indication

For the symptomatic relief of cough. Has also been applied locally in the oral cavity in adults by releasing the drug from the liquid-filled capsules to provide oropharyngeal anesthesia for conscious intubation.

pharmacology

Benzonatate, a non-narcotic antitussive agent chemically related to tetracaine and other ester-type local anesthetics, is used to suppress cough associated with both acute and chronic respiratory conditions. The drug acts peripherally by anesthetizing the stretch receptors located in the respiratory passages, lungs, and pleura through the dampening of their activity, which reduces the cough reflex.

mechanism of action

Benzonatate acts peripherally, anesthetizing the stretch receptors of vagal afferent fibers in the alveoli of the lungs, bronchi, and pleura. Since these receptors are responsible for mediating the cough reflex, anesthetizing these receptors result in the inhibiton of cough production. Benzonatate also suppresses transmission of the cough reflex at the level of the medulla where the afferent impulse is transmitted to the motor nerves. When applied locally, Benzonatate binds within the intracellular portion of voltage-gated sodium channels, decreasing the rate of membrane depolarization and increasing the threshold for electrical excitability.

toxicity

Restlessness, tremors, seizures and unconsciousness.

biotransformation

Benzonatate is hydrolyzed to para-aminobenzoic acid (PABA) by plasma esterases

half life

3-8 hours