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R Chapados

Publications and source records attributed to R Chapados.

7 recordsLinked to original sources

Evaluation of zolpidem, triazolam, and placebo as hypnotic drugs the night before surgery.

STUDY OBJECTIVE: To compare the hypnotic effects of a bedtime dose of zolpidem, triazolam, and placebo. DESIGN: "Double-blind, randomized, placebo- and active-controlled, parallel-group" trial. SETTING: Six Canadian hospitals. PATIENTS: 357 patients (aged 19 to 71 years) hospitalized the night before a surgical procedure. INTERVENTIONS: At bedtime, each patient received either zolpidem 10 mg, triazolam 0.25 mg, or placebo, and was allowed to sleep for a maximum of 8 hours. MEASUREMENTS: Outcome measures were subjective in nature and included a morning questionnaire, visual analog scales, and observation forms by study personnel. All continuous variables were analyzed by analysis of variance. All categorical data were compared using the Cochran-Mantel-Haenszel (CMH) test, and the percentage of patients asleep was compared using a CMH chi-square analysis. When significant overall treatment effects were observed, pairwise comparisons were undertaken. Compared with the placebo group, the following parameters were significantly (p < 0.001) different in the zolpidem and triazolam groups: sleep latency was shorter, total sleep time was longer, patients fell asleep more easily, and the number of patients awake 2 hours after drug administration was lower. There were no differences between any groups in next-morning somnolence or ability to concentrate. Both drugs were well tolerated, with adverse event incidence rates nearly identical to placebo. CONCLUSIONS: In patients suffering from transient insomnia, a single dose of zolpidem 10 mg was as effective as triazolam 0.25 mg, and both were more effective than placebo and were well tolerated.

Adult↗

Differences in cardioprotective efficacy of adrenergic receptor antagonists and Ca2+ channel antagonists in an animal model of dilated cardiomyopathy. Effects on gross morphology, global cardiac function, and twitch force.

Turkey poults fed furazolidone (Fz) in high concentrations (700 ppm) develop dilated cardiomyopathy (Fz-DCM). We tested whether five cardioactive agents were cardioprotective in this model of heart failure, ie, whether they prevented dilatation and wall thinning and improved contractile performance. We compared the effects of chronic administration of a beta 1-selective and a nonselective beta-receptor antagonist, an alpha-receptor antagonist, and two Ca2+ channel antagonists in the presence of Fz administration. The greatest cardioprotection was found with treatment with either propranolol or nifedipine. At the gross morphological level, the effect of propranolol (a nonselective beta-adrenergic antagonist) was greater than the effect of atenolol (a selective beta 1-adrenergic antagonist), and the effect of nifedipine was greater than that of verapamil (Ca2+ channel antagonists), with all agents more cardioprotective than phenoxybenzamine (an alpha 1-adrenergic > alpha 2-adrenergic antagonist). Differences in cardioprotective efficacy of each agent increased with increased concentration. These data indicate that the dose and choice of a specific type of Ca2+ channel antagonist or beta-receptor antagonist might be important in the treatment of dilated cardiomyopathy. All agents that were cardioprotective caused similar functional improvements at both the whole heart and isolated muscle levels. Compared with control animals, Fz-DCM animals showed a significant reduction in peak left ventricular (LV) developed pressure (92 +/- 17 versus 143 +/- 24 mm Hg, P < .05), +dP/dt (1151 +/- 219 versus 2454 +/- 549 mm Hg/s), and -dP/dt (1128 +/- 291 versus 1875 +/- 396 mm Hg/s), with a significant increase in LV end-diastolic volumes (2.8 +/- 0.7 versus 0.16 +/- 0.1 mL for control animals, P < .05). In contradistinction, LV + dP/dt and -dP/dt values for animals receiving Fz plus a cardioactive agent that demonstrated cardioprotection were not significantly different from control values. Peak LV developed pressures were also similar for Fz animals receiving an agent that demonstrated cardioprotection and control animals not receiving any pharmacologic agent. Isolated muscles from Fz-DCM animals as well as animals receiving Fz plus cardioprotective pharmacologic agents responded normally with regard to increasing extracellular Ca2+ concentrations. Peak twitch forces were greater for animals receiving cardioprotective agents plus Fz than control animals not receiving any pharmacologic agents or Fz alone. At higher stimulation rates, Fz-DCM muscles demonstrated a significantly reduced peak twitch force (4 +/- 0.5 versus 1.5 +/- 0.4 g/mm2 for control muscles versus Fz-DCM muscles, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