Benzocaine Explained

Image Class:skin-invert-image
Width:200
Image Class2:bg-transparent
Width2:200
Tradename:Anbesol, Lanacane, Orajel, others
Routes Of Administration:Topical, Oral
Atc Prefix:C05
Atc Suffix:AD03
Atc Supplemental:,,,
Legal Au:S4
Legal Au Comment:/Schedule 2[1]
Legal Uk:GSL, P
Legal Us:OTC
Cas Number:94-09-7
Pubchem:2337
Drugbank:DB01086
Chemspiderid:13854242
Unii:U3RSY48JW5
Kegg:D00552
Chebi:116735
Chembl:278172
Iupac Name:Ethyl 4-aminobenzoate
C:9
H:11
N:1
O:2
Smiles:O=C(OCC)c1ccc(N)cc1
Stdinchi:1S/C9H11NO2/c1-2-12-9(11)7-3-5-8(10)6-4-7/h3-6H,2,10H2,1H3
Stdinchikey:BLFLLBZGZJTVJG-UHFFFAOYSA-N

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 anesthetic ointments such as products for oral ulcers. It is combined with 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.[2] [3]

It was first synthesised in 1890 in Germany and approved for medical use in 1902.[4]

Medical uses

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

Examples of combination medications of benzocaine include:

Other uses

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:

Side effects

Benzocaine is generally well tolerated and non-toxic when applied topically as recommended.[21]

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.[22]

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.[23]

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

Chemistry

Benzocaine is the ethyl ester of p-aminobenzoic acid (PABA). It can be prepared from PABA and ethanol[29] by Fischer esterification or via the reduction of ethyl p-nitrobenzoate. Benzocaine is sparingly soluble in water; it is more soluble in dilute acids and very soluble in ethanol, chloroform, and ethyl ether. The melting point of benzocaine is 88–92 Â°C,[30] and the boiling point is about 310 Â°C.[31] The density of benzocaine is 1.17 g/cm3.

Synthesis

Benzocaine can be prepared by esterification using 4-aminobenzoic acid and ethanol.[32] [33] It can also be prepared by reduction of ethyl 4-nitrobenzoate to the amine.[34] In industrial practice, the reducing agent is usually iron and water in the presence of a little acid.[35]

History

Benzocaine was first synthesized in 1890 by the German chemist Eduard Ritsert (1859–1946),[36] in the town of Eberbach[37] and introduced to the market in 1902 under the name "AnĂ€sthesin".[38] [39]

Society and culture

Benzocaine is found, particularly in Britain, as an additive in street cocaine and also as a bulking agent in "legal highs".[40] 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.[41]

Veterinary uses

Bath solutions of benzocaine and its derivatives are commonly used to anesthetize amphibians for surgery.[42] [43] Benzocaine-based anesthetics are potent and highly effective for both anesthesia and euthanasia in amphibians.[44]

