An anesthetic (

American English American English, sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. English is the Languages of the United States, most widely spoken lang ...

) or anaesthetic (

British English British English is the set of Variety (linguistics), varieties of the English language native to the United Kingdom, especially Great Britain. More narrowly, it can refer specifically to the English language in England, or, more broadly, to ...

; see spelling differences) is a

drug A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via insufflation (medicine), inhalation, drug i ...

used to induce

anesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

⁠— ⁠in other words, to result in a temporary loss of

sensation Sensation (psychology) refers to the processing of the senses by the sensory system. Sensation or sensations may also refer to: In arts and entertainment In literature *Sensation (fiction), a fiction writing mode *Sensation novel, a British ...

awareness In philosophy and psychology, awareness is the perception or knowledge of something. The concept is often synonymous with consciousness. However, one can be aware of something without being explicitly conscious of it, such as in the case of bli ...

. They may be divided into two broad classes:

general anesthetic General anaesthetics (or anesthetics) 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 aware ...

s, which result in a reversible loss of

consciousness Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...

, and

local anesthetic A local anesthetic (LA) is a medication that causes absence of all sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sensati ...

s, which cause a reversible loss of sensation for a limited region of the body without necessarily affecting consciousness. A wide variety of drugs are used in modern anesthetic practice. Many are rarely used outside

anesthesiology Anesthesiology, anaesthesiology or anaesthesia is the medical specialty concerned with the total perioperative medicine, perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critica ...

, but others are used commonly in various fields of healthcare. Combinations of anesthetics are sometimes used for their

synergistic Synergy is an interaction or cooperation giving rise to a whole that is greater than the simple sum of its parts (i.e., a non-linear addition of force, energy, or effect). The term ''synergy'' comes from the Attic Greek word συνεργία ' f ...

and

additive Additive may refer to: Mathematics * Additive function, a function in number theory * Additive map, a function that preserves the addition operation * Additive set-function see Sigma additivity * Additive category, a preadditive category with fin ...

therapeutic effects. Adverse effects, however, may also be increased. Anesthetics are distinct from

analgesics An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...

, which block only sensation of

pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

ful stimuli. Analgesics are typically used in conjunction with anesthetics to control pre-, intra-, and postoperative pain.

Local anesthetics

Ester-based

Benzocaine Benzocaine, sold under the brand name Orajel amongst others, is a local anesthetic, belonging to the amino ester drug class, commonly used as a topical painkiller or in cough drops. It is the active ingredient in many over-the-counter ...

Cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

(rarely used medically) *

Procaine Procaine is a local anesthetic drug of the amino ester group. It is most commonly used in dental procedures to numb the area around a tooth and is also used to reduce the pain of intramuscular injection of penicillin. Owing to the ubiquity of ...

Tetracaine Tetracaine, also known as amethocaine, is an ester local anesthetic used to numb the eyes, nose, or throat. It may also be applied to the skin before starting intravenous therapy to decrease pain from the procedure. Typically it is applied as a l ...

(sometimes called

Amethocaine Tetracaine, also known as amethocaine, is an ester local anesthetic used to numb the eyes, nose, or throat. It may also be applied to the skin before starting intravenous therapy to decrease pain from the procedure. Typically it is applied as a l ...

)

Amide-Based

Bupivacaine Bupivacaine, marketed under the brand name Marcaine among others, is a medication used to decrease sensation in a specific small area. In nerve blocks, it is injected around a nerve that supplies the area, or into the spinal canal's epidural ...

Cinchocaine Cinchocaine ( INN/ BAN) or dibucaine ( USAN) is an amide local anesthetic. Among the most potent and toxic of the long-acting local anesthetics, current use of cinchocaine is generally restricted to spinal and topical anesthesia. It is sold under ...

(

INN Inns are generally establishments or buildings where travelers can seek lodging, and usually, food and drink. Inns are typically located in the country or along a highway. Before the advent of motorized transportation, they also provided accomm ...

/ BAN)/

Dibucaine Cinchocaine (INN/ BAN) or dibucaine ( USAN) is an amide local anesthetic. Among the most potent and toxic of the long-acting local anesthetics, current use of cinchocaine is generally restricted to spinal and topical anesthesia. It is sold under t ...

