The preclinical and phase 1 development of the novel oral cathepsin C inhibitor BI 1291583

Preclinical and phase 1 study results indicate that BI 1291583 is a reversible, highly potent and highly selective CatC inhibitor that markedly inhibits active NSP production in a dose-dependent manner, supporting phase 2 trials in bronchiectasis patients https://bit.ly/47PZ8E5.

Baseline characteristics from a 3-year longitudinal study to phenotype subjects with COPD: the FOOTPRINTS study

BACKGROUND

FOOTPRINTS® is a prospective, longitudinal, 3-year study assessing the association between biomarkers of inflammation/lung tissue destruction and chronic obstructive pulmonary disease (COPD) severity and progression in ex-smokers with mild-to-severe COPD. Here, we present baseline characteristics and select biomarkers of study subjects.

METHODS

The methodology of FOOTPRINTS® has been published previously. The study population included ex-smokers with a range of COPD severities (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stages 1-3), ex-smokers with COPD and alpha-1-antitrypsin deficiency (A1ATD) and a control group of ex-smokers without airflow limitation (EwAL). At study entry, data were collected for: demographics, disease characteristics, history of comorbidities and COPD exacerbations, symptoms, lung function and volume, exercise capacity, soluble biomarkers, and quantitative and qualitative computed tomography. Baseline data are presented with descriptive statistical comparisons for soluble biomarkers in the individual GOLD and A1ATD groups versus EwAL.

RESULTS

In total, 463 subjects were enrolled. The per-protocol set comprised 456 subjects, mostly male (64.5%). The mean (standard deviation) age was 60.7 (6.9) years. At baseline, increasing pulmonary symptoms, worse lung function, increased residual volume, reduced diffusing capacity of the lung for carbon monoxide (DLco) and greater prevalence of centrilobular emphysema were observed with increasing disease severity amongst GOLD 1-3 subjects. Subjects with A1ATD (n = 19) had similar lung function parameters to GOLD 2-3 subjects, a high residual volume comparable to GOLD 3 subjects, and similar air trapping to GOLD 2 subjects. Compared with EwAL (n = 61), subjects with A1ATD had worse lung function, increased residual volume, reduced DLco, and a greater prevalence of confluent or advanced destructive emphysema. The soluble inflammatory biomarkers white blood cell count, fibrinogen, high-sensitivity C-reactive protein and plasma surfactant protein were higher in GOLD 1-3 groups than in the EwAL group. Interleukin-6 was expressed less often in EwAL subjects compared with subjects in the GOLD and A1ATD groups. Soluble receptor for advanced glycation end product was lowest in GOLD 3 subjects, indicative of more severe emphysema.

CONCLUSIONS

These findings provide context for upcoming results from FOOTPRINTS®, which aims to establish correlations between biomarkers and disease progression in a representative COPD population.

TRIAL REGISTRATION NUMBER

NCT02719184, study start date 13/04/2016.

A Phase 2 randomised study to establish efficacy, safety and dosing of a novel oral cathepsin C inhibitor, BI 1291583, in adults with bronchiectasis: Airleaf

New therapies are needed to prevent exacerbations, improve quality of life and slow disease progression in bronchiectasis. Inhibition of cathepsin C (CatC) activity has the potential to decrease activation of neutrophil-derived serine proteases in patients with bronchiectasis, thereby reducing airway inflammation, improving symptoms, reducing exacerbations and preventing further airway damage. Here we present the design of a phase 2 trial (Airleaf™; NCT05238675) assessing the efficacy and safety of a novel CatC inhibitor, BI 1291583, in adult patients with bronchiectasis. This multinational, randomised, double-blind, placebo-controlled, parallel-group, dose-finding study has a screening period of at least 6 weeks, a treatment period of 24-48 weeks and a follow-up period of 4 weeks. ∼240 adults with bronchiectasis of multiple aetiologies will be randomised to placebo once daily, or BI 1291583 1 mg once daily, 2.5 mg once daily or 5 mg once daily in a 2:1:1:2 ratio, stratified by Pseudomonas aeruginosa infection and maintenance use of macrolides. The primary efficacy objective is to evaluate the dose-response relationship for the three oral doses of BI 1291583 versus placebo on time to first pulmonary exacerbation up to Week 48 (the primary end-point). Efficacy will be assessed using exacerbations, patient-reported outcomes, measures of symptoms, sputum neutrophil elastase activity and pulmonary function testing. Safety assessment will include adverse event reporting, physical examination, monitoring of vital signs, safety laboratory parameters, 12-lead electrocardiogram, and periodontal and dermatological assessments. If efficacy and safety are demonstrated, results will support further investigation of BI 1291583 in phase 3 trials.

Nintedanib modulates type III collagen turnover in viable precision-cut lung slices from bleomycin-treated rats and patients with pulmonary fibrosis

BACKGROUND

Aberrant extracellular matrix (ECM) deposition and remodelling is important in the disease pathogenesis of pulmonary fibrosis (PF). We characterised neoepitope biomarkers released by ECM turnover in lung tissue from bleomycin-treated rats and patients with PF and analysed the effects of two antifibrotic drugs: nintedanib and pirfenidone.

METHODS

Precision-cut lung slices (PCLS) were prepared from bleomycin-treated rats or patients with PF. PCLS were incubated with nintedanib or pirfenidone for 48 h, and levels of neoepitope biomarkers of type I, III and VI collagen formation or degradation (PRO-C1, PRO-C3, PRO-C6 and C3M) as well as fibronectin (FBN-C) were assessed in the culture supernatants.

RESULTS

In rat PCLS, incubation with nintedanib led to a reduction in C3M, reflecting type III collagen degradation. In patient PCLS, incubation with nintedanib reduced the levels of PRO-C3 and C3M, thus showing effects on both formation and degradation of type III collagen. Incubation with pirfenidone had a marginal effect on PRO-C3. There were no other notable effects of either nintedanib or pirfenidone on the other neoepitope biomarkers studied.

CONCLUSIONS

This study demonstrated that nintedanib modulates neoepitope biomarkers of type III collagen turnover and indicated that C3M is a promising translational neoepitope biomarker of PF in terms of therapy assessment.

POS0853 EFFECTS OF NINTEDANIB ON CIRCULATING BIOMARKERS IN SUBJECTS WITH SYSTEMIC SCLEROSIS-ASSOCIATED INTERSTITIAL LUNG DISEASE (SSc-ILD)

Background

In the SENSCIS trial in subjects with SSc-ILD, nintedanib reduced the rate of decline in forced vital capacity (FVC) over 52 weeks by 44% compared with placebo.

Objectives

To investigate the effects of nintedanib on circulating biomarkers of extracellular matrix (ECM) turnover, epithelial injury and inflammation in the SENSCIS trial.

