Prevention of ethanol-induced sympathetic overactivity and degeneration by dexmedetomidine

Gastroprotective properties of Lupeol-derived ester: Pre-clinical evidences of Lupeol-stearate as a potent antiulcer agent

Lupeol (1) was isolated from hexane branch extract of Maytenus salicifolia and the Lupeol stearate (2), Lupeol palmitate (3), Lupeol myristate (4), Lupeol laurate (5) and Lupeol caprylate (6) were obtained reacting 1 with an adequate carboxylic acid. Swiss mice were treated with vehicle, carbenoxolone or Lupeol esters before administration of ethanol/HCl or indomethacin. Additionally, the involvement of nitric oxide (NO), sulfhydryl compounds (NP-SH), α-2 adrenergic receptors (α2-AR) and prostaglandins (PGE) in antiulcer effects was investigated using appropriate inhibitors or antagonist. Oxidative and inflammatory parameters were measured after euthanasia and anti-secretory effects was evaluated in pylorus-ligated rats. Ethanol/HCl ulcerated the gastric mucosa by 64.45 ± 6.58 mm², which the oral treatment with 1, 4 and 6 (10 mg/kg), and 3 and 5 (30 mg/kg) reduced the lesion area. Interestingly, 2 reduced the gastric ulcer by oral route in a potent and dose-dependent manner (ED₅₀ = 0.40 mg/kg), which was accompanied by the increase in reduced glutathione levels and by the reduction of lipids peroxidation and myeloperoxidase and superoxide dismutase activities. Moreover, 2 (0.1 mg/kg) also prevented the ulcerogenesis by intraperitoneal route. The participation of NO, NP-SH, α2-AR and PGE in 2-mediated gastroprotection was confirmed. In indomethacin-induced ulcer, 2 (1 mg/kg, p.o) also reduced the ulcer area and increased the PGE₂ levels. However, 2 did not alter the gastric acid secretion. Therefore, these findings indicate that the obtention of 2 potentiated the antiulcer activity of 1 and that this compound can elicit gastroprotective action due a diversified mode of action.

Dexmedetomidine in the Treatment of Withdrawal Syndromes in Cardiothoracic Surgery Patients

Dexmedetomidine (Precedex, Abbott Laboratories, Abbott Park, IL) is an• 2adrenergic agonist that possesses a high ratio of specificity for the• 2versus the• 1receptor. It is currently approved for the provision of sedation during mechanical ventilation in adults. Given previous experience with clonidine for the treatment of substance withdrawal and the preliminary anecdotal experience with dexmedetomidine, it appears that dexmedetomidine may be a useful agent for treatment of substance withdrawal in the intensive care setting. The authors present their experience with the use of dexmedetomidine to control withdrawal behavior in 3 patients following cardiothoracic surgery. Previous reports regarding the use of dexmedetomidine to treat withdrawal and its potential application in this clinical arena are reviewed.

Evaluating the effects of dexmedetomidine compared to propofol as adjunctive therapy in patients with alcohol withdrawal

BACKGROUND

In severe alcohol withdrawal (AW), benzodiazepines may be inadequate to control symptoms. In many situations, benzodiazepine dosing escalates despite no additional efficacy and introduces potential toxicities. Severe cases of AW may require additional agents to control symptoms. Case reports and studies have shown benefits with dexmedetomidine and propofol in severe AW, but these agents have not been compared with one another. This study compares the effects of dexmedetomidine and propofol on benzodiazepine and haloperidol utilization in patients with AW.

METHODS

A retrospective chart review was completed on 41 patients with AW who received adjunctive dexmedetomidine or propofol. The primary objective was to compare benzodiazepine and haloperidol utilization before and after initiation of dexmedetomidine or propofol. Secondary measures included AW and sedation scoring, analgesic use, intensive care unit length of stay, rates of intubation, and adverse events.

RESULTS

Among the dexmedetomidine and propofol groups, significant reductions in benzodiazepine (P≤0.0001 and P=0.043, respectively) and haloperidol (P≤0.0001 and P=0.026, respectively) requirements were observed. These reductions were comparable between groups (P=0.933 and P=0.465, respectively). A trend toward decreased intensive care unit length of stay in the dexmedetomidine group (123.6 hours vs 156.5 hours; P=0.125) was seen. Rates of intubation (14.7% vs 100%) and time of intubation (19.9 hours vs 97.6 hours; P=0.002) were less in the dexmedetomidine group. Incidence of hypotension was 17.6% in the dexmedetomidine group vs 28.5% in the propofol group. Incidence of bradycardia was 17.6% in the dexmedetomidine group vs 0% in the propofol group. No differences were observed in other secondary outcomes.

