BackgroundBalancing between opioid analgesia and respiratory depression continues to challenge clinicians in perioperative, emergency department, and other acute care settings. Morphine and... Show moreBackgroundBalancing between opioid analgesia and respiratory depression continues to challenge clinicians in perioperative, emergency department, and other acute care settings. Morphine and hydromorphone are postoperative analgesic standards. Nevertheless, their comparative effects and side effects, timing, and respective variabilities remain poorly understood. This study tested the hypothesis that IV morphine and hydromorphone differ in onset, magnitude, duration, and variability of analgesic and ventilatory effects.MethodsThe authors conducted a randomized crossover study in healthy volunteers. Forty-two subjects received a 2-h IV infusion of hydromorphone (0.05 mg/kg) or morphine (0.2 mg/kg) 1 to 2 weeks apart. The authors measured arterial opioid concentrations, analgesia in response to heat pain (maximally tolerated temperature, and verbal analog pain scores at discrete preset temperatures to determine half-maximum temperature effect), dark-adapted pupil diameter and miosis, end-expired carbon dioxide, and respiratory rate for 12 h after dosing.ResultsFor morphine and hydromorphone, respectively, maximum miosis was less (3.9 [3.4 to 4.2] vs. 4.6 mm [4.0 to 5.0], P < 0.001; median and 25 to 75% quantiles) and occurred later (3.1 ± 0.9 vs. 2.3 ± 0.7 h after infusion start, P < 0.001; mean ± SD); maximum tolerated temperature was less (49 ± 2 vs. 50 ± 2°C, P < 0.001); verbal pain scores at end-infusion at the most informative stimulus (48.2°C) were 82 ± 4 and 59 ± 3 (P < 0.001); maximum end-expired CO2 was 47 (45 to 50) and 48 mmHg (46 to 51; P = 0.007) and occurred later (5.5 ± 2.8 vs. 3.0 ± 1.5 h after infusion start, P < 0.001); and respiratory nadir was 9 ± 1 and 11 ± 2 breaths/min (P < 0.001), and occurred at similar times. The area under the temperature tolerance-time curve was less for morphine (1.8 [0.0 to 4.4]) than hydromorphone (5.4°C-h [1.6 to 12.1] P < 0.001). Interindividual variability in clinical effects did not differ between opioids.ConclusionsFor morphine compared to hydromorphone, analgesia and analgesia relative to respiratory depression were less, onset of miosis and respiratory depression was later, and duration of respiratory depression was longer. For each opioid, timing of the various clinical effects was not coincident. Results may enable more rational opioid selection, and suggest hydromorphone may have a better clinical profile. Show less
Hellinga, M.; Algera, M.H.; Schrier, R.V.; Sarton, E.; Velzen, M. van; Dahan, A.; ... ; Niesters, M. 2023
Opioids are commonly used painkillers and drugs of abuse and have serious toxic effects including potentially lethal respiratory depression. It remains unknown which respiratory parameter is the... Show moreOpioids are commonly used painkillers and drugs of abuse and have serious toxic effects including potentially lethal respiratory depression. It remains unknown which respiratory parameter is the most sensitive biomarker of opioid-induced respiratory depression (OIRD). To evaluate this issue, we studied 24 volunteers and measured resting ventilation, resting end-tidal PCO2 (PETCO2) and the hypercapnic ventilatory response (HCVR) before and at 1-h intervals following intake of the opioid tapentadol. Pharmacokinetic/pharmacodynamic analyses that included CO2 kinetics were applied to model the responses with focus on resting variables obtained without added CO2, HCVR slope and ventilation at an extrapolated PETCO2 of 55 mmHg (V˙E55). The HCVR, particularly V˙E55 followed by slope, was most sensitive in terms of potency; resting variables were least sensitive and responded slower to the opioid. Using V˙E55 as biomarker in quantitative studies on OIRD allows standardized comparison among opioids in the assessment of their safety. Show less
Dam, C.J. van; Schrier, R. van der; Velzen, M. van; Lemmen, M. van; Simons, P.; Kuijpers, K.W.K.; ... ; Niesters, M. 2023