Methods

Subjects had SSc with first non-Raynaud symptom in the prior ≤7 years, extent of fibrotic ILD on high-resolution computed tomography (HRCT) ≥10% and FVC ≥40% predicted. Patients were randomised to receive nintedanib or placebo stratified by anti-topoisomerase I antibody (ATA). Blood samples were taken at baseline and at weeks 4, 24 and 52. Fold changes in adjusted mean levels of circulating biomarkers were analyzed using a linear mixed model for repeated measures. Data were log10 transformed before analysis and estimates of change from baseline were back-transformed.

Results

A total of 576 subjects received trial drug (288 nintedanib, 288 placebo). A transient increase in fold change from baseline in C-reactive protein (CRP) (a marker of inflammation) was observed in subjects who received nintedanib versus placebo at week 4. After an initial increase at week 4 in the fold change from baseline in CRP degraded by MMP-1/8 (CRPM) (a marker of ECM turnover), a trend to decreasing levels was observed in subjects who received nintedanib compared with placebo at week 52. Decreases in the fold change from baseline in collagen 3 degraded by MMP-9 (C3M) and N-terminal propeptide of type VI collagen (pro-C6) (markers of ECM turnover) were observed in subjects who received nintedanib compared with placebo from week 24 and week 4, respectively. A decrease in fold change from baseline in Krebs von den Lungen-6 (KL-6) (a marker of epithelial injury) was observed in subjects who received nintedanib versus placebo at week 52. A decrease in fold change from baseline in cancer antigen 125 (CA-125) (a marker of epithelial injury) was observed in subjects who received nintedanib versus placebo from week 4 (Figure 1).

Conclusion

Data from the SENSCIS trial suggest that nintedanib reduced circulating levels of markers of ECM turnover and epithelial injury in subjects with SSc-ILD.

Acknowledgements

The SENSCIS trial was funded by Boehringer Ingelheim. Masataka Kuwana, Toby M Maher and Oliver Distler were members of the SENSCIS trial Steering Committe.

Disclosure of Interests

Shervin Assassi Speakers bureau: On speaker bureau for Integrity Continuing Education, Consultant of: Abbvie, AstraZeneca, Boehringer Ingelheim, CSL Behring, Novartis, Grant/research support from: Boehringer Ingelheim, Janssen, Masataka Kuwana Speakers bureau: AbbVie, Asahi Kasei Pharma, Astellas, Boehringer Ingelheim, Chugai, Eisai, GlaxoSmithKline, Janssen, Nippon Shinyaku, Tanabe-Mitsubishi, Ono Pharmaceuticals, Consultant of: AstraZeneca, Boehringer Ingelheim, Corbus, Mochida

Kissei, Grant/research support from: Boehringer Ingelheim, MBL, Ono Pharmaceuticals, Christopher P Denton Speakers bureau: Boehringer Ingelheim, Janssen, Consultant of: Abbvie, Acceleron, Boehringer Ingelheim, Corbus, CSL Behring, GlaxoSmithKline, Roche, Grant/research support from: ARXX Therapeutics, GlaxoSmithKline, Horizon Therapeutics, Servier, Toby Maher Speakers bureau: Boehringer Ingelheim, Galapagos, Genentech, Consultant of: AstraZeneca, Bayer, Blade Therapeutics, Boehringer Ingelheim, Bristol-Myers Squibb, Galapagos, Galecto, GlaxoSmithKline R&D, IQVIA, Pliant, Respivant, Roche, Theravance and Veracyte, Grant/research support from: AstraZeneca, GlaxoSmithKline, Claudia Diefenbach Employee of: Claudia Diefenbach is an employee of Boehringer Ingelheim, Carina Ittrich Employee of: Carina Ittrich is an employee of Boehringer Ingelheim, Martina Gahlemann Employee of: Martina Gahlemann is an employee of Boehringer Ingelheim, Oliver Distler Speakers bureau: OD has/had relationships with the following companies in the area of potential treatments for systemic sclerosis and its complications in the last three calendar years:

Speaker fee: Bayer, Boehringer Ingelheim, Janssen, Medscape, Consultant of: OD has/had relationships with the following companies in the area of potential treatments for systemic sclerosis and its complications in the last three calendar years:

Consultancy fee: Abbvie, Acceleron, Alcimed, Amgen, AnaMar, Arxx, AstraZeneca, Baecon, Blade, Bayer, Boehringer Ingelheim, Corbus, CSL Behring, 4P Science, Galapagos, Glenmark, Horizon, Inventiva, Kymera, Lupin, Miltenyi Biotec, Mitsubishi Tanabe, MSD, Novartis, Prometheus, Roivant, Sanofi and Topadur

OD has/had relationships with the following companies in the area of potential treatments for arthritides in the last three calendar years:

Consultancy fee: Abbvie, Grant/research support from: OD has/had relationships with the following companies in the area of potential treatments for systemic sclerosis and its complications in the last three calendar years:

Research Grants: Boehringer Ingelheim, Kymera, Mitsubishi Tanabe,

FOOTPRINTS study protocol: rationale and methodology of a 3-year longitudinal observational study to phenotype patients with COPD

INTRODUCTION

A better understanding is needed of the different phenotypes that exist for patients with chronic obstructive pulmonary disease (COPD), their relationship with the pathogenesis of COPD and how they may affect disease progression. Biomarkers, including those associated with emphysema, may assist in characterising patients and in predicting and monitoring the course of disease. The FOOTPRINTS study (study 352.2069) aims to identify biomarkers associated with emphysema, over a 3-year period.

METHODS AND ANALYSIS

The FOOTPRINTS study is a prospective, longitudinal, multinational (12 countries), multicentre (51 sites) biomarker study, which has enrolled a total of 463 ex-smokers, including subjects without airflow limitation (as defined by the 2015 Global Initiative for Chronic Obstructive Lung Disease (GOLD) strategy report), patients with COPD across the GOLD stages 1-3 and patients with COPD and alpha1-antitrypsin deficiency. The study has an observational period lasting 156 weeks that includes seven site visits and additional phone interviews. Biomarkers in blood and sputum, imaging data (CT and magnetic resonance), clinical parameters, medical events of special interest and safety are being assessed at regular visits. Disease progression based on biomarker values and COPD phenotypes are being assessed using multivariate statistical prediction models.

ETHICS AND DISSEMINATION

The study protocol was approved by the authorities and ethics committees/institutional review boards of the respective institutions where applicable, which included study sites in Belgium, Canada, Denmark, Finland, Germany, Japan, Korea, Poland, Spain, Sweden, UK and USA; written informed consent has been obtained from all study participants. Ethics committee approval was obtained for all participating sites prior to enrolment of the study participants. The study results will be reported in peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT02719184.

