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PubMed2001

Dexamethasone modulates hypotension induced by opioids in anaesthetised rats.

The effect of dexamethasone on hypotension induced by mu-, kappa- and delta-opioid receptor agonists was investigated in pentobarbital-anaesthetised rats. Morphine (nonselective opioid receptor agonist), DAGO (D-Ala2-N-methyl-[Phe4-Gly5-ol]enkephalin; mu-opioid receptor-selective agonist), U50-488H (trans(+/-)-3,4-dichloro-N-methyl-N-(2[1pyrrolidynyl]cyclohexyl)-benzeneacetamide; kappa-opioid receptor-selective agonist) and deltorphin II (delta-opioid receptor-selective agonist), given intravenously, 5 micromol/kg, induced hypotension in rats. This hypotension was characterised by a fall in mean arterial blood pressure in 1-2 min that recovered in 30 min for morphine and U50-488H and in 5 or 20 min for DAGO and deltorphin II, respectively. Dexamethasone per se at a dose of 7.5 micromol/kg, i.v. did not significantly modify the mean arterial blood pressure of animals. Dexamethasone administration 90 min, but not 30 or 60 min, before the opioid agonists injection, prevented the hypotension induced by morphine or U50-488H, but not that induced by DAGO or deltorphin II. Pretreatment with RU-38486 (mifepristone; 7.5 micromol/kg, i.v.), a glucocorticoid receptor antagonist, 15 min before the steroid, prevented dexamethasone inhibition of hypotension induced by morphine and U50-488H. Furthermore, pretreatment with cycloheximide, a protein synthesis inhibitor (3.5 micromol/kg, i.v.), was also able to abolish the effects of dexamethasone on morphine- and U50-488H-induced hypotension. Results of the present study indicate that dexamethasone inhibited kappa-opioid receptor-mediated hypotension in rats, indicating a further important functional interaction between corticosteroids and the opioid system at kappa receptors. The ability of cycloheximide and RU-38486 to block dexamethasone effects indicates that steroid interference with kappa-opioid receptor-mediated hypotension involves a protein synthesis-dependent mechanism via glucocorticoid receptors.

Animals↗
PubMed2003

Facilitation of ischemia-induced release of dopamine and neuronal damage by dexamethasone in the rat striatum.

Glucocorticoids have been reported to aggravate ischemia-induced neuronal damage in both humans and experimental animals. Because an excess release of neurotransmitters is closely related to the outcome of ischemic neuronal damage, we evaluated the effects of dexamethasone on monoaminergic release and histological outcome. Changes in the extracellular concentrations of monoamines and their metabolites in the striatum produced by occlusion of the middle cerebral artery for 20 min were measured using a microdialysis high-performance liquid chromatography procedure, and the effects of intracerebroventricular administration of dexamethasone (10 microg) were evaluated in halothane-anesthesized rats. The histological outcome was evaluated by light microscopy 7 days after ischemia. Additionally, the effects of lesioning of the substantia nigra were estimated. The extracellular concentrations of neither dopamine nor serotonin were affected by the administration of dexamethasone in the nonischemic state. The occlusion of the middle cerebral artery produced a marked increase in the extracellular concentration of dopamine in the striatum, the peak value being 240 times that before ischemia. The preischemic administration of dexamethasone enhanced the increase in dopamine level during ischemia, and the peak value in the dexamethasone group was 640% of that in the vehicle group. After 7 days, ischemic neuronal damage in the dexamethasone group was severe compared with that in the vehicle group. In rats receiving the substantia nigra lesion, the ischemic release of dopamine was abolished, and the aggravation of ischemic neuronal damage by dexamethasone was completely alleviated. Changes in the release of monoamines may be a contributing factor in the development of the ischemic neuronal damage induced by glucocorticoids.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Effect of dexamethasone on cyclophosphamide-induced cystitis in rats: lack of relation with bradykinin B1 receptor-mediated motor responses.

