anesthetic

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As anesthetic (plural anesthetics ) or anesthetic is called a drug intended for the production of an anesthetic is used, thus producing a state of sensibility for the purpose of operating or diagnostic measure.

history

Since ancient times, doctors have tried to relieve pain. In addition to the administration of intoxicants to produce an anesthetic-like state, for example in Arabic medicine, the pinching off of limbs was used as a method of pain suppression. In the middle of the 17th century, the surgeon Marco Aurelio Severino (1580–1656) discovered cold anesthesia , but it was soon forgotten.

In 1499 the Spanish priest Thomas Ortiz mentioned the coca leaves as a food and beverage of the natives. Cocaine, the first medicine to eliminate local pain, is an alkaloid from a shrub native to South America . In 1880, the surgeon Vassili Konstantinovich Anrep (1852–1918) requested that cocaine be tested as a local anesthetic based on animal and self-tests. In 1883/84 Sigmund Freud also found it to have anesthetic effects on the skin and mucous membranes and recommended it as a remedy for depression , nausea and gastric catarrh. In 1884, Carl Koller suggested cocaine as an anesthetic for the eye. In 1885, the American surgeon William Stewart Halsted (1852–1922) discovered the injection of the drug solution near the nerve. In 1892, the German surgeon Carl Ludwig Schleich (1859-1922) developed infiltration anesthesia . By applying a half percent cocaine solution to the spinal canal , the surgeon August Bier (1861–1949) achieved complete anesthesia of the lower extremities in 1898 and thus established lumbar anesthesia . In search of an anesthetic with lower toxicity, the pharmacist Eduard Ritsert (1859–1946) discovered benzocaine in 1890 and in 1902 led to the production of the anesthetic, which was mainly used as a surface anesthetic. Georg Merling (1856–1939) saw methylpiperidine as the functional group in cocaine responsible for the local anesthetic effect, and in 1895 produced Eucain A. Eucaine A was less toxic than cocaine and heat-sterilizable, but irritative effects and hyperemia occurred after injection . In 1897, Carl Dietrich Harries (1866–1923) and Albrecht Schmidt (1864–1945) independently produced eucaine B, which was able to replace cocaine as a much less toxic compound. In contrast, the chemist Alfred Einhorn (1856–1917) made the nitrogen-free part of the cocaine molecule responsible for the anesthetic effect. In 1897 he got to the orthoform, which was used as a surface anesthetic for several years. In 1898 Richard Willstätter was able to clarify the structure of cocaine and confirm Einhorn's finding that the benzoic acid ester itself, like its substitution products, has an anesthetic effect. Of the compounds produced by Einhorn, novocaine turned out to be particularly suitable and was able to replace cocaine almost completely. In the following years the novocaine molecule was systematically modified. In 1931 tetracaine , a surface anesthetic , was introduced into therapy. Lidocaine in particular was characterized by greater hydrolytic stability, longer duration of action, faster onset of action and greater potency.

Systematics

Depending on whether the active ingredients act on the whole organism or only part of it (locally), two groups of anesthetics are distinguished. However, locally effective anesthetics usually have to be applied in such a way that the active ingredient cannot be distributed in the organism, since, for example, an (accidental) intravenous injection can lead to serious side effects.

Local anesthetic

If the drug reduces the sensation of pain in a localized manner, it is called a local anesthetic . They are used in the context of local anesthesia (or regional anesthesia ), i.e. a local elimination of pain in the area of ​​nerve endings or conduction pathways without impairing consciousness.

General anesthetic

A general anesthetic or narcotic is used to refer to agents that produce general anesthesia or, colloquially, anesthesia , i.e. cause pain and consciousness to be switched off in the central nervous system , from which the patient cannot be awakened. General anesthesia consists of sensory (blockade of pain perception ), mental (blockage of consciousness and memory ), motor (blockade of motor reaction) and reflex components (inhibition of vegetative reactions ). These are caused by different active ingredients to different degrees. Injection anesthetics , which are injected into a vein, are differentiated from inhalation anesthetics , which are administered with the breath, as subgroups according to the route of administration . In general, hypnotics such as propofol , etomidate and barbiturates (rarely GHB ), sedatives such as benzodiazepines , pain relievers ( analgesics ) such as opioids and ketamine, and sometimes, in a broader sense, muscle relaxants are counted among the injection anesthetics .

The term narcotics includes a similar group of substances, but as a legal term from the German Narcotics Act (BtMG) it is not congruent.

Working theories

Although the anesthetics used today can also be described according to the Meyer-Overton correlation , theories about the mechanisms of action of anesthetics that are based on them (influence on the lipid components of the central nervous system) can no longer be upheld. The idea of ​​a uniform mechanism ( unitarity principle ) of anesthetics is now viewed as outdated and has been replaced by the concept of multiple mechanisms of action and sites of action . Effects on a number of ( protein- based) receptors and ion channels ( opioid receptor , GABA A receptor , NMDA receptor , sodium and potassium channels ) and other modification of synaptic signal transmission in different areas of the central nervous system that are relevant for individual Anesthetics exist in varying degrees, but based on current knowledge, they are held responsible for the various dimensions of anesthesia. However, there is no comprehensive anesthesia theory that can be explained by the known mechanisms, so that an effect according to the Meyer-Overton hypothesis cannot ultimately be ruled out and is sometimes controversially discussed.

Web links

Commons : Anesthetics  - collection of images, videos and audio files
Wiktionary: anesthetic  - explanations of meanings, word origins, synonyms, translations
Wiktionary: Narcotic  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ A b Wolf-Dieter Müller-Jahncke , Christoph Friedrich , Ulrich Meyer: Medicinal history . 2., revised. and exp. Ed. Wiss. Verl.-Ges, Stuttgart 2005, ISBN 978-3-8047-2113-5 , pp. 147-151 .
  2. HA Adams, E. Kochs, C. Krier: Today's anesthesia methods - attempt at a system . In: Anästhesiol Intensivmed Emergency Med Schmerzther, 36, 2001, pp. 262–267. PMID 11413694
  3. ^ NP Franks: Molecular targets underlying general anesthesia . In: Br J Pharmacol . , 2006 Jan, 147 Suppl, 1, pp. S72-581. Review, PMID 16402123