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Escalating Doses (escalating + dose)
Selected AbstractsDecrease of D2 receptor binding but increase in D2 -stimulated G-protein activation, dopamine transporter binding and behavioural sensitization in brains of mice treated with a chronic escalating dose ,binge' cocaine administration paradigmEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2008A. Bailey Abstract Understanding the neurobiology of the transition from initial drug use to excessive drug use has been a challenge in drug addiction. We examined the effect of chronic ,binge' escalating dose cocaine administration, which mimics human compulsive drug use, on behavioural responses and the dopaminergic system of mice and compared it with a chronic steady dose (3 × 15 mg/kg/day) ,binge' cocaine administration paradigm. Male C57BL/6J mice were injected with saline or cocaine in an escalating dose paradigm for 14 days. Locomotor and stereotypy activity were measured and quantitative autoradiographic mapping of D1 and D2 receptors, dopamine transporters and D2 -stimulated [35S]GTP,S binding was performed in the brains of mice treated with this escalating and steady dose paradigm. An initial sensitization to the locomotor effects of cocaine followed by a dose-dependent increase in the duration of the locomotor effect of cocaine was observed in the escalating but not the steady dose paradigm. Sensitization to the stereotypy effect of cocaine and an increase in cocaine-induced stereotypy score was observed from 3 × 20 to 3 × 25 mg/kg/day cocaine. There was a significant decrease in D2 receptor density, but an increase in D2 -stimulated G-protein activity and dopamine transporter density in the striatum of cocaine-treated mice, which was not observed in our steady dose paradigm. Our results document that chronic ,binge' escalating dose cocaine treatment triggers profound behavioural and neurochemical changes in the dopaminergic system, which might underlie the transition from drug use to compulsive drug use associated with addiction, which is a process of escalation. [source] Effects of subanaesthetic and anaesthetic doses of sevoflurane on regional cerebral blood flow in healthy volunteers.ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2004A positron emission tomographic study Background:, We tested the hypothesis that escalating drug concentrations of sevoflurane are associated with a significant decline of cerebral blood flow in regions subserving conscious brain activity, including specifically the thalamus. Methods:, Nine healthy human volunteers received three escalating doses using 0.4%, 0.7% and 2.0% end-tidal sevoflurane inhalation. During baseline and each of the three levels of anaesthesia one PET scan was performed after injection of . Cardiovascular and respiratory parameters were monitored and electroencephalography and bispectral index (BIS) were registered. Results:, Sevoflurane decreased the BIS values dose-dependently. No significant change in global cerebral blood flow (CBF) was observed. Increased regional CBF (rCBF) in the anterior cingulate (17,21%) and decreased rCBF in the cerebellum (18,35%) were identified at all three levels of sedation compared to baseline. Comparison between adjacent levels sevoflurane initially (0 vs. 0.2 MAC) decreased rCBF significantly in the inferior temporal cortex and the lingual gyrus. At the next level (0.2 MAC vs. 0.4 MAC) rCBF was increased in the middle temporal cortex and in the lingual gyrus, and decreased in the thalamus. At the last level (0.4 MAC vs. 1 MAC) the rCBF was increased in the insula and decreased in the posterior cingulate, the lingual gyrus, precuneus and in the frontal cortex. Conclusion:, At sevoflurane concentrations at 0.7% and 2.0% a significant decrease in relative rCBF was detected in the thalamus. Interestingly, some of the most profound changes in rCBF were observed in structures related to pain processing (anterior cingulate and insula). [source] Pharmacokinetics of andolast after administration of single escalating doses by inhalation in mild asthmatic patientsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2001S. Persiani Abstract The pharmacokinetics of andolast, a new tetrazolyl-benzamido derivative with