Benzocaine

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Benzocaine
Systematic (IUPAC) name
ethyl 4-aminobenzoate
Identifiers
CAS number	94-09-7
ATC code	C05AD03 D04 AB04, N01 BA05, R02 AD01
PubChem	2337
DrugBank	APRD00539
Chemical data
Formula	C₉H₁₁N O₂
Mol. mass	165.189 g/mol
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	topical

Benzocaine is a local anesthetic commonly used as a topical pain reliever. It is the active ingredient in many over-the-counter analgesic ointments. Most commonly oral pain relievers such as Orajel™

1 Chemical properties
2 History
3 How it relieves pain
4 Side-effects
5 Related products
6 Other uses
7 References
8 External links

[edit] Chemical properties

Benzocaine is an ester, a compound made from the organic acid PABA (para-aminobenzoic acid) and ethanol. The process in which this ester is created is known as Fischer esterification.

[edit] History

Benzocaine was first synthesised by a German chemical firm named Ritsert, in the town of Eberbach, in Baden-Württemberg in 1902.

[edit] How it relieves pain

Pain is caused by the stimulation of nerve endings. When the nerve endings are stimulated, sodium enters the nerve ending, which causes an electrical signal to build up in the nerve. Once the electrical signal becomes big enough, it is able to travel to the brain, which then interprets this as pain.

Esters of PABA work as a chemical barrier, stopping the sodium from being able to enter the nerve ending.

[edit] Side-effects

Allergic reactions occur with ester local anaesthetics (like benzocaine) because of the PABA structure.

Benzocaine also is a well-known cause of methemoglobinemia. Because it may be used in topical creams with a concentration as much as 20%, it is not difficult to administer a dose sufficient to cause this problem.

[edit] Related products

There are various other products that are also made from esters of PABA, many of which have similar anaesthetic properties. Dentists use Procaine (also called Novocaine) to numb teeth and gums.

Benzocaine is also contained in products such as:

First aid creams
Sore-throat spray
Sore-throat drops w/ Menthol
Sore-throat relief strips
Sunburn remedies
Premature ejaculation treatment

[edit] Other uses

Benzocaine can also be used as a fish anesthetic. Due to its low solubility in water, stock solution can be made with ethanol (95%). 25 g of benzocaine per 200 ml ethanol will make a solution strong enough to knock saltwater fish out in 2-4 minutes. They will regain equilibrium after 10-15 minutes. Use 5 ml stock solution per 1 L of saltwater. Some benzocaine will precipitate out of solution when added to the saltwater, so it is recommended to add the volume of stock solution you will be using to a separate container and mix it with some saltwater before adding it to the tank.

Benzocaine is also used as a key ingredient in Phenazone, an anti-inflammatory, and Glycerol, a moisture absorber for use in removing excess wax as well as ear conditions such as Otitis Media and Swimmers Ear.

It is also used in certain condoms to prolong sex by numbing the penis.^[1]