Pharmacodynamics of Orally Administered Sustained- release Hydromorphone in Humans

2001 ◽  
Vol 94 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Martin S. Angst ◽  
David R. Drover ◽  
Jörn Lötsch ◽  
Bhamini Ramaswamy ◽  
Sujata Naidu ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Sustained Release ◽  
Analgesic Effect ◽  
Time Course ◽  
Plasma Concentrations ◽  
Experimental Pain ◽  
Immediate Release ◽  
Double Blind ◽  
Sustained Release Formulation ◽  
Analgesic Effects

Background The disposition kinetics of hydromorphone generally necessitates oral administration every 4 h of the conventional immediate-release tablet to provide sustained pain relief. This trial examined time course and magnitude of analgesia to experimental pain after administration of sustained-release hydromorphone as compared with that after immediate-release hydromorphone or placebo. Methods Using a 4 x 4 Latin square double-blind design, 12 subjects were randomized to receive a single dose of 8, 16, and 32 mg sustained-release hydromorphone and placebo. The same subjects had received 8 mg immediate-release hydromorphone before this study. Using an electrical experimental pain paradigm, analgesic effects were assessed for up to 30 h after administration, and venous hydromorphone plasma concentrations were measured at corresponding times. Results The hydromorphone plasma concentration peaked significantly later (12.0 h [12.0--18.0] vs. 0.8 h [0.8--1.0]; median and interquartile range) but was maintained significantly longer at greater than 50% of peak concentration (22.7 +/- 8.2 h vs. 1.1 +/- 0.7 h; mean +/- SD) after sustained-release than after immediate-release hydromorphone. Similarly, sustained-release hydromorphone produced analgesic effects that peaked significantly later (9.0 h [9.0--12.0] vs. 1.5 h [1.0--2.0]) but were maintained significantly longer at greater than 50% of peak analgesic effect (13.3 +/- 6.3 h vs. 3.6 +/- 1.7 h). A statistically significant linear relation between the hydromorphone plasma concentration and the analgesic effect on painful stimuli existed. Conclusion A single oral dose of a new sustained-release formulation of hydromorphone provided analgesia to experimental pain beyond 24 h of its administration.

A New Model of Electrically Evoked Pain and Hyperalgesia in Human Skin

2001 ◽  
Vol 95 (2) ◽  
pp. 395-402 ◽  
Author(s):  
Wolfgang Koppert ◽  
Sara K. Dern ◽  
Reinhard Sittl ◽  
Sven Albrecht ◽  
Jürgen Schüttler ◽  
...  
Keyword(s):  
Time Course ◽  
Rating Scale ◽  
High Current Density ◽  
Experimental Pain ◽  
Numeric Rating Scale ◽  
Human Model ◽  
High Temporal Resolution ◽  
Double Blind ◽  
New Model ◽  
Analgesic Effects

Background The authors used the analgesics alfentanil, S(+)-ketamine, and systemic lidocaine to examine a new human model of experimental pain and hyperalgesia. Methods Transcutaneous electrical stimulation at a high current density (5 Hz, 67.5+/-6.6 mA) was used to provoke acute pain (numeric rating scale, 5 of 10), stable areas of secondary mechanical hyperalgesia to pin prick (43.6+/-32.1 cm2), and light touch (27.5+/-16.2 cm2) for 2 h. Alfentanil, S(+)-ketamine, and lidocaine were applied for 20 min in a double-blind, placebo-controlled, crossover design in 12 subjects using target controlled infusions. Results In the placebo session, pain ratings and areas of hyperalgesia were stable during the stimulation period, which facilitated the assessment of analgesic effects. Alfentanil effectively inhibited electrically evoked pain and reduced pin prick hyperalgesia and allodynia during its infusion. S(+)-ketamine-induced inhibition of secondary hyperalgesia was more pronounced and lasted for the whole experimental protocol. Therapeutic levels of systemic lidocaine showed only marginal analgesic effects, but lasting antihyperalgesic effects. Conclusions A new model of electrically induced pain and hyperalgesia was established, which enabled assessment of the time course of analgesic and antihyperalgesic effects with high temporal resolution and minimum tissue damage and which was further validated by use of common intravenous anesthetics.

scholarly journals A Randomized, Double-Blind Study of the Effects of a Sustained Release Formulation of Sodium Nitrite (SR-nitrite) on Patients with Diabetic Neuropathy

