PharmSmart: This Cough is Making Me Crazy!

By Seasons | January 12, 2021

Cough is one of the most common symptoms experienced by patients. We all have coughed at one point in our life. So why is coughing so common? Coughing is an essential protective function for our airways and lungs. It results from the stimulation of mechanical or chemical afferent nerve receptors in the bronchial tree.

It helps our body clear out irritants from our airways such as our throat and chest. Without it, we are at risk for the blockage of our airways by secretions and aspirated material predisposing us to infection, the collapse of a lung, and respiratory compromise. On the other hand, excessive coughing can adversely affect personal and work life, and often can cause the discomfort of the throat and chest wall. In severe cases, a cough can cause pain, dyspnea, incontinence, sleep disturbances and rib fractures! In most cases, cough is an expected and accepted manifestation of most diseases however persistent cough in the absence of other respiratory symptoms can be a sign of severe underlying disease.

Let’s consider a case… Mr. Johnson is a 68 year old man diagnosed with stage 4 non-small cell lung cancer. On admission to hospice he complains of pain in his left rib area (metastatic cancer), which is made considerably worse when he rolls onto his left side, or when he coughs. He has a pleural effusion which probably is responsible for his complaint of cough, chest heaviness/tightness, and being short of breath (he cannot lie flat, and he gets very winded when he walks). He tells you he just feels dreadful, but the worst is when he gets “in a coughing fit because my ribs are on FIRE!” He tells you he’s been swigging Robitussin DM right from the bottle and it doesn’t seem to be helping! Now what?

Assessing a cough

We can use the same PQRSTU model to assess a cough as we do for pain or other symptoms. The elements of symptom analysis applied to cough would be as follows:

P

Precipitating

Does anything in particular trigger the cough?

P

Palliating

Does anything you do relieve the cough (from a non-drug perspective)?

P

Previous treatment or therapy

What have you tried to treat the cough, how well did it work, and did you have any side effects?

Q

Quality

What’s the quality of cough? Productive (a “wet” cough) or nonproductive (or a “dry” cough)

R

Region/Radiation

This element doesn’t apply very well for a cough!

S

Severity

Would you rate the cough as mild, moderate or severe?

T

Temporal

How long have you had the cough (is it acute [lasting < 3 weeks], subacute [lasting 3-8 weeks], or chronic [lasting > 8 weeks]? Is the cough mostly during the daytime, mostly at night, or there is no consistent pattern?

U

You - Associated Symptoms

How does the cough affect you? What does the cough keep you from doing? Does it impact your sleep? Cause you to lose your breath or worsen your pain?

 

Causes of cough

Cough can be related to cancer; it could be a direct effect of the tumor (e.g., airway obstruction, atelectasis, esophagorespiratory fistula, superior vena cava syndrome, lymphangitic carcinomatosis) or an indirect effect of the tumor (e.g., pleural effusion, pericardial effusion, treatment-induced pneumonitis, bronchiectasis or aspiration). There are a variety of non-malignant causes of cough, as described below.

Acute cough arises mostly due to upper and lower respiratory tract infection (e.g., common cold, community-acquired pneumonia), aspiration, and inhalation of chemical irritants (smoke, fumes cleaning products). Less common causes of acute cough include heart failure (HF), hay fever (allergic rhinitis), occupational factors, pulmonary embolism, foreign bodies, and bronchiectasis. Acute cough that is due to respiratory infection usually resolves within 3 weeks in the vast majority (more than 90%) of patients.

Subacute cough arises mostly due to postinfectious cough. It can be a result of post viral airway inflammation with bronchial hyperresponsiveness, mucus hypersecretion or upper airway cough syndrome (postnasal discharge), or asthma.

Chronic cough arises mostly due to gastroesophageal reflux disease (GERD), postnasal drip from sinus infections or allergies, chronic lung conditions such as asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, interstitial lung diseases, upper airway cough syndrome (UACS) UACS, or drugs (ex: angiotensin-converting enzyme (ACE) inhibitor therapy). Additional testing might be required to identify the cause of chronic cough.

Mr. Johnson tells you his cough is dry and nonproductive. He’s had the cough for about a month and he would rate it as mild to moderate, but it causes screaming rib pain every time he coughs, which escalates the whole situation to severe in his opinion.

What are the treatment options?

Cough may resolve by itself, which does not seem to be the case with Mr. Johnson. In cases where it doesn’t resolve spontaneously, our treatment considerations should target the underlying cause of the cough and any other factors that could be exacerbating it.

Non-pharmacologic options may include repositioning to minimize coughing due to reflux or aspiration. Nebulized saline may help reduce dryness and irritation of airways. Chest PT may help the patient to expectorate mucus, as well as increased hydration as tolerated. Ingestion of honey, breathing exercises and cough suppression techniques may offer some relief.

For a mild cough, benzonatate (Tessalon Perles, 100-200 mg three times/day to a maximum of 600 mg/day) is a reasonable treatment option. Benzonatate acts to anesthetize stretch receptors in the lungs and pleura.

For a moderate to severe cough (e.g., cough interferes with sleep and does not respond to a peripherally active agents such as benzonatate), centrally active agents may be useful. Although most practitioners would reach for a dextromethorphan-containing product, the evidence shows it is of limited usefulness. Opioids are preferred agents for palliative care patients with a cough, even in opioid-naïve patients. Suggested regimens may include morphine, hydrocodone or oxycodone 5 mg every four hours. For opioid-tolerant patients, a 25-50% increase in the dose may be trialed to treat the cough. Codeine is often recommended, but evidence is limited and many patients experience significant nausea with codeine.

Alternatives to opioid therapy for a moderate to severe cough include gabapentin and pregabalin. Because these medications are sedating, it is advisable to start with a low dose and titrate every 1-3 days as tolerated until cough is controlled. A gabapentinoid may be used with opioid therapy, but this does increase the risk of sedation and opioid-related toxicity.

But wait – what about Mr. Johnson’s Robitussin DM? This is an interesting product – it contains two ingredients. Guaifenesin which is an expectorant – in other words, it’s thought to work by reducing the viscosity of secretions so they can be more easily coughed up. Dextromethorphan, on the other hand, acts by suppressing a cough. So putting them together in one bottle you have one medication that hypothetically acts to facilitate bringing up the secretions, and another medication to suppress the cough and secretions. So, how’s that working for you? Actually the data for guaifenesin is very weak as well, and for better effect, additional fluids would need to be administered which can be a challenge in a patient with advanced illness.

In Mr. Johnson’s case, he is already receiving MS Contin 30 mg po q12h and oral morphine solution 5 mg every 2 hours as needed (takes about 3-4 times per day, for a total daily morphine dose of 75-80 mg). Let’s suggest increasing the MS Contin to 45 mg po q12h and increasing the oral morphine solution to 10 mg every 2 hours as needed. Next steps may be adding low-dose gabapentin. And let’s make sure he’s on an appropriate adjuvant analgesic for the metastatic bone pain (such as a steroid or nonsteroidal anti-inflammatory drug!).

Suggested readings:

PharmSmart is a monthly article dedicated to best practices in drug management for patients nearing the end of life, with a little cheer and lightheartedness woven throughout. It is edited by Dr. Mary Lynn McPherson, PharmD. Dr. McPherson is the Executive Director of Advanced Post-Graduate Education in Palliative Care at University of Maryland. Dr. McPherson is a consultant pharmacist to Seasons, and answers complex medication questions for our clinical teams at all hours of the day or night. She is a nationally-recognized expert in medication management for hospice and palliative care patients.

This edition of PharmSmart was written with the assistance of Yeabsera Tadesse, student pharmacist.

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