Biomarkers of extracellular matrix turnover in patients with idiopathic pulmonary fibrosis given nintedanib (INMARK study): a randomised, placebo-controlled study

BACKGROUND

A hallmark of idiopathic pulmonary fibrosis is the excess accumulation of extracellular matrix in the lungs. Degradation of extracellular matrix generates free-circulating protein fragments called neoepitopes. The aim of the INMARK trial was to investigate changes in neoepitopes as predictors of disease progression in patients with idiopathic pulmonary fibrosis and the effect of nintedanib on these biomarkers.

METHODS

In this randomised, double-blind, placebo-controlled trial, patients with a diagnosis of idiopathic pulmonary fibrosis within the past 3 years and forced vital capacity (FVC) of 80% predicted or higher were eligible to participate. Patients were recruited from hospitals, private practices, clinical research units, and academic medical centres. Patients were randomly assigned (1:2) with the use of a pseudo-random number generator to receive oral nintedanib 150 mg twice a day or placebo for 12 weeks in a double-blind fashion, followed by open-label nintedanib for 40 weeks. The primary endpoint was the rate of change in C-reactive protein (CRP) degraded by matrix metalloproteinases 1 and 8 (CRPM) from baseline to week 12 in the intention-to-treat population. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02788474, and with the European Clinical Trials Database, number 2015-003148-38.

FINDINGS

Between June 27, 2016, and May 15, 2017, 347 patients were randomly assigned to the nintedanib group (n=116) or to the placebo group (n=231). One patient from the placebo group was not treated owing to a randomisation error. At baseline, mean FVC was 97·5% (SD 13·5) predicted. In the double-blind period, 116 patients received nintedanib and 230 patients received placebo. The rate of change in CRPM from baseline to week 12 was -2·57 × 10^-3 ng/mL/month in the nintedanib group and -1·90 × 10^-3 ng/mL/month in the placebo group (between-group difference -0·66 × 10^-3 ng/mL/month [95% CI -6·21 × 10^-3 to 4·88 × 10^-3]; p=0·8146). The adjusted rate of change in FVC over 12 weeks was 5·9 mL in the nintedanib group and -70·2 mL in the placebo group (difference 76·1 mL/12 weeks [31·7 to 120·4]). In patients who received placebo for 12 weeks followed by open-label nintedanib, rising concentrations of CRPM over 12 weeks were associated with disease progression (absolute decline in FVC ≥10% predicted or death) over 52 weeks. In the double-blind period, serious adverse events were reported in eight (7%) patients given nintedanib and 18 (8%) patients given placebo. Grade 3 diarrhoea was reported in two (2%) patients in the nintedanib group and two (1%) patients in the placebo group. No patients had grade 4 diarrhoea.

INTERPRETATION

In patients with idiopathic pulmonary fibrosis and preserved lung function, treatment with nintedanib versus placebo for 12 weeks did not affect the rate of change in CRPM but was associated with a reduced rate of decline in FVC. These results suggest that change in CRPM is not a marker of response to nintedanib in patients with idiopathic pulmonary fibrosis.

FUNDING

Boehringer Ingelheim.

Investigating the effects of nintedanib on biomarkers of extracellular matrix turnover in patients with IPF: design of the randomised placebo-controlled INMARK®trial

Introduction

A feature of the pathogenesis of idiopathic pulmonary fibrosis (IPF) is the excess accumulation of extracellular matrix (ECM) in the lungs. Cleavage of the ECM by metalloproteinases (MMPs) generates free-circulating protein fragments known as neoepitopes. The PROFILE study suggested that changes in ECM turnover proteins may be of value as markers of disease progression in patients with IPF. Nintedanib is an approved treatment for IPF that slows disease progression by reducing decline in forced vital capacity (FVC).

Methods and analysis

The INMARK® trial is evaluating the effect of nintedanib on the rates of change of biomarkers of ECM turnover in patients with IPF, the value of changes in these biomarkers as predictors of disease progression and whether nintedanib affects the associations between changes in these biomarkers and disease progression. Following a screening period, 347 patients with IPF and FVC ≥80% predicted were randomised 1:2 to receive nintedanib 150 mg two times a day or placebo for 12 weeks, followed by an open-label period in which all patients will receive nintedanib for 40 weeks. The primary endpoint is the rate of change in C reactive protein degraded by MMP-1/8 from baseline to week 12.

Ethics and dissemination

This trial is being conducted in compliance with the protocol, the ethical principles detailed in the Declaration of Helsinki and in accordance with the International Conference on Harmonisation Harmonised Tripartite Guideline for Good Clinical Practice. The results of the trial will be presented at national and international meetings and published in peer-reviewed journals.

Trial registration number

NCT02788474.

Lung tissue destruction by proteinase 3 and cathepsin G mediated elastin degradation is elevated in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by high levels of protease activity leading to degradation of elastin followed by loss of elasticity of the lung and the development of emphysema. Elastin is an essential structural component of the lung parenchyma to support the expansion and recoil of the alveoli during breathing. The lung extracellular matrix is vulnerable to pathological structural changes upon upregulation of serine proteases, including cathepsin G (CG) and proteinase 3 (PR3). In this study, we explored the diagnostic features of elastin neo-epitopes generated by CG and PR3. Two novel competitive enzyme-linked immunosorbent assays (ELISA) measuring CG and PR3 generated elastin fragments (EL-CG and ELP-3 respectively) were developed for assessment in serum. Both assays were technically robust and biologically validated in serum from patients with COPD. Serological levels of both elastin fragments were significantly elevated in patients with COPD compared to healthy controls. These data suggest that EL-CG and ELP-3 may serve as plausible biologic markers of destructive changes in COPD.

Serological assessment of neutrophil elastase activity on elastin during lung ECM remodeling

Background

During the pathological destruction of lung tissue, neutrophil elastase (NE) degrades elastin, one of the major constituents of lung parenchyma. However there are no non-invasive methods to quantify NE degradation of elastin. We selected specific elastin fragments generated by NE for antibody generation and developed an ELISA assay (EL-NE) for the quantification of NE-degraded elastin.

Methods

Monoclonal antibodies were developed against 10 NE-specific cleavage sites on elastin. One EL-NE assay was tested for analyte stability, linearity and intra- and inter-assay variation. The NE specificity was demonstrated using elastin cleaved in vitro with matrix metalloproteinases (MMPs), cathepsin G (CatG), NE and intact elastin. Clinical relevance was assessed by measuring levels of NE-generated elastin fragments in serum of patients diagnosed with idiopathic pulmonary fibrosis (IPF, n = 10) or lung cancer (n = 40).