BackgroundIn humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ9-tetrahydrocannabinol (THC) remains unknown, particularly when THC is... Show moreBackgroundIn humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ9-tetrahydrocannabinol (THC) remains unknown, particularly when THC is combined with an opioid. We studied the effect of THC on breathing without and with oxycodone pretreatment. We hypothesised that THC causes respiratory depression, which is amplified when THC and oxycodone are combined.MethodsIn this randomised controlled crossover trial, healthy volunteers were administered inhaled Bedrocan® 100 mg (Bedrocan International B.V., Veendam, The Netherlands), a pharmaceutical-grade high-THC cannabis variant (21.8% THC; 0.1% cannabidiol), after placebo or oral oxycodone 20 mg pretreatment; THC was inhaled 1.5 and 4.5 h after placebo or oxycodone intake. The primary endpoint was isohypercapnic ventilation at an end-tidal Pco2 of 55 mm Hg or 7.3 kPa (VE55), measured at 1-h intervals for 7 h after placebo/oxycodone intake.ResultsIn 18 volunteers (age 22 yr [3]; 9 [50%] female), oxycodone produced a 30% decrease in VE55, whereas placebo was without effect on VE55. The first cannabis inhalation resulted in VE55 changing from 20.3 (3.1) to 23.8 (2.4) L min−1 (P=0.06) after placebo, and from 11.8 (2.8) to 13.0 (3.9) L min−1 (P=0.83) after oxycodone. The second cannabis inhalation also had no effect on VE55, but slightly increased sedation.ConclusionsIn humans, THC has no effect on ventilatory control after placebo or oxycodone pretreatment. Show less
Simons, P.; Schrier, R. van der; Lemmen, M. van; Jansen, S.; Kuijpers, K.W.K.; Velzen, M. van; ... ; Dahan, A. 2023
Background: Oliceridine is a G protein–biased μ-opioid, a drug class thatis associated with less respiratory depression than nonbiased opioids, suchas morphine. The authors quantified the... Show moreBackground: Oliceridine is a G protein–biased μ-opioid, a drug class thatis associated with less respiratory depression than nonbiased opioids, suchas morphine. The authors quantified the respiratory effects of oliceridine andmorphine in elderly volunteers. The authors hypothesized that these opioidsdiffer in their pharmacodynamic behavior, measured as effect on ventilation atan extrapolated end-tidal Pco2 at 55 mmHg, V̇E55.Methods: This four-arm double-blind, randomized, crossover study examinedthe respiratory effects of intravenous 0.5 or 2 mg oliceridine and 2 or8 mg morphine in 18 healthy male and female volunteers, aged 55 to 89 yr, onfour separate occasions. Participants’ CYP2D6 genotypes were determined,hypercapnic ventilatory responses were obtained, and arterial blood sampleswere collected before and for 6 h after treatment. A population pharmacokinetic–pharmacodynamic analysis was performed on V̇E55, the primary endpoint;values reported are median ± standard error of the estimate.Results: Oliceridine at low dose was devoid of significant respiratory effects.High-dose oliceridine and both morphine doses caused a rapid onset of respiratorydepression with peak effects occurring at 0.5 to 1 h after opioid dosing.After peak effect, compared with morphine, respiratory depression inducedby oliceridine returned faster to baseline. The effect-site concentrationscausing a 50% depression of V̇E55 were 29.9 ± 3.5 ng/ml (oliceridine) and21.5 ± 4.6 ng/ml (morphine), the blood effect-site equilibration half-lives differedby a factor of 5: oliceridine 44.3 ± 6.1 min and morphine 214 ± 27 min.Three poor CYP2D6 oliceridine metabolizers exhibited a significant differencein oliceridine clearance by about 50%, causing higher oliceridine plasma concentrationsafter both low- and high-dose oliceridine, compared with the otherparticipants.Conclusions: Oliceridine and morphine differ in their respiratory pharmacodynamicswith a more rapid onset and offset of respiratory depression foroliceridine and a smaller magnitude of respiratory depression over time. Show less
Hellinga, M.; Algera, M.H.; Olofsen, E.; Schrier, R. van der; Sarton, E.; Velzen, M. van; ... ; Niesters, M. 2023
The widely prescribed opioid oxycodone may cause lethal respiratory depression. We compared the effects of oxycodone on breathing and antinociception in healthy young volunteers. After... Show moreThe widely prescribed opioid oxycodone may cause lethal respiratory depression. We compared the effects of oxycodone on breathing and antinociception in healthy young volunteers. After pharmacokinetic/pharmacodynamic (PK/PD) modeling, we constructed utility functions to combine the wanted and unwanted end points into a single function. We hypothesized that the function would be predominantly negative over the tested oxycodone concentration range. Twenty-four male and female volunteers received 20 (n = 12) or 40 (n = 12) mg oral oxycodone immediate-release tablets. Hypercapnic ventilatory responses (visit 1) or responses to 3 nociceptive assays (pain pressure, electrical, and thermal tests; visit 2) were measured at regular intervals for 7 hours. the PK/PD