2018 ◽  
Vol 1 (21;1) ◽  
pp. 179-190 ◽  
Author(s):  
Amol Soin
Keyword(s):  
Neuropathic Pain ◽  
Diabetic Neuropathy ◽  
Sustained Release ◽  
Sodium Nitrite ◽  
Immediate Release ◽  
Double Blind ◽  
Release Formulation ◽  
Sustained Release Formulation ◽  
Pain Scores ◽  
The Mean

Background: Background: Sodium nitrite has been reported to be effective in reducing chronic peripheral pain. Objectives: To evaluate the safety and efficacy of 40 and 80 mg, BID, of an oral sustained release formulation of sodium nitrite (SR-nitrite) in patients suffering from diabetic neuropathy, and to determine whether SR-nitrite would reduce the frequency of headaches reported previously by subjects receiving the same doses of an immediate release formulation. Study Design: Phase II, single-center, randomized, double-blind, placebo controlled clinical trial. Setting: The Ohio Pain Clinic and Kettering Medical Center. Methods: Twenty-four patients were randomized to 40 mg or 80 mg SR-nitrite or placebo twice daily for 12 weeks. The primary objective was to determine whether headaches would be reduced using SR-nitrite. The primary efficacy endpoint was the mean difference in the change of the Neuropathic Pain Symptom Inventory (NPSI) pain score from baseline to that reported after 12 weeks of treatment. Secondary endpoints included changes from baseline for the Brief Pain Inventory (BPI) Scale, the RAND 36 questionnaire, Short Form McGill Questionnaire, daily patient reported score for neuropathic pain, changes in HbA1c, PulseOx and quantitative sensory testing. Results: The number of subjects reporting adverse events and the number of adverse events did not change with dose. There were no reports of treatment-related headaches. Although no significant differences were identified in patient responses to the questionnaires, a trend was observed. In the NPSI assessment, patients in the 40 mg and 80 mg dose group reported a 12.7% and 22.0% reduction in pain, respectively, compared to an 8.4% reduction by patients in the placebo group. A trend was also observed with the BPI total severity score. However, the 40 mg dosing group reported the greatest reduction in pain using the McGill Pain index and via patient logs of daily pain scores, where the mean of pain scores reported by subjects in the 40 mg group dropped by day 41 and generally stayed lower than the mean of scores reported by subjects in either of the other two groups. Patients in the 80 mg SR-nitrite group had an improvement in both Nerve Sensory Conductance and Nerve Sensory Velocity. No changes were observed in HbA1c levels or PulseOx. Limitations: Small sample size. Conclusion: Sustained release sodium nitrite prevents the prevalent reports of headaches by patients treated with an immediate release formulation of sodium nitrite. In a previous study of patients with peripheral arterial disease (PAD), 40 mg BID treatment led to a statistically significant reduction in reported pain, similar trends were observed at the end of the trial period for most of the pain questionnaires used in the study. The 80 mg BID treatment had the more pronounced affect on bioactivity (quantitative sensory testing), which was similar to the PAD study, where this dose group had the greatest improvement in FMD {AU: spell out FMD}. The ability to alleviate pain with BID treatment of SR-nitrite offers promise for a new non-addictive, non-sedating treatment of chronic pain and warrants further study. Key words: diabetes, diabetic neuropathy, neuropathic pain, peripheral neuropathy, sodium nitrite

Nimodipine pharmacokinetics after intraventricular injection of sustained-release nimodipine for subarachnoid hemorrhage

2021 ◽  
Vol 134 (1) ◽  
pp. 95-101 ◽  
Author(s):  
R. Loch Macdonald ◽  
Daniel Hänggi ◽  
Poul Strange ◽  
Hans Jakob Steiger ◽  
J Mocco ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Sustained Release ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
External Ventricular Drain ◽  
Plasma Concentrations ◽  
Intraventricular Injection ◽  
World Federation ◽  
Maximum Plasma ◽  
Clinical Trial Registration ◽  
Sustained Release Formulation

