dibucaine

Dibucaine, also known as cinchocaine in some regions, is a local anesthetic of the amide type used topically to relieve pain and itching associated with minor skin and mucous membrane conditions. It is formulated in creams, ointments, gels, and similar preparations and is commonly used for symptomatic relief of irritations, burns, minor wounds, and hemorrhoidal discomfort.

Dibucaine works by blocking voltage-gated sodium channels in nerve membranes, thereby stabilizing neuronal membranes and reducing nerve impulse conduction. This produces temporary numbness in the treated area. The onset and duration of effect depend on the concentration, formulation, and site of application. Absorption through intact skin is limited, but absorption can increase with mucous membranes or damaged skin, affecting systemic exposure and risk of toxicity. Metabolism occurs primarily in the liver, and excretion is in the urine.

Adverse effects are usually local and mild, such as transient burning, stinging, or contact dermatitis. More serious systemic toxicity can occur with extensive topical use or impaired absorption control and may include central nervous system symptoms (e.g., dizziness, tinnitus, seizures) and cardiovascular effects (e.g., arrhythmias, hypotension). Dibucaine should be avoided in individuals with known hypersensitivity to local anesthetics of the amide type and used with caution in those with significant hepatic impairment or in situations where extensive absorption is likely.

In laboratory medicine, dibucaine is also used in a diagnostic test to determine pseudocholinesterase activity (the dibucaine number), aiding in the assessment of atypical cholinesterase deficiency that can affect anesthesia management.