Benzocaine was introduced in the late 19th century as a local anesthetic rather than an antibiotic. It was first synthesized in 1890 by the German chemist Eduard Ritsert and later became widely used for its pain-relieving properties. Unlike antibiotics, benzocaine does not kill bacteria; instead, it works by blocking nerve signals in the body to reduce pain and discomfort. It is commonly used in topical applications to relieve pain from minor cuts, scrapes, burns, insect bites, sore throats, and dental irritation. Benzocaine is often available over the counter in creams, gels, sprays, and lozenges, sometimes combined with other antiseptics or soothing agents. Its primary function is to provide temporary relief by numbing the affected area rather than preventing or treating infections.
BRAND NAMES
Some common brand names of Benzocaine include Orajel, Anbesol, Americaine, and Lanacane. These products are widely used for temporary pain relief in conditions like toothaches, sore throats, and minor skin irritations.
MECHANISM OF ACTION
The mechanism of action of Benzocaine involves blocking nerve signals in the body to produce a numbing effect. It works by inhibiting voltage-gated sodium channels in nerve cell membranes, which prevents the initiation and transmission of nerve impulses. As a result, pain signals from the affected area are not sent to the brain, leading to temporary relief from discomfort.
PHARMACOKINETICS
Absorption
Benzocaine is minimally absorbed through intact skin and mucous membranes, so it mainly acts at the site of application. Small amounts may be absorbed if applied to damaged skin or large areas, but it generally has very low systemic absorption.
Distribution
Benzocaine shows minimal distribution in the body because very little of it enters the bloodstream. It mainly stays at the site of application, and any small amount absorbed is distributed in low, clinically insignificant levels.
Metabolism
Benzocaine is rapidly metabolized in the body by plasma cholinesterases. It is broken down into para-aminobenzoic acid (PABA) and other metabolites, which are then processed further for elimination.
Excretion
Benzocaine is mainly excreted through the urine after being metabolized into compounds like para-aminobenzoic acid (PABA). Only small amounts enter the bloodstream because its absorption is minimal.
PHARMACODYNAMICS
Benzocaine works by blocking sodium channels in nerve endings, which prevents pain signals from reaching the brain. This provides fast, short-term relief from localized pain.
ADMINISTRATION
Benzocaine is administered topically in the form of creams, gels, sprays, ointments, or lozenges. It is applied directly to the affected area for relief of pain, itching, or irritation, usually several times a day as needed.
DOSAGE AND STRENGTH
Benzocaine is available in 5–20% concentrations in creams, gels, sprays, and lozenges. The dose depends on the product and severity of symptoms and should be used according to the instructions to avoid overuse.
FOOD INTERACTIONS
Benzocaine has no significant food interactions because it acts locally and is minimally absorbed into the bloodstream. Eating or drinking does not generally affect its effectiveness when used for oral or topical pain relief.
DRUG INTERACTIONS
Benzocaine has few drug interactions due to low absorption, but using it with other anesthetics or drugs like dapsone can increase the risk of methemoglobinemia, a rare blood disorder.
CONTRAINDICATIONS
Benzocaine should not be used by people allergic to benzocaine or other ester anesthetics, or by those with a history of methemoglobinemia or related blood disorders.
SIDE EFFECTS
Irritation cutanée
Rougeur
Sensation de brûlure au site d'application
Méthémoglobinémie
Réactions allergiques
Gonflement
TOXICITY
Benzocaine toxicity is rare but can cause methemoglobinemia, reducing the blood’s ability to carry oxygen. Symptoms include bluish skin, shortness of breath, and dizziness, and severe cases need immediate medical attention.