We investigated the role of bradykinin B receptors in inducing urinary bladder contraction and maintaining bladder compliance in anaesthetized rats following cyclophosphamide-induced bladder inflammation and the influence of dexamethasone treatment on these responses. In the group treated with cyclophosphamide the amplitude of the contraction induced by the selective bradykinin B1 receptor agonist des-Arg9-bradykinin was larger than that in controls and dexamethasone prevented the up-regulation of this response induced by inflammation. The specific binding of [3H]des-Arg10-kallidin to bladder membranes was only detected in cyclophosphamide-treated rats: this binding was prevented by dexamethasone pretreatment. The bladder contraction induced by des-Arg9-bradykinin in cyclophosphamide-treated rats was antagonized by the bradykinin B1 receptor antagonist des-Arg9-D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin (des-Arg10-Hoe 140). Cyclophosphamide treatment increased the bladder weight and dexamethasone reversed this effect. Bladder compliance was decreased in the bladder inflammation group and this effect was partially reversed by dexamethasone pretreatment. Neither des-Arg10-Hoe 140 nor the combined administration of des-Arg10Hoe 140 and the selective bradykinin B2 receptor antagonist D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin (Hoe 140) affected bladder compliance, thus excluding a role of kinins in the maintenance of bladder tone during inflammation. These results indicate that: (1) dexamethasone pretreatment ameliorates cyclophosphamide-induced bladder inflammation: (2) dexamethasone pretreatment prevents cyclophosphamide-induced up-regulation of bradykinin B receptors; (3) kinins do not contribute to the increased vesical tone during inflammation.

Animals↗
PubMed1994

The effect of dexamethasone administration on rat intestinal permeability: the role of bacterial adherence.

BACKGROUND/AIMS: Previous studies have shown that dexamethasone administration to rats results in diminution of biliary secretory immunoglobulin A concentration and alters intestinal barrier function to bacteria. The aims of this study were to examine and characterize the effect of dexamethasone on intestinal permeability and to determine the possible influence of bacterial adherence to the mucosa in this process. METHODS: Groups of adult Fisher rats were studied, and the effects of dexamethasone administration and bowel decontamination on bacterial adherence and intestinal permeability were determined in various bowel segments. RESULTS: Dexamethasone administration was associated with a significant increase in bacterial adherence to the mucosa, which was most pronounced in the cecum (4.33 +/- 0.2 colony forming units (cfu) (log10) per gram of mucosa for control vs. 6.23 +/- 0.2 for dexamethasone). This was accompanied by significant alterations in intestinal permeability as measured by a decrease in transepithelial electrical resistance (49.5 +/- 4.1 omega.cm2 for control vs. 25.4 +/- 2.5 omega.cm2 for dexamethasone). Dual sodium-mannitol flux analysis showed this defect to be predominantly paracellular. Antibiotic decontamination of the intestine completely abrogated the intestinal permeability defect observed in this model. CONCLUSIONS: Bacterial-mucosal cell interactions may be responsible for alterations in intestinal permeability after dexamethasone administration.

Animals↗
PubMed1998

The effects of prenatal intraamniotic surfactant or dexamethasone administration on lung development are comparable to changes induced by tracheal ligation in an animal model of congenital diaphragmatic hernia: studies of lung glycogen content, elastic fiber density, and collagen content.

