Pharmacology, part 4: Respiratory Medications - Expectorants, Mucolytics, Decongestants, Antihistamines

by Cathy Parkes April 28, 2020

Full Transcript

Alright. In this video, we are going to finish up with our key respiratory medications. I will be talking about expectorants, mucolytics, decongestants, as well as antihistamines. So let's first talk about our expectorants. A key medication that falls within this class is Guaifenesin. So guaif kind of sounds like cough, which is my way of remembering that Guaifenesin is used for a nonproductive cough associated with some kind of respiratory infection. It works by reducing the viscosity of the secretions. So it helps to thin the secretions which makes your cough more productive. So side effects are usually pretty minimal but can include GI upset as well as a little dizziness. In terms of patient teaching, you want to teach your patient to take this medication with a full glass of water.

Alright. Now let's talk about mucolytics. So the key medication in this class that I'd be familiar with is acetylcysteine, or Mucomyst is the brand name. So this medication is used for pulmonary disorders that have thick mucus secretions, for example, cystic fibrosis. It can also be used as an antidote for acetaminophen overdose. So acetylcysteine can be used for an acetaminophen overdose and acetaminophen is Tylenol. So the mode of action of acetylcysteine is to break down the molecules in the mucus to help it become less viscous. So side effects can include bronchospasm, however, so you really want to use this medication cautiously in asthma patients. It can also cause nausea and vomiting as well as rash. And you also want to give your patient a heads up that this medication kind of smells like rotten eggs. So one student gave me a little tip. Acetylcysteine starts with A, and this medication also smells like something that starts with A. So if that helps you to remember that, then that's great.

Alright. Now let's talk about decongestants. The two decongestants that I would be familiar with include pseudoephedrine and phenylephrine. So the way I remember pseudoephedrine is that I am fed up with my congestion, so I'm going to take pseudoephedrine. Pseudoephedrine is the generic name for Sudafed, which you may be more familiar with. It is used for rhinitis or nasal congestion. It works by causing vasoconstriction of the respiratory tract mucosa. Side effects are very common and include things such as nervousness, palpitations, weakness, insomnia, and possible rebound congestion when you stop using pseudoephedrine. So pseudoephedrine is actually one of the key ingredients in meth, so you can’t buy it just over the counter, like in the aisles of your drugstore. It's kept behind the pharmacy counter, so you need to go and ask for it. And they will ask to see your license and do some checking and make sure you're not buying too much of the stuff. So you can get it without a prescription, but it is behind the pharmacy counter because of all the meth issues in our country. Also, over-the-counter cold products that you can find in the aisles usually contain phenylephrine instead these days because they're really trying to limit the use of pseudoephedrine.

Alright. To wrap things up, we are going to last talk about antihistamines. So we have first-generation antihistamines, such as diphenhydramine, which is the generic name for Benadryl. And then we have second-generation antihistamines such as loratadine, which is Claritin, and cetirizine, which is Zyrtec. So these medications can be used for allergy symptoms such as rhinitis, which is that runny nose, itchy, watery eyes, or sneezing. Antihistamines can also be used for motion sickness as well as urticaria which is a fancy name for hives. So antihistamines work by competitively blocking H1 receptors which reduces the effect of histamine in the body. Side effects are more common with first-generation antihistamines. There's not a lot of big side effects with second-generation antihistamines. With first-generation, you will get side effects such as sedation, as well as anticholinergic side effects which include dry mouth, constipation, urinary retention as well as photosensitivity. So the way that I remember anticholinergic side effects is I remember the saying, "Can't pee. Can't see. Can't spit and can't poop." So these first-generation antihistamines definitely have those side effects. So if your patient is going to be taking diphenhydramine, or Benadryl, you're going to want to implement fall precautions because this medication causes sedation. So we need to keep our patients safe.

Okay. So that is it for our respiratory medications. I'd like to say that we will be able to get through our cardiovascular medications just as fast. But sadly, there's a big difference in the number of medications that are used for cardiovascular disorders versus respiratory. But we will get through it together, so hang in there with me. And I'll see you on my next video


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