disease burden with significant morbidity and serious consequences for patients mainly in immunocompromised settings. There is a need for new drugs that reduce symptoms, recurrences, and effectively suppress viral shedding. WHAT QUESTION DID THIS STUDY ADDRESS? How safe is the administration of HDIT101, a first‐in‐class humanized monoclonal antibody recognizing the exclusively viral target glycoprotein B? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? HDIT101 is the first clinically tested monoclonal antibody against HSV. It was well tolerated by healthy volunteers and could be safely administered up to very high doses. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? Our findings pave the way for efficacy trials in patients to evaluate the promising first‐in‐class therapeutic antibody for patients suffering from HSV‐related diseases.     

Managing endothelial dysfunction in COVID‐19 with statins,beta blockers,nicorandil, and oral supplements: A pilot,double‐blind,placebo‐controlled,randomized clinical trial

Coronavirus disease 2019 (COVID‐19) is associated with endothelial dysfunction. Pharmacologically targeting the different mechanisms of endothelial dysfunction may improve clinical outcomes and lead to reduced morbidity and mortality. In this pilot, double‐blind, placebo‐controlled, randomized clinical trial, we assigned patients who were admitted to the hospital with mild, moderate, or severe COVID‐19 infection to receive, on top of optimal medical therapy, either an endothelial protocol consisting of (Nicorandil, L‐arginine, folate, Nebivolol, and atorvastatin) or placebo for up to 14 days. The primary outcome was time to recovery, measured by an eight category ordinal scale and defined by the time to being discharged from the hospital or hospitalized for infection‐control or other nonmedical reasons. Secondary outcomes included the composite outcome of intensive care unit (ICU) admission or the need for mechanical ventilation, all‐cause mortality, and the occurrence of side effects. Of 42 randomized patients, 37 were included in the primary analysis. The mean age of the patients was 57 years; the mean body mass index of study participants was 29.14. History of hypertension was present in 27% of the patients, obesity in 45%, and diabetes mellitus in 21.6%. The median (interquartile range) time to recovery was not significantly different between the endothelial protocol group (6 [4–12] days) and the placebo group (6 [5–8] days; p value = 0.854). Furthermore, there were no statistically significant differences in the need for mechanical ventilation or ICU admission, all‐cause mortality, or the occurrence of side effects between the endothelial protocol group and the placebo group. Among patients hospitalized with mild, moderate, or severe COVID‐19 infection, targeting endothelial dysfunction by administering Nicorandil, L‐arginine, Folate, Nebivolol, and Atorvastatin on top of optimal medical therapy did not decrease time to recovery. Based on this study’s findings, targeting endothelial dysfunction did not result in a clinically significant improvement in outcome and, as such, larger trials targeting this pathway are not recommended.     

Safety,tolerability, and pharmacokinetics of oral baicalein tablets in healthy Chinese subjects: A single‐center,randomized, double‐blind,placebo‐controlled multiple‐ascending‐dose study

Baicalein is a biologically important flavonoid in extracted from the Scutellaria baicalensis Georgi, which can effectively inhibit the influenza virus. This study aimed to analyze the safety and pharmacokinetic (PK) characteristics of baicalein tablets in healthy Chinese subjects and provide more information for phase II clinical trials. In this multiple‐ascending‐dose placebo‐controlled trial, 36 healthy subjects were randomized to receive 200, 400, and 600 mg of baicalein tablet or placebo once daily on day 1 and day 10, 3 times daily on days 4–9. All groups were intended to produce safety and tolerability outcomes (lowest dose first). Blood and urine samples were collected from subjects in the 600 mg group for baicalein PK analysis. Our study had shown that Baicalein tablet was generally safe and well‐tolerated. All adverse events were mild and resolved without any intervention except one case of fever reported in the 600 mg group, which was considered as moderate but not related with baicalein as judged by the investigator. Oral baicalein tablets were rapidly absorbed with peak plasma levels being reached within 2 h after multiple administration. The highest urinary excretion of baicalein and its metabolites peaked in 2 h, followed by 12 h, with a double peak trend.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

Many studies have shown that baicalin has an anti‐influenza effect in cell and animal experiments. The primary mechanism of action is that baicalein has a strong inhibitory effect on the sialidase of the influenza virus.

