PTCB Guide to Respiratory MedicinesOct 19th, 2023
Introduction to Respiratory Medicines
8.3% of people in the United States have asthma. Of these 26.5 million people, 20.4 million are adults and 6.1 million are children.
Given the prevalence of asthma and COPD in the US, pharmacy technicians are expected to have a thorough knowledge of respiratory medicines.
Technicians should expect at least a few questions on respiratory medicines. Here, we have put together a neat and effective PTCB guide to respiratory medicines – covering the basic but essential details that all technicians are expected to know.
Throughout this guide, we will study the following seven respiratory drug classes:
- Beta-2 agonists
- Inhaled / nasal corticosteroids
- Leukotriene antagonists
- Inhaled anticholinergics
Note that whilst this guide is not intended to be exhaustive, it does provide a thorough platform upon which you can build your knowledge further. We start this PTCB guide to respiratory medicines by studying one of the most commonly prescribed respiratory medicines – antihistamines.
Histamine plays a central role in causing allergic asthma, a mediator that is released from mast cells in the body. As the allergic response is partly caused by histamine, blocking this neurotransmitter can help alleviate symptoms and asthma and COPD.
Histamine causes airway obstruction through smooth muscle contraction of the lung. It also increases bronchial secretions and causes airway mucosal inflammation. All three factors worsen symptoms for patients with asthma, COPD, or other respiratory diseases.
Antihistamines have been used for decades. The evidence-base for their effectiveness is very high. In terms of side effects, antihistamines are very well-tolerated. First-generation antihistamines tend to impact the central nervous system, hence why they are associated with drowsiness. They are also more likely to cause dry mouth compared to second-generation antihistamines.
Beta-2 agonists are highly effective drugs used in the management of both asthma and COPD.
Beta-2 receptors can be found on the lung surface. When activated, they cause smooth muscle relaxation, helping the patient to breathe (agonism = receptor activation). This effect alleviates the breathlessness that many patients experience with respiratory conditions.
Side effects of beta-2 agonists include palpitations, anxiety, increased heart rate, and fine tremors.
New, ultra-long-acting drugs have also been developed. Examples include indacaterol and vilanterol.
We already studied beta-2 agonists in detail. Take a few minutes to learn more about beta-2 agonists.
Inhaled / Nasal Corticosteroids
Steroid inhalers are typically used in combination with other drugs, such as beta-2 agonists.
Corticosteroids are used in asthma and COPD for the following reasons:
• To reduce mucosal inflammation
• To widen airways
• To reduce mucus secretion
This improves symptoms whilst reducing flare-ups for patients with COPD.
Corticosteroids have an immunosuppressive effect, so one of the most common side effects is oral thrush (oral candidiasis). They can also cause a hoarse voice.
Inhaled corticosteroids are administered to patients in aerosol (metered-dose inhaler) or dry powder form. Patients must be instructed on how to use their inhaler properly and effectively, and this technique should be checked at every consultation.
Leukotriene Receptor Antagonists
Leukotriene receptor antagonists are less commonly used than antihistamines, beta-2 agonists, or corticosteroids.
However, they are nonetheless an effective drug treatment option for patients who may not have responded to other therapy, or who require add-on therapy to their existing medicines.
Leukotriene receptor antagonists work by blocking the action of leukotriene D4 in the lungs – reducing inflammation and causing smooth muscle relaxation.
Montelukast is the fourteenth most prescribed medicine in the United States. Note that it has a black-box warning for causing neuropsychiatric adverse effects.
Anticholinergic drugs block the effects of the neurotransmitter,acetylcholine.
By blocking acetylcholine from interacting with its receptor, it causes the following effects:
• Increased heart rate and conduction
• Reduced smooth muscle tone, including in the lungs
• Reduced mucus secretions from glands, including in the lungs
It’s these two latter effects that make anticholinergic drugs effective in the management of asthma and COPD.
Apart from causing a dry mouth, they are very well-tolerated drugs.
Decongestants are widely dispensed medicines used for nasal congestion, to alleviate congestion and help the patient breathe normally.
There is a limit to how much pseudoephedrine a patient can purchase each day and within a single month. A patient may purchase no more than 9 grams per 30-day period (sales limit per day is 3.6 grams).
Antitussives are cough suppressants – drugs that suppress the cough reflex.
|Codeine (with guaifenesin)||Cheracol with Codeine|
Guaifenesin is an example of an expectorant – a drug used to make coughing easier whilst also enhancing the production of mucus and phlegm in the upper respiratory tract. It is commonly used alongside other cough and cold medicine – in the example above, codeine.
Respiratory medicines are routinely tested on the PTCB exam.
Throughout this guide, we sought to put together the most comprehensive minimum details that pharmacy technicians are expected to know.
Whilst technicians are not expected to understand each drug class in intimate detail, you are expected to know the basics. This means knowing about each drug class name, briefly how each class works, and any major side effects or major drug interactions associated with that class.
Technicians should also be aware of inhalers and the correct technique that patients are expected to follow.
Have these details in mind, and you can be sure to succeed at any questions that may arise on respiratory medicines for the pharmacy technician exam.
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