Results

Analyte recovery of EL-NE for human serum was between 85% and 104%, the analyte was stable for four freeze/thaw cycles and after 24 h storage at 4°C. EL-NE was specific for NE-degraded elastin. Levels of NE-generated elastin fragments for elastin incubated in the presence of NE were 900% to 4700% higher than those seen with CatG or MMP incubation or in intact elastin. Serum levels of NE-generated elastin fragments were significantly increased in patients with IPF (137%, p = 0.002) and in patients with lung cancer (510%, p < 0.001) compared with age- and sex-matched controls.

Conclusions

The EL-NE assay was specific for NE-degraded elastin. The EL-NE assay was able to specifically quantify NE-degraded elastin in serum. Serum levels of NE-degraded elastin might be used to detect excessive lung tissue degradation in lung cancer and IPF.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0048-5) contains supplementary material, which is available to authorized users.

Attenuation of a rocuronium-induced neuromuscular block in patients receiving prednisolone

BACKGROUND

This study tested the influence of continuous medication (more than 4 weeks) with prednisolone on a rocuronium-induced neuromuscular block.

METHODS

The time course of a rocuronium-induced neuromuscular blockade (0.3 mg/kg) was investigated in 40 patients with chronic inflammatory bowel disease undergoing elective abdominal surgery. The primary end point was the time from the start of injection of rocuronium until recovery of the TOF ratio to 0.9. Twenty patients received continuous medication with prednisolone (group A), and 20 were without glucocorticoid medication (group B). Additionally, another 20 patients without inflammatory bowel disease and without glucocorticoid medication served as control (group C).

RESULTS

The onset time was prolonged in group A [253 (51.2) s] compared with group B [187 (61.3) s]. Twitch height at the onset of the block was higher in group A [16.5 (0-61)%] than that in group B [5.0 (0-33)%]. The duration to 25% twitch height was shorter in group A [12.6 (0-20.7) min] compared with group B [16.7 (0-25.3) min] and group C [16.9 (0-29.3) min]. The recovery to a train-of-four ratio of 0.9 was reduced in group A [25.7 (23-34.3) min] compared with group B [34.7 (32.7-44.2) min] and group C [36.5 (31.7-42.3) min].

CONCLUSIONS

Prednisolone treatment in patients with inflammatory bowel disease is associated with a delayed onset and a shorter duration of action of rocuronium. The presence of an inflammatory bowel disease did not influence the neuromuscular block.

Influence of a continuous prednisolone medication on the time course of neuromuscular block of atracurium in patients with chronic inflammatory bowel disease

BACKGROUND

Corticosteroids interact with neuromuscular blocking agents. However, experimental data are contradictory: enhancement and attenuation of the neuromuscular block has been observed. This study tested the influence of long-term medication with prednisolone on atracurium-induced neuromuscular block.

METHODS

Sixty patients with chronic inflammatory bowel disease undergoing elective abdominal surgery were investigated. Thirty patients received a long-term medication with prednisolone (Group A) and 30 were without corticoid medication (Group B). Additionally, another 30 patients without inflammatory bowel disease and without corticoid medication served as control (Group C). The following parameters of an atracurium-induced neuromuscular block (0.25 mg kg(-1)) were measured: onset time, maximum block, recovery to 25% first twitch height, recovery index (time from 25% until 75% recovery of first twitch), duration to recovery to a train-of-four (TOF) rate of 0.7 and 0.9.

RESULTS

The groups did not differ with regard to onset time, maximum block, and recovery index. The duration to 25% twitch height was significantly lower in Group A [18.1 (0-30.7) min] compared with Group B [23.5 (0-36.7) min; P<0.05]. Duration to a TOF rate of 0.7 and 0.9, respectively, were significantly reduced in Group A [36.1 (7.9) and 40.9 (9.0 min)] compared with Group B [47.9 (7.6) and 53.4 (9.2) min; P<0.001].

CONCLUSIONS

Long-term medication with prednisolone resulted in a shorter duration of an atracurium-induced neuromuscular block in patients with Crohn's disease or ulcerative colitis. The presence of the inflammatory bowel disease did not influence the time course of the neuromuscular block.

Concept for postoperative analgesia after pedicled TRAM flaps: continuous wound instillation with 0.2% ropivacaine via multilumen catheters. A report of two cases

Pedicled TRAM flap surgery is a complex procedure characterised by an extensive wound site. We present two patients with efficient postoperative pain relief by continuous wound instillation of ropivacaine 0.2% via two multilumen catheters. The catheters were placed subcutaneously before the wound closure through the umbilicus into the abdominal wound, and under the autologous flap into the breast. Each multilumen catheter provides even distribution for local anaesthetics over 12.5 cm. At the end of surgery, patients received a single shot dose of local anaesthetic via the pain catheters. After surgery the continuous infusion of ropivacaine 0.2% was commenced at a rate of 10 ml/h per catheter. Pain scores at rest and on coughing were low on the first postoperative day, and later zero. No medication for breakthrough pain was required throughout the recovery period, and the patients experienced no adverse events linked to the analgesia scene. Patient satisfaction was excellent, and quality of recovery score was superior.

[The use of neuromuscular monitoring in Germany]

AIM

As there are no reliable epidemiological data for the use of muscle relaxants in Germany,we conducted a mailing study. The aim of the study was to compare the use of muscle relaxants between German anaesthesia departments. In the present part of the presentation we focused on neuromuscular monitoring (NMM) and management of residual paralysis.

METHODS

A total number of 2,996 questionnaires were sent to all registered anaesthesiological facilities in Germany and the return was 68.6% (2054 questionnaires).

RESULTS

In 574 of the returned questionnaires (28%) the regular use of NMM was confirmed. Intraoperative monitoring of neuromuscular block and assessment of neuromuscular recovery were the most frequent applications of NMM, i.e. 25% and 18% of returned questionnaires, respectively. Clinical signs, however, are still the most popular way to estimate the degree of neuromuscular blockade. Moreover, routine reversal at the end of surgery with a neostigmin/atropine mixture was not practiced in 75% of the anaesthesia departments.

CONCLUSIONS

This survey revealed that NMM is still very rarely used in daily clinical practice. Especially the seldom use of NMM to assess residual paralysis has to be improved.

