<unk>  is chemically similar to other local anesthetics such as tetracaine and procaine, and shares their pharmacology. Mechanism of action Similar to other local anesthetics,<unk>  is a potent voltage-gated sodium channel inhibitor. After absorption and circulation to the respiratory tract,<unk>  acts as a local anesthetic, decreasing the sensitivity of vagal afferent fibers and stretch receptors in the bronchi, alveoli, and pleura in the lower airway and lung. This dampens their activity and reduces the cough reflex.<unk>  also has central antitussive activity on the cough center in central nervous system at the level of the medulla. However, there is minimal inhibition of the respiratory center at a therapeutic dosage. Pharmacokinetics The antitussive effect of<unk>  begins within 15 to 20 minutes after oral administration and typically lasts between 3 and 8 hours.<unk>  is hydrolyzed by plasma butyrylcholinesterase (BChE) to the metabolite 4-(butylamino)benzoic acid (BABA) as well as polyethylene glycol monomethyl esters. Like many other local anesthetic esters, the hydrolysis of the parent compound is rapid. There are concerns that those with pseudocholinesterase deficiencies may have an increased sensitivity to<unk>  as this hydrolysis is impaired, leading to increased levels of circulating medication.
Benzonatate
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