OBJECTIVEThe objective of this study was to measure the concentration of nimodipine in CSF and plasma after intraventricular injection of a sustained-release formulation of nimodipine (EG-1962) in patients with aneurysmal subarachnoid hemorrhage (SAH).METHODSPatients with SAH repaired by clip placement or coil embolization were randomized to EG-1962 or oral nimodipine. Patients were classified as grade 2–4 on the World Federation of Neurosurgical Societies grading scale for SAH and had an external ventricular drain inserted as part of their standard of care. Cohorts of 12 patients received 100–1200 mg of EG-1962 as a single intraventricular injection (9 per cohort) or they remained on oral nimodipine (3 per cohort). Plasma and CSF were collected from each patient for measurement of nimodipine concentrations and calculation of maximum plasma and CSF concentration, area under the concentration-time curve from day 0 to 14, and steady-state concentration.RESULTSFifty-four patients in North America were randomized to EG-1962 and 18 to oral nimodipine. Plasma concentrations increased with escalating doses of EG-1962, remained stable for 14 to 21 days, and were detectable at day 30. Plasma concentrations in the oral nimodipine group were more variable than for EG-1962 and were approximately equal to those occurring at the EG-1962 800-mg dose. CSF concentrations of nimodipine in the EG-1962 groups were 2–3 orders of magnitude higher than in the oral nimodipine group, in which nimodipine was only detected at low concentrations in 10% (21/213) of samples. In the EG-1962 groups, CSF nimodipine concentrations were 1000 times higher than plasma concentrations.CONCLUSIONSPlasma concentrations of nimodipine similar to those achieved with oral nimodipine and lasting for 21 days could be achieved after a single intraventricular injection of EG-1962. The CSF concentrations from EG-1962, however, were at least 2 orders of magnitude higher than those with oral nimodipine. These results supported a phase 3 study that demonstrated a favorable safety profile for EG-1962 but yielded inconclusive efficacy results due to notable differences in clinical outcome based on baseline disease severity.Clinical trial registration no.: NCT01893190 (ClinicalTrials.gov).

scholarly journals Changing the Drug Delivery System: Does it Add to Non-Compliance Ramifications Control? A Simulation Study on the Pharmacokinetics and Pharmacodynamics of Atypical Antipsychotic Drug

Pharmaceutics ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 297
Author(s):  
Mohammed H. Elkomy
Keyword(s):  
Monte Carlo ◽  
Plasma Concentration ◽  
Monte Carlo Simulations ◽  
Time Course ◽  
Rating Scale ◽  
Test Dose ◽  
Immediate Release ◽  
State Recovery ◽  
Psychiatric Rating ◽  
Psychiatric Rating Scale

This study investigates the pharmacokinetic (PK) and pharmacodynamic (PD) consequences of shifting from Quetiapine fumarate immediate-release (IR) to extended-release (XR) formulation in non-adherent schizophrenia patients. Monte-Carlo simulations using population PK and PD models were implemented to predict the time course of plasma concentration and Brief Psychiatric Rating Scale (BPRS) scores following the oral administration of 200 mg Seroquel® every 12 h and 400 mg Seroquel XR® every 24 h in patients experiencing dose delay, omission or doubling. Parameters were computed and their distributions were compared using the Kolmogorov–Smirnov test. Dose irregularities with both formulations had different effects on plasma concentration and %reduction in BPRS scores from baseline. However, the odds ratio of getting a %reduction in BPRS below 14%, or plasma concentration exceeding 500 µg/L, were comparable for adherent and non-adherent patients. Plasma therapeutic concentration after treatment cessation was maintained for <24 h in 48% and 29.6% of patients, and a steady state recovery time of <48 h was achieved in 51% and 13.4% of patients on the IR and XR formulations, respectively. Monte-Carlo simulations predict that the risks associated with the IR dose irregularities are not worsened when the XR formulation is used instead. Non-adherence events involving a single dose of either formulation do not require rescue doses.

Lack of Analgesic Activity of Morphine-6-glucuronide after Short-term Intravenous Administration in Healthy Volunteers 

1997 ◽  
Vol 87 (6) ◽  
pp. 1348-1358 ◽  
Author(s):  
Jorn Lotsch ◽  
Gerd Kobal ◽  
Anne Stockmann ◽  
Kay Brune ◽  
Gerd Geisslinger ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Analgesic Activity ◽  
Intravenous Administration ◽  
Opioid Analgesic ◽  
Plasma Concentrations ◽  
Experimental Pain ◽  
Controlled Study ◽  
Short Term ◽  
Analgesic Effects ◽  
Relative Contribution