• WHAT QUESTION DID THIS STUDY ADDRESS?

This study aimed to analyze the safety and pharmacokinetic (PK) characteristics of baicalein tablets in healthy Chinese subjects and provide more information for phase II clinical trials.

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

Our study results have shown that baicalein tablets were administered multiple times within the studied dose range were safe and well‐tolerated in healthy Chinese subjects with no serious or severe adverse effects. The highest urinary excretion of baicalein and its metabolites peaked in 2 h, followed by 12 h, with a double peak trend. Oral baicalein tablets were rapidly absorbed with peak plasma levels reached within 2 h after multiple administration.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

Our study addresses the safety outcomes of baicalein tablets and emphasizes the PKs of baicalein, which provides a better understanding and a scientific basis of the clinical application of baicalein for further evaluation.     

Cannabis smoking impairs driving performance on the simulator and real driving: a randomized,double‐blind,placebo‐controlled,crossover trial

Driving experiments in real conditions are considered as a ‘gold standard’ to evaluate the effects of drugs on driving performance. Several constraints are difficult to manage in these conditions, so driving simulation appears as the best alternative. A preliminary comparison is crucial before being able to use driving simulation as a valid evaluation method. The aim of this study was to design a driving simulation method for assessing drug effects on driving. We used cannabis (THC) as a positive control and assessed whether THC affects driving performance in simulation conditions and whether these effects are consistent with performance in real driving conditions. A double‐blind, placebo‐controlled, two successive two‐way crossover design was performed using cigarettes containing 20 mg of THC. Healthy occasional users of THC, aged 25–35 years, who had a consistent driving experience were included. The first two sessions were realized in simulation conditions, and the last two sessions were in real driving conditions. Driving performance was estimated through inappropriate line crossings (ILC) and the standard deviation of the vehicle's lateral position. Participants felt significantly drowsier and more tired after THC, whatever the driving condition. Driving stability was significantly impaired after THC, both in simulated and real driving conditions. We also found that ILC were significantly more numerous in driving simulation conditions, as compared to real driving. In conclusion, the driving simulator was proven to be more sensitive for demonstrating THC‐induced effects on driving performances. Driving simulation appears to be a good qualitative predictor of driving safety after drug intake.     

A phase I,randomized, double‐blind,placebo‐controlled,single‐ and multiple dose escalation study evaluating the safety,pharmacokinetics and pharmacodynamics of VX‐128, a highly selective Nav1.8 inhibitor,in healthy adults

Selective inhibition of certain voltage‐gated sodium channels (Na_vs), such as Na_v1.8, is of primary interest for pharmacological pain research and widely studied as a pharmacological target due to its contribution to repetitive firing, neuronal excitability, and pain chronification. VX‐128 is a highly potent and selective Na_v1.8 inhibitor that was being developed as a treatment for pain. We evaluated the safety, tolerability, and pharmacokinetics of VX‐128 in healthy subjects in a single‐ and multiple‐ascending dose (MAD) first‐in‐human study. Pharmacodynamics were evaluated in the MAD part using a battery of evoked pain tests. Overall, single doses of VX‐128 up to 300 mg were well‐tolerated, although adverse effect (AE) incidence was higher in subjects receiving VX‐128 (41.7%) compared with placebo (25.0%). After multiple dosing of up to 10 days, skin rash events were observed at all dose levels (up to 100 mg once daily [q.d.]), in five of 26 (19.2%) subjects, including one subject receiving VX‐128 (100 mg q.d.) who had a serious AE of angioedema. A trend in pain tolerance were observed for cold pressor‐ and pressure pain, which was dose‐dependent for the latter. VX‐128 was rapidly absorbed (median time to maximum plasma concentration between 1 and 2 h) with a half‐life of ~80 h at 10 mg q.d., and approximately two‐fold accumulation ratio after 10 and 30 mg q.d. Although VX‐128, when given in a multiple dose fashion, resulted in early study termination due to tolerability issues, effects were observed on multiple pain tests that may support further investigation of Na_v1.8 inhibitors as pain treatments.