BACKGROUND/PURPOSE: A new noninvasive therapeutic strategy, which consisted of prenatal intraamniotic administration of porcine surfactant or dexamethasone, was previously used to prevent the functional and structural immaturity of lungs associated with congenital diaphragmatic hernia (CDH), and its effects on lung development were comparable with the changes induced by tracheal ligation (TL). The purpose of this study is to verify if this novel therapeutic modality has any effect in the elevated concentration of lung glycogen and altered contents of lung elastic fiber and collagen promoted by CDH. METHODS: A pilot study was performed to investigate in the rabbit model if the infused drugs in the amniotic cavity were aspirated by the CDH and non-CDH fetuses, and if there was correspondence between lung immaturity and high glycogen concentration in lung tissue. Experimental groups consisted of 50 pregnant rabbits that underwent surgery on gestational day 24 or 25 to create left-sided diaphragmatic hernias in 56 fetuses, which were divided in groups according to the procedures: CDH (n = 12), CDH plus TL (n = 16), CDH plus intraamniotic administration of Curosurf (40 mg, n = 12), and CDH plus intraamniotic administration of dexamethasone (n = 16). On gestational day 30, the fetuses were delivered by cesarean section, and 28 normal unoperated fetuses served as controls. The lungs were weighed and submitted to biochemical determination of glycogen, morphometric evaluation of elastic fibers, and colorimetric analysis of collagen. RESULTS: In all CDH and non-CDH fetuses of the pilot study, the amniotic content was massively aspirated into the lungs and trachea. There was an increase in lung glycogen content of fetuses at 24 days' gestation in comparison with 20-day gestational age fetuses, followed by a decrease in the near full-term fetuses. In the fetuses of the experimental groups, CDH decreased the lung weight to body weight ratios of lungs ipsilateral to the hernia. These changes were reversed by TL but not by intraamniotic administration of surfactant or dexamethasone. Lung glycogen concentrations in the lungs of CDH fetuses were significantly higher than those in the control group. These changes were reversed by intraamniotic administration of surfactant but not by dexamethasone administration or TL. In the lungs ipsilateral to the hernia, surfactant administration promoted a significant decrease in glycogen content to levels lower than control lungs. CDH promoted a decrease in the linear density of elastic fibers in both lungs, ipsilateral and contralateral to the hernia. This alteration was partially corrected by TL and surfactant administration, although dexamethasone administration had no effect. The concentrations of collagen in both lungs were increased significantly by CDH, and these alterations could not be reversed by TL. In the lungs ipsilateral to the hernia, intraamniotic administration of surfactant or dexamethasone promoted a significant decrease in the lung concentration of collagen but not to control levels. CONCLUSIONS: The positive effects of intraamniotic surfactant or dexamethasone administration on lung maturity of fetuses with CDH were observed. This therapy may be a substitute for TL.

Animals↗
PubMed1990

Early postnatal dexamethasone therapy in premature infants with severe respiratory distress syndrome: a double-blind, controlled study.

To determine whether early (less than or equal to 12 hours) postnatal dexamethasone therapy would facilitate removal of the endotracheal tube and improve outcome in premature infants with severe respiratory distress syndrome, we conducted a double-blind, controlled study of 57 infants whose birth weights were less than 2000 gm. The placebo (n = 29) and treated (n = 28) groups were comparable in birth weight (mean +/- SD: 1273 +/- 323 vs 1318 +/- 359 gm), gestational age (30.1 +/- 2.1 vs 30.8 +/- 2.7 weeks), postnatal age (8.7 +/- 3.1 vs 8.5 +/- 3.1 hours), and pulmonary function at the start of the study. The dose of dexamethasone was 1.0 mg/kg/day for 3 days and then was progressively decreased for 12 days. Infants in the dexamethasone group had significantly higher pulmonary compliance, tidal volume, and minute ventilation, and required lower mean airway pressure for ventilation than infants in the placebo group. The endotracheal tube was successfully removed from more infants in the dexamethasone group (16/28 vs 8/29; p less than 0.025). Nineteen infants (65%) in the placebo group and 11 (39%) in the dexamethasone group (p less than 0.05) had lung injuries. Dexamethasone therapy was associated with a temporary increase in blood pressure and plasma glucose concentration and a delay in somatic growth. We conclude that early postnatal dexamethasone therapy improves pulmonary status, facilitates removal of the endotracheal tube, and minimizes lung injuries in premature infants with severe respiratory distress syndrome.

Clinical Trials as Topic↗
PubMed1995

Twenty-month outcome in ventilator-dependent, very low birth weight infants born during the early years of dexamethasone therapy.

