Benzocaine

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Benzocaine
Clinical data
Trade namesAnbesol, Lanacane, Orajel, others
AHFS/Drugs.comMonograph
Routes of
administration		Topical, Oral
ATC code
Legal status
Legal status
  • UK: GSL, P
  • US: OTC
Identifiers
  • Ethyl 4-aminobenzoate
JSmol)
  • O=C(OCC)c1ccc(N)cc1
  • InChI=1S/C9H11NO2/c1-2-12-9(11)7-3-5-8(10)6-4-7/h3-6H,2,10H2,1H3 checkY
  • Key:BLFLLBZGZJTVJG-UHFFFAOYSA-N checkY
  (verify)

Benzocaine, sold under the brand name Orajel amongst others, is a

antipyrine to form A/B ear drops. In the US, products containing benzocaine for oral application are contraindicated in children younger than two years old.[1] In the European Union, the contraindication applies to children under 12 years of age.[medical citation needed
]

It was first synthesised in 1890 in Germany and approved for medical use in 1902.[2]

Medical uses

Benzocaine is indicated to treat a variety of pain-related conditions. It may be used for:

  • Local anesthesia of oral and pharyngeal mucous membranes (sore throat, cold sores, mouth ulcers, toothache, sore gums, denture irritation)[3]
  • Otic pain (earache)[3]
  • Surgical or procedural local anesthesia[4]
  • Relief of skin pain caused by
    hemorrhoids, [5]

Examples of

combination medications
of benzocaine include:

Other uses

Jiffy Toothache Drops bottle (7.75% Benzocaine)

Benzocaine is used as a key ingredient in numerous pharmaceuticals:

Available forms

Benzocaine can come in a variety of preparations including:

Oral preparations:

Topical preparations:

Otic preparations:

  • Solution (ex. Allergen)

Side effects

Benzocaine is generally well tolerated and non-toxic when applied topically as recommended.[19]

However, there have been reports of serious, life-threatening adverse effects (e.g., seizures, coma, irregular heart beat, respiratory depression) with over-application of topical products or when applying topical products that contain high concentrations of benzocaine to the skin.[20]

Overapplication of oral anesthetics such as benzocaine can increase the risk of pulmonary aspiration by relaxing the gag-reflex and allowing regurgitated stomach contents or oral secretions to enter the airway.[medical citation needed] Applying an oral anesthetic and consuming beverages before going to bed can be particularly hazardous.[medical citation needed]

The topical use of higher concentration (10–20%) benzocaine products applied to the mouth or mucous membranes has been found to be a cause of methemoglobinemia, a disorder in which the amount of oxygen carried by the blood is greatly reduced.[21] This side effect is most common in children under two years of age.[22] As a result, the FDA has stated that benzocaine products should not be used in children under two years of age, unless directed by and supervised by a healthcare professional.[23] In European countries, the contraindication applies to children under 12 years of age. Symptoms of methemoglobinemia usually occur within minutes to hours of applying benzocaine, and can occur upon the first-time use or after additional use.[23]

Benzocaine may cause allergic reactions.[24][25][26][27] These include:

Pharmacology

Pharmacodynamics

nerve endings are stimulated, sodium enters the neuron, causing depolarization of the nerve and subsequent initiation of an action potential. The action potential is propagated down the nerve toward the central nervous system, which interprets this as pain. Benzocaine acts to inhibit the voltage-gated sodium channels (VGSCs) on the neuron membrane, stopping the propagation of the action potential.[citation needed
]

Chemistry

Benzocaine is the

ethyl ether. The melting point of benzocaine is 88–92 °C,[30] and the boiling point is about 310 °C.[31] The density
of benzocaine is 1.17 g/cm3.

Benzocaine is commonly found, particularly in Britain, as an additive in street cocaine and also as a bulking agent in "legal highs".[32] Benzocaine gives a numbing effect similar to cocaine and as a bulking and binding agent it can not be detected once mixed. It is the most popular cutting agent worldwide.[33]

Treatment of benzocaine with hydrazine leads to aminostimil, a compound related to isoniazid.

Synthesis

Benzocaine can be prepared by

4-aminobenzoic acid and ethanol.[34][35] It can also be prepared by reduction of ethyl 4-nitrobenzoate to the amine.[36][37] In industrial practice, the reducing agent is usually iron and water in the presence of a little acid.[38]

History

Benzocaine was first synthesized in 1890 by the German chemist Eduard Ritsert (1859–1946),[39] in the town of Eberbach[40] and introduced to the market in 1902 under the name "Anästhesin".[41][42]

Veterinary medicine

Bath solutions of benzocaine and its derivatives are commonly used to anesthetize

amphibians for surgery.[43][44] Benzocaine-based anesthetics are potent and highly effective for both anesthesia and euthanasia in amphibians.[45]

