Pharm, part 38: Gastrointestinal Medications - Antidiarrheals and Antiemetics

by Cathy Parkes September 10, 2021 Updated: September 14, 2021

Full Transcript

Hi, I'm Cathy with Level Up RN. In this video, I'm going to continue our coverage of gastrointestinal medications, and specifically, I'll be covering antidiarrheal and antiemetic medications. At the end of the video, I'm going to provide you guys a quiz to test your knowledge of some of the key points I'll be covering in this video. So definitely stay tuned for that. If you have our Pharmacology 2nd Edition Flashcards, definitely pull those out, so you can follow along as well.

Let's start with our antidiarrheal. So Loperamideis one antidiarrheal that I would know. It works by inhibiting peristalsis and increasing the transit time of fecal matter in the intestines. Side effects can include constipation, drowsiness, and dry mouth.

Another antidiarrheal agent that's going to be important to know is Diphenoxylate/Atropine. So it's a combination drug of these two medications. So this medication works by decreasing GI motility. Side effects include anticholinergic side effects because of that Atropine component of this medication. So anticholinergic side effects can include constipation, urinary retention, and dry mouth. Other side effects can include dizziness, as well as the risk for dependence because the first part of that medication, Diphenoxylate, is actually, chemically related to a narcotic, and it can cause a feeling of euphoria. So they combined it with Atropine such that, if you take too much of this medication, you're going to get those yucky anticholinergic side effects. So it really discourages abuse of this medication. So with either of these antidiarrheal agents, so Loperamide or Diphenoxylate/Atropine, dry mouth is definitely a side effect. So you want to encourage your patient to suck on hard candy or chew gum to help alleviate that side effect.

Next, we have our antiemetics. So these are medications that are used to treat nausea and vomiting, and I know all about these medications because I had hyperemesis when I was pregnant. So they tried all of these things pretty much to no avail. But I do know about them. So let's go over the key meds I think you need to know.

The first one is Ondansetron. So this is used to treat nausea and vomiting, and it works by blocking that serotonin receptors in the CTZ, which is the chemoreceptor trigger zone. Side effects can include headache, constipation or diarrhea, as well as QT prolongation. So because of that side effect of QT prolongation, we're going to want to monitor our patients EKG to check for that.

A couple of other medications that are used to treat nausea and vomiting include Promethazine and Maclacin. So these medications can not only be used for nausea and vomiting, they can also be used for motion sickness. They work by blocking the effects of histamine, and they also have anticholinergic activity. Side effects can include drowsiness and dry mouth. So if we are administering an antiemetic for a patient who is receiving chemotherapy, which can obviously cause nausea and vomiting, we want to administer the antiemetic prior to therapy versus treating nausea and vomiting that is already occurring. So we want to get ahead of the situation.

Our little cool chicken hint for remembering Ondansetron is that I threw up on Dan and better get me some Ondansetron. So there's anyone named Dan who is watching this video, you should leave me a comment. Let me know how you feel about my hint, or if you've ever thrown up on somebody named Dan, I'd love to hear about that, too. So definitely leave me a comment.

Next, let's talk about the prokinetic agent, Metoclopramide. So Metoclopramide can be used to treat nausea and vomiting, as well as a disorder called gastroparesis. So gastroparesis is typically caused by diabetes, and it results in delayed gastric emptying. Metoclopramide can also be used to treat GERD. It works by accelerating gastric emptying. So in the case of nausea and vomiting, it's attempting to get the stomach contents down into the intestines before you have a chance to throw it up. Side effects of Metoclopramide can include drowsiness, GI upset, as well as extrapyramidal symptoms. So these extrapyramidal symptoms may include muscle rigidity, tremors, and tardive dyskinesia. So tardive dyskinesia is where the patient has these involuntary muscle movements. So Metoclopramide actually carries a black box warning because of the side effect of tardive dyskinesia. In terms of patient teaching, you want them to take this medication 30 minutes before meals and at bed time.

All right, you guys ready for a quiz? I have three questions for you. First question; what antidiarrheal agent can cause anticholinergic side effects and result independence? The answer is Diphenoxylate/Atropine. Second question; what antiemetic carries the risk for QT prolongation? The answer is Ondansetron. Third question; what antiemetic is used to treat gastroparesis by accelerating gastric emptying. The answer is Metoclopramide.

Hope you did well on that quiz. If you like my quiz questions, and this video was helpful for you, be sure to leave me a comment and like this video as well. Take care and good luck studying.

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