We sought to examine the effect of the introduction of dexamethasone therapy on health, growth, and neurodevelopmental outcome in very low birth weight (VLBW) infants at 20 months of age. We compared outcomes in all 86 VLBW infants (mean birth weight 871 gm, mean gestational age 26.4 weeks) who were ventilator dependent on day 21 of life during the 2 years preceding October 1988 (period 1), when dexamethasone therapy became accepted clinical practice in our unit, with outcomes in all 124 infants (mean birth weight 891 gm, mean gestational age 26.9 weeks) with similar ventilator status during the subsequent 2 years (period 2). In addition, we compared outcomes in infants who received dexamethasone during period 2 with those in a concurrent cohort of less ill infants who were not given dexamethasone. There were no significant differences between periods 1 and 2 in mortality rates after 21 days (17% vs 21%), need for home oxygen (23% vs 25%), oxygen dependence at 20 months of corrected age (11% vs 10%), rate of neurosensory impairment (24% vs 25%), and mean Bayley Mental scores (81.5 vs 77.2) or Psychomotor Development Index (81.6 vs 71.1). Infants who received dexamethasone during period 2 had significantly more severe lung disease and poorer respiratory, growth, and developmental outcomes. We conclude that VLBW infants with ventilator-dependent chronic lung disease have very poor outcomes, even when treated with dexamethasone. More information is needed from prospective, randomized trials before dexamethasone can be accepted as routine therapy for chronic lung disease.

Child Development↗
PubMed1998

Qualitative assessment of general movements in high-risk preterm infants with chronic lung disease requiring dexamethasone therapy.

OBJECTIVE: The objective of this study was to determine in preterm infants at risk for severe chronic lung disease (1) the quality of general movements (GMs) and (2) the effect of dexamethasone treatment on spontaneous motor activity. STUDY DESIGN: In 15 very low birth weight infants the quality of GMs was assessed from repeated videotape recordings. Recordings were made at weekly intervals during the preterm period until term age and thereafter three times until the twentieth postterm week. All infants required dexamethasone therapy, and additional recordings were made a few hours before and 24 hours, 48 hours, and 7 days after dexamethasone was started. The relationship among movement quality, brain ultrasonographic abnormalities, and long-term outcome was explored. Acute effects of dexamethasone on motor activity were examined. RESULTS: After dexamethasone therapy was started, a significant transient reduction of the quantity of most spontaneous movements (p < 0.05) and a reduction of speed and amplitude of GMs was found (p < 0.05). A significant relationship was found between the severity of brain ultrasonographic abnormalities and the extent to which developmental trajectories of GMs were abnormal (p < 0.001). The development of cerebral palsy was related to the presence of cramped-synchronized movements near term (p < 0.02) and to the absence of fidgety movements at the age of 3 months after term (p < 0.05). CONCLUSION: In preterm infants with severe chronic lung disease and brain lesions, dexamethasone treatment leads to an acute reduction in motility and changes in the speed and amplitude of GMs. Until more is known about long-term neurologic sequelae, a cautious use of systemic dexamethasone therapy in preterm infants is recommended.

Chronic Disease↗
PubMed1997

Dexamethasone inhibition of acute opioid physical dependence in vitro is reverted by anti-lipocortin-1 and mimicked by anti-type II extracellular PLA2 antibodies.

Dexamethasone has been shown to inhibit opiate withdrawal, in an in vitro model. In this respect, we suggested that dexamethasone could reduce opiate withdrawal by blocking the release of prostaglandins' precursor, arachidonic acid through protein synthesis dependent-mechanisms (1). Since arachidonic acid is released by the enzyme phospholipase A2 (PLA2) in the present paper we evaluate whether dexamethasone effect may by related to inhibition of PLA2 activity. Therefore, the effect of a neutralizing anti-lipocortin-1 antibody and a polyclonal anti-type II extracellular phospholipase A2 antibody on the opiate withdrawal in vitro was considered. Following a 4 min in vitro exposure to morphine a strong contracture of guinea-pig isolated ileum was observed after the addition of naloxone. Dexamethasone at concentration of 5x10(-5) M reduces of 50% morphine withdrawal and the polyclonal anti-type II extracellular PLA2 antibody (in a dilution 1:1000) mimicked dexamethasone inhibitory effect. Incubation of the ileum preparation with a neutralizing anti-lipocortin-1 antibody (at a dilution of 1:10.000) 30 min before dexamethasone reverted the steroid effects. These results suggest that dexamethasone inhibition of opiate withdrawal is due to extracellular type II PLA2 inhibition through lipocortin-1.

