BACKGROUND There is evidence from animal studies suggesting the existence of a ceiling effect for buprenorphine-induced respiratory depression. To study whether an apparent ceiling effect exists for respiratory depression induced by buprenorphine, we compared the respiratory effects of buprenorphine and fentanyl in humans and rats. METHODS In healthy volunteers, the opioids were infused i.v. ...

This study investigated the effect of delta opioid receptor blockade by naltrindole on the development of physical dependence and tolerance to the antinociceptive and respiratory depressive effects of morphine in rats. Chronic morphine was delivered either by s.c. injection of increasing amounts of morphine over 5 days or by s.c. implantation of morphine pellets. Animals were cotreated with sal...

IN the past decade narcotic analgesics have been widely used to supplement thiopentone-nitrous oxide-oxygen anaesthesia. Pethidine (Neff, Mayer and Perales, 1947) and alphaprodine (Siker, Foldes, Pahk and Swerdlow, 1954) have been most frequently employed, but many other narcotics, e.g. levorphanol (Brotman, Cullen and Wilkins, 1950) and anileridine (Riffin et al., 1958) have also been used. In...

Effects of different neuroactive substances on morphine-induced respiratory depression were studied in medullary respiration-related structures using in vitro brainstem-spinal cord preparation from 1 to 4-day-old rats. Application of morphine (10 microM) reduced respiratory rhythm (fR) as measured by C4 ventral root activity. The depressant effects of morphine were reversed by acetylcholine (10...

Introduction Chlormethiazole is a sedative and hypnotic with marked anti-convulsant properties. It is widely used in the treatment of states characterized by convulsions and agitation, including delirium tremens. Although rarely causing side effects, the drug has been shown to depress the respiratory centre (Lechat, 1966) and toxic interactions with alcohol have been found in animals (Vapaatalo...

Opioids were available in clinical practice since before the birth of modern anaesthesia--Setürner isolated morphine in 1806. They have a record of safety which is reflected in their high therapeutic ratios, especially the synthetic opioids introduced recently (table III). The most serious immediate adverse effect, respiratory depression, is a predictable effect related closely to analgesia. It...

BACKGROUND Pre-operative administration of benzodiazepines can cause hypoventilation-a decrease in minute ventilation (MV)-commonly referred to as "respiratory compromise or respiratory depression." Respiratory depression can lead to hypercarbia and / or hypoxemia, and may heighten the risk of other respiratory complications. Current anesthesia practice often places patients at risk for respira...

Interactions of mu-opioid receptors with the benzodiazepine system were studied by examining the modulatory effects of flumazenil (a benzodiazepine antagonist) and alprazolam (a benzodiazepine agonist) on the respiratory effects of the opioid peptide dermorphin. Dermorphin, 1-30 nmol administered i.c.v., to conscious, unrestrained rats decreased ventilation rate (VR) and minute volume (MV) dose...

In 40 patients anaesthetized with thiopentone, 66% nitrous oxide and 1% halothane, the effects of a single i.v. dose of nalbuphine 4.5, 8, 15, 25 or 50 mg/70 kg or morphine 3, 5, 10 or 17.5 mg/70 kg on total ventilation and end-tidal carbon dioxide concentration have been measured. Depression of respiration occurred with both drugs and with all doses. The lower doses of nalbuphine produced more...

Acute exposure to high doses of toluene can generate respiratory depression. However, neurotoxic mechanism of its action in the brainstem is not completely clear. In this work, acute, but not subchronic, exposure of rats to toluene increased leu-enkephalin immunostaining in several myelencephalic nuclei implicated in cardiorespiratory control. Due to the physiological role of enkephalins in the...