Anesthesia Drugs in Common Use
Numerous choices exist for every aspect of anesthetic care; the way in which they are sequenced depends partially on the personal preference of the person administering them.
• For 50 years, the most commonly used induction agents were rapidly acting, water-soluble barbiturates such as thiopental, methohexital, and thiamylal. These drugs are not commonly in use today.
• Propofol, a nonbarbiturate intravenous anesthetic, has displaced barbiturates in many anesthesia practices.
• The use of propofol is associated with less postoperative nausea and vomiting and a more rapid, clear-headed recovery.o In addition to being an excellent induction agent, propofol can be administered by slow intravenous infusion instead of vapor to maintain the anesthesia.o Among its disadvantages are the facts that it often causes pain on injection and that it is prepared in a lipid emulsion, which, if not handled using meticulous aseptic precautions, can be a medium for rapid bacterial growth.
• Anesthesia can also be induced by inhalation of a vapor. This is how all anesthetics were once given and is a common and useful technique in uncooperative children. It is reemerging as a choice in adults. Sevoflurane is most commonly used for this purpose.
Traditional opioid analgesics
• Morphine, meperidine, and hydromorphone are widely used in anesthesia as well as in emergency departments, surgical wards, and obstetric suites.
• In addition, anesthesia providers have at their disposal a range of synthetic opioids, which, in general, cause less fluctuation in blood pressure and are shorter acting. These include fentanyl, sufentanil, and remifentanil.
• Succinylcholine, a rapid-onset, short-acting depolarizing muscle relaxant, has traditionally been the drug of choice when rapid muscle relaxation is needed.
• For decades, anesthesia providers have used it extensively despite numerous predictable and unpredictable adverse effects associated with its use.o The search for a drug that replicates its onset and offset speed without its adverse effects is the holy grail of muscle relaxant research.
• Other relaxants have durations of action ranging from 15 minutes to more than 1 hour.
• Older drugs in this class, such as pancuronium or curare, were often associated with changes in heart rate or blood pressure. Newer muscle relaxants are devoid of these adverse properties.
• Muscle relaxants generally are excreted by the kidney, but some preparations are broken down by plasma enzymes and can be used safely in patients with partial or complete renal failure.
• These are highly potent chlorofluorocarbons, which are delivered with precision from vaporizers and directly into the patient's inhaled gas stream. They may be mixed with nitrous oxide, a much weaker but nonetheless useful anesthetic gas.
• The prototype of modern anesthetic vapors is halothane. It is no longer used in routine clinical practice. In the 1980s, it was displaced by isoflurane and enflurane, agents that were cleared from the lungs faster and thus were associated with more rapid anesthetic emergences.
• In the late 1990s, desflurane and sevoflurane came into use. These inhaled anesthetics are much more maneuverable than their predecessors and are associated with a more rapid emergence. Intense commercial interest is present in anesthesia drug research, and the continuous introduction of new and better drug products for many years to come seems inevitable.