Background The analgesic activity of morphine-6-glucuronide (M-6-G) is well recognized for its contribution to the effects of morphine and its possible use as an opioid analgesic with a wider therapeutic range than morphine. The present study attempted to quantify the relative contribution of M-6-G to analgesia observed after systemic administration of morphine. Methods In a placebo-controlled, sixfold crossover study in 20 healthy men, the effects of M-6-G were assessed at steady-state plasma concentrations of M-6-G identical to and two and three times higher than those measured after administration of morphine. Morphine and M-6-G were administered as an intravenous bolus followed by infusion over 4 h. Dosage A was M-6-G-bolus of 0.015 mg/kg plus infusion of 0.0072 mg x kg(-1) x h(-1). Dosage B was M-6-G-bolus of 0.029 mg/kg plus infusion of 0.014 mg x kg(-1) x h(-1). Dosage C was M-6-G-bolus of 0.044 mg/kg plus infusion of 0.022 mg x kg(-1) x h(-1). Dosage D was a morphine bolus of 0.14 mg/kg plus infusion of 0.05 mg x kg(-1) x h(-1) for 4 h. Dosage E was M-6-G combined with morphine (doses A + D). Dosage F was a placebo. The analgesic effects of M-6-G and morphine were measured before administration of the bolus and after 3.5 h using an experimental pain model based on pain-related cortical potentials and pain ratings after specific stimulation of the nasal nociceptor with short pulses of gaseous carbon dioxide. Results Morphine significantly reduced subjective and objective pain correlates compared with placebo. In contrast, M-6-G produced no statistically significant effects. The addition of M-6-G to morphine did not increase the effects of morphine. Morphine produced significantly more side effects than M-6-G. Conclusion After short-term intravenous administration at doses that produce plasma concentrations of M-6-G similar to those seen after administration of morphine, M-6-G had no analgesic effects in the present placebo-controlled study in healthy volunteers.

scholarly journals Pharmacokinetics of Sustained-release, Oral, and Subcutaneous Meloxicam over 72 Hours in Male Beagle Dogs

2020 ◽  
Vol 59 (6) ◽  
pp. 737-741
Author(s):  
Brian J Smith ◽  
Stephen M Kirschner ◽  
Lon V Kendall
Keyword(s):  
Sustained Release ◽  
Adult Male ◽  
Plasma Concentrations ◽  
Beagle Dogs ◽  
Release Formulation ◽  
Sustained Release Formulation ◽  
Subcutaneous Dose ◽  
Cynomolgus Macaques ◽  
Animal Handling ◽  
Time Point

In cynomolgus macaques, plasma levels of sustained-release formulations of meloxicam meet or exceed efficacious concentrations for 48 to 72 h, thereby allowing less animal handling and providing more consistent efficacy than standard formulations of meloxicam. The goal of this study was to compare the pharmacokinetics of a single subcutaneous dose of a sustained-release formulation of meloxicam (Melox-SR) with those of oral (Melox-PO) and standard subcutaneous (Melox-SC) formulations dosed every 24 h for 3 consecutive days. Dogs (5 or 6 adult male Beagles) each received the following 3 treat- ments: first, Melox-SR (10 mg/mL, 0.6 mg/kg SC once), next Melox-SC (0.2 mg/kg SC once, followed by 0.1 mg/kg SC every 24 h), and finally Melox-PO (same dosage as Melox-SC), with a washout period of at least 2 wk between formulations. Blood was collected at 0 (baseline), 1, 4, 8, 12, 24, 48, and 72 h after the initial administration of each formulation for comparison of meloxicam plasma concentrations. Blood was also collected before administration and at 48 h after Melox-SR injection for CBC and chemistry analysis. Plasma concentrations (mean ± 1 SD) of Melox-SR peaked at the 1-h time point (2180 ± 359 ng/ mL), whereas those of Melox-PO (295 ± 55 ng/mL) and Melox-SC (551 ± 112 ng/mL) peaked at the 4-h time point. Melox-SR yielded significantly higher plasma concentrations than Melox-PO and Melox-SC until the 48 and 72-h time points, respec- tively. Melox-SC plasma concentrations were significantly higher than those of Melox-PO at 4, 8, 12, 24, 48 and 72 h. No lesions were noted at the Melox-SR injection sites, and Melox-SR administration was not associated with changes in the CBC and serum chemistry panels. A single 0.6-mg/kg dose of Melox-SR can yield plasma concentrations that exceed 350 ng/mL for at least 72 h in adult male dogs.