[Application of muscle relaxants for rapid-sequence induction of anaesthesia]

The present study evaluates the use of muscle relaxants for rapid-sequence induction (RSI) and different application techniques (pre-curarisation, priming, timing) as a part of a nationwide survey in Germany. In 86.8% of anaesthesia departments succinylcholine is used for RSI and an average of 56.5% of respondents used only succinylcholine for RSI. Of all non-depolarising muscle relaxants rocuronium is the most frequently used alternative. Of the anaesthesia departments 2.6% use rocuronium regularly in patients with increased risk for aspiration of stomach contents; level one centres significantly more than others, 12.9% answered that pre-curarisation techniques were never used, whereas 45.6% use non-depolarising neuromuscular blocking drugs before giving succinylcholine in 80-100% of cases. Priming is not used by 64.4% of respondents, as opposed to 9.8% who utilise this technique regularly. The statements regarding timing are 71.1% and 5.4%, respectively. Alcuronium is used for RSI in departments in which the financial aspect is the primary decision criteria. Despite ist known side-effects and the on-going discussion over the past years, succinylcholine is still the most frequently used muscle relaxants for RSI. Priming is often declined by anaesthetists in Germany, most probably due to the absence of clear advantages and the possibility of severe complications. It is the opinion of the authors that timing but also drugs with a slow onset (e.g., alcuronium and Pancuronium) are obsolete in the context of RSI.

[The use of muscle relaxants for routine induction of anesthesia in Germany]

The aim of this study was to evaluate the use of muscle relaxants during induction of anesthesia in patients without risk of aspiration of stomach contents. Of the 2,996 questionnaires sent out, 2,054 (68.6%) could be analysed and the results show that succinylcholine is used regularly in 13.6% of anesthesia departments. The next most commonly used muscle relaxants are atracurium, vecuronium and mivacurium, followed by cis-atracrium, rocuronium and pancuronium. Alcuronium is the least frequently used muscle relaxant. During induction of an elective anesthesia procedure, a priming technique is used by 19% of anesthesiologists, 22% utilize precurarization, and a timing technique is performed in 7.1%. The use of muscle relaxants for on-going relaxation follows the same pattern as for induction of neuromuscular blockade and succinylcholine is used in 1.4% if further relaxation is needed. The desire for specific qualities of muscle relaxants is correlated with higher use of the specific substance: short onset time for rocuronium, good controllability with mivacurium, no side-effects with cisatracurium and economical aspects with alcuronium. Of the participants 76.6% voiced the desire for a non-depolarizing replacement for succinylcholine.Private practices use mivacurium more often than hospitals, level one hospitals use rocuronium and cisatracurium more often. This survey could not show a definite standard of use in terms of muscle relaxants for an elective case.Precurarization, priming and timing are used frequently in patients not at risk of aspiration. This should be reduced by on-going teaching.

[Application of muscle relaxants in Germany. A survey of German anaesthesia departments]

AIM

The aim of this study was to evaluate the use and application of muscle relaxants and neuromuscular monitoring in Germany.

METHODS

A total of 2,996 questionnaires were sent out to the heads of German anaesthesia departments and private anaesthesia practices. The questions covered frequency of muscle relaxants used,how they were used, and neuromuscular monitoring. Influences on the way muscle relaxants were used could be derived from the desire for specific properties of a muscle relaxant, the desire for different monitoring conditions and from the size of the institution. We correlated these features with application practice using logistic regression analyses.

RESULTS

Of the 2,996 questionnaires 2,058 could be analysed (68.6%). Amongst those were 102 level one hospitals (5%) and 903 private practices (44%). The replies from 350 (17%) departments were based on surveyed data, 1,613 (78.5%) were based on estimations. The desire for certain properties of muscle relaxants correlated with the use in practice, as were the desire for a non-depolarizing replacement for succinylcholine, the size of the department and the frequency of use of neuromuscular monitoring. Over 50% of all German anaesthesia departments limited the use of muscle relaxants to three. The use of laryngeal masks reduced the use of muscle relaxants.

CONCLUSIONS

The survey regarding use of muscle relaxants in Germany could for the first time give an overview on the use of anaesthesia-specific substances in Germany. From the different frequencies of use and use modalities,conclusions could be drawn towards a standard of application for the year 2000. Changes in this standard would raise the need for further trend surveys. The methods of statistical analysis and survey evaluation can be used as a base for further surveys.

Epidural combination of ropivacaine with sufentanil for postoperative analgesia after total knee replacement: a pilot study

BACKGROUND AND OBJECTIVE

We assessed the analgesic efficacy of postoperative epidural infusions of ropivacaine 0.1 and 0.2% combined with sufentanil 1 microg mL(-1) in a prospective, randomized, double-blinded study.

METHODS

Twenty-two ASA I-III patients undergoing elective total-knee replacement were included. Lumbar epidural blockade using ropivacaine 0.75% was combined with either propofol sedation or general anaesthesia for surgery. After surgery, the epidural infusion was commenced. Eleven patients in each group received either an epidural infusion of ropivacaine 0.1% with 1 microg mL(-1) sufentanil (Group 1) or ropivacaine 0.2% with 1 microg mL(-1) sufentanil (Group 2) at a rate of 5-9 mL h(-1). All patients had access to intravenous pirinatrimide (piritramide) via a patient-controlled analgesia (PCA) device.

RESULTS

Motor block was negligible for the study duration in both groups. There was no significant difference with the 100 mm visual analogue scale (VAS) scores, with the consumption of rescue analgesia or with patient satisfaction. Patients in Group 1 experienced significantly less nausea (P < 0.05) than those in Group 2. Both treatment regimens provided effective postoperative analgesia with only a minimal use of supplemental opioid PCA.

CONCLUSIONS

We recommend the use of ropivacaine 0.1% with 1 microg mL(-1) sufentanil for postoperative analgesia after total knee replacement as it provides efficient pain relief with no motor block of the lower limbs. In addition, compared with 0.2% ropivacaine with sufentanil, the mixture reduces local anaesthetic consumption without compromise in patient satisfaction or VAS scores. Patients even experience less nausea.

[Cesarian section and local anaesthesia: insufficient spread of spinal anaesthesia with hyperbaric bupivacaine 0.5%/5% glucose compared to hyperbaric bupivacaine 0.5%/8% glucose?]

In our hospital hyperbaric Carbostesin 0.5% (AstraZeneca) had been substituted by hyperbaric Bucain 0.5% (Curasan) and both drugs were believed to be identical in their actions.However, both local anaesthetics differ in the amount of glucose they contain. We report about three patients who underwent cesarian section under spinal anaesthesia. In two patients we observed an insufficient spread of spinal anaesthesia after administration of hyperbaric Bucain 0.5%. The third patient received the normally used combination of hyperbaric Carbostesin 0.5% and fentanyl and the subarachnoid block proceeded completely uneventfully. According to the literature the clinical efficacy of hyperbaric Carbostesin 0.5% and hyperbaric Bucain 0.5% should be identical and therefore a critical dilution of the Bucain should not have occurred because of the addition of fentanyl.

