Editing Local anesthetic (section)

== Types ==
[[File:LA syringe.JPG|thumbnail|right|This LA system is designed to prevent [[needlestick injury]]. A cartridge of LA fits into the disposable needle, which can be locked when not in use and can be separated from the handle.]]
Local anesthetic solutions for injection typically consist of:<ref>{{cite web|title=Allergic Reactions|url=https://www.clevelandclinicmeded.com/medicalpubs/pharmacy/JanFeb2001/allergicreaction.htm|publisher=Cleveland Clinic|access-date=11 April 2014}}</ref>
* The local anesthetic agent itself
* A vehicle, which is usually water-based or just sterile water
* [[Vasoconstrictor]] possibly (see below)
* [[Reducing agent]] (antioxidant), e.g. if epinephrine is used, then [[sodium metabisulfite]] is used as a reducing agent
* [[Preservative]], e.g. [[methylparaben]]
* [[Buffer solution|Buffer]]

[[Amino esters|Esters]] are prone to producing allergic reactions, which may necessitate the use of an [[amide]].  The names of each locally clinical anesthetic have the suffix "-caine".
Most ester LAs are metabolized by [[Butyrylcholinesterase|pseudocholinesterase]], while amide LAs are metabolized in the liver. This can be a factor in choosing an agent in patients with liver failure,<ref name="isbn0-07-136704-7">{{cite book | vauthors = Stern A |title=Pharmacology: PreTest self-assessment and review |url=https://archive.org/details/pharmacology00arno |url-access=registration |publisher=McGraw-Hill, Medical Pub. Division |location=New York |year=2002 |isbn=978-0-07-136704-2 }}</ref> although since cholinesterases are produced in the liver, physiologically (e.g. very young or very old individual) or pathologically (e.g. [[cirrhosis]]) impaired hepatic metabolism is also a consideration when using esters.

Sometimes, LAs are combined, e.g.:
* [[Lidocaine/prilocaine]] (EMLA, eutectic mixture of local anesthetic)
* Lidocaine/tetracaine (Rapydan)
* [[Topical tac|TAC]]

LA solutions for injection are sometimes mixed with vasoconstrictors ([[combination drug]]) to increase the duration of local anesthesia by constricting the blood vessels, thereby safely concentrating the anesthetic agent for an extended duration, as well as reducing [[hemorrhage]].<ref>{{cite journal | vauthors = Yagiela JA | title = Vasoconstrictor agents for local anesthesia | journal = Anesthesia Progress | volume = 42 | issue = 3–4 | pages = 116–120 | year = 1995 | pmid = 8934977 | pmc = 2148913 }}</ref> Because the vasoconstrictor temporarily reduces the rate at which the systemic circulation removes the local anesthetic from the area of the injection, the maximum doses of LAs when combined with a vasoconstrictor is higher compared to the same LA without any vasoconstrictor. Occasionally, cocaine is administered for this purpose. Examples include:
* [[Prilocaine]] hydrochloride and [[epinephrine]] ([[trade name]] Citanest Forte)
* [[Lidocaine]], [[bupivacaine]], and [[epinephrine]] (recommended final concentrations of 0.5, 0.25, and 0.5%, respectively)
* [[Iontocaine]], consisting of lidocaine and epinephrine
* Septocaine (trade name Septodont), a combination of [[articaine]] and epinephrine
One combination product of this type is used topically for surface anaesthesia, TAC (5–12% [[tetracaine]],<sup>1</sup>/<sub>2000</sub> (0.05%, 500&nbsp;[[Parts-per notation#ppm|ppm]], {{frac|1|2}} per mille) adrenaline, 4 or 10% cocaine).

Using LA with vasoconstrictor is safe in regions supplied by [[End artery|end arteries]].
The commonly held belief that LA with vasoconstrictor can cause [[necrosis]] in extremities such as the nose, ears, fingers, and toes (due to constriction of end arteries), is invalidated, since no case of necrosis has been reported since the introduction of commercial lidocaine with epinephrine in 1948.<ref>{{cite journal | vauthors = Nielsen LJ, Lumholt P, Hölmich LR | title = [Local anaesthesia with vasoconstrictor is safe to use in areas with end-arteries in fingers, toes, noses and ears] | journal = Ugeskrift for Laeger | volume = 176 | issue = 44 | pages = 44 | date = October 2014 | pmid = 25354008 }}</ref>

===Ester group===
[[File:Procaine.svg|class=skin-invert-image|thumb|[[Procaine]]]]
* [[Benzocaine]]
* [[Chloroprocaine]]
* [[Cocaine]]
* [[Cyclomethycaine]]
* [[Dimethocaine]] (Larocaine)
* [[Piperocaine]]
* [[Propoxycaine]]
* [[Procaine]] (Novocaine)
* [[Proparacaine]]
* [[Tetracaine]] (Amethocaine)

===Amide group===
[[File:Lidocaine.svg|class=skin-invert-image|thumb|[[Lidocaine]]]]
* [[Articaine]]
* [[Bupivacaine]]
* [[Cinchocaine]] (Dibucaine)
* [[Etidocaine]]
* [[Levobupivacaine]]
* [[Lidocaine]] (Lignocaine)
* [[Mepivacaine]]
* [[Prilocaine]]
* [[Ropivacaine]]
* [[Trimecaine]]

===Naturally derived===
[[File:Tetrodotoxin.svg|class=skin-invert-image|thumb|[[Tetrodotoxin]]]]
* [[Saxitoxin]]
* [[Neosaxitoxin]]
* [[Tetrodotoxin]]
* [[Menthol]]
* [[Eugenol]]
* [[Cocaine]]
* [[Spilanthol]]

Most naturally occurring local anesthetics with the exceptions of menthol, eugenol and cocaine are [[neurotoxin]]s, and have the suffix -toxin in their names.  Cocaine binds the [[intracellular]] side of the channels while saxitoxin, neosaxitoxin and tetrodotoxin bind to the [[extracellular]] side of sodium channels.