In general, three different agents/classes of agent are used—narcotics, benzodiazepines and propofol. In a recent survey of Australian anesthetists,45 propofol use was virtually universal for endoscopic sedation and a majority of respondents used both fentanyl and midazolam. Most of the anesthetists who were surveyed administered propofol sedation in private clinics and private hospitals, although there has been an increasing use of anesthetist-administered propofol in public hospitals. These findings were similar to those reported by Clarke et al.,46 also from Australia,

with each of these drugs being given by general practitioner sedationists in over 97% of cases. In Australia, fentanyl is the narcotic used most commonly,45,46 and there is also significant use of pethidine. A group from London has shown a shorter recovery period for patients undergoing endoscopy if fentanyl and midazolam are used compared with the use www.selleckchem.com/products/Trichostatin-A.html of pethidine and midazolam, and there was no difference in pain perception.47 Fentanyl is a synthetic opioid with a rapid onset and short duration of action. The half life is 2–7 h; this variation stems largely from differences in redistribution into adipose tissues and is independent of renal function. Fentanyl metabolites

are not active and true allergy to it is very rare. These properties make it suitable for use in procedures of short Metformin chemical structure duration. As with other opiates, it can lead to respiratory depression and hypotension. Hypovolemic patients and those

with reduced respiratory reserve are particularly at risk of developing these complications.48 In the elderly and frail and those with high ASA status, the dose of fentanyl should be reduced or opiate analgesia not used. Adult doses typically range from 25 µg to 100 µg (0.35–1.4 µg/kg). Naloxone, which Florfenicol competitively binds to µ-opioid receptors, is a reversal agent, the administration of which may be required to prevent or attenuate the above complications. Repeated administration may be necessary. Benzodiazepines are also used very frequently for endoscopy throughout the world. They have amnestic, sedative and anxiolytic properties in addition to their well-known anticonvulsant and muscle relaxant effects. These actions are thought to be mediated by attachment to gamma-amino butyric acid (GABA) receptors in the central nervous system. Its anxiolytic and muscle relaxant properties are not only mediated through GABA receptors but also through glycine receptors in the spinal cord.49,50 Respiratory depression, which is probably related to a direct effect on the respiratory centre in the brain stem, leading to hypoventilation is an important adverse effect. Cardiovascular compromise with diminished cardiac output and peripheral resistance leading to hypotension, usually does not occur unless administration occurs during deep sedation.