Notes and References

  1. Web site: May 2025 . Therapeutic Goods (Poisons Standard— June 2025) Instrument 2025 . August 31, 2025 . Therapeutic Goods Administration (TGA) . pdf.
  2. Web site: Safety Alerts for Human Medical Products - Oral Over-the-Counter Benzocaine Products: Drug Safety Communication - Risk of Serious and Potentially Fatal Blood Disorder . https://web.archive.org/web/20180907192533/https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm608612.htm . September 7, 2018 . May 26, 2018 . U.S. Food and Drug Administration (FDA).
  3. Web site: Safety Information on Benzocaine-Containing Products . U.S. Food and Drug Administration (FDA) . June 25, 2018 . December 1, 2025.
  4. Book: Analogue-based Drug Discovery . Fischer J, Ganellin CR . 2006 . John Wiley & Sons . 978-3-527-60749-5 . 475 .
  5. AHFS Drug Information 2007. McEvoy GK, ed. Benzocaine. Bethesda, MD: American Society of Health-System Pharmacists; 2007: 2844-5.
  6. Sultan Healthcare. Topex metered spray (benzocaine 20%) prescribing information. Englewood, NJ; 2006.
  7. https://www.drugs.com/mtm/benzocaine-topical.html Benzocaine topical
  8. Web site: Antipyrine-Benzocaine Otic: MedlinePlus Drug Information . March 28, 2023 . medlineplus.gov .
  9. Web site: Cepacol Sore Throat (Benzocaine-Menthol) Mucous Membrane: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD . March 28, 2023 . www.webmd.com .
  10. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b8bd9280-f20a-4b2a-aef7-a0ba7b3b8701 STING-KILL - benzocaine and menthol solution
  11. News: June 17, 2002 . 'Longer-lasting' condom launched . BBC News.
  12. News: December 15, 2002 . Endurance Condoms . The New York Times . Garner D.
  13. Eslamian L, Borzabadi-Farahani A, Edini HZ, Badiee MR, Lynch E, Mortazavi A . September 2013 . The analgesic effect of benzocaine mucoadhesive patches on orthodontic pain caused by elastomeric separators, a preliminary study . Acta Odontologica Scandinavica . 71 . 5 . 1168–1173 . 10.3109/00016357.2012.757358 . 23301559 . 22561192 . free.
  14. Web site: Produkty PUDRODERM . https://web.archive.org/web/20161018103519/https://pampa.com.pl/page.php?cat=produkty&doc=pudroderm . October 18, 2016 . May 9, 2014 . pl.
  15. Web site: Cepacol . June 2, 2015 . Cepacol.com.
  16. Web site: Ultra Chloraseptic Anaesthetic Throat Spray 0.71% - Summary of Product Characteristics (SmPC) - (eMC) . https://web.archive.org/web/20180505205738/https://www.medicines.org.uk/emc/product/5708/smpc . May 5, 2018 . May 5, 2018 . www.medicines.org.uk.
  17. Web site: Topex Metered Spray-Sultan Healthcare . June 2, 2015 . Sultanhc.com.
  18. Web site: May 11, 2015 . Orajel - Oral Care for the Whole Family . June 2, 2015 . Orajel.com.
  19. Web site: Kank-A Canker Sore Treatment & Pain Relief . November 29, 2023 .
  20. Web site: Colgate Orabase Paste with Benzocaine | Indications | Dental Products . June 2, 2015 . Colgateprofessional.com.
  21. Lexicomp Online, Adult and Pediatric Lexi-Drugs Online, Hudson, Ohio: Lexi-Comp, Inc.; 2013; April 15, 2013.
  22. Web site: May 23, 2018 . Risk of serious and potentially fatal blood disorder prompts FDA action on oral over-the-counter benzocaine products used for teething and mouth pain and prescription local anesthetics . live . https://web.archive.org/web/20250926052320/https://www.fda.gov/drugs/drug-safety-and-availability/risk-serious-and-potentially-fatal-blood-disorder-prompts-fda-action-oral-over-counter-benzocaine . September 26, 2025 . November 30, 2025 . U.S. Food and Drug Administration (FDA).
  23. Shua-Haim JR, Gross JS . May 1995 . Methemoglobinemia toxicity from topical benzocaine spray . Journal of the American Geriatrics Society . 43 . 5 . 590 . 10.1111/j.1532-5415.1995.tb06117.x . 7730550 . 19563675 . free.
  24. Web site: Allergy to Benzocaine . https://web.archive.org/web/20140320095658/https://www.bedfordhospital.nhs.uk/upload_folder/patient%20information/allergy%20to%20benzocaine.pdf . March 20, 2014 . March 20, 2014.
  25. Sidhu SK, Shaw S, Wilkinson JD . June 1999 . A 10-year retrospective study on benzocaine allergy in the United Kingdom . American Journal of Contact Dermatitis . 10 . 2 . 57–61 . 10.1016/s1046-199x(99)90000-3 . 10357712.
