The Hospice Clinician Blog

Coughing is beneficial to help clear the airways of secretions and foreign matter. It should generally be encouraged. Coughing is considered problematic when the cough is:

? Ineffective

? Interfering with sleep, rest, eating, or social activity

? Causing other adverse symptoms such as vomiting, muscle strain, rib fracture, headache, syncope

There are two primary categories of drugs that may be employed to treat inappropriate coughing: protussives and antitussives.

Protussives, also known as expectorants, work by making the sputum less thick and tenacious so that the patient can more effectively expectorate it. Protussives do not impair the cough reflex. As the name suggests, antitussives interfere with the normal cough reflex. The decision-tree for drug treatment selection starts with the question of whether the patient's cough is "wet" or "dry".

In a hospice patient with a wet cough (sputum, secretions are present) a protussive may help the patient expectorate material that may be irritating the throat and reduce the frequency of coughing. A protussive agent, such as guaifenesin, is the appropriate initial therapy for wet cough and response will be enhanced if the level of hydration can be increased as well. An antitussive may be added later if there is a lack of desired response. For dry cough the initial treatment step is an antitussive.

Antitussives can be divided into peripherally acting agents and centrally acting ones. Peripherally active agents include the demulcents, which are (non-drug) syrup or glycerol containing products such as the various OTC lozenges that work by stimulating the production of saliva and soothing the oropharynx, thus interfering with the cough reflex. The therapeutic response to these products is relatively short-lived.

Local anesthetic solutions such as lidocaine and bupivicaine are other examples of peripherally active antitussives. They act by inhibiting the sensory nerves in the airways involved in the cough reflex. The use of these products is very limited due to bitter taste, oropharyngeal numbness, and a short duration of action (approx. 30min).

Benzonatate (Tessalon) is chemically related to the local anesthetics and is believed to act by peripherally inhibiting the stretch receptors along the airways. It has a longer duration than the local anesthetics, in the range of 6 to 8 hours. It also has the advantage of being available in a capsule form for added convenience and this dosage-form also eliminates the possibility of non-compliance due to bad-taste.

The centrally acting antitussives are primarily opioids or opioid derivatives such as dextromethorphan. These drugs act by suppressing the cough reflex center in the brain stem. Codeine and hydrocodone are the most common opioid drugs found in cough preparations, however, all opioids have significant antitussive activity.

In hospice and palliative care, patients are often already receiving strong opioids. If a PRN dose of the regular opioid relieves the cough it may continue to be used as a PRN or the hospice patient's routine opioid dose may be increased accordingly. If no improvement is seen with the current opioid PRN dose, there is generally no advantage to adding another opioid such as codeine for cough suppression.

Benzonatate or dextromethorphan are often the initial antitussives of choice due to good efficacy and low incidence of side effects. Opioids are more effective but present a potential for more significant side effects. For patients with persistent cough, unresponsive to opioids, the antidepressant, paroxetine (Paxil) 10-20mg daily, has been demonstrated to be very effective in series of patients.⁽¹⁾

Ideally, the primary cause of the hospice patient's cough should be identified and specifically addressed, e.g. drug discontinuation in the case of ACE-inhibitor induced cough or antibiotics for infection-related cough. However, when the cause of the cough is unknown or not amenable to treatment, it is appropriate to institute measures to suppress the cough.

(1) Zylicz, Krajnik J Pain Symptom Manage.2004;27(2):180-184

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