(

USAN 280px, "Samguk Sagi" Book 04. Silla's Records. In 512, Usan-guk（于山國）was Ulleungdo（鬱陵島） Usan-guk, or the State of Usan, occupied Ulleung-do and the adjacent islands during the Korean Three Kingdoms period. According to t ...

) *

Etidocaine Etidocaine, marketed under the trade name Duranest, is an amide-type local anesthetic given by Injection (medicine), injection during surgery, surgical procedures and childbirth, labor and delivery. Etidocaine has a long duration of activity, and ...

Levobupivacaine Levobupivacaine (International nonproprietary name, rINN) is a Local anesthetic, local anaesthetic drug indicated for minor and major General anaesthesia, surgical anaesthesia and pain management. It is a long-acting amide-type local anaesthetic ...

Lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...

Mepivacaine Mepivacaine is a local anesthetic of the amide type. Mepivacaine has a reasonably rapid onset (less rapid than that of procaine) and medium duration of action (longer than that of procaine) and is marketed under various trade names including Ca ...

Prilocaine Prilocaine () is a local anesthetic of the amino amide type first prepared by Claes Tegner and Nils Löfgren. In its injectable form (trade name Citanest), it is often used in dentistry. It is also often combined with lidocaine as a topical ...

Ropivacaine Ropivacaine (International Nonproprietary Name, rINN) is a local anaesthetic drug belonging to the amino amide group. The name ropivacaine refers to both the racemate and the marketed ''S''-enantiomer. Ropivacaine hydrochloride is commonly mark ...

Local anesthetic agents prevent the transmission of nerve impulses without causing unconsciousness. They act by reversibly binding to fast

sodium channels Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels. Classification They are classified into 2 types: Function In e ...

from within

nerve fiber An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pot ...

s, thereby preventing sodium from entering the fibres, stabilising the cell membrane and preventing

action potential An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

propagation. Each of the local anesthetics has the suffix "–caine" in their names. Local anesthetics can be either

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

- or

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

-based. Ester local anesthetics are generally unstable in solution and fast-acting, are rapidly metabolised by

cholinesterases The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters: : an acylcholine + H2O = choline + a carboxylate Several of these serve as neurotransmitter ...

in the

blood plasma Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up ...

and

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, and more commonly induce

allergic reactions Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...

. Amide local anesthetics are generally heat-stable, with a long shelf life (around two years). Amides have a slower onset and longer half-life than ester anesthetics, and are usually

racemic In chemistry, a racemic mixture or racemate () is a mixture that has equal amounts (50:50) of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as r ...

mixtures, with the exception of levobupivacaine (which is S(-) -bupivacaine) and ropivacaine (S(-)-ropivacaine). Although general rules exist for onset and duration of anesthesia between

- or

-based local anesthetics, these are properties are ultimately dependent on myriad factors including the lipid solubility of the agent, the concentration of the solution, and the p''K''_a. Amides are generally used within regional and epidural or spinal techniques, due to their longer duration of action, which provides adequate analgesia for surgery, labor, and symptomatic relief. Some esters, such as

benzocaine Benzocaine, sold under the brand name Orajel amongst others, is a local anesthetic, belonging to the amino ester drug class, commonly used as a topical painkiller or in cough drops. It is the active ingredient in many over-the-counter ...

and

tetracaine Tetracaine, also known as amethocaine, is an ester local anesthetic used to numb the eyes, nose, or throat. It may also be applied to the skin before starting intravenous therapy to decrease pain from the procedure. Typically it is applied as a l ...

, are found in topical formulations to be absorbed through the skin. Only

preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or ...

-free local anesthetic agents may be injected

intrathecal Intrathecal administration is a route of administration for drugs via an injection into the spinal canal, or into the subarachnoid space (sin. ''intrathecal space'') so that it reaches the cerebrospinal fluid (CSF). It is useful in several applic ...

ly.

Pethidine Pethidine, also known as meperidine and sold under the brand name Demerol among others, is a fully synthetic opioid pain medication of the phenylpiperidine class. Synthesized in 1938 as a potential anticholinergic agent by the German chemist Ot ...

also has local anesthetic properties, in addition to its opioid effects.

