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. 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.
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)
Otic pain (earache)
Surgical or procedural local anesthesia
Relief of skin pain caused by sunburn, ingrown toenails, hemorrhoids,
Examples of combination medications of benzocaine include:
Antipyrine-benzocaine otic consists of antipyrine and benzocaine, and is used to relieve ear pain and remove earwax.
Cepacol consists of menthol and benzocaine, and is used to treat sore throat.
A solution of benzocaine and menthol is marketed for the treatment of bee stings, mosquito bites, jellyfish stings, and other insect bites
Other uses
Jiffy Toothache Drops bottle (7.75% Benzocaine)
Benzocaine is used as a key ingredient in numerous pharmaceuticals:
Some glycerol-based ear medications for use in removing excess wax as well as relieving ear conditions such as otitis media and swimmer’s ear.
And some previous diet products such as Ayds.
Some condoms designed to prevent premature ejaculation. Benzocaine largely inhibits sensitivity on the penis, and can allow for an erection to be maintained longer (in a continuous act) by delaying ejaculation. Conversely, an erection will also fade faster if stimulus is interrupted.
Benzocaine mucoadhesive patches have been used in reducing orthodontic pain.
In Poland it is included, together with menthol and zinc oxide, in the liquid powder (not to be confused with the liquid face powder) used mainly after mosquito bites. Today’s ready-made Pudroderm was once used there as pharmaceutical compound.
Pharmacodynamics
Pain is caused by the stimulation of free nerve endings. When the 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.
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 It is 88–92 °C, and the boiling point is about 310 °C. 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”. 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.
Treatment of benzocaine with hydrazine leads to aminostimil, a compound related to isoniazid.
Indications and Usage
Benzocaine is a colorless trapezial crystal. Its melting point is 92℃ (88-90℃), boiling point is 183-184°C (1.87kPa). 1g of this drug is soluble in about 2500ml water, 5ml ethanol, 2ml chloroform, 4ml ether or 30-50ml almond oil and olive oil, and it is also soluble in dilute acid. It is stable in air, odorless, and slightly bitter.
Benzocaine is a lipid-soluble surface anesthetic, and it weaker than other local anesthetics such as lidocaine and tetracaine, so it will not cause any discomfort due to its anesthetizing effects when acting on mucosa. Benzocaine is a type of drug with relatively strong lipid-solubility and will bind with mucosa and the fatty layer of skin, but it will not easily penetrate into the body and cause poisoning. It can be used as a precursor for Ossur imitation, orthocaine, and procaine,and used as a local anesthetic and can stop pain and itching.
Also is mainly used in pain and itch prevention on wounds, ulcer surfaces, mucous membrane surfaces and hemorrhoids. Its paste form can also lubricate and stop pain for the nasopharynx and endoscope. Benzocaine’s aural solution is used to alleviate acute congestion, concentrated otitis externa, and the pain and itching of swimming otitis. Benzocaine is also effective for toothaches, sore throat, oral ulcers, all kinds of hemorrhoids, anal fissures, and vulvar itching. It can be used as a male sex organ numbing agent to slow ejaculation. It can also be used as a numbing lubricant for the pharynx and endoscope, and it can be used as a UV absorbing agent for cosmetics.benzocaine powder
Uses
Benzocaine is a local anaesthetic of the ester type with a poor solubility in water. The drug benzocaine is normally used as a topical pain reliever or as a common ingredient in cough drops. Benzocaine is used in multiple forms including lotion, gel, liquid, lozenges, and sprays. When Benzocaine is applied in any form it temporarily numbs or blocks the nerve endings, which leads to a decreases in the amount of pain. It is used in cattle, sheep, swine and horses for local and prolonged low epidural anaesthesia. Standard therapeutic doses of It ranged from 150 to 750 mg per animal. Benzocaine is also currently used as surface anaesthetic as ointments (0.5% benzocaine) for wounds and ulcerated surfaces in horses, cattle and sheep applied twice a day until healing.
A commonly used topical pain reliever. Main active ingredient in anesthetic ointments.
Anesthetic;Na+ channel blocker
Benzocaine acts on the central nervous system, cardiovascular system, neuromuscular junctions and ganglion synapse. Its mechanism of action is to prevent the generation and conduction of the nerve impulse. Local anaesthetics block conduction by decreasing or preventing the large transient increase in the permeability of excitable membranes to Na+ that is produced by a slight depolarisation. This action of local anaesthetics is due to their direct interaction with voltage-sensitive Na+ channels. It is mainly hydroxylated in the metabolite para-aminobenzoic acid (PABA) that inhibits the action of sulphonamides.
Benzocaine is distributed in the body, crosses the placenta and is metabolised in the liver and in the plasma by non-specific cholinesterases. and its main metabolite (para-aminobenzoic acid) are excreted into urine.
