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 emphyse-ma. 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.

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) depres-sants, including alcohol, barbiturates, phenothiazines, and seda-tive-hypnotics, may increase CNS depression, resulting in drowsi-ness, lethargy, stupor, respiratory depression, coma, and even death. (See Adverse reactions to antitussives.)