analyses, that included carbon dioxide kinetics, stood at the basis of the utility function: probability of antinociception minus probability of respiratory depression. Oxycodone had rapid onset/offset times (30–40 minutes) with potency values (effect-site concentration causing 50% of effect) ranging from 0.05 to 0.13 ng/mL for respiratory variables obtained at hypercapnia and antinociceptive responses. Ventilation at an extrapolated end-tidal carbon dioxide partial pressure of 55 mmHg, was used for creation of 3 utility functions, one for each of the nociceptive tests. Contrary to expectation, the utility functions were close to zero or positive over the clinical oxycodone concentration range. The similar or better likelihood for antinociception relative to respiratory depression may be related to oxycodone's receptor activation profile or to is high likeability that possibly alters the modulation of nociceptive input. Oxycodone differs from other μ-opioids, such as fentanyl, that have a consistent negative utility. Show less
Dam, C.J. van; Velzen, M. van; Kramers, C.; Schellekens, A.; Olofsen, E.; Niesters, M.; Dahan, A. 2023
Background Opioids continue to be widely prescribed for chronic noncancer pain, despite the awareness that opioids provide only short-time pain relief, lead to dose accumulation, have numerous... Show moreBackground Opioids continue to be widely prescribed for chronic noncancer pain, despite the awareness that opioids provide only short-time pain relief, lead to dose accumulation, have numerous adverse effects, and are difficult to wean. As an alternative, we previously showed advantages of using pharmaceutical-grade cannabis in a population of chronic pain patients with fibromyalgia. It remains unknown whether combining an opioid with pharmaceutical-grade cannabis has advantages, such as fewer side effects from lesser opioid consumption in chronic pain.Methods Trial design: a single-center, randomized, three-arm, open-label, exploratory trial.Trial population: 60 patients with fibromyalgia according to the 2010 definition of the American College of Rheumatologists.Intervention: Patients will be randomized to receive up to 4 daily 5 mg oral oxycodone sustained release (SR) tablet, up to 5 times 150 mg inhaled cannabis (Bediol (R), containing 6.3% delta(9)-tetrahydrocannabinol and 8% cannabidiol), or the combination of both treatments. Treatment is aimed at self-titration with the daily maximum doses given. Treatment will continue for 6 weeks, after which there is a 6-week follow-up period.Main trial endpoint: The number of side effects observed during the course of treatment using a composite adverse effect score that includes the following 10 symptoms: dizziness (when getting up), sleepiness, insomnia, headache, nausea, vomiting, constipation, drug high, hallucinations, and paranoia.Secondary and tertiary endpoints include pain relief and number of oxycodone doses and cannabis inhalations.Discussion The trial is designed to determine whether self-titration of oxycodone and cannabis will reduce side effects in chronic pain patients with fibromyalgia. Show less
Schrier, R. van der; Velzen, M. van; Roozekrans, M.; Sarton, E.; Olofsen, E.; Niesters, M.; ... ; Dahan, A. 2022
Background: Due the increasing need for storage of carbon dioxide (CO2) more individuals are prone to be exposed to high concentrations of CO2 accidentally released into atmosphere, with... Show moreBackground: Due the increasing need for storage of carbon dioxide (CO2) more individuals are prone to be exposed to high concentrations of CO2 accidentally released into atmosphere, with deleterious consequences. Methods: We tested the effect of increasing CO2 concentrations in humans (6–12%) and rats (10–50%) at varying inhalation times (10–60 min). In humans, a continuous positive airway pressure helmet was used to deliver the gas mixture to the participants. Unrestrained rats were exposed to CO2 in a transparent chamber. In both species regular arterial blood gas samples were obtained. After the studies, the lungs of the animals were examined for macroscopic and microscopic abnormalities. Results: In humans, CO2 concentrations of 9% inhaled for >10 min, and higher concentrations inhaled for <10 min were poorly or not tolerated due to exhaustion, anxiety, dissociation or acidosis (pH < 7.2), despite intact oxygenation. In rats, concentrations of 30% and higher were associated with CO2 narcosis, epilepsy, poor oxygenation and, at 50% CO2, spontaneous death. Lung hemorrhage and edema were observed in the rats at inhaled concentrations of 30% and higher. Conclusion: This study provides essential insight into the occurrence of physiological changes in humans and fatalities in rats after acute exposure to high levels of CO2. Humans tolerate 9% CO2 and retain their ability to function coherently for up to 10 min. These data support reconsideration of the current CO2 levels (<7.5%) that pose a risk to exposed individuals (<7.5%) as determined by governmental agencies to ≤9%. Show less
