Benzonatate

Benzonatate is a prescription non-opioid alternative for the symptomatic relief of cough.[1][3] It has been shown to improve cough associated with a variety of respiratory conditions including asthma, bronchitis, pneumonia, tuberculosis, pneumothorax, opiate-resistant cough in lung cancer, and emphysema.[1][9][10]

Benzonatate also reduces the consistency and volume of sputum production associated with cough in those with chronic obstructive pulmonary disorder (COPD).[9]

Compared to codeine, benzonatate has been shown to be more effective in reducing the frequency of induced cough in experiments.[1]

Benzonatate does not treat the underlying cause of the cough.[11]

Benzonatate has been shown to have use in the suppression of hiccups.[2]

Benzonatate acts as a local anesthetic and the liquid inside the capsule can be applied in the mouth to numb the oropharynx for awake intubation.[1] However, there can be life-threatening adverse effects when the medication is absorbed by the oral mucosa, including choking, hypersensitivity reactions, and circulatory collapse.[1]

Benzonatate is structurally related to anesthetic medications of the para-aminobenzoic acid (PABA) class which includes procaine and tetracaine.[4][13] Procaine and tetracaine, previously used heavily in the fields of dentistry and anesthesiology, have fallen out of favor due to allergies associated with their metabolites.[13] Similarly, severe hypersensitivity reactions to benzonatate have been reported and include symptoms of laryngospasm, bronchospasm, and cardiovascular collapse.[4][14] These reactions are possibly associated with chewing, sucking, or crushing the capsule in the mouth.[4][13]

Benzonatate should be swallowed whole.[4] Crushing or sucking on the liquid-filled capsule, or "softgel," will cause release of benzonatate from the capsule and can produce a temporary local anesthesia of the oral mucosa.[4] Rapid development of numbness of the tongue and choking can occur.[4][13] In severe cases, excessive absorption can lead to laryngospasm, bronchospasm, seizures, and circulatory collapse.[4][13] This may be due to a hypersensitivity reaction to benzonatate or a systemic local anesthetic toxicity, both of which have similar symptoms.[13] There is a potential for these adverse effects to occur at a therapeutic dose, that is, a single capsule, if chewed or sucked on in the mouth.[13]

Isolated cases of bizarre behavior, mental confusion, and visual hallucinations have been reported during concurrent use with other prescribed medications.[4] Central nervous system effects associated with other para-aminobenozic acid (PABA) derivative local anesthetics, for example procaine or tetracaine, could occur with benzonatate and should be considered.[1]

Safety and efficacy in children below the age of 10 have not been established.[4] Accidental ingestion resulting in death has been reported in children below the age of 10.[4] Benzonatate may be attractive to children due to its appearance, a round-shaped liquid-filled gelatin capsule, which looks like candy.[14][15] Chewing or sucking of a single capsule can cause death of a small child.[4][15] Signs and symptoms can occur rapidly after ingestion (within 15–20 minutes) and include restlessness, tremors, convulsions, coma, and cardiac arrest.[15] Death has been reported within one hour of ingestion.[12][15]

In the U.S., benzonatate is classified by the U.S. Food and Drug Administration (FDA) as pregnancy category C.[5] It is not known if benzonatate can cause fetal harm to a pregnant woman or if it can affect reproduction capacity.[4][5] Animal reproductive studies have not yet been conducted with benzonatate to evaluate its teratogenicity.[4] Benzonatate should only be given to a pregnant woman if it is clearly needed.[4][5]

It is not known whether benzonatate is excreted in human milk.[4][5] It is recommended to exercise caution when benzonatate is given to a nursing woman.[4][5]

Similar to other local anesthetics, benzonatate is a potent voltage-gated sodium channel inhibitor.[13] After absorption and circulation to the respiratory tract, benzonatate 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.[1][2] This damps their activity and reduces the cough reflex.[1][4] Benzonatate also has central antitussive activity on the cough center in central nervous system at the level of the medulla.[1][9] However, there is minimal inhibition of the respiratory center at a therapeutic dosage.[4]

The antitussive effect of benzonatate begins within 15 to 20 minutes after oral administration and typically lasts between 3 and 8 hours.[4][9]

Benzonatate is hydrolyzed by plasma butyrylcholinesterase (BChE) to the metabolite 4-(butylamino)benzoic acid (BABA) as well as polyethylene glycol monomethyl ethers.[13] Like many other local anesthetic esters, the hydrolysis of the parent compound is rapid.[13] There are concerns that those with pseudocholinesterase deficiencies may have an increased sensitivity to benzonatate as this hydrolysis is impaired, leading to increased levels of circulating medication.[13]

In the United States between 2004 and 2009, prescriptions increased 50% from 3.1 million to 4.7 million, the market share of benzonatate among antitussives increased from 6.3% to 13%, and the estimated number of children under the age of 10 years receiving benzonatate increased from 10,000 to 19,000.[13][11] Throughout this same period, greater than 90% of prescriptions were given to those 18 or older.[11] The majority of prescriptions were given by general, family, internal, and osteopathic physicians with pediatricians account for about 3% of prescribed benzonatate.[11]

In 2020, it was the 157th most commonly prescribed medication in the United States, with more than 3 million prescriptions.[7][8]

Tessalon is a brand name version of benzonatate manufactured by Pfizer, Inc.[13][11] It is available as perles or capsules.[17] Zonatuss was a brand name manufactured by Atley Pharmaceuticals, Inc. and Vertical Pharmaceuticals, Inc.[18][19]