Animals↗
PubMed2002

Dexamethasone for the prevention of nausea and vomiting after dilatation and curettage: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of dexamethasone administered intravenously at three different doses (4 mg, 8 mg, 16 mg) for the prevention of nausea and vomiting after dilatation and curettage. METHODS: In a prospective, randomized, double-masked, placebo-controlled trial, 120 women received placebo or dexamethasone intravenously at doses of 4 mg, 8 mg, or 16 mg immediately before induction of anesthesia (n = 30 in each group). Propofol-based general anesthetic was used. Emetic episodes and safety assessments were performed. To estimate a sufficient sample size, it was calculated that 30 patients per group would be required with alpha =.05 and beta =.2. RESULTS: The rate of patients who were emesis-free (no nausea, retching, or vomiting) 0-24 hours after anesthesia was 57% with dexamethasone 4 mg (P =.796), 87% with dexamethasone 8 mg (P =.005), and 87% with dexamethasone 16 mg (P =.005), compared with placebo (50%). Patients who had received dexamethasone 8 mg or 16 mg were more satisfied than those who had received placebo (P <.05). No clinically important adverse events were observed in any of the groups. CONCLUSION: Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0-24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy. Increasing the dose to 16 mg provided no additional benefit.

Adult↗
PubMed2003

The effects of dexamethasone, bupivacaine and topical lidocaine spray on pain after tonsillectomy.

OBJECTIVE: To compare the administration of bupivacaine hydrochloride, dexamethasone and lidocaine hydrochloride in decreasing post-tonsillectomy pain. METHODS: Eighty patients were enrolled in the study in ENT Clinic, Firat University, and in ENT Clinic Elaziğ SSK Hospital, Elaziğ (Turkey). Children between 6 and 14 years of age referred to our department for bilateral tonsillectomy for either recurrent tonsillitis or tonsillar hypertrophy. Data from 80 patients were analyzed. The first group had bupivacaine hydrochloride. The second group had dexamethasone infiltrated around each tonsil. The third group was given equal doses of 10% lidocain hydrochloride sprayed on the tonsillectomy fossa four times a day, and a placebo group received 9% NaCl applied to the tonsillar fossa four times a day. Pain scores, determined by visual analog scale, were obtained in the first, third and seventh postoperative days. RESULTS: Pain scores in the postoperative period were identical in the first, third and seventh postoperative days. According to VAS results the groups were compared on the basis of postoperative pain. In the first postoperative day, the difference between bupivacaine-placebo, dexamethasone-placebo and lidocaine-placebo groups was found to be statistically significant (P<0.05). Nevertheless the difference between bupivacaine-dexamethasone, bupivacaine-lidocaine and dexamethasone-lidocaine were not significant (P>0.05). In the third postoperative day, the difference between bupivacaine and lidocaine group found to be statistically significant (P<0.05). In the seventh post-operative day the results of bupivacaine, dexamethasone, lidocaine and placebo groups were similar (P>0.05). CONCLUSION: Bupivacaine, Dexamethasone and Lidocaine nasal aerosol decreased the pain significantly in the first postoperative day when it was compared with the placebo group. These three medicines can be used to reduce pain for children during the postoperative period applied tonsillectomy during the post-operative period. But lidocaine was more preferable, reducing pain in the third postop day better than bupivacaine.

Administration, Topical↗
PubMed2002

Differential modulation of insulin actions by dexamethasone: studies in primary cultures of adult rat hepatocytes.