Algera, H.; Schrier, R. van der; Cavalla, D.; Velzen, M. van; Roozekrans, M.; McMorn, A.; ... ; Dahan, A. 2022
Background: Animal data suggest that the antidepressant and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor modulator tianeptine is able to prevent opioid-induced respiratory... Show moreBackground: Animal data suggest that the antidepressant and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor modulator tianeptine is able to prevent opioid-induced respiratory depression. The hypothesis was that oral or intravenous tianeptine can effectively prevent or counteract opioid-induced respiratory depression in humans. Methods: Healthy male and female volunteers participated in two studies that had a randomized, double blind, placebo-controlled, crossover design. First, oral tianeptine (37.5-, 50-, and 100-mg doses with 8 subjects) pretreatment followed by induction of alfentanil-induced respiratory depression (alfentanil target concentration, 100 ng/ml) was tested. Primary endpoint was ventilation at an extrapolated end-tidal carbon dioxide concentration of 55 mmHg (V?(E)55). Next, the ability of four subsequent and increasing infusions of intravenous tianeptine (target tianeptine plasma concentrations 400, 1,000, 1,500, and 2,000 ng/ml, each given over 15 min) to counteract remifentanil-induced respiratory depression was determined in 15 volunteers. Ventilation was measured at isohypercpania (baseline ventilation 20 +/- 2 l/min). The primary endpoint was minute ventilation during the 60 min of tianeptine versus placebo infusion. Results: Alfentanil reduced V?(E)55 to 13.7 (95% CI, 8.6 to 18.8) l/min after placebo pretreatment and to 17.9 (10.2 to 25.7) l/min after 50-mg tianeptine pretreatment (mean difference between treatments 4.2 (-11.5 to 3.0) l/min, P = 0.070). Intravenous tianeptine in the measured concentration range of 500 to 2,000 ng/ml did not stimulate ventilation but instead worsened remifentanil-induced respiratory depression: tianeptine, 9.6 +/- 0.8 l/min versus placebo 15.0 +/- 0.9 l/min; mean difference, 5.3 l/min; 95% CI, 2.5 to 8.2 l/min; P = 0.001, after 1 h of treatment. Conclusions: Neither oral nor intravenous tianeptine were respiratory stimulants. Intravenous tianeptine over the concentration range of 500 to 2000 ng/ml worsened respiratory depression induced by remifentanil. Show less
Simons, P.; Olofsen, E.; Velzen, M. van; Lemmen, M. van; Dasselaar, T. van; Mohr, P.; ... ; Dahan, A. 2022
Ketamine is a versatile drug used for many indications and is administered via various routes. Here, we report on the pharmacodynamics of sublingual and buccal fast-dissolving oral-thin-films that... Show moreKetamine is a versatile drug used for many indications and is administered via various routes. Here, we report on the pharmacodynamics 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 50 mg S-ketamine oral thin films in a crossover design, placed for 10 min sublingually (n = 15) or buccally (n = 5). The following measurements were made for 6 h following the film placement: antinociception using three distinct pain assay; electrical, pressure, and heat pain, and drug high on an 11-point visual analog scale. Blood samples were obtained for the measurement of plasma S-ketamine, S-norketamine, and S-hydroxynorketamine concentrations. A population pharmacodynamic analysis was performed in NONMEM to construct a pharmacodynamic model of S-ketamine and its metabolites. P-values < 0.01 were considered significant. The sublingual and buccal 50 and 100 mg S-ketamine oral thin films were antinociceptive and produced drug high with effects lasting 2–6 h, although a clear dose-response relationship for antinociception could not be established. The effects were solely related to the parent compound with no contribution from S-norketamine or S-hydroxynorketamine. S-ketamine potency was lower for antinociception (C50 ranging from 1.2 to 1.7 nmol/mL) than for drug high (C50 0.3 nmol/ml). The onset/offset of effect as defined by the blood-effect-site equilibration half-life did not differ among endpoints and ranged from 0 to 5 min. In conclusion, the 50-mg S-ketamine oral thin film was safe and produced long-term antinociception in all three nociceptive assays with side effects inherent to the use of ketamine. The study was registered at the trial register of the Dutch Cochrane Center (www.trialregister.nl) under identifier NL9267 and the European Union Drug Regulating Authorities Clinical Trials (EudraCT) database under number 2020-005185-33. Show less