Comparison of continuous epidural infusion of ropivacaine and sufentanil with intravenous patient-controlled analgesia after total hip replacement

We assessed the efficacy of an epidural infusion of ropivacaine 0.1% and sufentanil 1 microg x ml(-1), comparing it with intravenous patient-controlled analgesia using piritramide in this prospective, randomised, double-blind study of 24 ASA physical status I-III patients undergoing elective total hip replacement. Lumbar epidural block using ropivacaine 0.75% was combined with either propofol sedation or general anaesthesia for surgery. Epidural infusion and patient-controlled analgesia were started after surgery. Twelve patients received an epidural infusion of ropivacaine 0.1% and sufentanil 1 microg x ml(-1) at a rate of 5-9 ml x h(-1) and an intravenous patient-controlled analgesia device loaded with saline. Eleven patients received an epidural infusion of saline at the same rate and intravenous piritramide via the patient-controlled analgesia device. Motor block was negligible in both groups. The epidural ropivacaine group had significantly lower visual analogue pain scores at rest 4 h after surgery (p < 0.01), and on movement 4 h (p < 0.01) and 8 h (p < 0.05) after surgery, than the intravenous piritramide group. The piritramide group experienced significantly more adverse events than the epidural group (p < 0.001), especially hypotension (p < 0.01) and vomiting (p < 0.05). Patients in the epidural ropivacaine group were more satisfied with the pain management (p < 0.05). We conclude that the epidural infusion of ropivacaine 0.1% and sufentanil 1 microg x ml(-1) is superior to intravenous opioid by patient-controlled analgesia in preventing pain after total hip replacement, with fewer adverse effects and greater patient satisfaction.

[Papillary fibroelastoma of the aortic valve--a rare cause of thromboembolic cerebral infarct]

We report on a case of papillary fibroelastoma of the aortic valve in a 55 year old female patient, who had thrombembolic complications and subsequent stroke. The tumor was resected without disturbing the structure and function of the aortic valve.

Failure of autologous fresh frozen plasma to reduce blood loss and transfusion requirements in coronary artery bypass surgery

BACKGROUND

Previous studies failed to demonstrate any benefit from prophylaxis with fresh frozen plasma (FFP) after cardiopulmonary bypass (CPB). The results, however, were limited by either retrospective study design or use of FFP in subtherapeutic doses (2-3 units). The authors evaluated whether a therapeutic dose (15 ml/kg) of FFP reduces blood loss and transfusion requirements in elective coronary artery bypass surgery. The risks of multiple allogeneic blood donor exposure were circumvented by using autologous plasma.

METHODS

Sixty adult patients scheduled for elective primary coronary artery bypass grafting were randomized to receive, after CPB, an intravenous infusion of 15 ml/kg of either autologous FFP (30 patients) or 6% hydroxyethyl starch 450/0.7 (HES; 30 patients). Autologous plasma was obtained by platelet-poor plasmapheresis several weeks before surgery. Perioperative blood transfusions were administered per protocol. Postoperative blood loss was defined as the chest tube drainage during the first 24 h after surgery.

RESULTS

The data from 56 patients (FFP group, 27 patients; HES group, 29 patients) who completed the study according to protocol were analyzed. Median postoperative blood loss was 630 ml (range, 450-1,840 ml) and 830 ml (range, 340-1,980 ml) in the FFP and HES groups, respectively (P = 0.08). Both postoperative (0-24 h) and total perioperative erythrocyte transfusion requirements did not differ significantly between the groups (P = 0.32 and 0.14, respectively).

CONCLUSION

The prophylactic administration of a therapeutic dose (15 ml/kg) of autologous FFP after CPB failed to reduce blood loss and transfusion requirements in patients undergoing uncomplicated, elective, primary coronary artery bypass surgery.

Survival from a lethal blood concentration of cyanide with associated alcohol intoxication

We present a patient with a lethal blood concentration of cyanide. Additionally, he was found to have an alcohol blood level of 270 mg. dl-1, but made a complete recovery following administration of the antidotes dimethylaminophenol and thiosulphate. It is postulated that the patient may have been able to detoxify himself as a result of metabolism of cyanide to the non-toxic form, thiocyanate.

[Accuracy and dose dependency of the train-of-four count]

The estimation of a nondepolarizing neuromuscular block using the train-of-four (TOF) count shows wide differences compared to the mechanomyographic measurement. The purpose of this study was to evaluate the clinical significance of these differences.

METHODS

89 patients (ASA I-II) in 6 groups received general anesthesia with fentanyl, propofol and a single dose atracurium (150, 200, 250, 300, 450 and 600 microg/kg). Neuromuscular transmission was monitored by stimulation of the ulnar nerve at the wrist with supramaximal TOF stimuli repeated every 15 s using a peripheral nerve stimulator. The isometric force contraction of the m. adductor pollicis was recorded. The height of T1 at reappearance of the second (T2) and fourth (T4) twitch was noted. Also noted was the time difference between the first reappearance of T4 and the 25% recovery of T1. Statistical significance of the results was calculated by the h-test of Kruskal and Wallis. Testing the reliability of the TOF count, a 95% interval of confidence was calculated

RESULTS

There were no significant differences between the mean ages, heights and weights of the six groups. T2 and T4 re-appeared at 11+/-2% and 24+/-6% recovery of T1, respectively. Again, there were no significant differences between the six dose groups (Fig. 1). The time difference between the re-appearance of T4 and the 25% recovery was -1.0+/-2 (range: -5-3) minutes. The calculation of a 95% interval of confidence indicated a recovery between 14% and 33% at reappearance of T4, 25% recovery can be expected 5 min before to 3 min after reappearance of T4, respectively.

CONCLUSIONS

At reappearance of T4, a recovery of neuromuscular block of 25% is missed only by 3 to 5 min during relaxation with atracurium. We consider this margin of error as unimportant for clinical use. More-over we were able to show that the TOF-count is not dose dependent.

Pseudocholinesterase-activity reduction during cardiopulmonary bypass: the role of dilutional processes and pharmacological agents

1. Pseudocholinesterase (ChE) activity is a determinant of the elimination kinetics of several drugs used in anesthesia. The time course of ChE activity was investigated in 16 patients undergoing cardiosurgery for a cardiopulmonary bypass (CPB) in normothermia or hypothermia. 2. The onset of the CPB was accompanied by a decrease in ChE activity (-37%) (P<0.05) and protein concentration (-24%) (P<0.05). The quotient ChE activity/protein concentration was numerically reduced to a smaller extent (-15%) (P>0.05). After the CPB was finished, ChE activity and the protein concentration remained low for the remaining operation time. 3. There was no difference in ChE activity, measured in vitro at 37 degrees C, between the normothermic and hypothermic group (P>0.05). 4. There was no correlation between heparin concentration in serum and reduction of ChE activity in vitro (P>0.05). In vitro, the ChE activity was not affected by either heparin in doses as high as 10,000 U/ml or aprotinin in doses as high as 10,000 U/ml (P>0.05). 5.