BACKGROUND/AIMS: Steroid diabetes is associated with hepatic insulin resistance; in hepatic cell models, however, mainly insulin-permissive effects have been described. Here we investigate modulation by dexamethasone of a larger number of insulin actions. METHODS: Adult rat hepatocytes were cultured+/-dexamethasone for 48 h; insulin actions were studied subsequently. RESULTS: Stimulation of glycolysis by insulin but not by glucose required culture with dexamethasone. Activation of glycogen synthesis by insulin or glucose was strongly enhanced by dexamethasone, the insulin effects on glycogenolysis and amino acid uptake were not modulated. When dexamethasone was omitted from the culture, insulin was incapable to activate glycogen synthase, inactivate glycogen phosphorylase or elevate the level of fructose 2,6-bisphosphate. Dexamethasone did not alter insulin binding, insulin receptor number or kinase activity, insulin receptor substrate-1 and Akt protein expression/phosphorylation. Insulin-stimulated association of phosphatidylinositol 3-kinase with insulin receptor substrates-1 and -2 was increased with dexamethasone, the increased association with IRS-2 may, at least partially, be explained by higher IRS-2 protein expression. CONCLUSIONS: The steroid does not cause hepatic resistance in vitro. The differential attenuation under steroid deprivation points to defects in branches of the insulin signal chain and/or loss of hormonal regulation at the level of target enzymes.

Age Factors↗
PubMed1993

Modulation of parathyroid hormone-sensitive adenylate cyclase in ROS 17/2.8 cells by dexamethasone 1,25-dihydroxyvitamin D3 and protein kinase C.

We tested whether the protein kinase C (PKC) modulation of PTH-sensitive adenylate cyclase in ROS 17/2.8 cells is affected by the glucocorticoid dexamethasone and the vitamin D hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Basal and PTH- and forskolin-stimulated adenylate cyclase activities were determined in the presence or absence of 100 nM phorbol 12-myristate 13-acetate (PMA), the activator of PKC, in ROS 17/2.8 cells that had been previously cultured with or without dexamethasone or 1,25(OH)2D3. Dexamethasone treatment increased the basal, PMA-, PTH-, (PTH + PMA)- and (forskolin + PMA)-sensitive adenylate cyclase while 1,25(OH)2D3 decreased these effects. The stimulatory and inhibitory effects were dose-dependent with respect to dexamethasone and 1,25(OH)2D3, respectively. Dexamethasone increased, while 1,25(OH)2D3 decreased the maximal activity of both PTH-sensitive and PKC-modulated PTH-sensitive adenylate cyclase without affecting the half-maximal concentration (ED50) of PTH required for the activation of the enzyme. Additionally, dexamethasone, 1,25(OH)2D3 and PKC did not affect each other's ED50. Our results suggest that the effects of dexamethasone, 1,25(OH)2D3 and PKC on PTH-sensitive adenylate cyclase in ROS 17/2.8 cells are independent of each other.

Adenylyl Cyclases↗
PubMed1995

Nebulized dexamethasone versus oral prednisone in the emergency treatment of asthmatic children.

STUDY OBJECTIVE: To compare nebulized dexamethasone with oral prednisone in the treatment of children with asthma. DESIGN: A randomized, double-blind, double-placebo study. SETTING: An urban pediatric emergency department. PARTICIPANTS: Patients aged 1 to 17 years with acute asthma. INTERVENTIONS: Patients with moderate asthma exacerbation received frequent aerosolized albuterol and either 1.5 mg/kg of nebulized dexamethasone or 2 mg/kg of oral prednisone. RESULTS: A total of 111 children was evaluated; 21% of those treated with dexamethasone required hospitalization, compared with 31% of those treated with prednisone (P = .26). A significantly greater proportion of dexamethasone-treated children were discharged home within 2 hours (23% versus 7%, P = .02). In the dexamethasone group, 8% who received the drug by mouthpiece were hospitalized compared with 33% who received it by face mask (P = .06). Fewer children treated with dexamethasone vomited (0% versus 15%, P = .001) and fewer relapsed within 48 hours of ED discharge (0% versus 16%, P = .008). CONCLUSION: Nebulized dexamethasone was as effective as oral prednisone in the ED treatment of moderately ill children with acute asthma and was associated with more rapid clinical improvement, more reliable drug delivery, and fewer relapses.