General anesthetics

Inhaled agents

Desflurane Desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether) is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane, and isoflurane, it is a racemic mixture of (''R'') and (''S'') optic ...

(common) *

Enflurane Enflurane (2-chloro-1,1,2-trifluoroethyl difluoromethyl ether) is a halogenated ether. Developed by Ross Terrell in 1963, it was first used clinically in 1966. It was increasingly used for inhalational anesthesia during the 1970s and 1980s but ...

(largely discontinued) *

Halothane 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 ...

(inexpensive, discontinued) *

Isoflurane Isoflurane, sold under the brand name Forane among others, is a halogenated ether used as a general anesthetic. It can be used to start or maintain anesthesia; however, other medications are often used to start anesthesia, due to airway irritat ...

(common) *

Methoxyflurane Methoxyflurane, sold under the brand name Penthrox among others, is an inhaled medication primarily used to reduce pain following trauma. It may also be used for short episodes of pain as a result of medical procedures. Onset of pain relief i ...

Nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or factitious air, among others, is a chemical compound, an Nitrogen oxide, oxide of nitrogen with the Chemical formula, formula . At room te ...

Sevoflurane Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflu ...

(common) *

Xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

(rarely used) Volatile agents are typically organic liquids that evaporate readily. They are given by inhalation for induction or maintenance of general anesthesia. Nitrous oxide and xenon are gases, so they are not considered volatile agents. The ideal volatile anesthetic should be non-flammable, non-explosive, and lipid-soluble. It should possess low blood gas solubility, have no end-organ (heart, liver, kidney) toxicity or side-effects, should not be metabolized, and should not irritate the respiratory pathways. No anaesthetic agent currently in use meets all these requirements, nor can any anaesthetic agent be considered completely ''safe''. There are inherent risks and drug interactions that are specific to each and every patient. The agents in widespread current use are

isoflurane Isoflurane, sold under the brand name Forane among others, is a halogenated ether used as a general anesthetic. It can be used to start or maintain anesthesia; however, other medications are often used to start anesthesia, due to airway irritat ...

desflurane Desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether) is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane, and isoflurane, it is a racemic mixture of (''R'') and (''S'') optic ...

sevoflurane Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflu ...

, and nitrous oxide. Nitrous oxide is a common

adjuvant In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Anal ...

gas, making it one of the most long-lived drugs still in current use. Because of its low potency, it cannot produce anesthesia on its own but is frequently combined with other agents. Halothane, an agent introduced in the 1950s, has been almost completely replaced in modern anesthesia practice by newer agents because of its shortcomings. Partly because of its side effects, enflurane never gained widespread popularity. In theory, any inhaled anesthetic agent can be used for induction of general anesthesia. However, most of the halogenated anesthetics are irritating to the airway, perhaps leading to coughing, laryngospasm and overall difficult inductions. If induction needs to be conducted with an inhaled anesthetic agent,

is often used due to a relatively low pungency, rapid increase in alveolar concentration, and a higher blood solubility than other agents. These properties allow for a less irritating and quicker induction as well as a rapid emergence from anesthesia compared to other inhaled agents. All of the volatile agents can be used alone or in combination with other medications to maintain anesthesia (nitrous oxide is not potent enough to be used as a sole agent). Volatile agents are frequently compared in terms of potency, which is inversely proportional to the

minimum alveolar concentration Minimum alveolar concentration or MAC is the concentration, often expressed as a percentage by volume, of a vapour in the alveoli of the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) sti ...

. Potency is directly related to lipid solubility. This is known as the

Meyer-Overton hypothesis Minimum alveolar concentration or MAC is the concentration, often expressed as a percentage by volume, of a vapour in the alveoli of the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) sti ...

. However, certain pharmacokinetic properties of volatile agents have become another point of comparison. Most important of those properties is known as the blood/gas partition coefficient. This concept refers to the relative solubility of a given agent in blood. Those agents with a lower blood solubility (i.e., a lower blood–gas partition coefficient; e.g., desflurane) give the anesthesia provider greater rapidity in titrating the depth of anesthesia, and permit a more rapid emergence from the anesthetic state upon discontinuing their administration. In fact, newer volatile agents (e.g., sevoflurane, desflurane) have been popular not due to their potency (minimum alveolar concentration), but due to their versatility for a faster emergence from anesthesia, thanks to their lower blood–gas partition coefficient.