antiallergic, antiinflammatory, mucosal protective and antisecretive activities, have been investigated in patients suffering from mild asthma (FEV1,70% of predicted) in whom obstruction was reversible (FEV1 increase,15% of initial) after the administration of 0.2 mg of salbutamol by inhalation. Twelve out-patients (seven males and five females) were enrolled in the present study and were treated with a single dose of andolast of 2, 4 and 8 mg by inhalation using the MIAT Monohaler® device according to a randomised crossover design. Plasma samples were collected before drug administration and up to 540 min after dosing. Andolast plasma concentrations were determined using a validated LC-MS/MS method with a limit of quantitation of 0.2 ng ml,1. Pharmacokinetic analysis was carried out using standard non-compartmental methods. In addition, andolast safety and tolerability were evaluated by performing standard laboratory tests, by recording vital signs and ECGs and by monitoring the occurrence of adverse events throughout the study period. Andolast was absorbed after inhalation and was available to the systemic circulation. The mean peak plasma concentrations were 6.3, 10.9 and 30.5 ng ml,1 at the three doses, respectively, and occurred at 30, 52.5 and 30 min (median tmax). The mean AUCt values were 1852, 2889 and 7677 ng min ml,1. The apparent plasma clearance (CL/F) and volume of distribution (Vz/F) were, respectively, 1168 ml min,1 and 430 l at the dose of 2 mg, 1143 ml min,1 and 468 l at the dose of 4 mg, and 1141 ml min,1 and 486 l at the dose of 8 mg. The apparent elimination half-life averaged 4.5, 5.0 and 4.6 h at the three doses, respectively. Even though the small number of subjects participating in the present study reduced the power of the statistical test, there was no statistically significant evidence of non-proportionality for all the andolast pharmacokinetic parameters calculated at the three doses. Thus, the data obtained as a whole suggest that andolast pharmacokinetics are dose-independent in the dose range investigated. Finally, the safety and tolerabilty of the drug administered to mild asthmatic patients was good up to the maximum investigated dose of 8 mg. Copyright © 2001 John Wiley & Sons, Ltd. [source] Hypertonic saline nasal provocation and acoustic rhinometryCLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2002J. N. Baraniuk Summary Background Hypertonic saline (HTS) acts as an airway irritant in human nasal mucosa by stimulating nociceptive nerves and glandular secretion. HTS does not change vascular permeability. In asthma, HTS causes airflow obstruction. Objective To determine the effect of HTS on mucosal swelling using acoustic rhinometry (AcRh). Potential vasodilator effects were controlled by maximally constricting mucosal vessels with oxymetazoline (Oxy). Method Normal subjects had AcRh before and 30 min after either 0.05% Oxy or saline (0.9% NaCl) nasal treatments. Nasal provocations followed immediately with five step-wise incremental escalating doses of HTS administered at 6-min intervals. AcRh was performed 1, 3 and 5 min after each HTS administration, and then after blowing the nose at 5 min. The minimum cross-sectional area (Amin), volume of the anterior 6 cm of nasal cavity (V6) and incremental changes from pre-drug treatment baseline levels (,, mean ±,SEM) were calculated. Results Oxy increased Amin by 46% (, = 0.48 ± 0.07 cm2, P = 0.0001) and V6 by 53% (, = 9.9 ± 1.5 mL, P < 1 × 10,7) during the first 30 min. Saline (vehicle) treatment had no effect. The maximum HTS dose had no effect after 1 or 3 min. However, in the 4th and 5th minutes there were reductions in Amin (, = 0.07 ± 0.03 cm2, P = 0.035) and V6 (, = 1.57 ± 0.42 mL, P = 0.004) with an increase in the weight of secretions (, = 700 ± 100 mg, P < 0.05). Blowing the nose returned Amin and V6 towards baseline. Oxy had no effect on HTS-induced changes in Amin, V6, pain, rhinorrhea or weight of secretions. Conclusion HTS induced nociceptive nerve stimulation and mucus secretion, and reduced V6 and Amin. Oxy caused vasoconstriction but did not alter HTS-induced effects. HTS may stimulate neurogenic axon response-mediated glandular secretion that contributes to perceptions of nasal obstruction in normal subjects. [source] | ||||||||||