Benzocaine appears as a moderately toxic compound after single administration. The acute intraperitoneal LD50 value was 216 mg/kg bw in mice. Benzocaine may induce methemoglobinemia in several species such as sheep, cats and dogs.
Description
Benzocaine (ethyl p-aminobenzoate) is used topically by itself or in combination with menthol or phenol in nonprescription dosage forms such as gels, creams, ointments, lotions, aerosols, and lozenges to relieve pain or irritation caused by such conditions as sunburn, insect bites, toothache, teething, cold sores or canker sores in or around the mouth, and fever blisters. Benzocaine is a lipophilic local anesthetic agent with a short duration of action.
Like most amino ester-type local anesthetics, it is easily hydrolyzed by plasma cholinesterase. Because of its low pKa, however, it is un-ionized under most physiological conditions and, therefore, can only bind to the lipid side of the local anesthetic receptor. It also can easily cross membranes into systemic circulation to cause systemic toxicities. Furthermore, being a PABA derivative, it has similar allergenic properties to procaine and is contraindicated with sulfonamide antibacterial agents.
Chemical Properties
Benzocaine is a white odourless needle-like crystal, slightly soluble in water and easily soluble in organic solvents. For example: ethanol, chloroform, ether, soluble in almond oil, olive oil.
Uses Benzocaine is used as an anesthetic (Local and topical) that in products such as burn and sunburn remedies, hemorrhoidal creams, suppositories, creams for treatment of poison ivy, oral and gingival products, sore-throat sprays/lozenges, astringents, appetite suppressants, callus and wart remedies, athlete’s-foot remedies, toothache- and denture-irritation products.
Definition ChEBI: Benzocaine is a benzoate ester having 4-aminobenzoic acid as the acid component and ethanol as the alcohol component. A surface anaesthetic, it is used to suppress the gag reflex, and as a lubricant and topical anaesthetic on the larynx, mouth, nasal cavity, respiratory tract, oesophagus, rectum, urinary tract, and vagina. It has a role as a topical anaesthetic, an antipruritic drug, an allergen and a sensitiser. It is a benzoate ester and a substituted aniline.
General Description
Benzocaine is a unique local anesthetic because it does notcontain a tertiary amine. The pKa of the aromatic amine is 3.5ensuring that benzocaine is uncharged at physiological pH.Because it is uncharged, it is not water soluble but is ideal fortopical applications. The onset of action is within 30 secondsand the duration of drug action is 10 to 15 minutes.
Biochem/physiol Actions Benzocaine is the ethyl ester of p-aminobenzoic acid (PABA). Benzocaine acts to inhibit the voltage-dependent sodium channels (VDSCs) on the nerve membrane, stopping the propagation of the action potential.
Clinical Use
Benzocaine is used for endoscopy, bronchoscopy, and topicalanesthesia. Benzocaine is available as a 20% solution topicalspray, in a 1% gel for mucous membrane application, and a14% glycerin suspension for topical use in the outer ear.Toxicity to benzocaine can occur when the topical doseexceeds 200 to 300 mg resulting in methemoglobinemia.Infants and children are more susceptible to this and methemoglobinemiahas been reported after benzocaine lubricationof endotracheal tubes and after topical administration to treata painful diaper rash.
Safety Profile Poison by ingestion and intraperitoneal routes. Human systemic effects by rectal route: methemoglobinemia/carboxyhemoglobinem ia in infants. A skin irritant and a mild sensitizer. Local contact may cause contact dermatitis. Used as a topical anesthetic and as a sun-screening agent. When heated to decomposition it emits highly toxic fumes of NOx. See also ETHYL ALCOHOL and ESTERS
Benzocaine Chemical Properties benzocaine gel
Melting point 88-90 °C
Boiling point 172 °C (12.7517 mmHg)
density 1.17
refractive index 1.5600 (estimate)
Fp 172°C/13mm
storage temp. 2-8°C
solubility alcohol: soluble1 gm in 5 ml
form Crystalline Powder
pka 2.5(at 25℃)
color White
Odor odorless
Water Solubility Soluble in ethanol, chloroform, ethyl ether and dilute acids. Sparingly soluble in water
Merck 14,1086
BRN 638434
Stability: Stable. Combustible. Incompatible with strong oxidizing agents.
InChIKey BLFLLBZGZJTVJG-UHFFFAOYSA-N
LogP 1.860
CAS DataBase Reference 94-09-7(CAS DataBase Reference)
NIST Chemistry Reference Benzoic acid, 4-amino-, ethyl ester(94-09-7)
EPA Substance Registry System Benzocaine (94-09-7)
More Introduction:https://en.wikipedia.org/wiki/Benzocaine