Intravenous agents (non-opioid)

While there are many drugs that can be used intravenously to produce anesthesia or sedation, the most common are: *

Barbiturate Barbiturates are a class of depressant, depressant drugs that are chemically derived from barbituric acid. They are effective when used medication, medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological a ...

s **

Amobarbital Amobarbital (formerly known as amylobarbitone or sodium amytal as the soluble sodium salt) is a drug that is a barbiturate derivative. It has sedative-hypnotic properties. It is a white crystalline powder with no odor and a slightly bitter taste. ...

(

trade name A trade name, trading name, or business name is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is fictitious business name. Registering the fictitious name with ...

: Amytal) **

Methohexital Methohexital or methohexitone (marketed under the brand names Brevital and Brietal) is a drug which is a barbiturate derivative. It is classified as short-acting, and has a rapid onset of action. It is similar in its effects to sodium thiopental ...

(trade name: Brevital) **

Thiamylal Thiamylal (Surital) is a barbiturate derivative invented in the 1950s. It has sedative, anticonvulsant, and hypnotic effects, and is used as a strong but short acting sedative. Thiamylal is still in current use, primarily for induction in surgica ...

(trade name: Surital) **

Thiopental Sodium thiopental, also known as Sodium Pentothal (a trademark of Abbott Laboratories), thiopental, thiopentone, or Trapanal (also a trademark), is a rapid-onset short-acting barbiturate general anesthetic. It is the thiobarbiturate analog ...

(trade name: Penthothal, referred to as ''thiopentone'' in the UK) *

Benzodiazepines Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat co ...

Diazepam Diazepam, sold under the brand name Valium among others, is a medicine of the benzodiazepine family that acts as an anxiolytic. It is used to treat a range of conditions, including anxiety disorder, anxiety, seizures, alcohol withdrawal syndr ...

Lorazepam Lorazepam, sold under the brand name Ativan, Tavor among others, is a benzodiazepine medication. It is used to treat anxiety (including anxiety disorders), insomnia, severe agitation, active seizures including status epilepticus, alcoh ...

Midazolam Midazolam, sold under the brand name Versed among others, is a benzodiazepine medication used for anesthesia, premedication before surgical anesthesia, and procedural sedation, and to treat psychomotor agitation, severe agitation. It induces ...

Etomidate Etomidate (United States Adopted Name, USAN, International Nonproprietary Name, INN, British Approved Name, BAN; marketed as Amidate) is a short-acting intravenous anaesthetic agent used for the induction of general anaesthesia and sedation for ...

Ketamine Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its S- (esketamine) a ...

Propofol Propofol is the active component of an intravenous anesthetic formulation used for induction and maintenance of general anesthesia. It is chemically termed 2,6-diisopropylphenol. The formulation was approved under the brand name Diprivan. Nu ...

Among the barbiturates mentioned above,

thiopental Sodium thiopental, also known as Sodium Pentothal (a trademark of Abbott Laboratories), thiopental, thiopentone, or Trapanal (also a trademark), is a rapid-onset short-acting barbiturate general anesthetic. It is the thiobarbiturate analog ...

and

methohexital Methohexital or methohexitone (marketed under the brand names Brevital and Brietal) is a drug which is a barbiturate derivative. It is classified as short-acting, and has a rapid onset of action. It is similar in its effects to sodium thiopental ...

are ultra-short-acting and are used to induce and maintain anesthesia. However, though they produce unconsciousness, they provide no

analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals ...

(pain relief) and must be used with other agents. Benzodiazepines can be used for

sedation Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...

before or after surgery and can be used to induce and maintain general anesthesia. When benzodiazepines are used to induce general anesthesia, midazolam is preferred. Benzodiazepines are also used for sedation during procedures that do not require general anesthesia. Like barbiturates, benzodiazepines have no pain-relieving properties.

is one of the most commonly used intravenous drugs employed to induce and maintain general anesthesia. It can also be used for sedation during procedures or in the ICU. Like the other agents mentioned above, it renders patients unconscious without producing pain relief. Compared to other IV agents, etomidate causes minimal depression of the cardiopulmonary system. Additionally, etomidate results in a reduction in intracranial pressure and cerebral blood flow. Because of these favorable physiological effects, was a favored agent in the ICU. However, etomidate has since been shown to produce adrenocortical suppression, resulting in decreased use to avoid an increased mortality rate in severely ill patients. Ketamine is infrequently used in anesthesia because of the unpleasant experiences that sometimes occur on emergence from anesthesia, which include "vivid dreaming, extracorporeal experiences, and

illusions An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people. Illusions may ...

