Benzonatate
Encyclopedia
Benzonatate or 2,5,8,11,14,17,20,23,26-nonaoxaoctacosan-28-yl para-butylaminobenzoate is a non-opioid
oral antitussive (cough suppressant) with effects that last from 6 to 8 hours. Since it is not an opioid, benzonatate is not prone to abuse like some other cough medications such as codeine
. Benzonatate was approved by the U.S. Food and Drug Administration
(FDA) in 1958.
, chemically related to other ester
local anesthetics such as procaine
and tetracaine
.
s in the lower airway and lung, thereby reducing the drive to cough after taking a deep breath.
It has been used in small doses as a topical anesthetic for mouth or pharyngeal pain. This practice is not recommended, because the oropharyngeal anesthesia may result in pulmonary aspiration
.
Due to its potency and potential toxicity, the capsules must be swallowed intact in order to allow slower release of the medication.
. There are numerous reports of death related to overdose of benzonatate, mostly in children.
Para-aminobenzoic acid (PABA) is a metabolite
of the ester class of local anesthetics, which includes benzonatate, as well as procaine
and tetracaine
. Severe allergic reactions have been reported in patients who are allergic to PABA. Severe sensitivity reactions to benzonatate have resulted in respiratory side effects such as bronchospasm
, laryngospasm
and cardiac arrest
.
Excessive absorption of benzonatate (a local anesthetic) in the oral mucosa will result in the rapid development of numbness of the mouth and throat. In extreme cases, the mouth and pharynx may become so numb that pulmonary aspiration
may occur.
Excessive absorption of benzonatate will occur if the gelcaps are chewed or allowed to dissolve in the mouth. This may lead to an overdose of the drug. Overdose of benzonatate may manifest as central nervous system side effects, such as mental confusion and hallucination, restlessness and tremors, followed in extreme cases by convulsions and death.
Opioid
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...
oral antitussive (cough suppressant) with effects that last from 6 to 8 hours. Since it is not an opioid, benzonatate is not prone to abuse like some other cough medications such as codeine
Codeine
Codeine or 3-methylmorphine is an opiate used for its analgesic, antitussive, and antidiarrheal properties...
. Benzonatate was approved by the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA) in 1958.
Chemical structure
Benzonatate is a butylamineN-Butylamine
n-Butylamine is an organic compound with the formula CH3CH2CH2CH2NH2. This colourless liquid is one of the four isomeric amines of butane, the others being sec-butylamine, tert-butylamine and isobutylamine. At standard temperature and pressure, n-butylamine is a liquid having the fishy,...
, chemically related to other ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
local anesthetics such as procaine
Procaine
Procaine is a local anesthetic drug of the amino ester group. It is used primarily to reduce the pain of intramuscular injection of penicillin, and it was also used in dentistry. Owing to the ubiquity of the trade name Novocain, in some regions procaine is referred to generically as novocaine...
and tetracaine
Tetracaine
Tetracaine is a potent local anesthetic of the ester group...
.
Pharmacologic mechanisms of action
Benzonatate is thought to act as a local anesthetic, decreasing the sensitivity of stretch receptorStretch receptor
Stretch receptors are mechanoreceptors responsive to distention of various organs and muscles, and are neurologically linked to the medulla in the brain stem via afferent nerve fibers...
s in the lower airway and lung, thereby reducing the drive to cough after taking a deep breath.
Indications
An antitussive, benzonatate is employed to reduce coughing in various respiratory conditions such as, bronchitis, emphysema, influenza, and pneumonia. It should never be used to suppress a productive cough or in place of treatment of the actual cause of cough, such as asthma treatment.It has been used in small doses as a topical anesthetic for mouth or pharyngeal pain. This practice is not recommended, because the oropharyngeal anesthesia may result in pulmonary aspiration
Pulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
.
Dosage and administration
Benzonatate is sold as yellow or blue 100 mg and 200 mg softgel capsules. Initial dose is one 100 mg perle (gelcap) by mouth, 3 times a day. Dosage may be increased as necessary, up to a maximum of 600 mg per day.Due to its potency and potential toxicity, the capsules must be swallowed intact in order to allow slower release of the medication.
Adverse reactions
Reported side effects include drowsiness, dizziness, and dysphagiaDysphagia
Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia....
. There are numerous reports of death related to overdose of benzonatate, mostly in children.
Para-aminobenzoic acid (PABA) is a metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
of the ester class of local anesthetics, which includes benzonatate, as well as procaine
Procaine
Procaine is a local anesthetic drug of the amino ester group. It is used primarily to reduce the pain of intramuscular injection of penicillin, and it was also used in dentistry. Owing to the ubiquity of the trade name Novocain, in some regions procaine is referred to generically as novocaine...
and tetracaine
Tetracaine
Tetracaine is a potent local anesthetic of the ester group...
. Severe allergic reactions have been reported in patients who are allergic to PABA. Severe sensitivity reactions to benzonatate have resulted in respiratory side effects such as bronchospasm
Bronchospasm
Bronchospasm or a bronchial spasm is a sudden constriction of the muscles in the walls of the bronchioles. It is caused by the release of substances from mast cells or basophils under the influence of anaphylatoxins...
, laryngospasm
Laryngospasm
In medicine, laryngospasm is an uncontrolled/involuntary muscular contraction of the laryngeal cords. The condition typically lasts less than 60 seconds, and causes a partial blocking of breathing in, while breathing out remains easier. It may be triggered when the vocal cords or the area of the...
and cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
.
Excessive absorption of benzonatate (a local anesthetic) in the oral mucosa will result in the rapid development of numbness of the mouth and throat. In extreme cases, the mouth and pharynx may become so numb that pulmonary aspiration
Pulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
may occur.
Excessive absorption of benzonatate will occur if the gelcaps are chewed or allowed to dissolve in the mouth. This may lead to an overdose of the drug. Overdose of benzonatate may manifest as central nervous system side effects, such as mental confusion and hallucination, restlessness and tremors, followed in extreme cases by convulsions and death.