In response to a surge of deaths from synthetic opioid overdoses, there have been increased efforts to distribute naloxone products in community settings. Prior research has assessed the... Show moreIn response to a surge of deaths from synthetic opioid overdoses, there have been increased efforts to distribute naloxone products in community settings. Prior research has assessed the effectiveness of naloxone in the hospital setting; however, it is challenging to assess naloxone dosing regimens in the community/first-responder setting, including reversal of respiratory depression effects of fentanyl and its derivatives (fentanyls). Here, we describe the development and validation of a mechanistic model that combines opioid mu receptor binding kinetics, opioid agonist and antagonist pharmacokinetics, and human respiratory and circulatory physiology, to evaluate naloxone dosing to reverse respiratory depression. Validation supports our model, which can quantitatively predict displacement of opioids by naloxone from opioid mu receptors in vitro, hypoxia-induced cardiac arrest in vivo, and opioid-induced respiratory depression in humans from different fentanyls. After validation, overdose simulations were performed with fentanyl and carfentanil followed by administration of different intramuscular naloxone products. Carfentanil induced more cardiac arrest events and was more difficult to reverse than fentanyl. Opioid receptor binding data indicated that carfentanil has substantially slower dissociation kinetics from the opioid receptor compared with nine other fentanyls tested, which likely contributes to the difficulty in reversing carfentanil. Administration of the same dose of naloxone intramuscularly from two different naloxone products with different formulations resulted in differences in the number of virtual patients experiencing cardiac arrest. This work provides a robust framework to evaluate dosing regimens of opioid receptor antagonists to reverse opioid-induced respiratory depression, including those caused by newly emerging synthetic opioids. Show less
Simons, P.; Olofsen, E.; Velzen, M. van; Lemmen, M. van; Mooren, R.; Dasselaar, T. van; ... ; Dahan, A. 2022
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... Show moreKetamine 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. Show less
Honing, G.H.M.; Torensma, B.; Martini, C.H.; Hoek, K.B.; Velzen, M. van; Olofsen, E.; ... ; Boon, M. 2022
Study objective: Quantitative neuromuscular monitoring is traditionally evaluated at the adductor pollicis muscle. By contrast, the TOF-Cuff compressomyograph evaluates neuromuscular block (NMB) at... Show moreStudy objective: Quantitative neuromuscular monitoring is traditionally evaluated at the adductor pollicis muscle. By contrast, the TOF-Cuff compressomyograph evaluates neuromuscular block (NMB) at the upper arm. However, compressomyography has not been fully validated against other monitoring entities. This study evaluates the agreement between NMB measured by compressomyography at the upper arm and electromyography at the adductor pollicis muscle during various levels of neuromuscular block in patients with and without obesity. Interventions: NMB was measured at the upper arm by compressomyography (TOF-Cuff) and by electromyography (GE-NMT) at the adductor pollicis. Design: Prospective, multicenter, observational study. Setting: Secondary and tertiary care hospitals' operating theatres. Patients: 200 non-obese and 50 obese patients. Measurements: During onset and offset of deep (post-tetanic-count 1-15 twitches), moderate (Train-of-Four-count 1-3 twitches) and shallow (Train-of-Four-ratio 0.01-1.0) depths of NMB were measured in obese and non-obese patients. The bias and limits of agreement of both devices were calculated using a Bland-Altman analysis for repeated measurements. Data obtained during spontaneous recovery (i.e. without the use of reversal agents) were used in the primary analyses. Main results: Data from enrolled patients yielded 942 paired post-tetanic-counts, 1175 paired train-of-four-counts and 1574 paired train-of-four ratios