  26. GonzĂĄlez-RodrĂ­guez AJ, GutiĂ©rrez-Paredes EM, Revert FernĂĄndez Á, JordĂĄ-Cuevas E . March 2013 . Allergic contact dermatitis to benzocaine: the importance of concomitant positive patch test results . Actas Dermo-Sifiliograficas . 104 . 2 . 156–158 . 10.1016/j.ad.2011.07.023 . 22551703 . https://web.archive.org/web/20160303234050/https://apps.elsevier.es/watermark/ctl_servlet?_f=10&pident_articulo=90193182&pident_usuario=0&pcontactid=&pident_revista=403&ty=87&accion=L&origen=cardio&web=http%3A%2F%2Fwww.revespcardiol.org&lan=en&fichero=403v104n02a90193182pdf001.pdf . March 3, 2016 . March 20, 2014.
  27. News: February 5, 2008 . Go easy on medicated lotions, creams, gels . March 20, 2014 . CNN . Goldman L.
  28. Cetylite Industries. Cetacaine (benzocaine 14%, tetracaine 2% and butamben 2%) spray, gel and liquid prescribing information. Pennsauken, NJ; 2006 Sept.
  29. Demare P, Regla I . 2012 . Synthesis of Two Local Anesthetics from Toluene: An Organic Multistep Synthesis in a Project-Oriented Laboratory Course . Journal of Chemical Education . 89 . 1 . 147 . 2012JChEd..89..147D . 10.1021/ed100838a.
  30. Web site: Benzocaine . March 27, 2023 . PubChem . U.S. National Library of Medicine .
  31. Book: D'Ans-Lax, Taschenbuch fĂŒr Chemiker und Physiker . 1983 . Springer Verlag . 3-540-12263-X . 4th . Organische Verbindungen . Berlin.
  32. Salkowski H . 1895 . Ueber Esterbildung bei aromatischen AmidosĂ€uren . Berichte der Deutschen Chemischen Gesellschaft . 28 . 2 . 1917–1923 . 10.1002/cber.189502802150.
  33. Erlenmeyer E, Wanklyn JA . 1865 . Ueber das durch Einwirkung von Jodwasserstoff auf Mannit beziehungsweise auf Melampyrin (Dulcit) entstehende ÎČ HexyljodĂŒr und einige seiner Derivate . Annalen der Chemie und Pharmacie . 135 . 2 . 129–151 . 10.1002/jlac.18651350202.
  34. Limpricht H . 1898 . Ueber die Verbindungen aus Benzoylchlorid oder Phtalylchlorid und den Estern der drei OxybenzoĂ«sĂ€uren . Justus Liebig's Annalen der Chemie . 303 . 3 . 274–289 . 10.1002/jlac.18983030303.
  35. Book: Benzocaine . Ali SL . Academic Press . 1983 . 978-0-12-260812-4 . Analytical Profiles of Drug Substances . 12 . 73–104 . 10.1016/S0099-5428(08)60164-1.
  36. Biography of Eduard Ritsert (in German): Deutsche Biographie: Ritsert, Eduard.
  37. Web site: 100 years of Dr. Ritsert . https://web.archive.org/web/20170909185714/http://www.ritsert.de/index.php?option=com_content&task=view&lang=en&id=13&Itemid=27 . September 9, 2017 . March 14, 2010 . Dr. Ritsert Pharma.
  38. Book: Lehrbuch der pharmazeutischen Chemie . Auterhoff H . 1968 . Wissenschaftliche Verlagsgesellschaft . Stuttgart, Germany.
  39. Ritsert E . 1925 . Über den Werdegang des AnĂ€sthesins . On the development of Anaesthetics . Pharmazeutische Zeitung . German . 60 . 1006–1008. See also: Friedrich C, Klimonow M . 150. Geburtstag: Eduard Ritsert und das Anaesthesin . https://web.archive.org/web/20140320125425/https://www.pharmazeutische-zeitung.de/index.php?id=31537 . March 20, 2014 . 150th birthday: Eduard Ritsert and AnĂ€sthetsin [Benzocaine] . German . Pharmazeutische Zeitung Online . December 2014 . First published clinical study demonstrating the efficacy of benzocaine: von Noorden C . 1902 . Ueber para-AminobenzoesĂ€ure-Ester als locales AnĂ€sthetikum . On [an] ester of para-aminobenzoic acid as a local anaesthetic . German . Klinische Wochenschrift . 39 . 373–375 .
  40. News: August 9, 2010 . Drug war targets cutting agents . BBC News.
  41. News: August 11, 2012 . Drug prices: All cut up: Cocaine is cheaper, but weaker . The Economist.
  42. GuĂ©nette SA, Giroux MC, Vachon P . 2013 . Pain perception and anaesthesia in research frogs . Experimental Animals . 62 . 2 . 87–92 . 10.1538/expanim.62.87 . 23615302 . free.
  43. Web site: November 8, 2010 . Amphibian Anesthesia — Research at Penn State . https://web.archive.org/web/20181103081918/https://www.research.psu.edu/arp/anesthesia/amphibian-anesthesia.html . November 3, 2018 . August 24, 2017 . PennState Animal Resource Program . The Pennsylvania State University . State College, U.S..
  44. Barros AL, Lima AP, Fachin-Espinar MT, Nunez CV . 2020 . Evaluation of benzocaine-based anesthetic gel in anuran skins extracts: A case study using the frog Lithodytes lineatus (Anura: Leptodactylidae) . PLOS ONE . 15 . 12 . 2020PLoSO..1543654B . 10.1371/journal.pone.0243654 . 7723253 . 33290419 . free . e0243654.

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