Study Highlights

• WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?

Selective sodium channel (Na_v) inhibitors have been proposed as an alternative to opioids for pain management. Their potential, however, has yet to be confirmed, as none of the multiple selective Na_v inhibitors that have been investigated for pain management has reached the market.

• WHAT QUESTION DID THIS STUDY ADDRESS?

We investigated the safety, tolerability, and initial analgesic effects of VX‐128, a novel and highly selective Na_v1.8 inhibitor, in healthy volunteers.

• WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?

This is the first study to describe clinical data obtained on the highly selective Na_v1.8 inhibitor VX‐128, and the first to report analgesic effects of this selective Na_v inhibitor in humans. VX‐128 administered as a single dose was well‐tolerated, but dose‐limiting skin rashes occurred after multiple doses resulting in a premature study halt. Although the study had a parallel design and was not necessarily powered to detect pharmacodynamic effects, nociceptive test results suggest that VX‐128 leads to dose‐dependent analgesic effects.

• HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?

Our findings substantiate research that is performed on evaluating selective Na_v1.8 inhibitors as treatment for pain, and suggests that the cold pressor‐ and pressure pain models are suitable to evaluate selective Na_v1.8 inhibitors.     

A randomised,double‐blind,placebo‐controlled trial of dolasetron,a 5‐hydroxytryptamine 3 receptor antagonist,in patients with fibromyalgia

Objective: The purpose of the study was to evaluate the efficacy and safety of dolasetron for symptomatic relief of pain associated with fibromyalgia (FM). Methods: This prospective, double‐blind, placebo‐controlled trial randomly assigned 60 patients with FM to receive placebo (n =31) or dolasetron (n =29) 12.5 mg/d via the intravenous route on 4 days at baseline (M0), 1 month (M1), 2 months (M2) and 3 months (M3) with follow‐up to month 12. The primary outcome variable was the reduction in pain intensity measured by visual analogue scale (VAS) between M0 and M3. The secondary outcome variables were patient global impression of change (PGIC), the FM impact questionnaire, assessment of quality of life (SF‐36), the hospital anxiety and depression scale, the manual tender point count, and functional symptoms associated with FM. Results: Reduction in pain intensity at M3 was significantly greater in dolasetron‐treated patients (p =0.04, ?21.3 on a 0–100 scale) compared with placebo controls (?5.9). More patients in the dolasetron group had ≥30% and ≥50% improvement in pain (42.5% and 28% respectively in the dolasetron group versus 25% and 16% in the placebo group). The PGIC was significantly greater in the dolasetron group at M3 (p =0.02). The other secondary outcomes failed to reach statistical significance. The most common adverse events were constipation, nausea, dizziness and headache, with no significant differences between the two groups. Conclusion: Intermittent IV dolasetron was safe and efficacious for the reduction of pain intensity associated with FM at 3 months.     

Pain relief by applying transcutaneous electrical nerve stimulation (TENS) during unsedated colonoscopy: A randomized double‐blind placebo‐controlled trial

Transcutaneous electrical nerve stimulation (TENS) is a noninvasive alternative to traditional pain treatments. TENS has been studied in the past as a pain reduction modality in colonoscopy with limited success. Reviews and meta‐analysis have shown that the inconclusive results of TENS may be due to the lack of randomized controlled trials and the difficulty in defining precise output parameters. The objective of this double‐blind randomized placebo‐controlled trial was to investigate the pain‐relieving effect of a new application of TENS in unsedated screening colonoscopy. Ninety patients undergoing unsedated screening colonoscopy were randomly allocated to one of three groups: a control group (n=30), a group to receive active TENS (n=30), or a group to receive placebo TENS (n=30). A visual analogue scale (VAS) and a five‐point Likert scale were used to assess pain 5min into the procedure and at the end of the procedure. The patient's bloating sensation during colonoscopy and the effect on the duration of the procedure were also evaluated. Throughout the procedure, the active TENS group experienced a VAS pain score reduction ≥50% compared to the placebo TENS group (P<0.001) and the control group (P<0.001). On the five‐point Likert scale, there was also a significant reduction in pain score in the active TENS group compared to the placebo TENS and control groups (P=0.009). No significant differences were found between the study groups as to the bloating sensation and the duration of the procedure. We conclude that TENS can be used as a pain relief therapy in unsedated screening colonoscopy.     