during spontaneous recovery. In non-obese patients, mean bias (95% CI) between the two devices was 3.405 (2.294 to 4.517) during deep NMB;-0.023 (-0.205 to 0.160) during moderate NMB and 0.312 (0.287 to 0.338) during shallow NMB. In obese patients, bias was-0.170 (-2.872 to 2.531); 0.178 (-0.202 to 0.558); 0.384 (0.299 to 0.469) for deep, moderate and shallow NMB respectively. Conclusions: There is variable disagreement between the level of NMB measured at the upper arm by compressomyography and at the adductor pollicis muscle measured by electromyography, throughout the various stages of NMB in obese and non-obese patients. Recovery of NMB on compressomyography preceded recovery on electromyography, which may have consequences for reversal and extubation decisions in clinical practice. Show less
BACKGROUND: Potent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu... Show moreBACKGROUND: Potent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu-opioid receptor partial agonist buprenorphine may prevent fatalities by reducing binding of potent opioids to the opioid receptor, limiting respiratory depression. METHODS: To characterize buprenorphine-fentanyl interaction at the level of the mu-opioid receptor in 2 populations (opioid-naive individuals and individuals who chronically use high-dose opioids), the effects of escalating i.v. fentanyl doses with range 0.075???0.35 mg/70 kg (opioid naive) and 0.25???0.70 mg/70 kg (chronic opioid use) on iso-hypercapnic ventilation at 2???3 background doses of buprenorphine (target plasma concentrations range: 0.2???5 ng/mL) were quantified using receptor association/dissociation models combined with biophase distribution models. RESULTS: Buprenorphine produced mild respiratory depression, while high doses of fentanyl caused pronounced respiratory depression and apnea in both populations. When combined with fentanyl, buprenorphine produced a receptor binding???dependent reduction of fentanyl-induced respiratory depression in both populations. In individuals with chronic opioid use, at buprenorphine plasma concentrations of 2 ng/mL or higher, a protective effect against high-dose fentanyl was observed. CONCLUSION: Overall, the results indicate that when buprenorphine mu-opioid receptor occupancy is sufficiently high, fentanyl is unable to activate the mu-opioid receptor and consequently will not cause further respiratory depression in addition to the mild respiratory effects of buprenorphine. Show less
Olofsen, E.; Kamp, J.; Henthorn, T.K.; Velzen, M. van; Niesters, M.; Sarton, E.; Dahan, A. 2022
Background: Ketamine produces potent analgesia combined with psychedelic effects. It has been suggested that these two effects are associated and possibly that analgesia is generated by ketamine... Show moreBackground: Ketamine produces potent analgesia combined with psychedelic effects. It has been suggested that these two effects are associated and possibly that analgesia is generated by ketamine-induced dissociation. The authors performed a post hoc analysis of previously published data to quantify the pharmacodynamic properties of ketamine-induced antinociception and psychedelic symptoms. The hypothesis was that ketamine pharmacodynamics (i.e., concentration-effect relationship as well as effect onset and offset times) are not different for these two endpoints. Methods: Seventeen healthy male volunteers received escalating doses of S- and racemic ketamine on separate occasions. Before, during, and after ketamine infusion, changes in external perception were measured together with pain pressure threshold. A population pharmacokinetic-pharmacodynamic analysis was performed that took S- and R-ketamine and S- and R-norketamine plasma concentrations into account. Results: The pharmacodynamics of S-ketamine did not differ for antinociception and external perception with potency parameter (median [95% CI]) C-50, 0.51 (0.38 to 0.66) nmol/ml; blood-effect site equilibration half-life, 8.3 [5.1 to 13.0] min), irrespective of administration form (racemic ketamine or S-ketamine). R-ketamine did not contribute to either endpoint. For both endpoints, S-norketamine had a small antagonistic effect. Conclusions: The authors conclude that their data support an association or connectivity between ketamine analgesia and dissociation. Given the intricacies of the study related to the pain model, measurement of dissociation, and complex modeling of the combination of ketamine and norketamine, it is the opinion of the authors that further studies are needed to detect functional connectivity between brain areas that produce the different ketamine effects. Show less