References

  1. ^ "Safety Alerts for Human Medical Products - Oral Over-the-Counter Benzocaine Products: Drug Safety Communication - Risk of Serious and Potentially Fatal Blood Disorder". www.fda.gov. Archived from the original on September 7, 2018. Retrieved May 26, 2018.
  2. ISBN 9783527607495
    .
  3. ^ a b AHFS Drug Information 2007. McEvoy GK, ed. Benzocaine. Bethesda, MD: American Society of Health-System Pharmacists; 2007: 2844-5.
  4. ^ Sultan Healthcare. Topex metered spray (benzocaine 20%) prescribing information. Englewood, NJ; 2006.
  5. ^ Benzocaine topical
  6. ^ "Antipyrine-Benzocaine Otic: MedlinePlus Drug Information". medlineplus.gov. Retrieved March 28, 2023.
  7. ^ "Cepacol Sore Throat (Benzocaine-Menthol) Mucous Membrane: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD". www.webmd.com. Retrieved March 28, 2023.
  8. ^ STING-KILL - benzocaine and menthol solution
  9. ^ "'Longer-lasting' condom launched". BBC News. June 17, 2002.
  10. ^ Garner D (December 15, 2002). "Endurance Condoms". The New York Times.
  11. S2CID 22561192
    .
  12. ^ "Produkty | PUDRODERM" (in Polish). Archived from the original on October 18, 2016. Retrieved May 9, 2014.
  13. ^ "Cepacol". Cepacol.com. Retrieved June 2, 2015.
  14. ^ "Ultra Chloraseptic Anaesthetic Throat Spray 0.71% - Summary of Product Characteristics (SmPC) - (eMC)". www.medicines.org.uk. Archived from the original on May 5, 2018. Retrieved May 5, 2018.
  15. ^ "Topex Metered Spray-Sultan Healthcare". Sultanhc.com. Retrieved June 2, 2015.
  16. ^ "Orajel - Oral Care for the Whole Family". Orajel.com. May 11, 2015. Retrieved June 2, 2015.
  17. ^ "Kank-A | Canker Sore Treatment & Pain Relief". Retrieved November 29, 2023.
  18. ^ "Colgate Orabase Paste with Benzocaine | Indications | Dental Products". Colgateprofessional.com. Retrieved June 2, 2015.
  19. ^ Lexicomp Online, Adult and Pediatric Lexi-Drugs Online, Hudson, Ohio: Lexi-Comp, Inc.; 2013; April 15, 2013.
  20. ^ Food and Drug Administration. FDA Public Health Advisory: Life-threatening side effects with use of skin products containing numbing ingredients for cosmetic procedures. 2007 Feb 6, updated 2007 Feb 9. From FDA website
  21. S2CID 19563675
    .
  22. ^ "Benzocaine Topical Products: Sprays, Gels and Liquids – Risk of Methemoglobinemia". Drugs.com. Retrieved March 20, 2014.
  23. ^ a b "FDA Drug Safety Communication: Reports of a rare, but serious and potentially fatal adverse effect with the use of over-the-counter (OTC) benzocaine gels and liquids applied to the gums or mouth". Fda.gov. Retrieved June 2, 2015.
  24. ^ "Allergy to Benzocaine" (PDF). Archived from the original (PDF) on March 20, 2014. Retrieved March 20, 2014.
  25. PMID 10357712
    .
  26. PMID 22551703. Archived from the original
    (PDF) on March 3, 2016. Retrieved March 20, 2014.
  27. ^ Goldman L (February 5, 2008). "Go easy on medicated lotions, creams, gels". CNN. Retrieved March 20, 2014.
  28. ^ a b Cetylite Industries. Cetacaine (benzocaine 14%, tetracaine 2% and butamben 2%) spray, gel and liquid prescribing information. Pennsauken, NJ; 2006 Sept.
  29. doi:10.1021/ed100838a
    .
  30. ^ "Benzocaine". PubChem. U.S. National Library of Medicine. Retrieved March 27, 2023.
  31. ISBN 3-540-12263-X
    .
  32. ^ "Drug war targets cutting agents". BBC News. August 9, 2010.
  33. ^ "Drug prices: All cut up : Cocaine is cheaper, but weaker". The Economist. August 11, 2012.
  34. doi:10.1002/cber.189502802150
    .
  35. doi:10.1002/jlac.18651350202
    .
  36. doi:10.1002/jlac.18983030303
    .
  37. ^ Adams R, Cohen FL (1928). "Ethyl p-aminobenzoate". Organic Syntheses. 8: 66; Collected Volumes, vol. 1, p. 240.
  38. ISBN 978-0-12-260812-4
    .
  39. ^ Biography of Eduard Ritsert (in German): Deutsche Biographie: Ritsert, Eduard.
  40. ^ "100 years of Dr. Ritsert". Dr. Ritsert Pharma. Archived from the original on September 9, 2017. Retrieved March 14, 2010.
  41. ^ Auterhoff H (1968). Lehrbuch der pharmazeutischen Chemie. Stuttgart, Germany: Wissenschaftliche Verlagsgesellschaft.
  42. ^ Ritsert E (1925). "Über den Werdegang des Anästhesins" [On the development of Anaesthetics]. Pharmazeutische Zeitung (in German). 60: 1006–1008. See also: Friedrich C, Klimonow M (December 2014). "150. Geburtstag: Eduard Ritsert und das Anaesthesin" [150th birthday: Eduard Ritsert and Anästhetsin [Benzocaine]]. Pharmazeutische Zeitung online (in German). Archived from the original on March 20, 2014. First published clinical study demonstrating the efficacy of benzocaine: von Noorden C (1902). "Ueber para-Aminobenzoesäure-Ester als locales Anästhetikum" [On [an] ester of para-aminobenzoic acid as a local anaesthetic]. Klinische Wochenschrift (in German). 39: 373–375.
  43. PMID 23615302
    .
  44. ^ "Amphibian Anesthesia — Research at Penn State". PennState Animal Resource Program. State College, U.S.: The Pennsylvania State University. November 8, 2010. Retrieved August 24, 2017.
  45. PMID 33290419
    .