Benzocaine

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Structural formula
Structure of benzocaine
General
Non-proprietary name Benzocaine
other names
  • 4-aminobenzoic acid ethyl ester
  • ethyl para- aminobenzoate
  • ethyl p -aminobenzoate
Molecular formula C 9 H 11 NO 2
Brief description

colorless solid

External identifiers / databases
CAS number 94-09-7
EC number 202-303-5
ECHA InfoCard 100.002.094
PubChem 2337
DrugBank DB01086
Wikidata Q422745
Drug information
ATC code

R02 AD01 , D04 AB04 , C05 AD03

Drug class

Local anesthetic

properties
Molar mass 165.19 g mol −1
Physical state

firmly

Melting point

89-92 ° C

boiling point

172 ° C (17 h Pa )

pK s value

2.51 (protonated form)

solubility

very bad in water

safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS labeling of hazardous substances
07 - Warning

Caution

H and P phrases H: 315-317-319
P: 280-302 + 352-305 + 351 + 338
Toxicological data

3042 mg kg −1 ( LD 50ratoral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Benzocaine ( 4-aminobenzoic acid ethyl ester ) is a local anesthetic of the ester type for surface anesthesia with a rapid onset of action and a relatively short duration of action.

Applications

Benzocaine is mainly used for local pain therapy of the skin and mucous membranes , for example in the mouth and throat area, as well as in medicines for colds , cough suppressants , pain relievers such as solutions or lozenges for throat, stomach and teething problems , astringents . Topical preparations such as creams , solutions and powders are used for athlete's foot , corns , warts and calluses , suppositories for the treatment of hemorrhoidal diseases and anal discomfort such as anal pruritus and anal localized eczema .

Use as a delay cream

Benzocaine can also be applied to the penis . The aim here is to reduce the sensations through the anesthetic effect in order to avoid premature ejaculation .

Benzocaine is commercially available for this purpose as "delay cream", "long-term spray" or similar names. The remedy is applied to the glans before the beginning of the act of love - with the foreskin completely retracted . To improve the delay effect, the agent should be carefully distributed and massaged in. The anesthetic usually starts after about 1 minute, but often begins to subside after 10 minutes.

Benzocaine is also used in some condoms (e.g. Performa from Durex , max.LOVE from Condomi or Control from Crest). In the reservoir of these special condoms there is a pea-sized amount of benzocaine ointment that dissolves through the heat of the penis and then desensitizes the glans. The effect of benzocaine with this dosage form is rather less than with the targeted application of creams and sprays: Either the dosage of the agent is insufficient or the glans is not sufficiently wetted.

Mode of action

Benzocaine reversibly prevents the depolarization of the nerve cells by binding to voltage-dependent sodium channels , which prevents the transmission of an action potential .

presentation

Para-nitrotoluene is oxidized to para-nitrobenzoic acid by potassium dichromate under sulfuric acid reaction conditions. The resulting carboxylic acid is reacted with ethanol in an acidic environment to form the ethyl para-nitrobenzoate. The nitro group in the para position is then reduced to the aromatic amino group by elemental iron in the acid .

Benzocaine synthetic route

Alternatively, benzocaine, by esterification of 4-amino benzoic acid with ethanol are obtained. Other esters of 4-aminobenzoic acid, such as procaine , are also used as local anesthetics.

Side effects

As a substance with a para-primary aromatic amino group, benzocaine has a significantly higher allergy potential ( para-group allergy ) than, for example, the non-para-substituted lidocaine . The incidence of benzocaine allergy appears to vary from country to country. A positive patch test rate of 2.6 percent is reported for benzocaine in the United States . In Europe this varies from 1 percent in Denmark to 10 percent in Germany.

In addition, stomach cramps and intestinal discomfort can occur after oral use.

A rare but dangerous side effect of benzocaine can be methaemoglobinemia .

Trade names

Monopreparations

Anaestherit (A), Anaesthesin (D)

Combination preparations

Dequalinetten (A), Dolo-Dobendan (D), Dorithricin (D), Herposicc (A), Insecticum Gel (A), "Kremser" ear drops (A), Néocônes (CH), Rectosan (A), rheumatic ointment (A) , Sulgan 99 (A), tyrothricin (A)

Individual evidence

  1. a b c Entry on benzocaine in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  2. a b sheet ethyl 4-aminobenzoate (benzocaine) (PDF) at Merck , accessed on 26 February 2010 .
  3. Entry on Benzocaine in the DrugBank of the University of Alberta , accessed April 23, 2016.
  4. Data sheet Ethyl 4-aminobenzoate from Acros, accessed on February 26, 2010.
  5. Benzocaine data sheet at AlfaAesar, accessed on February 26, 2010 ( PDF )(JavaScript required) .
  6. E. Weisshaar, D. Becker et al .: Reasons for assessing the impact of an allergy to benzocaine in the context of the MdE assessment (PDF; 73 kB) Dermatology in Work and Environment, Volume 56, No. 3/2008, p 117-119.
  7. SK Sidhu, S. Shaw, JD Wilkinson: A 10-year retrospective study on benzocaine allergy in the United Kingdom. In: American Journal of Contact Dermatitis . Volume 10, Number 2, June 1999, pp. 57-61, PMID 10357712
  8. ^ Avoxa media group Deutscher Apotheker GmbH: Benzocaine: Warning of dangerous side effects. Retrieved September 25, 2019 .
  9. Red List online, as of September 2009.
  10. AM comp. d. Switzerland, as of September 2009.
  11. AGES-PharmMed, as of September 2009.