Background: Opioid-induced respiratory depression driven by ligand binding to mu-opioid receptors is a leading cause of opioid-related fatalities. Buprenorphine, a partial agonist, binds with high... Show moreBackground: Opioid-induced respiratory depression driven by ligand binding to mu-opioid receptors is a leading cause of opioid-related fatalities. Buprenorphine, a partial agonist, binds with high affinity to mu-opioid receptors but displays partial respiratory depression effects. The authors examined whether sustained buprenorphine plasma concentrations similar to those achieved with some extended-release injections used to treat opioid use disorder could reduce the frequency and magnitude of fentanyl-induced respiratory depression. Methods: In this two-period crossover, single-centre study, 14 healthy volunteers (single-blind, randomized) and eight opioid-tolerant patients taking daily opioid doses >= 90 mg oral morphine equivalents (open-label) received continuous intravenous buprenorphine or placebo for 360 minutes, targeting buprenorphine plasma concentrations of 0.2 or 0.5 ng/mL in healthy volunteers and 1.0, 2.0 or 5.0 ng/mL in opioid-tolerant patients. Upon reaching target concentrations, participants received up to four escalating intravenous doses of fentanyl. The primary endpoint was change in isohypercapnic minute ventilation (V-E). Additionally, occurrence of apnea was recorded. Results: Fentanyl-induced changes in V-E were smaller at higher buprenorphine plasma concentrations. In healthy volunteers, at target buprenorphine concentration of 0.5 ng/mL, the first and second fentanyl boluses reduced V-E by [LSmean (95% CI)] 26% (13-40%) and 47% (37-59%) compared to 51% (38-64%) and 79% (69-89%) during placebo infusion (p = 0.001 and < .001, respectively). Discontinuations for apnea limited treatment comparisons beyond the second fentanyl injection. In opioid-tolerant patients, fentanyl reduced V-E up to 49% (21-76%) during buprenorphine infusion (all concentration groups combined) versus up to 100% (68-132%) during placebo infusion (p = 0.006). In opioid-tolerant patients, the risk of experiencing apnea requiring verbal stimulation following fentanyl boluses was lower with buprenorphine than with placebo (odds ratio: 0.07; 95% CI: 0.0 to 0.3; p = 0.001). Interpretation: Results from this proof-of-principle study provide the first clinical evidence that high sustained plasma concentrations of buprenorphine may protect against respiratory depression induced by potent opioids like fentanyl. Show less
Martini, C.H.; Honing, G.H.M.; Bash, L.D.; Olofsen, E.; Niesters, M.; Velzen, M. van; ... ; Boon, M. 2022
Introduction: Muscle relaxants are often given during general anesthesia to facilitate endotracheal intubation. However lingering effects after anesthesia-end may lead to respiratory compromise in... Show moreIntroduction: Muscle relaxants are often given during general anesthesia to facilitate endotracheal intubation. However lingering effects after anesthesia-end may lead to respiratory compromise in the PACU. Strategies to reduce these adverse events include monitoring neuromuscular block, the use of short-acting agents and active pharmacological reversal before extubation. At Leiden University Medical Center (LUMC), a tertiary care academic hospital in the Netherlands, various muscle relaxants and reversal agents are freely available to all clinicians without restrictions. In this setting, we intended to evaluate how patient and surgical characteristics impacted the use of these agents for a variety of non-cardiac surgeries.Material and Methods: This is a retrospective database study of adult patients that had received elective, non-cardiac surgery and general anesthesia with endotracheal intubation between 2016 and 2020 at LUMC in the Netherlands. Exclusion criteria consisted of patients pharmacologically reversed with both sugammadex and neostigmine during the same procedure, diagnosed with myasthenia gravis, receiving pyridostigmine therapy, or with renal failure (eGFR <30 mL.min.1.73m(2)).Results: We retrieved 23,373 patient records of which 9742 were excluded because one or more exclusion criteria were met. The final cohort consisted of 13,631 cases. Rocuronium was the most commonly used muscle relaxant (88.5%); sugammadex was the most commonly used reversal agent (99.9% of those pharmacologically reversed). Of all cases that received rocuronium as muscle relaxant, 76.9% of patients were not reversed, while 23.1% were reversed with sugammadex. The odds of reversal increased with age, HMI, ASA class (1-3) and shorter duration of surgery.Conclusion: In an unrestricted clinical environment, rocuronium and sugammadex are the preferred agents for muscle relaxation and reversal. Pharmacologic reversal of neuromuscular block was uncommon overall, but more likely in older and obese patients, higher ASA classification and shorter lasting procedures. Sugammadex has largely replaced neostigmine for this purpose. Show less
