 | This article needs more medical references for verification or relies too heavily on primary sources .(February 2022) |  |
A preanesthetic agent (or preanaesthetic agent) is a drug that is given before the administration of an anesthetic.
| This article needs more medical references for verification or relies too heavily on primary sources .(February 2022) | |
A preanesthetic agent (or preanaesthetic agent) is a drug that is given before the administration of an anesthetic.
Examples of preanesthetic agents are:
These drugs are used before the administration of an anesthetic to improve patient comfort, reduce possible side effects such as Postanesthetic shivering, relieve pain, and increase the effectiveness of the anesthetic.
General anaesthetics are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma that causes lack of awareness to painful stimuli, sufficient to facilitate surgical applications in clinical and veterinary practice. General anaesthetics do not act as analgesics and should also not be confused with sedatives. General anaesthetics are a structurally diverse group of compounds whose mechanisms encompasses multiple biological targets involved in the control of neuronal pathways. The precise workings are the subject of some debate and ongoing research.
Sodium thiopental, also known as Sodium Pentothal, thiopental, thiopentone, or Trapanal, is a rapid-onset short-acting barbiturate general anesthetic. It is the thiobarbiturate analog of pentobarbital, and an analog of thiobarbital. Sodium thiopental was a core medicine in the World Health Organization's List of Essential Medicines, but was supplanted by propofol. Despite this, thiopental is listed as an acceptable alternative to propofol, depending on local availability and cost of these agents. It was previously the first of three drugs administered during most lethal injections in the United States, but the US manufacturer Hospira stopped manufacturing the drug and the European Union banned the export of the drug for this purpose. Although thiopental abuse carries a dependency risk, its recreational use is rare.
Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical purposes. It may include some or all of analgesia, paralysis, amnesia, and unconsciousness. A person under the effects of anesthetic drugs is referred to as being anesthetized.
Halothane, sold under the brand name Fluothane among others, is a general anaesthetic. It can be used to induce or maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be particularly useful in those who are difficult to intubate. It is given by inhalation.
A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general anesthetic. When it is used on specific nerve pathways, paralysis also can be achieved.
Isoflurane, sold under the brand name Forane among others, is a general anesthetic. It can be used to start or maintain anesthesia, however other medications are often used to start anesthesia rather than isoflurane, due to airway irritation with isoflurane. Isoflurane is given via inhalation.
Propofol, marketed as Diprivan, among other names, is a short-acting medication that results in a decreased level of consciousness and a lack of memory for events. Its uses include the starting and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. It is also used for status epilepticus if other medications have not worked. It is given by injection into a vein, and the maximum effect takes about two minutes to occur and typically lasts five to ten minutes. Propofol is also used for medical assistance in dying in Canada.
An anesthetic or anaesthetic is a drug used to induce anesthesia — in other words, to result in a temporary loss of sensation or awareness. They may be divided into two broad classes: general anesthetics, which result in a reversible loss of consciousness, and local anesthetics, which cause a reversible loss of sensation for a limited region of the body without necessarily affecting consciousness.
An inhalational anesthetic is a chemical compound possessing general anesthetic properties that can be delivered via inhalation. They are administered through a face mask, laryngeal mask airway or tracheal tube connected to an anesthetic vaporiser and an anesthetic delivery system. Agents of significant contemporary clinical interest include volatile anesthetic agents such as isoflurane, sevoflurane and desflurane, as well as certain anesthetic gases such as nitrous oxide and xenon.
Xylazine is an analogue of clonidine and an agonist at the α2 class of adrenergic receptor. It is used for sedation, anesthesia, muscle relaxation, and analgesia in animals such as horses, cattle and other non-human mammals. Veterinarians also use xylazine as an emetic, especially in cats.
Pentobarbital is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment of insomnia but has been largely replaced by the benzodiazepine family of drugs.
Minimum alveolar concentration or MAC is the concentration of a vapour in the alveoli of the lungs that is needed to prevent movement in 50% of subjects in response to surgical (pain) stimulus. MAC is used to compare the strengths, or potency, of anaesthetic vapours. The concept of MAC was first introduced in 1965.
Iontocaine was an anesthetic medication, marketed under the two brand names Numby and Phoresor PM900 by IOMED inc. It is a local anesthetic with vasoconstrictor, administered via iontophoresis through the skin. It can numb up to 10 mm of skin in as little as 10 minutes. It is a 2% lidocaine, 0.01 mg/ml epinephrine solution. It was manufactured by IOMED, Inc.
Isoxsuprine is a drug used as a vasodilator in humans and equines. Isoxsuprine is a β2 adrenoreceptor agonist that causes direct relaxation of uterine and vascular smooth muscle via β2 receptors.
Alfaxalone, also known as alphaxalone or alphaxolone and sold under the brand name Alfaxan, is a neuroactive steroid and general anesthetic which is used currently in veterinary practice as an induction agent for anesthesia and as an injectable anesthetic. Though it is more expensive than other induction agents, it often preferred due to the lack of depressive effects on the cardiovascular system. The most common side effect seen in current veterinary practice is respiratory depression when Alfaxan is administered concurrently with other sedative and anesthetic drugs; when premedications aren't given, veterinary patients also become agitated and hypersensitive when waking up.
Medetomidine is a synthetic drug used as both a surgical anesthetic and analgesic. It is often used as the hydrochloride salt, medetomidine hydrochloride, a crystalline white solid. It is an α2 adrenergic agonist that can be administered as an intravenous drug solution with sterile water.
Dental anesthesia is the application of anesthesia to dentistry. It includes local anesthetics, sedation, and general anesthesia.
Embutramide is a potent opioid analgesic and sedative drug that is structurally related to methadone. It was developed by Hoechst A.G. in 1958 and was investigated as a general anesthetic agent, but was found to have a very narrow therapeutic window, with a 50 mg/kg dose producing effective sedation and a 75 mg/kg dose being fatal. Along with strong sedative effects, embutramide also produces respiratory depression and ventricular arrhythmia. Because of these properties, it was never adopted for medical use as an anesthetic as it was considered too dangerous for this purpose. Instead it is used for euthanasia in veterinary medicine, mainly for the euthanization of dogs.
ORG-25435 is a synthetic drug developed by Organon International, which acts as a GABAA receptor positive allosteric modulator, and produces sedative effects. It has been researched for use as an intravenous anesthetic agent, with positive results in initial trials, although negative side effects like hypotension and tachycardia, as well as unpredictable pharmacokinetics at higher doses, have meant it has ultimately not been adopted for medical use.
The effects of early-life exposures to anesthesia on the brain in humans are controversial. Evidence from nonhuman primate research suggests significant developmental neurotoxicity and long-term social impairment, with a dose–response relationship where repeated exposures cause a more severe impact than single ones. Research in humans has not found conclusive clinical evidence of cognitive impairment; however, systematic reviews imply the possibility of greater behavioural impairments in children exposed to anesthesia before the age of three than control subjects.