CONCLUSION

In patients with severe AW who require sedation, both dexmedetomidine and propofol have unique and advantageous properties. Both agents appear to have equivalent efficacy in reducing AW-related symptoms and benzodiazepine and haloperidol requirements. These results should be validated in a larger, prospective trial.

Mechanisms involved in the gastroprotective activity of Celtis iguanaea (Jacq.) Sargent on gastric lesions in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Celtis iguanaea (Canabaceae) is popularly known as esporão-de-galo, stands out among the medicinal plants used for treatment of gastric ulcers. In Brazil, the leaves they are used traditionally in infusion forms as an analgesic, antiasthmatic, digestive and diuretic.

AIM OF THE STUDY

The present study was aimed to investigate the antiulcer mechanisms of hexane extract Celtis iguanaea leaves (HE) in several induced-gastric ulcer and characterize its chemical composition.

MATERIALS AND METHODS

The HE was obtained by exhaustive extraction in Soxhlet apparatus. The chemical characterization of HE was performed by Electrospray Fourier transform ion cyclotron mass spectrometry (ESI FT-ICR MS) analysis. Mice were used for the evaluation of the gastroprotective activity. HE was analyzed in the HCl/ethanol, hypothermic restraint stress ulcer and acetic acid. In the investigation of the gastroprotective mechanisms of HE, were performed the amount of adhered gastric mucus, participation of the α2-adrenoceptor, nitric oxide (NO) and prostaglandins (PGs) using the HCl/ethanol-induced gastric mucosa lesion model.

RESULTS

ESI FT-ICR MS analysis of HE suggest the presence of compounds as lipids, sterol lipids, steroids glycosides and polyphenol glycosides. The oral administration of HE at doses of 100 mg/kg or 200 mg/kg was able to protect the gastric mucosa against HCl/ethanol (10 mL/kg p.o.), and HE at dose of 100mg/kg protected against hypothermic-restraint stress and acetic -induced gastric lesions. The pretreatment with Yoimbine (2mg/kg, s.c.), an antagonist α2-adrenergic, L-NAME (20mg/kg, s.c.), an inhibitor of nitric oxide synthesis or indomethacin (10mg/kg, s.c.), an inhibitor of prostaglandin production, reversed the gastroprotective activity of HE (100mg/kg, p.o.).

CONCLUSIONS

Our results suggest that the Celtis iguanaea HE exhibits gastroprotective activity in different gastric ulcer models. The mechanism of gastroprotective effect of Celtis iguanaea HE suggests the participation of mucus as well as the involvement of α2-adrenergic receptors, NO and prostaglandins. The hydroxyl-linolenic acid, linoleic acids and conjugated oxo-linoleic acids are among the phytoconstituents that were identified in the Celtis iguanaea HE.

Dexmedetomidine for the treatment of alcohol withdrawal syndrome: rationale and current status of research

Dexmedetomidine is currently used in the US in the treatment of alcohol withdrawal syndrome (AWS) in the intensive care unit (ICU) setting, although data to support this practice are limited. Dexmedetomidine targets the noradrenergic system, an important but frequently overlooked secondary mechanism in the development of AWS, and, in doing so, may reduce the need for excessive benzodiazepine use which can increase the risk of γ-aminobutyric acid (GABA)-mediated deliriogenesis and respiratory depression. The purpose of this narrative review is to evaluate available literature reporting on the safety and efficacy of dexmedetomidine for AWS in the ICU setting. An English-language MEDLINE search (1966 to July 2013) was performed to identify articles evaluating the efficacy and safety of dexmedetomidine for AWS. Case series, case reports and controlled trials were evaluated for topic relevance and clinical applicability. Reference lists of articles retrieved through this search were reviewed to identify any relevant publications. Studies focusing on the safety and efficacy of dexmedetomidine for AWS in humans were selected. Studies were included if they were published as full articles; abstracts alone were not included in this review. Eight published case studies and case series were identified. Based on a limited body of evidence, dexmedetomidine shows promise as a potentially safe and possibly effective adjuvant treatment for AWS in the ICU. Prospective, well-controlled studies are needed to confirm the safety and efficacy of the use of dexmedetomidine in AWS.