BACKGROUND It is generally accepted that a neuraxial blockade strengthens the sedative effects of propofol. Deafferentation caused by neuraxial blockade is thought to play a key role. OBJECTIVES... Show moreBACKGROUND It is generally accepted that a neuraxial blockade strengthens the sedative effects of propofol. Deafferentation caused by neuraxial blockade is thought to play a key role. OBJECTIVES The objective is to determine whether epidural blockade affects the bispectral index (BIS) of propofol and two other pharmacodynamic endpoints, mean arterial pressure (MAP) and cardiac output (CO). DESIGN Randomised, placebo-controlled study. SETTING University hospital. PATIENTS Patients scheduled for surgery needing epidural analgesia. INTERVENTION 28 ASA one or two patients received 0, 50, 100 or 150 mg of epidural ropivacaine. After stabilisation of the epidural blockade, propofol was given by target-controlled infusion. The propofol plasma target concentrations were increased at 6-min intervals from 0 to 1, 2.5, 4 and 6 mu g ml(-1). The study was performed before surgery. MAIN OUTCOME MEASURES Three endpoints, BIS, mean arterial blood pressure and CO were measured from baseline (prior to the administration of epidural ropivacaine) until 2 h after the start of propofol infusion. The propofol concentration-effect data were analysed to determine the interaction between epidural blockade and propofol sedation. RESULTS In the absence of propofol, the increase in number of epidural blocked segments from 0 to 15.5 (range 6 to 21) reduced the MAP by 30%, without affecting BIS or CO. In the absence of epidural blockade, the increase in propofol concentration to 6 mu g ml(-1) reduced BIS, MAP and CO. When combined, epidural anaesthesia and intravenous propofol exhibited no pharmacodynamic interaction on any of the three endpoints. In addition, epidural blockade did not affect the propofol effect-site equilibration half-life for its haemodynamic effects (11.5 +/- 0.5 min) or for its effects on the BIS (4.6 +/- 0.4 min). CONCLUSION Epidural blockade reduces the propofol requirements for sedative end points. This is not the result of a pharmacodynamic interaction. Show less
Kamp, J.; Velzen, M. van; Aarts, L.; Niesters, M.; Dahan, A.; Olofsen, E. 2021
Background: Ketamine has cardiac excitatory side-effects. Currently, data on the effects of ketamine and metabolite concentrations on cardiac output are scarce. We therefore developed a... Show moreBackground: Ketamine has cardiac excitatory side-effects. Currently, data on the effects of ketamine and metabolite concentrations on cardiac output are scarce. We therefore developed a pharmacodynamic model derived from data from a randomised clinical trial. The current study is part of a larger clinical study evaluating the potential mitigating effect of sodium nitroprusside on the psychedelic effects of ketamine.Methods: Twenty healthy male subjects received escalating esketamine and racemic ketamine doses in combination with either placebo or sodium nitroprusside on four visits: (i) esketamine and placebo, (ii) esketamine and sodium nitroprusside, (iii) racemic ketamine and placebo, and (iv) racemic ketamine and sodium nitroprusside. During each visit, arterial blood samples were obtained and cardiac output was measured. Nonlinear mixed-effect modelling was used to analyse the cardiac output time-series data. Ketamine metabolites were added to the model in a sequential manner to evaluate the effects of metabolites.Results: A model including an S-ketamine and S-norketamine effect best described the data. Ketamine increased cardiac output, whereas modelling revealed that S-norketamine decreased cardiac output. No significant effects were detected for R-ketamine, metabolites other than S-norketamine, or sodium nitroprusside on cardiac output.Conclusions: S-Ketamine, but not R-ketamine, increased cardiac output in a dose-dependent manner. In contrast to Sketamine, its metabolite S-norketamine reduced cardiac excitation in a dose-dependent manner. Show less