scholarly journals Regular, sustained-release morphine for chronic breathlessness: a multicentre, double-blind, randomised, placebo-controlled trial

Thorax ◽  
2019 ◽  
Vol 75 (1) ◽  
pp. 50-56 ◽  
Author(s):  
David Currow ◽  
Sandra Louw ◽  
Philip McCloud ◽  
Belinda Fazekas ◽  
John Plummer ◽  
...  
Keyword(s):  
Sustained Release ◽  
Primary Endpoint ◽  
Controlled Trial ◽  
Oral Morphine ◽  
Immediate Release ◽  
Morphine Group ◽  
Double Blind ◽  
Intention To Treat ◽  
Palliative Care Services ◽  
Secondary Endpoints

IntroductionMorphine may decrease the intensity of chronic breathlessness but data from a large randomised controlled trial (RCT) are lacking. This first, large, parallel-group trial aimed to test the efficacy and safety of regular, low-dose, sustained-release (SR) morphine compared with placebo for chronic breathlessness.MethodsMultisite (14 inpatient and outpatient cardiorespiratory and palliative care services in Australia), parallel-arm, double-blind RCT. Adults with chronic breathlessness (modified Medical Research Council≥2) were randomised to 20 mg daily oral SR morphine and laxative (intervention) or placebo and placebo laxative (control) for 7 days. Both groups could take ≤6 doses of 2.5 mg, ‘as needed’, immediate-release morphine (≤15 mg/24 hours) as required by the ethics review board. The primary endpoint was change from baseline in intensity of breathlessness now (0–100 mm visual analogue scale; two times per day diary) between groups. Secondary endpoints included: worst, best and average breathlessness; unpleasantness of breathlessness now, fatigue; quality of life; function; and harms.ResultsAnalysed by intention-to-treat, 284 participants were randomised to morphine (n=145) or placebo (n=139). There was no difference between arms for the primary endpoint (mean difference −0.15 mm (95% CI −4.59 to 4.29; p=0.95)), nor secondary endpoints. The placebo group used more doses of oral morphine solution during the treatment period (mean 8.7 vs 5.8 doses; p=0.001). The morphine group had more constipation and nausea/vomiting. There were no cases of respiratory depression nor obtundation.ConclusionNo differences were observed between arms for breathlessness, but the intervention arm used less rescue immediate-release morphine.Trial registration numberACTRN12609000806268.

scholarly journals Comparison of pharmacokinetics of omega-3 fatty acid supplements in monoacylglycerol or ethyl ester in humans: a randomized controlled trial

2020 ◽  
Author(s):  
Laurie Chevalier ◽  
Mélanie Plourde
Keyword(s):  
Plasma Concentration ◽  
Ethyl Ester ◽  
Controlled Trial ◽  
Plasma Concentrations ◽  
Controlled Clinical Trial ◽  
Omega 3 Fatty Acids ◽  
Omega 3 ◽  
Post Dose ◽  
Double Blind ◽  
Omega 3 Fatty Acid

Abstract Background A diet low in omega-3 fatty acids (n-3 FA) results in low plasma concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the two main long chain n-3 FA. n-3 FA supplements on the market are esterified in triglycerides (TG) or ethyl ester (EE); the latter is absorbed less than other esterification forms. The objective of this study was to test and compare the pharmacokinetics of n-3 FA esterified in monoacylglycerides (MAG), a predigested form, with the EE form. Methods This study was a randomized, double-blind, crossover, controlled, clinical trial. Ten men and ten women between 18 and 60 years old were recruited. Participants received a single oral dose of 3 g of n-3 FA esterified in EE or MAG. Eleven blood samples were collected over 24 h post-dose. Plasma total lipids were extracted, methylated, and analyzed using gas chromatography. Results After receiving the MAG form, plasma EPA and DHA peaked at a concentration 3 and 2.5 times higher, respectively, than with the EE form. When provided in MAG form, n-3 FA plasma concentration during the absorption phase was on average 3–5 times higher than in EE form. When n-3 FAs were provided esterified in MAG, their concentration 24 h post-dose was higher than in EE. Males had a lower n-3 FA plasma concentration than females when n-3 FAs were provided in EE but there was no sexe difference when provided in MAG. Conclusions Plasma concentration of DHA and EPA was higher when provided in MAG than EE form.

