Antitussives
Antitussives
Antitussive drugs suppress or inhibit coughing.
Types of antitussives
Antitussives are typically used to treat dry, nonproductive coughs. The major antitussives include:
- benzonatate
- codeine
- dextromethorphan
- hydrocodone bitartrate.
Pharmacokinetics
Antitussives are absorbed well through the GI tract, metabolized in the liver, and excreted in urine.
Pharmacodynamics
Antitussives act in slightly different ways.
Removing the sensation
Benzonatate acts by anesthetizing stretch receptors throughout the bronchi, alveoli, and pleurae.
Taking direct action
Codeine, dextromethorphan, and hydrocodone suppress the cough reflex by direct action on the cough center in the medulla of the brain, thus lowering the cough threshold.
Pharmacotherapeutics
The uses of these drugs vary slightly, but each treats a serious, nonproductive cough that interferes with a patient’s ability to rest or carry out activities of daily living.
Put it to the test
Benzonatate relieves cough caused by pneumonia, bronchitis, the common cold, and chronic pulmonary diseases such as emphysema. It can also be used during bronchial diagnostic tests, such as bronchoscopy, when the patient must avoid coughing.
Top of the charts
Dextromethorphan is the most widely used cough suppressant in the United States and may provide better antitussive effects than codeine. Its popularity may stem from the fact that it isn’t associated
with sedation, respiratory depression, or addiction at usual doses
with sedation, respiratory depression, or addiction at usual doses
.
Warning!
Adverse reactions to antitussives
Benzonatate
Benzonatate needs to be swallowed whole; chewing or crushing it can produce a local anesthetic effect in the mouth and throat, which can compromise the airway. These reactions can also occur when taking benzonatate:
- dizziness
- sedation
- headache
- nasal congestion
- burning in the eyes
- GI upset or nausea
- constipation
- rash, eruptions, or itching
- chills
- chest numbness.
Opioid antitussives
The most common reactions include nausea, vomiting, sedation, dizziness, and constipation. Other reactions include:
- pupil constriction
- bradycardia
- tachycardia
- hypotension
- stupor
- seizures
- circulatory collapse
- respiratory arrest.
Use opioid antitussives cautiously in the patient with current or previous opioid addiction and in the patient with a respiratory disorder, such as asthma or chronic obstructive pulmonary disease.
For really tough coughs
The opioid antitussives (typically codeine and hydrocodone) are reserved for treating an intractable cough.
Drug interactions
Antitussives may interact with other drugs.
- Codeine and hydrocodone may cause excitation, an extremely elevated temperature, hypertension or hypotension, and coma when taken with monoamine oxidase inhibitors (MAOIs).
- Dextromethorphan use with MAOIs may produce excitation, an elevated body temperature, hypotension, and coma.
- Codeine taken with other central nervous system (CNS) depressants, including alcohol, barbiturates, phenothiazines, and sedative-hypnotics, may increase CNS depression, resulting in drowsiness, lethargy, stupor, respiratory depression, coma, and even death
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