." When it is used, it is often paired with a benzodiazepine such as

midazolam Midazolam, sold under the brand name Versed among others, is a benzodiazepine medication used for anesthesia, premedication before surgical anesthesia, and procedural sedation, and to treat psychomotor agitation, severe agitation. It induces ...

for amnesia and sedation. However, like etomidate it is frequently used in emergency settings and with sick patients because it produces fewer adverse physiological effects. Unlike the intravenous anesthetic drugs previously mentioned, ketamine produces profound pain relief, even in doses lower than those that induce general anesthesia. Also unlike the other anesthetic agents in this section, patients who receive ketamine alone appear to be in a

cataleptic Catalepsy (from Ancient Greek , , "seizing, grasping") is a neurological condition characterized by muscular rigidity and fixity of posture regardless of external stimuli, as well as decreased sensitivity to pain. Signs and symptoms Sympt ...

state, unlike other states of anesthesia that resemble normal

sleep Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...

. Ketamine-anesthetized patients have profound analgesia but keep their eyes open and maintain many reflexes.

Intravenous opioid analgesic agents

While opioids can produce unconsciousness, they do so unreliably and with significant side effects. So, while they are rarely used to induce anesthesia, they are frequently used along with other agents such as intravenous non-opioid anesthetics or inhalational anesthetics. Furthermore, they are used to relieve pain of patients before, during, or after surgery. The following opioids have short onset and duration of action and are frequently used during general anesthesia: *

Alfentanil Alfentanil, sold under the brand name Alfenta among others, is a potent, short-acting synthetic opioid analgesic drug used for anesthesia in surgery. It is an analogue of fentanyl with around one-fourth to one-tenth the potency, one-third the dura ...

Fentanyl Fentanyl is a highly potent synthetic piperidine opioid primarily used as an analgesic (pain medication). It is 30 to 50 times more Potency (pharmacology), potent than heroin and 50 to 100 times more potent than morphine. Its primary Medici ...

Remifentanil Remifentanil, marketed under the brand name Ultiva is a potent, short-acting synthetic opioid analgesic drug. It is given to patients during surgery to relieve pain and as an adjunct to an anesthetic. Remifentanil is used for sedation as well a ...

* Sufentanil, which is not available in Australia. The following agents have longer onset and duration of action and are frequently used for post-operative pain relief: *

Buprenorphine Buprenorphine, sold under the brand name Subutex among others, is an opioid used to treat opioid use disorder, acute pain, and chronic pain. It can be used under the tongue (sublingual), in the cheek (buccal), by injection (intravenous a ...

Butorphanol Butorphanol is a morphinan-type synthetic agonist–antagonist opioid analgesic developed by Bristol-Myers. Butorphanol is most closely structurally related to levorphanol. Butorphanol is available as the tartrate salt in injectable, tablet, and ...

Diamorphine Heroin, also known as diacetylmorphine and diamorphine among other names, is a morphinan opioid substance synthesized from the Opium, dried latex of the Papaver somniferum, opium poppy; it is mainly used as a recreational drug for its eupho ...

, also known as heroin, not available for use as an analgesic in any country but the UK. *

Hydromorphone Hydromorphone, also known as dihydromorphinone, and sold under the brand name Dilaudid among others, is a morphinan opioid used to treat moderate to severe pain. Typically, long-term use is only recommended for pain due to cancer. It may b ...

Levorphanol Levorphanol (brand name Levo-Dromoran) is an opioid medication used to treat moderate to severe pain. It is the levorotatory enantiomer of the compound racemorphan. Its dextrorotatory counterpart is dextrorphan. It was first described in Ge ...

, also called meperidine in North America. *

Methadone Methadone, sold under the brand names Dolophine and Methadose among others, is a synthetic opioid used medically to treat chronic pain and opioid use disorder. Prescribed for daily use, the medicine relieves cravings and opioid withdrawal sym ...