Lack of efficacy of alpha‐lipoic acid in burning mouth syndrome: A double‐blind,randomized, placebo‐controlled study

Background: A systematic review from the Cochrane Collaboration stated that alpha‐lipoic acid (ALA) may help in the management of burning mouth syndrome (BMS). Because all of the data on ALA came from a single group, it has been stressed that its effectiveness should be reproduced in other populations. Aim: A double‐blind, randomized, placebo‐controlled study, including two test groups (Group A and Group B) and one control group (Group C), was carried out to evaluate the efficacy of systemic ALA (400mg) and ALA (400mg) plus vitamins in the treatment of BMS. Methods: Sixty‐six patients (54 females and 12 males) were included in an 8‐week trial. Symptoms were evaluated by using a visual analogue scale (VAS) and the McGill Pain Questionnaire (MPQ) at 0, 2, 4, 8 and 16 weeks. Results: Fifty‐two patients (43 females and 9 males, aged 67.3±11.9 years) completed the study. All three groups had significant reductions in the VAS score and in the mixed affective/evaluative subscale of the MPQ; the responders’ rate (at least 50% improvement in the VAS score) was about 30%. No significant differences were observed among the groups either in the response rate or in the mean latency of the therapeutic effect. Conclusions: The fairly high placebo effect observed is very similar to data obtained from patients affected by atypical facial pain. This study failed to support a role for ALA in the treatment of BMS, and further investigations are needed to identify the cause of BMS in order to develop efficacious therapies.     

Comparison of the effects of perineural or intravenous dexamethasone on thoracic paravertebral block in Ivor‐Lewis esophagectomy: A double‐blind randomized trial

Efforts to prolong thoracic paravertebral block (TPVB) analgesia include local anesthetic adjuvants, such as dexamethasone (Dex). Previous studies showed that both perineural (PN) and intravenous (i.v.) routes could prolong analgesia. As PN Dex is an off‐label use, anesthesiologists should be fully informed of the clinical differences, if any, on block duration. This study was designed to evaluate the two administration routes of Dex for duration of analgesia in TPVB. Ninety‐five patients scheduled for Ivor‐Lewis esophagectomy were randomized to receive TPVB (0.5% ropivacaine 15 ml), PN or i.v. Dex 8 mg. The primary end point was the duration of analgesia. The secondary end points included pain scores, analgesic consumption, adverse effects rate, and incidence of chronic pain at 3 months postoperatively. The PN‐Dex group showed better analgesic effects than the i.v.‐Dex group (p < 0.05). Similarly, the visual analogue scale scores in patients at 2, 4, 8, and 12 h postoperatively were lower in the PN‐Dex group than the i.v.‐Dex group (p < 0.05). The analgesic consumption in both the PN‐Dex and i.v.‐Dex groups was significantly lower than that in the control group (p < 0.05). Regarding the incidence of chronic pain, regardless of route, Dex decreased the incidence of chronic postsurgical pain and neuropathic pain at 3 months after surgery (p < 0.05), but there were no clinical differences between the i.v.‐Dex and PN‐Dex groups. Perineural dexamethasone improved the magnitude and duration of analgesia compared to that of the i.v.‐Dex group in TPVB in Ivor‐Lewis esophagectomy. However, there were no clinically significant differences between the two groups in the incidence of chronic pain.

Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Both perineural (PN) and intravenous (i.v.) dexamethasone (Dex) could prolong the duration of a nerve block, but the superiority of either route is still inconclusive. WHAT QUESTION DID THIS STUDY ADDRESS? The study investigated the effects of the two routes of Dex added to ropivacaine on analgesic effects of thoracic paravertebral block in patients undergoing Ivor‐Lewis esophagectomy. WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? These results extend the knowledge of the superior analgesic effect of Dex for the management of perioperative pain in the setting of Ivor‐Lewis Esophagectomy. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? Because PN Dex is an off‐label use, our study conformed the safety of Dex as PN adjuvants and extended its application field in clinical work.