Dexmedetomidine as adjunct treatment for severe alcohol withdrawal in the ICU

BACKGROUND

Patients undergoing alcohol withdrawal in the intensive care unit (ICU) often require escalating doses of benzodiazepines and not uncommonly require intubation and mechanical ventilation for airway protection. This may lead to complications and prolonged ICU stays. Experimental studies and single case reports suggest the α2-agonist dexmedetomidine is effective in managing the autonomic symptoms seen with alcohol withdrawal. We report a retrospective analysis of 20 ICU patients treated with dexmedetomidine for benzodiazepine-refractory alcohol withdrawal.

METHODS

Records from a 23-bed mixed medical-surgical ICU were abstracted from November 2008 to November 2010 for patients who received dexmedetomidine for alcohol withdrawal. The main analysis compared alcohol withdrawal severity scores and medication doses for 24 h before dexmedetomidine therapy with values during the first 24 h of dexmedetomidine therapy.

RESULTS

There was a 61.5% reduction in benzodiazepine dosing after initiation of dexmedetomidine (n = 17; p < 0.001) and a 21.1% reduction in alcohol withdrawal severity score (n = 11; p = .015). Patients experienced less tachycardia and systolic hypertension following dexmedetomidine initiation. One patient out of 20 required intubation. A serious adverse effect occurred in one patient, in whom dexmedetomidine was discontinued for two 9-second asystolic pauses noted on telemetry.

CONCLUSIONS

This observational study suggests that dexmedetomidine therapy for severe alcohol withdrawal is associated with substantially reduced benzodiazepine dosing, a decrease in alcohol withdrawal scoring and blunted hyperadrenergic cardiovascular response to ethanol abstinence. In this series, there was a low rate of mechanical ventilation associated with the above strategy. One of 20 patients suffered two 9-second asystolic pauses, which did not recur after dexmedetomidine discontinuation. Prospective trials are warranted to compare adjunct treatment with dexmedetomidine versus standard benzodiazepine therapy.

Dexmedetomidine: applications for the pediatric patient with congenital heart disease

This study aimed to provide a general description of the cardiovascular and hemodynamic effects of dexmedetomidine and an evidence-based review of the literature regarding its use in infants and children with congenital heart disease (CHD). A computerized bibliographic search of the literature on dexmedetomidine use in infants and children with CHD was performed. The cardiovascular effects of dexmedetomidine have been well studied in animal and adult human models. Adverse cardiovascular effects include occasional episodes of bradycardia, with rare reports of sinus pause or cardiac arrest. Both hypotension and hypertension also have been reported. The latter is related to peripheral α(2B) agonism leading to vasoconstriction. No adverse effects on the pulmonary vasculature have been noted even in patients with preexisting pulmonary hypertension. Although there are no direct effects on myocardial function, decreased cardiac output may result from changes in heart rate or increases in afterload. Although not currently Food and Drug Administration (FDA)-approved for the pediatric population, findings have shown dexmedetomidine to be effective in various clinical scenarios of patients with CHD including sedation during mechanical ventilation, prevention of procedure-related anxiety, prevention of emergence delirium and shivering after anesthesia, and treatment of withdrawal. Although dexmedetomidine may have limited utility for painful or invasive procedures, preliminary data suggest that the addition of ketamine to the regimen may offer benefits. When used during the perioperative period, additional benefits include blunting of the sympathetic stress response with a reduction of endogenous catecholamine release, a decrease in intraoperative anesthetic requirements, and a limitation of postoperative opioid requirements.

Role of α2-agonists in the treatment of acute alcohol withdrawal

OBJECTIVE

To evaluate literature reporting on the role of norepinephrine in alcohol withdrawal and to determine the safety and efficacy of α(2)-agonists in reducing symptoms of this severe condition.