Morphine Morphine, formerly also called morphia, is an opiate that is found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (''Papaver somniferum''). It is mainly used as an analgesic (pain medication). There are ...

Codeine Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically use ...

Nalbuphine Nalbuphine, sold under the brand names Nubain among others, is an opioid analgesic which is used in the treatment of pain. It is given by injection into a vein, muscle, or fat. Side effects of nalbuphine include sedation, sweatiness, clam ...

Oxycodone Oxycodone, sold under the brand name Roxicodone and OxyContin (which is the extended-release form) among others, is a semi-synthetic opioid used medically for the treatment of moderate to severe pain. It is highly addictive and is a commonly ...

, not available intravenously in U.S. *

Oxymorphone Oxymorphone (sold under the brand names Numorphan and Opana among others) is a highly potent opioid analgesic indicated for treatment of severe pain. Pain relief after injection begins after about 5–10 minutes; after oral administration it ...

Pentazocine Pentazocine, sold under the brand name Talwin among others, is an analgesic medication used to treat moderate to severe pain. It is believed to work by activating (agonizing) κ-opioid receptors (KOR) and μ-opioid receptors (MOR). As such it i ...

Muscle relaxants

Muscle relaxants do not render patients unconscious or relieve pain. Instead, they are sometimes used after a patient is rendered unconscious (induction of anesthesia) to facilitate

intubation Intubation (sometimes entubation) is a medical procedure involving the insertion of a tube into the body. Most commonly, intubation refers to tracheal intubation, a procedure during which an endotracheal tube is inserted into the trachea to supp ...

or surgery by paralyzing skeletal muscle.These agents fall into two categories: depolarizing agents, which depolarize the

motor end plate A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to ...

to prevent further stimulation, and non-depolarizing agents, which prevent acetylcholine receptor activation through competitive inhibition. * Depolarizing muscle relaxants **

Succinylcholine Suxamethonium chloride (brand names Scoline and Sucostrin, among others), also known as suxamethonium or succinylcholine, or simply sux in medical abbreviation, is a medication used to cause short-term paralysis as part of general anesthesia. T ...

(also known as suxamethonium in the UK, New Zealand, Australia and other countries, "Celokurin" or "celo" for short in Europe) **

Decamethonium Decamethonium (Syncurine) is a depolarizing muscle relaxant or neuromuscular blocking agent, and is used in anesthesia to induce paralytic, paralysis. Pharmacology Decamethonium, which has a short action time, is similar to acetylcholine and ...

* Non-depolarizing muscle relaxants ** Short acting ***

Mivacurium Mivacurium chloride (formerly recognized as BW1090U81, BW B1090U or BW1090U) is a short-duration non-depolarizing neuromuscular-blocking drug or skeletal muscle relaxant in the category of non-depolarizing neuromuscular-blocking drugs, used adjun ...

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Rapacuronium Rapacuronium bromide (brand name Raplon) is a rapidly acting, non-depolarizing aminosteroid neuromuscular blocker formerly used in modern anaesthesia, to aid and enable endotracheal intubation, which is often necessary to assist in the control ...

** Intermediate acting ***

Atracurium Atracurium besilate, also known as atracurium besylate, is a medication used in addition to other medications to provide skeletal muscle relaxation during surgery or mechanical ventilation. It can also be used to help with endotracheal intubat ...

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Cisatracurium Cisatracurium besilate (INN; cisatracurium besylate ( USAN); formerly recognized as 51W89; trade name Nimbex) is a bisbenzyltetrahydroisoquinolinium that has effect as a non-depolarizing neuromuscular-blocking drug, used adjunctively in anesthesi ...

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Rocuronium Rocuronium bromide (brand names Zemuron, Esmeron) is an aminosteroid non-depolarizing neuromuscular blocker or muscle relaxant used in modern anaesthesia to facilitate tracheal intubation by providing skeletal muscle relaxation for surgery o ...

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Vecuronium Vecuronium bromide, sold under the brand name Norcuron among others, is a medication used as part of general anesthesia to provide skeletal muscle relaxation during surgery or mechanical ventilation. It is also used to help with endotracheal ...