Acute Disease↗
PubMed2003

Adrenal suppression and extubation rate after moderately early low-dose dexamethasone therapy in very preterm infants.

OBJECTIVE: A short course of moderately early dexamethasone therapy with a starting dose of 0.5 mg/kg/day improves lung compliance and shortens the duration of ventilatory support in preterm infants with respiratory distress syndrome (RDS). We conducted a double-blind, randomized study to evaluate whether a moderately early 14-day weaning course of low-dose dexamethasone affects adrenal function and facilitates weaning from the ventilator. PATIENTS AND METHODS: Thirty-six preterm infants with a gestational age < or =32 weeks who required ventilatory support for RDS on days 7-14 were randomized to a 14-day treatment course with dexamethasone (0.2 mg/kg/day start, tapering doses) or placebo (equivalent amounts of normal saline). Prior to the first study treatment and the day after completion of the treatment course, adrenal function was assessed from serum cortisol levels drawn before and 30 min after intravenous administration of 0.1 mg Cortrosyn. Extubation rate during treatment in both groups was compared. RESULTS: In both groups baseline serum cortisol levels decreased significantly during treatment, but stimulated cortisol levels did not change. After the 14-day treatment course, stimulated cortisol levels increased significantly from baseline levels in both groups (p<0.001), following Cortrosyn administration. More infants in the dexamethasone group were extubated within 7-14 days of study entry than in the placebo group (p<0.05). Hyperglycemia was more frequently diagnosed in the dexamethasone group and open-label dexamethasone treatment was given more frequently in the control group. CONCLUSIONS: A moderately early 14-day weaning course of low-dose dexamethasone does not significantly suppress the adrenal function of very preterm infants with RDS, but accelerates weaning from the ventilator.

Adrenal Glands↗
PubMed2002

Plasma concentrations of ACTH precursors correlate with pituitary size and resistance to dexamethasone in dogs with pituitary-dependent hyperadrenocorticism.

This study was performed to determine whether in dogs with pituitary-dependent hyperadrenocorticism (PDH) excessive release of adrenocorticotrophic hormone (ACTH) is accompanied by secretion of ACTH precursor molecules. In addition, we investigated whether the plasma ACTH precursor concentrations were correlated with the size of the pituitary gland and with the degree of resistance to negative glucocorticoid feedback. In 72 dogs with PDH, the plasma ACTH precursor concentration was determined by calculating the difference between the results of a radioimmunoassay (RIA) in which besides ACTH, ACTH precursors were also measured and a highly specific immunoradiometric assay (IRMA) using a polyclonal antibody against ACTH. The degree of resistance to glucocorticoid feedback was established by determining the effect of dexamethasone administration (0.1mg/kg) on the urinary corticoid/creatinine ratio. The pituitary height/brain area (P/B) ratio, determined by computed tomography, was used as a measure for the size of the pituitary gland. The plasma ACTH precursors concentration ranged from 18 to 2233ng/L (median 93ng/L). In 38 dogs, the pituitary was enlarged and plasma ACTH precursors concentrations in these dogs (median 130ng/L, range 24-2233ng/L) were significantly (P<0.05) higher than those in the dogs without pituitary enlargement (median 72ng/L, range 18-481ng/L). In concordance, P/B ratios correlated significantly with plasma ACTH precursor concentrations (r=0.35, P<0.01). In addition, the P/B ratios were significantly correlated with the degree of dexamethasone resistance (r=0.42, P<0.001). Plasma ACTH precursor concentrations in the dexamethasone-resistant dogs (median 210ng/L, range 24-628ng/L) were significantly higher (P<0.01) than those in the dexamethasone-sensitive dogs (median 72ng/L, range 18-2233ng/L). Similarly, the degree of dexamethasone resistance was also significantly correlated with the plasma ACTH precursor concentrations (r=0.33, P<0.01). Dogs with an elevated plasma alpha-MSH concentration (n=14) had significantly (P<0.001) higher plasma ACTH precursor concentrations (median 271ng/L, range 86-2233ng/L) than dogs with non-elevated alpha-MSH (median 73ng/L, range 18-481ng/L). In addition, the plasma concentrations of alpha-MSH correlated significantly with both plasma ACTH precursor concentrations (r=0.53, P<0.001) and P/B ratios (r=0.26, P<0.05). In conclusion, in all dogs with PDH the ACTH concentrations determined by the RIA were higher than the concentrations measured by IRMA indicating the presence of circulating ACTH precursors. High plasma ACTH precursor concentrations were especially found in dexamethasone-resistant dogs with large corticotroph adenomas, some of them probably of PI origin. In the association of large corticotroph adenoma, dexamethasone resistance and high plasma concentrations of ACTH precursors, the decreased sensitivity of the corticotroph cells to glucocorticoid feedback may play a pivotal role.