CONCLUSIONS

(1) ChE activity is reduced by CPB mainly by hemodilution and (2) the pharmacological agents used in the present anesthetic technique (heparin, aprotinin, midazolam, fentanyl, propofol and mivacurium) do not inhibit ChE activity at therapeutic serum concentrations.

[Coronary stent implantation without preliminary dilatation]

BACKGROUND

Extensive coronary dissections are rare but represent serious complications of percutaneous transluminal coronary angioplasty (PTCA). In order to prevent dissections in large coronary vessels (> or = 2.5 mm), we evaluated stent implantation without predilatation in 98 selected patients with favorable coronary anatomy and lesion morphology.

METHODS

Coronary stenting without predilatation was performed 41 times in the LAD, 41 times in the RCA, 11 times in the RCx, and 5 times in a vein graft. Mean diameter stenosis was 83 +/- 3%. Thirty-six patients had type A lesions and 62 patients type B lesions. Patients with type C lesions were excluded. Only premounted stents were used.

RESULTS

The clinical situation was stable angina in 68 patients, unstable angina in 18, and acute myocardial infarction in 12. Stenting without predilatation was successful in 92 patients (94%). In 6 cases (6%) it was not possible to cross the lesion with the premounted stent, and predilatation was necessary prior to successful stent implantation. Two out of 11 RCx-related lesions (18%) could not be stented without predilatation. However, ultimate success of PTCA was 100%. No stent was lost. Mean remaining stenosis amounted to 3 +/- 6%. Minor angiographically detectable dissections after stent deployment were noted in 8 patients (8%). Inflation time (30 +/- 22 s) and fluoroscopic time (4.5 +/- 2.1 min) compared favorably to standard procedures. During 30 d follow-up no subacute stent thrombosis, but 2 non-Q-wave myocardial infarctions due to lost side branches were reported.

CONCLUSIONS

Coronary stenting with premounted stents without predilation is feasible and safe in selected patients in order to reduce fluoroscopic and procedural time and to save costs. Furthermore, this procedure might reduce the risk of hazardous coronary dissections.

The significance of oncometry for infusion therapy during pediatric heart surgery

BACKGROUND

The colloid osmotic pressure (COP) is not routinely assessed during pediatric heart surgery. Two cases of unrecognized hyperoncotic states associated with renal failure have been observed after pediatric heart surgery. We studied the hypothesis that the COP cannot be estimated from the total plasma protein (TPP) or albumin level.

METHODS

The course of COP and its correlation to the TPP and albumin level were investigated in 25 children undergoing elective heart surgery. Infusion therapy was performed solely on the basis of clinical parameters and TPP/albumin levels. COP values were determined in a blinded fashion at the end of the study.

RESULTS

No correlation between TPP/albumin and the COP could be determined preoperatively. On arrival at the ICU correlation was strong. A weak correlation was observed at 24 hours and 48 hours after surgery. However, the observed wide range of the confidential bands indicates that the COP cannot be estimated correctly, neither from the TPP, nor from the albumin level. Due to colloidal oversubstitution COP was significantly increased compared to preoperative level at 48 hrs following surgery.

CONCLUSIONS

As estimation of COP from TPP or albumin level is inaccurate, oncometry should be performed during pediatric heart surgery.

[The clinical pharmacology of cisatracurium]

Cisatracurium (51W89) is one of the ten stereoisomers of atracurium, accounting for about 15% of the racemate. The ED95 of cisatracurium was determined to be about 50 micrograms/kg (cation, molecular weight 929), while the ED95 of atracurium (besylate salt, molecular weight 1245) was 250 micrograms/kg. Thus, on a molar basis in adult patients, cisatracurium is about 3.5 times as potent as the racemic atracurium mixture. We compared atracurium with cisatracurium in healthy adult patients and found an almost identical pharmacodynamic profile. In children, an ED95 of about 40 micrograms/kg was determined, while a 1-min-longer onset of cisatracurium was found in geriatric than in young adult patients. The presence of chronic renal failure did not prolong the duration of action of cisatracurium. The recovery of neuromuscular transmission from a cisatracurium infusion of up to 145 h was investigated in intensive care unit patients. Their time from the end of infusion to a train-of-four ratio > 0.7 (68 +/- 18 min) was on average only some 70% longer than after an infusion of cisatracurium for 2 h in normal surgical patients. In another study, no signs of histamine release nor any clinically relevant cardiovascular effects of cisatracurium were found in doses up to eight times ED95.

The significance of oncometry for infusion therapy during pediatric heart surgery

The colloid osmotic pressure (COP) is not routinely assessed during pediatric heart surgery. Two cases of unrecognized hyperoncotic states associated with renal failure have been observed after pediatric heart surgery. We studied the hypothesis that the COP cannot be estimated from the total plasma protein (TPP) or albumin level. The course of COP and its correlation to the TPP and albumin level were investigated in 25 children undergoing elective heart surgery. Infusion therapy was performed solely on the basis of clinical parameters and TPP/albumin levels. COP values were determined in a blinded fashion at the end of the study. No correlation between TPP/albumin and the COP could be determined preoperatively. On arrival at the ICU correlation was strong. A weak correlation was observed at 24 hours and 48 hours after surgery. However, the observed wide range of the confidential bands indicates that the COP cannot be estimated correctly, neither from the TPP, nor from the albumin level. Due to colloidal oversubstitution COP was significantly increased compared to preoperative level at 48 hrs following surgery. As estimation of COP from TPP or albumin level is inaccurate, oncometry should be performed during pediatric heart surgery.

[The clinical pharmacology of mivacurium]

Mivacurium is a short-acting, nondepolarising muscle relaxant of the benzylisoquinoline type that undergoes rapid breakdown by plasma cholinesterase. After 2.5 times the ED95 (0.2 mg/kg), tracheal intubation can be accomplished within 2-3 min following injection. The ensuing DUR 25% (i.e., time from injection to 25% recovery of control twitch tension) is three times as long as with succinylcholine. The principal side effects of mivacurium are facial flushing and a transient fall in blood pressure due to moderate histamine release following doses 3-4 times the ED95. In patients with end-stage liver or renal disease as well as those with atypical plasma cholinesterase, the duration of action of mivacurium is prolonged.