** Long acting *** Alcuronium *** Doxacurium ***

Gallamine Gallamine triethiodide (Flaxedil) is a non-depolarising muscle relaxant. It acts by combining with the cholinergic receptor sites in muscle and competitively blocking the transmitter action of acetylcholine. Gallamine is a non-depolarising typ ...

*** Metocurine ***

Pancuronium Pancuronium (trademarked as Pavulon) is an aminosteroid muscle relaxant with various medical uses. It is used in euthanasia and is used in some states as the second of three drugs administered during lethal injections in the United States. Mech ...

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Pipecuronium Pipecuronium (Arduan) is a bisquaternary aminosteroid muscle relaxant which blocks nicotinic acetylcholine receptors at the neuromuscular junction A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuro ...

***

Tubocurarine Tubocurarine (also known as ''d''-tubocurarine or DTC) is a toxic benzylisoquinoline alkaloid historically known for its use as an arrow poison. In the mid-1900s, it was used in conjunction with an anesthetic to provide skeletal muscle relaxat ...

A potential complication where neuromuscular blockade is employed is '

anesthesia awareness Awareness under anesthesia, also referred to as intraoperative awareness or accidental awareness during general anesthesia (AAGA), is a rare complication of general anesthesia where patients regain varying levels of consciousness during their sur ...

'. In this situation, patients paralyzed may awaken during their anesthesia, due to an inappropriate decrease in the level of drugs providing sedation or pain relief. If this is missed by the anesthesia provider, the patient may be aware of their surroundings, but be incapable of moving or communicating that fact. Neurological monitors are increasingly available that may help decrease the incidence of awareness. Most of these monitors use proprietary algorithms monitoring brain activity via evoked potentials. Additionally, anesthesia providers often have steps they follow to help prevent awareness, such as ensuring all equipment is working properly, monitoring that drugs are being delivered during surgery, and asking a series of questions (the Brice questions) to help detect awareness after surgery. If there is any suspicion of patient awareness, close follow-up and mental health professionals can help manage or avoid any traumatic stress associated with the awareness. Certain procedures, such as endoscopies or

colonoscopies Colonoscopy () or coloscopy () is a medical procedure involving the endoscopic examination of the large bowel (colon) and the distal portion of the small bowel. This examination is performed using either a CCD camera or a fiber optic camera, ...

, are managed a technique called

conscious sedation Procedural sedation and analgesia (PSA) is a technique in which a sedating/dissociative medication is given, usually along with an analgesic medication, in order to perform non-surgical procedures on a patient. The overall goal is to induce a decr ...

or monitored anesthesia care. These cases are performed with regional anesthetics and a "twilight sleep" achieved through sedation with propofol and analgesics, and patients may remember perioperative events. When this technique is used, patients should be advised that this is management is distinct from general anesthesia to help combat any belief or fear that they were "awake" during anesthesia.

Intravenous reversal agents

Flumazenil Flumazenil, also known as flumazepil, is a selective GABAA receptor, GABAA receptor antagonist administered via injection, otic insertion, or intranasally. Therapeutically, it acts as both an antagonist and antidote to benzodiazepines (partic ...

, reverses the effects of benzodiazepines *

Naloxone Naloxone, sold under the brand name Narcan among others, is an opioid antagonist, a medication used to reverse or reduce the effects of opioids. For example, it is used to restore breathing after an opioid overdose. Effects begin within two ...

, reverses the effects of opioids *

Neostigmine Neostigmine, sold under the brand name Bloxiverz, among others, is a medication used to treat myasthenia gravis, Ogilvie syndrome, and urinary retention without the presence of a blockage. It is also used in anaesthesia to end the effects of n ...

, helps to reverse the effects of non-depolarizing muscle relaxants *

Sugammadex Sugammadex, sold under the brand name Bridion, is a medication for the reversal of neuromuscular blockade induced by rocuronium and vecuronium in general anaesthesia. It is the first selective relaxant binding agent (SRBA). It is marketed by ...

, helps to reverse the effects of non-depolarizing muscle relaxants

References

External links

Anaesthetics
BBC Radio 4 discussion with David Wilkinson, Stephanie Snow & Anne Hardy (''In Our Time'', Mar. 29, 2007) {{Authority control