Adrenal Cortex↗
PubMed1997

A double-blind crossover study comparing prophylactic intravenous granisetron alone or in combination with dexamethasone as antiemetic treatment in controlling nausea and vomiting associated with chemotherapy.

The efficacies of granisetron plus dexamethasone and granisetron alone in controlling nausea and vomiting during two consecutive cycles of moderately emetogenic chemotherapy given for up to 5 days were compared in a two-centre, randomised, double-blind, placebo-controlled crossover study. In all, 110 evaluable patients received either dexamethasone, 20 mg i.v., or matching placebo, plus open-label granisetron, 3 mg i.v., given on each chemotherapy day. At cycle 2, patients crossed over to the alternative treatment; 72 patients completed the crossover. In these 72 patients, the complete response rates over 24 h for granisetron plus dexamethasone and granisetron plus placebo in cycle 1 were 87% and 70% (ns), respectively. In cycle 2 the complete response rates over 24 h were 73% and 62% (ns). Combining the two cycles, the complete response rates over 24 h were 80.6% (granisetron plus dexamethasone) and 65.3% (granisetron plus placebo; P = 0.015). Granisetron plus dexamethasone was significantly more effective in terms of times to less than complete response (P = 0.041), to first episode of moderate/severe nausea (P = 0.04), to first episode of vomiting (0.03) and to use of rescue medication (P = 0.02). Adverse events tended to be minor, with asthenia and insomnia the most common. Of those patients who expressed a preference, 67% preferred granisetron plus dexamethasone (P < 0.05). A single dose of dexamethasone added to granisetron thus enhances the efficacy of granisetron alone in preventing nausea and vomiting after moderately emetogenic chemotherapy.

Adolescent↗
PubMed2002

The role of alpha-adrenoceptors in the amnestic effect of intracerebroventricular dexamethasone.

Corticosteroids exert dual enhancing or impairing effects on cognitive functions. While their memory-enhancing effects have been well investigated, the mechanisms involved in their amnestic effects are not completely understood. Thus, we examined the role of alpha-adrenoceptors on dexamethasone-induced amnesia using step-through passive avoidance test in rat. Intracerebroventricular (i.c.v.) injection of dexamethasone (5 and 10 microg per rat) decreased the retention latencies. Likewise, intraperitoneal administration of alpha(2)-adrenoceptor agonist clonidine (0.1-0.3 mg kg(-1)) but not alpha(2)-adrenoceptor antagonist yohimbine (0.5-2 mg kg(-1)) decreased the retention latency. Yohimbine pre-treatment decreased the amnestic effects of dexamethasone or dexamethasone plus clonidine. On the other hand, intraperitoneal administration of alpha(1)-adrenoceptor agonist phenylephrine (0.5-2 mg kg(-1)) per se increased, while prazosin at 2 mg kg(-1) decreased the retention latency. Administration of phenylephrine before dexamethasone completely reversed the amnestic effect of the latter, while prozosin did not affect dexamethasone-induced amnesia. These data suggest that dexamethasone may induce its amnestic effect through activation of alpha(2)-adrenoceptors, leading to decreased alpha(1)-adrenergic activity.

Adrenergic alpha-Agonists↗