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Critical Thinking/Writing Assignment # 1

LASC 636 - Principles of Toxicology

Distributed: January 21, 2014

Due: February 4, 2014

Common/Trade Name(s): Orajel

For immediate toothache pain relief most adults (individuals 12+) look for over the counter topicalremedies such as Orajel.

Chemical Name(s):Benzocaine,Ethyl p-aminobenzoate

Benzocaine (ethyl amino benzoate) is a white crystalline ester commonly used as a topical pain reliever

in many over-the-counter analgesic products (Oxford Dictionaries, 2014).

Chemical Formula:C9H12CINO2 (Gupta et al, 2000)Molecular Weight: 165.19 g/mol (Sweetman, 2007)

Boiling/Freezing Point: 310C (590F)/89C (192.2F) (Sweetman, 2007)Vapor Pressure: 00018/crystalline, 00083/liquid (Gobble et al., 2013)

Solubility:Soluble in methanol, diethyl ether. Very slightly soluble in cold water. (Gobble et al., 2013)Manufacturer(s) or Source: Church & Dwight (http://www.orajel.com/)

Discovery of Chemical:

Environmental Fate/Half-Life: 55 mins. (Gupta et al, 2000)

LD50s (Oral, Dermal & Inhalational):

Bird (wild), with reported dose 56mg/kg (56mg/kg) (oral) ( Schafer, 1972) Mouse, 216mg/kg (216mg/kg) (oral) (Fitzgerald et al., 1974) Rat, 3040 mg/kg (oral) (Vestnik,1996) rabbit, 1150mg/kg (1150mg/kg) (oral) (Drugs in Japan,1982)

LC50s:

Acute Toxicity: In humans a disease known as methemoglobinemia from oral, rectal and dermal

exposures has been seen. There is disagreement whether this is an idiosyncratic event or a dose-relatedevent. No LD50 recorded. (Spiller, 2000)

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Literature Cited:

Benzocaine. Oxford Dictionaires Web 3 Feb 2014

www.http://oxforddictionaries.com/definition/american_english/benzocaine

Schafer, E. (1972) Toxicology and Applied Pharmacology. Vol. 21, Pg. 315.

Fitzgerald, T.J., Doull, J., and DeFeo, F.G. (1974)Radioprotective activity of p-aminopropiophenone.Structure-activity investigation.Journal of Medicinal Chemistry, Vol 17, Pg. 900.

Vestnik, T.T. (1996) (18-20 Vadkovskii per. Moscow, 101479, Russia) Vol.2 ,34.

Sweetman, S.C., ed. Martindale (2007)The Complete Drug Reference. 35th ed. London, England:

Pharmaceutical Press; 1808-1812.

Gobble, C., Gutterman, A., Chickos, J.S. (2013) Some thermodynamic properties of benzocaine.

Structural Chemistry. Vol. 24 1903-1907.

Spiller, H.A. (2000) Vet Hum Toxicolog. Vol. 42 (4): 228-31.

Gupta, P.M.,. Lala, D.S., Arsura, E.L. (2000) Benzocaine-Induced Methemoglobinemia.SouthernMedical Journal 93(1).

Drugs in Japan Vol. 6, Pg. 33, 1982.

http://www.orajel.com/ Accessed 31 February 2014

Klein, S.L., Nustad, R.A., Feinberg, S.E., Fonseca, R.J.(1983) Acute toxic methemoglobinemia caused

by a topical anesthetic. The American Academy of Pedodontics Vol. 5 (2)107-108.

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