Respiratory Drugs: Part 2

Reviewing More Respiratory Drugs

This article follows part 1, which introduced inhalers, corticosteroids, bronchodilators, and theophylline. Another important aspect of respiratory care is addressing different types of cough. This article will review the available medications for a cough.

There are three main classes of respiratory medications that act on the patient’s cough: mucolytics, expectorants, and antitussives.

Related Video – Respiratory Drugs – Part 1

1) Mucolytics

The most common mucolytic drug is acetylcysteine. This class of drugs acts directly on the mucus. A mucolytic drug attacks the chemical structure of mucus to make it less tenacious. It thins the mucus. 

Mucolytics are often used in combination with antibiotics because antibiotics are more effective on thinner mucus.

A mucolytic is useful for a patient who is having a difficult time coughing anything up. It makes it easier for the patient to cough the sputum up. Or, for a patient on a ventilator or with a tracheostomy, it will be easier to suction out those secretions.

Who takes mucolytics? One example is a patient with chronic obstructive pulmonary disease (COPD) who presents with a respiratory infection and thick secretions they are unable to cough up. The mucolytics loosen those secretions to help the antibiotics fight the infection.

Patients with cystic fibrosis will also use mucolytics. Cystic fibrosis is a disease characterized by thick, tenacious secretions that clog the airways. The mucolytics loosen the secretions to help the patient breathe.

Characterized by inflammation in the airways, people with COPD may have a sputum-producing cough.

Read: Respiratory Drugs: Part 1

2) Expectorants

The next class is the expectorants. One of the most common expectorants is guaifenesin. Expectorants help the patient cough up secretions. 

Expectorants work indirectly since they moisten the respiratory tract so that it is easier for a patient who already has a productive cough to cough up the secretions.

Expectorants work indirectly to loosen the present secretions. That helps the patient cough to eliminate the secretions.

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3) Antitussives

Antitussives are the final class of medications. They can be narcotics, such as codeine, or non-narcotics, such as dextromethorphan. Antitussives suppress the cough. They are only used in patients with a dry cough because if the patient has a productive cough, they need to expel the mucus. 

How do antitussives work? Narcotic antitussives, such as codeine, work directly on the cough center located in the medulla and suppress the medulla from initiating a cough reflex. Because it works directly on the medulla, it causes side effects such as drowsiness, lethargy, and sedation. These side effects need to be monitored.

The “cough center” of the brain is located in the medulla. Codeine works by suppressing the cough reflex in the medulla.

The non-narcotic antitussives, such as dextromethorphan, act on the respiratory tract. They reduce the response of the respiratory tract to stimulation by the medulla. Therefore, the non-narcotic antitussives do not work directly on the medulla, but they decrease the responsiveness to stimulation. Compared to the narcotic antitussives, the non-narcotic antitussives do not cause as much sedation or drowsiness.

Dextromethorphan is an antitussive, or cough suppressant, used for dry cough.

Antitussives are not given to patients with a productive cough, as the patient needs to be able to get those secretions out. Instead, they are prescribed to patients with a nonproductive, hacking cough that is causing harm.

Treating a cough is an essential aspect of respiratory care. The medications used to treat cough are mucolytics, expectorants, and antitussives. It is important to understand the mechanism of each of these medications, so the right one is prescribed based on the patient’s presentation and needs.