scholarly journals Formulation and in vitro Evaluation of Glimepiride Sustained Release Tablets: Comparison with Immediate Release Tablets

2015 ◽  
Vol 18 (2) ◽  
pp. 157-162
Author(s):  
Samira Karim ◽  
Mohiuddin Ahmed Bhuiyan ◽  
Md Sohel Rana
Keyword(s):  
Sustained Release ◽  
Immediate Release ◽  
Pharmaceutical Journal ◽  
In Vitro Dissolution ◽  
Release Formulation ◽  
Sustained Release Formulation ◽  
Zero Order Kinetics ◽  
Weight Variation ◽  
Sustained Release Tablets

This work aims at the design of a sustained release formulation of glimepiride which is currently available in the treatment of type 2 diabetes mellitus and to investigate the effect of polymers on the release profile of glimepiride. Glimepiride sustained release tablets were prepared by direct compression method using different ratios of various release retarding polymers such as carbopol, ethyl cellulose, methocel K4 MCR, methocel K15 MCR, methocel K100 MCR and xanthum gum. These formulations were also compared with glimepiride immediate release tablets. The prepared tablets were subjected to various physical parameter tests including weight variation, friability, hardness, thickness, diameter, etc. In vitro dissolution studies of the formulations were done at pH 6.8 in phosphate buffer using USP apparatus 2 (paddle method) at 50 rpm. The percent releases of all the formulations (30) were 73.11%- 98.76% after 8 hours. The release pattern followed zero order kinetics and the release of the drug was hindered by the polymers used in the study. On the other hand, 100% drug was released within 1 hour from the immediate release tablet of glimepiride. The study reveals that the polymers used have the capacity to retard the release of the drug from the sustained release tablets and the more is the amount of the polymer in the formulation the less is the release of drug showing more retardation of drug release.Bangladesh Pharmaceutical Journal 18(2): 157-162, 2015

Comparative Analgesic and Mental Effects of Increasing Plasma Concentrations of Dexmedetomidine and Alfentanil in Humans

2004 ◽  
Vol 101 (3) ◽  
pp. 744-752 ◽  
Author(s):  
Martin S. Angst ◽  
Bhamini Ramaswamy ◽  
M Frances Davies ◽  
Mervyn Maze
Keyword(s):  
Plasma Concentration ◽  
Receptor Agonist ◽  
Plasma Concentrations ◽  
Analgesic Efficacy ◽  
Intrathecal Administration ◽  
Experimental Models ◽  
Sedation Score ◽  
Systemic Administration ◽  
Double Blind ◽  
Cognitive Speed

Background In animals, systemic and intrathecal administration of the alpha2 -adrenergic receptor agonist dexmedetomidine results in robust antinociceptive effects in models of heat pain. In humans, systemically administered dexmedetomidine is approved for sedating patients in the intensive care unit. However, whether systemic administration of dexmedetomidine in humans produces significant analgesia at doses causing sedation but not unconsciousness remains controversial. Methods This study in human volunteers used a placebo-controlled, double-blind, and randomized design to examine whether dexmedetomidine at doses causing mild to severe sedation produces analgesia in experimental models of heat and electrical pain. Results were compared to the effects of the mu-opioid receptor agonist alfentanil. A computer-controlled infusion provided four median step-up plasma concentrations of dexmedetomidine (0.09, 0.24, 0.54, and 1.23 ng/ml) and alfentanil (13.4, 33.8, 67.8, and 126.1 ng/ml). Results Sedative and cognitive effects of dexmedetomidine were dose-dependent, resulting in a median sedation score of 95 of 100 and slowing of cognitive speed (reaction time, trail-making test) by a factor of about two at the highest plasma concentration. Dexmedetomidine did not attenuate heat or electrical pain. Alfentanil caused severe sedation (median sedation score 88 of 100) and slowed cognitive speed by a factor of approximately 1.4 at the highest plasma concentration. Alfentanil attenuated heat and electrical pain dose dependently. Conclusion This study documents that systemic dexmedetomidine lacks analgesic efficacy for heat and electrical pain at doses causing mild to severe sedation. These results provide further evidence suggesting that systemic administration of dexmedetomidine lacks broad analgesic activity in models of acute pain at doses not rendering humans unconscious.

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