DATA SOURCES

Articles evaluating the efficacy and safety of the α(2)-agonists clonidine and dexmedetomidine were identified from an English-language MEDLINE search (1966-December 2010). Key words included alcohol withdrawal, delirium tremens, clonidine, dexmedetomidine, α(2)-agonist, norepinephrine, and sympathetic overdrive.

STUDY SELECTION AND DATA EXTRACTION

Studies that focused on the safety and efficacy of clonidine and dexmedetomidine in both animals and humans were selected.

DATA SYNTHESIS

The noradrenergic system, specifically sympathetic overdrive during alcohol withdrawal, may play an important role in withdrawal symptom development. Symptoms of sympathetic overdrive include anxiety, agitation, elevated blood pressure, tachycardia, and tremor. Therefore, α(2)-agonists, which decrease norepinephine release, may have a role in reducing alcohol withdrawal symptoms. The majority of controlled animal and human studies evaluated clonidine, but the most recent literature is from case reports on dexmedetomidine. The literature reviewed here demonstrate that these 2 α(2)-agonists safely and effectively reduce symptoms of sympathetic overdrive and concomitant medication use. Dexmedetomidine may offer an advantage over current sedative medications used in the intensive care unit, such as not requiring intubation with its use, and therefore further study is needed to fully elicit its benefit in alcohol withdrawal.

CONCLUSION

Clonidine and dexmedetomidine may provide additional benefit in managing alcohol withdrawal by offering a different mechanism of action for targeting withdrawal symptoms. Based on literature reviewed here, the primary role for clonidine and dexmedetomidine is as adjunctive treatment to benzodiazepines, the standard of care in alcohol withdrawal.

Dexmedetomidine: applications in pediatric critical care and pediatric anesthesiology

OBJECTIVE

To provide a general descriptive account of the end-organ effects of dexmedetomidine and to provide an evidence-based review of the literature regarding its use in infants and children.

DATA SOURCE

A computerized bibliographic search of the literature regarding dexmedetomidine.

MAIN RESULTS

The end-organ effects of dexmedetomidine have been well studied in animal and adult human models. Adverse cardiovascular effects include occasional episodes of bradycardia with rare reports of sinus pause or cardiac arrest. Hypotension has also been reported as well as hypertension, the latter thought to be due to peripheral alpha2B agonism with peripheral vasoconstriction. Although dexmedetomidine has no direct effects on myocardial function, decreased cardiac output may result from changes in heart rate or increases in afterload. There are somewhat conflicting reports in the literature regarding its effects on ventilatory function, with some studies (both human and animal) suggesting a mild degree of respiratory depression, decreased minute ventilation, and decreased response to CO2 challenge whereas others demonstrate no effect. The central nervous system effects include sedation and analgesia with prevention of recall and memory at higher doses. Dexmedetomidine may also provide some neuroprotective activity during periods of ischemia. Applications in infants and children have included sedation during mechanical ventilation, prevention of emergence agitation following general anesthesia, provision of procedural sedation, and the prevention of withdrawal following the prolonged administration of opioids and benzodiazepines.

CONCLUSIONS

The literature contains reports of the use of dexmedetomidine in approximately 800 pediatric patients. Given its favorable sedative and anxiolytic properties combined with its limited effects on hemodynamic and respiratory function, there is growing interest in and reports of its use in the pediatric population in various clinical scenarios.

Dexmedetomidine alleviates ethanol withdrawal symptoms in the rat

The effect of dexmedetomidine, a selective alpha 2-adrenoceptor agonist, on ethanol withdrawal symptoms was studied in chronically ethanol-fed rats. After a 4-day ethanol intoxication period the rats were given s.c. injections of dexmedetomidine (3, 10, or 30 micrograms/kg) or saline (control group) at 10, 16, 22, and 39 h after the last dose of ethanol. The severity of ethanol withdrawal symptoms (rigidity, tremor, irritability, hypoactivity) was rated up to 58 h, blind to the treatments. The results showed that dexmedetomidine at doses 10 and 30 micrograms/kg significantly diminished the severity of the ethanol withdrawal reaction as measured by the sum score of the three most specific withdrawal signs (rigidity, tremor, and irritability). Dexmedetomidine at 10 micrograms/kg was the most effective dose, especially in the latter half of the withdrawal period (23-58 h after last dose of ethanol). The results suggest that dexmedetomidine in the treatment of ethanol withdrawal symptoms should be further studied.