Absorption, Distribution and Excretion
Following oral administration, benzonatate enters the systemic circulation via gastrointestinal absorption. The Cmax of benzonatate following oral administration of 100 mg in healthy Chinese volunteers was 1063 ± 460 ng/mL.
There is limited information on the route of elimination of benzonatate.
There is limited information on the volume of distribution of benzonatate.
There is limited information on the clearance of benzonatate.

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Metabolism / Metabolites
Benzonatate is hydrolyzed to the major metabolite 4-(butylamino)benzoic acid (BABA) by plasma butyrylcholinesterase (BChE).

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Biological Half-Life
The half life of benzonatate following oral administration of 100 mg in healthy Chinese volunteers was 1.01 ± 0.41 h.

Protein Binding
There is limited information on the protein binding profile of benzonatate.

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Interactions
Benzonatate is chemically related to anesthetic agents of the para-amino-benzoic acid class (e.g. procaine; tetracaine) and has been associated with adverse CNS effects possibly related to a prior sensitivity to related agents or interaction with concomitant medication.

[1]. Benzonatate toxicity in a teenager resulting in coma, seizures, and severe metabolic acidosis. J Pediatr Pharmacol Ther. 2012;17(3):270-273.

[2]. The Antitussive Benzonatate Is Not Tumorigenic in Rodent Carcinogenicity Studies. Toxicol Pathol. 2018;46(6):683-692.

Benzonatate is the ester obtained by formal condensation of 4-butylaminobenzoic acid with nonaethylene glycol monomethyl ether. Structurally related to procaine and benzocaine, it has an anaesthetic effect on the stretch sensors in the lungs, and is used as a non-narcotic cough suppressant. It has a role as an antitussive and an anaesthetic. It is a benzoate ester, a substituted aniline and a secondary amino compound. It is functionally related to a 4-(butylamino)benzoic acid and a nonaethylene glycol monomethyl ether.
Benzonatate is an oral antitussive drug used in the relief and suppression of cough in patients older than ten years of age. Currently, benzonatate is the only non-narcotic antitussive available as a prescription drug. It works to reduce the activity of cough reflex by desensitizing the tissues of the lungs and pleura involved in the cough reflex. Benzonatate was approved by the FDA in 1958 under the market name Tessalon Perles. Because its chemical structure resembles that of the anesthetic agents in the para-amino-benzoic acid class (such as [procaine] and [tetracaine]), benzonatate exhibits anesthetic or numbing action. Although it not prone to drug misuse or abuse, benzonatate is associated with a risk for severe toxicity and overdose, especially in children.
Benzonatate is a Non-narcotic Antitussive. The physiologic effect of benzonatate is by means of Decreased Tracheobronchial Stretch Receptor Activity.
Benzonatate is a synthetic butylamino-benzoate derivative related to tetracaine and a peripherally acting antitussive, nonnarcotic Benzonatate reduces the cough reflex by anesthetizing and depressing mechanoreceptors in the respiratory passages, lungs, and pleura. It is recommended for cough relief in the common cold, bronchitis, pneumonia, and for chronic cough such as in asthma. (NCI04)
See also: Ethylene Oxide (has monomer).

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Drug Indication
Benzonatate is indicated for the symptomatic relief of cough.

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Mechanism of Action
Benzonatate is a local anesthetic drug that acts peripherally by anesthetizing and reducing the activity of vagal stretch receptors or nerve fibres located in the respiratory passages, lungs, and pleura. Once the stretch receptors are stimulated, they send impulses to the cough centre located in the medulla via an afferent pathway consisting of sensory nerve fibres or the vagus nerve. The efferent signal is then generated that sends impulses to the expiratory muscles to produce a cough. Anesthetizing these receptors by benzonatate results in the inhibition of the cough reflex activity and cough production. Benzonatate also inhibits the transmission of impulses of the cough reflex in the vagal nuclei of the medulla. There are several proposed mechanisms of benzonatate; it is also a potent voltage-gated sodium channel inhibitor.
Benzonatate apparently inhibits cough production by anesthetizing stretch receptors of vagal afferent fibers in the bronchi, alveoli, and pleura that mediate the cough reflex; the drug also suppresses transmission of the cough reflex at the level of the medulla where the afferent impulse is transmitted to the motor nerves. The relationship between local anesthetic action and peripheral action on sensory nerve endings is not clear.

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Therapeutic Uses
Antitussive Agents
Tessalon is indicated for the symptomatic relief of cough. /Included in US product label/

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Drug Warnings
Accidental ingestion of Tessalon resulting in death has been reported in children below age 10. Signs and symptoms of overdose have been reported within 15-20 minutes and death has been reported within one hour of ingestion. If accidental ingestion occurs, seek medical attention immediately
Safety and effectiveness in children below the age of 10 have not been established. Accidental ingestion resulting in death has been reported in children below age 10. Keep out of reach of children.
Severe hypersensitivity reactions (including bronchospasm, laryngospasm and cardiovascular collapse) have been reported which are possibly related to local anesthesia from sucking or chewing the capsule instead of swallowing it. Severe reactions have required intervention with vasopressor agents and supportive measures.
Benzonatate is chemically related to anesthetic agents of the para-amino-benzoic acid class (e.g. procaine; tetracaine) and has been associated with adverse CNS effects possibly related to a prior sensitivity to related agents or interaction with concomitant medication.
For more Drug Warnings (Complete) data for Benzonatate (8 total), please visit the HSDB record page.

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Pharmacodynamics
Benzonatate suppresses cough associated with both acute and chronic respiratory conditions. Its works by desensitizing the pulmonary stretch receptors involved in the cough reflex. There are limited clinical trials of benzonatate; however, earlier studies demonstrated inhibition of experimentally-induced cough and subjectively-measured pathological cough by benzonatate. Benzonatate has no inhibitory effects on the respiratory center in recommended dosage. Its onset of action is within 15 to 20 minutes following administration and its duration of effect is about 3 to 8 hours.

C30H53NO11

603.74192

603.362

C, 59.68; H, 8.85; N, 2.32; O, 29.15

104-31-4

119568-55-7 (HCl);104-31-4;

7699

Colorless to light yellow oily liquid

1.096 g/cm3

346.3ºC

9.98E-17mmHg at 25°C

1.495

2.907

1

12

33

42

565

0

CCCCNC1=CC=C(C=C1)C(=O)OCCOCCOCCOCCOCCOCCOCCOCCOCCOC

MAFMQEKGGFWBAB-UHFFFAOYSA-N

InChI=1S/C30H53NO11/c1-3-4-9-31-29-7-5-28(6-8-29)30(32)42-27-26-41-25-24-40-23-22-39-21-20-38-19-18-37-17-16-36-15-14-35-13-12-34-11-10-33-2/h5-8,31H,3-4,9-27H2,1-2H3

2-[2-[2-[2-[2-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethoxy]ethoxy]ethoxy]ethoxy]ethoxy]ethyl 4-(butylamino)benzoate

Benzonatate; Tessalon; KM65; KM 65; KM-65; Exangit; Ventussin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~165.63 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.14 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.14 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.14 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)