[Esters and stereoisomers]

This review discusses concepts of isomers, stereoisomers, chirality, and enantiomers as applied to drugs used in anaesthesia. The inhalational anaesthetics enflurane and isoflurane are examples of stereoisomers. A chiral centre is formed when a carbon or quaternary nitrogen atom is connected to four different atoms. A molecule with one chiral centre is then present in one of two possible configurations termed enantiomers. A racemate is a mixture of both enantiomers in equal proportions. Many of the drugs used in anaesthesia are racemic mixtures (the inhalation anaesthetics, local anaesthetics, ketamine, and others). The shape of the atracurium molecule is comparable to that of a dumb-bell:the two isoquinoline groups representing the two bulky ends connected by an aliphatic chain. In each isoquinoline group there are two chiral centres, one formed by a carbon and the other by a quaternary nitrogen atom. From a geometric point of view, the connections from the carbon atom to a substituted benzene ring and from the quaternary nitrogen to the aliphatic chain may point in the same direction (cis configuration) or in opposite directions (trans configuration). The two isoquinoline groups in atracurium are paired in three geometric configurations: cis-cis, trans-trans, or cis-trans. However, the two chiral centres allow each isoquinoline group to exist in one of four stereoisometric configurations. In the symmetrical atracurium molecule, the number of possible stereoisomers is limited to ten. Among these, 1 R-cis, 1'R-cis atracurium was isolated and its pharmacologic properties studied. This isomer, named cis-atracurium, offers clinical advantages over the atracurium mixture, principally due to the lack of histamine-releasing propensity and the higher neuromuscular blocking potency. The ester groups appear in one of two steric configurations true and reverse esters. In the true esters, oxygen is positioned between the nitrogen atom and the carbonyl group, while in the reverse esters in its positioned on the other side of the carbonyl group. True esters, suxamethonium and mivacurium, are hydrolysed by the enzyme plasma cholinesterase (butyrylcholinesterase), albeit at different rates. The more rapid degradation of suxamethonium is responsible for its fast onset and short duration of action in comparison with mivacurium. The reverse esters, atracurium, cisatracurium, and remifentanil, are hydrolysed by nonspecific esterases in plasma (carboxyesterases). Remifentanil is hydrolysed rapidly; the degradation leads to its inactivation and short duration of action. Cis-atracurium is preferentially degraded and inactivated by a process known as Hofmann elimination. In a second step, one of the degradation products, the monoester acrylate, is hydrolysed by a nonspecific esterase.

Onset of the neuromuscular block simulated in an anatomical model

AIMS

The aim of this study was to develop a pharmacodynamic model for nondepolarizing muscle relaxants (neuromuscular blocking agents, NMBAs) based on anatomical, physiological, and pharmacological considerations and analyse whether the time to onset of the submaximal neuromuscular block (NMB) depends on the affinities of the NMBAs for the postsynaptic receptors or on the pharmacokinetic properties of the NMBAs.

METHODS

A quantitative description of the development of neuromuscular block was achieved by formulating a pharmacodynamic model based on anatomical, physiological and pharmacological considerations. The principal characteristics of the model are: (1) Diffusion of the NMBAs out of the capillaries into the interstitial space of muscle and from there into the synaptic space of the motor end plates (2) Receptor concentration in the synaptic space of 300 microM and the total amount of receptors in 100 g muscle of between 1.43 x (10(-11) to 10(-10) mol. (3) Interaction of NMBAs with the receptors defined by the association (k(assoc) = 4 x 10(8) min-1 x M-1) and dissociation (k(dissoc) one of 4, 40, or 400 min-1) rate constants.

RESULTS

The simulations demonstrated that different affinities of the NMBAs for the postsynaptic receptors (defined by k(assoc)/k(dissoc)) do not influence the onset of the submaximal NMB. On the other hand, the time to the peak submaximal NMB is dependent on the pharmacokinetic properties of the drugs: Those NMBAs that leave plasma rapidly produce the block faster but the fraction of the dose that contributes to the block is small. This fraction is larger for those NMBAs that produce NMB later and, hence, these NMBAs require smaller equieffective doses.

CONCLUSIONS

We conclude that those muscle relaxants that produce neuromuscular block rapidly require larger equieffective doses due to their more rapid initial disappearance from plasma.

[Muscle relaxants. New substances and neuromuscular monitoring]

INTRODUCTION

Recent developments in both the quantitative evaluation of neuromuscular blockade and new muscle relaxants are reviewed. With respect to nerve stimulation, neuromuscular recording, and definition of parameters, the results of the 1994 Copenhagen International Consensus Conference are highlighted. Future clinical studies should adhere to these standards.

MUSCLE RELAXANTS

Rocuronium, cisatracurium, and mivacurium are new muscle relaxants that were released for clinical use in 1995/1996. Of these, rocuronium has the shortest time of onset, whereas its recovery characteristics closely resemble those of vecuronium. Rocuronium is five times less potent than vecuronium. Twice the ED95 of rocuronium provides good or excellent intubating conditions within 60 to 90 s. Slight vagolytic effects were reported following injection of 0.6 mg/kg rocuronium, while histamine release was not observed. Cisatracurium is one of the ten steroisomers of atracurium. It is five times as potent as the chiral mixture while having a similar pharmacodynamic and -kinetic profile. Up to eight times the ED95 did not cause significant histamine release or clinically relevant cardiovascular effects. Mivacurium is a short-acting nondepolarizing benzylisoquinoline muscle relaxant that undergoes rapid break-down by plasma cholinesterase (PChE). Its duration of action is about one-half as long as that of equipotent doses of atracurium and vecuronium and three times as long as succinylcholine. Mivacurium has a moderate histamine-releasing potential. In patients with atypical or reduced PChE activity, the duration of action of mivacurium is prolonged.

A comparison of cisatracurium and atracurium: onset of neuromuscular block after bolus injection and recovery after subsequent infusion

Cisatracurium is a new nondepolarizing muscle relaxant. In patients randomized to receive either cisatracurium (n = 40) or atracurium (n = 20) we compared the time course of neuromuscular block. The initial bolus dose of cisatracurium was 0.1 mg/kg, that of atracurium 0.5 mg/kg. Neuromuscular block, maintained with an infusion of either drug, was reversed with neostigmine 45 micrograms/kg and atropine 20 micrograms/kg in one half of the patients. Neuromuscular transmission was assessed by recording the mechanical twitch response to train-of-four nerve stimulation. Onset times were 3.1 +/- 1.0 min with cisatracurium and 2.3 +/- 1.1 min with atracurium (P = 0.008). The infusion rates for a 95% +/- 4% neuromuscular block were 1.5 +/- 0.4 micrograms.kg-1.min-1 for cisatracurium and 6.6 +/- 1.7 micrograms.kg-1.min-1 for atracurium, 3.3 times those of cisatracurium when referenced to the active cations. After the infusion, the spontaneous recovery intervals 25%-75% of 18 +/- 11 min and 18 +/- 8 min for cisatracurium and atracurium (P = 0.896) were shortened to 5 +/- 2 min and 4 +/- 3 min (P = 0.921) after neostigmine. While attributing different onset times also to differences in the initial doses, we conclude that time profiles for neuromuscular block of both muscle relaxants, when given in equipotent doses, are not different.