Propofol (INN, marketed as Diprivan by AstraZeneca) is a short-acting, intravenously administered sedative agent. It has several uses in anesthesia and sedation, including induction of general anesthesia in adults and children, maintenance of general anesthesia, sedation for intubated, mechanically ventilated adults in the intensive care unit (ICU), sedation in procedures such as colonoscopy and endoscopy, and dental surgery; it is also commonly used in veterinary medicine. Propofol is approved for use in more than 50 countries, and generic versions are available.
Propofol is unrelated to the barbiturates, and has largely replaced sodium thiopental (trade name Pentothal) for induction of anesthesia, as recovery after propofol anesthesia is more rapid and 'clear' as compared to thiopental. Propofol is not considered an analgesic, so opioids such as fentanyl are also typically given during surgery for pain control.
Originally developed by Imperial Chemical Industries as ICI 35868, initial clinical trials followed in 1977 in a form solubilised in cremophor EL. However, due to anaphylactic reactions, it was withdrawn from the market and subsequently reformulated as an emulsion of a soya oil/propofol mixture in water. This was re-launched in 1986 by ICI (now AstraZeneca) with the brand name Diprivan (shortened version of diisopropyl intravenous anesthetic). The current preparation is 1% propofol, 10% soybean oil and 1.2% purified egg phospholipid (emulsifier), with 2.25% of glycerol as a tonicity-adjusting agent, and sodium hydroxide to adjust the pH. Diprivan contains EDTA as an antimicrobial agent. Newer generic formulations contain sodium metabisulfite or benzyl alcohol. Propofol emulsion appears as a highly opaque-white fluid due to the scattering of light from the tiny (~150 nm) oil droplets that it contains. It resembles milk, and is jocularly called "milk of amnesia" by medical professionals.
A water-soluble prodrug form, fospropofol, has recently been developed and tested with positive results, being rapidly broken down once in the body by the enzyme alkaline phosphatase to form propofol. Marketed as Lusedra, this new formulation might well have superior properties for use in humans, such as being more readily injectable and perhaps without the pain at injection site that often occurs with the traditional form of the drug. The US Food and Drug Administration approved the product in 2008.
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