Pharmacology, part 37: Gastrointestinal Medications - Laxatives

September 10, 2021 Updated: December 29, 2021 6 min read

Our coverage of the range of gastrointestinal medications continues with this look at the different types of laxatives. The Nursing Pharmacology video series follows along with our Pharmacology Second Edition Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.

Cool Chicken When you see this Cool Chicken, that indicates one of Cathy's silly mnemonics to help you remember. The Cool Chicken hints in these articles are just a taste of what's available across our Level Up RN Flashcards for nursing students!

Constipation

Laxatives are often prescribed to treat constipation. When a patient has constipation, it's important to provide additional teaching on how they can prevent constipation, rather than just administering laxatives. Preventative measures include increasing fluid and fiber intake. Encourage the patient to get up and move around as increasing their mobility can also help to stimulate peristalsis, the contraction of the stomach muscles and other muscles in the GI tract that move food along, which allows for digestion and bowel evacuation.

Stool softeners - docusate sodium (Colace), docusate calcium (Kaopectate)

Stool softeners, which include docusate sodium and docusate calcium, are medications used to treat and prevent constipation.

Stool softeners mode of action

Stool softeners work by drawing water into the stool, which helps to soften the stool.

Stool softeners side effects

Side effects of stool softeners like Colace and Kaopectate can include mild cramping and diarrhea.

Stool softeners patient teaching

When administering stool softeners like docusate sodium and docusate calcium, encourage the patient to take this medication with a full glass of water.

Cool Chicken The doc said if you ate more fiber, you wouldn’t need docusate to soften your stool!

Bulk forming laxatives - psyllium (Metamucil), methylcellulose

Bulk forming laxatives include psyllium and methylcellulose. These are medications used for constipation, as well as to prevent straining and to help manage chronic watery diarrhea.

Bulk forming laxatives mode of action

The mode of action of these bulk forming laxatives is to combine with water in the intestines to soften the stool and increase its bulk.

Bulk forming laxatives side effects

Side effects of bulk-forming laxatives like psyllium and methylcellulose can include mild cramping, as well as nausea or vomiting.

Bulk forming laxatives patient teaching

Hydration is very important when administering all laxatives — encourage the patient to take psyllium or methylcellulose with a full glass of water, then have them drink another glass of water after that.

Stimulant laxatives - bisacodyl (Dulcolax), sennosides (Senokot)

Stimulant laxatives, which include bisacodyl and sennosides, are medications used for constipation, as well as for bowel prep prior to a surgery or procedure.

Stimulant laxatives mode of action

Stimulant laxatives like bisacodyl and sennosides work by stimulating peristalsis, which causes bowel evacuation.

Stimulant laxatives side effects

The side effects of stimulant laxatives like bisacodyl and sennosides can include cramping, nausea, and vomiting.

Stimulant laxatives patient teaching

Stimulant laxatives are another medication that should be administered with a full glass of water. The patient should also increase their fiber and fluid intake. And they should increase their mobility to promote regularity.

Cool Chicken Bisacodyl will help you do your “Business” (BM).

Osmotic laxatives - magnesium hydroxide, magnesium citrate, lactulose, polyethylene glycol (MiraLax)

Osmotic laxatives, which include magnesium hydroxide, magnesium citrate, lactulose, and polyethylene glycol (also known as Miralax), are another type of medication used to treat constipation, as well as to prep the bowel prior to a surgery or procedure.

Osmotic laxatives mode of action

Osmotic laxatives work by drawing water into the intestine from the surrounding tissues — a process known as osmosis. This helps soften stools and make them easier to pass. This type of laxative also stimulates peristalsis.

Osmotic laxatives side effects

Side effects of osmotic laxatives can include cramping, bloating, and diarrhea.

Magnesium hydroxide or magnesium citrate are known to cause hypermagnesemia, elevated magnesium levels. Symptoms of hypermagnesemia include hypotension (low blood pressure), respiratory depression, and cardiac arrest. This means it is important to monitor the patient's magnesium levels if they're on one of these two medications.

Lactulose as treatment of hepatic encephalopathy

Lactulose, another osmotic laxative, may be used for the treatment of hepatic encephalopathy, a brain disorder caused by a buildup of ammonia in the body. When a patient has liver dysfunction, their body cannot eliminate toxins, including ammonia. That ammonia can flow through the bloodstream into the brain, where it affects brain function, often causing confusion.

Administering lactulose helps to lower the pH in the colon, which in turn promotes the excretion of ammonia resulting in lower ammonia levels.

Cool Chicken Lactulose will cause you to “lose” stool as it gets rid of excess ammonia from the body.


Full Transcript

Hi. I'm Cathy with Level Up RN. In this video I'm going to continue my coverage of gastrointestinal medications. Specifically, I'll be covering laxatives. At the end of this video I'll be giving you guys a little quiz to test your knowledge of some of the key facts I'll be covering in this video. So definitely stay tuned for that. If you have our Pharmacology Second Edition Flashcards, definitely pull those out so that you can follow along with me.

So as we talk about laxatives, many times laxatives are prescribed in order to treat constipation. When a patient has constipation, we're going to want to provide additional teaching versus just giving them laxatives on ways they can prevent constipation, this includes increasing their fluid intake as well as increasing their fiber intake. We also want to encourage our patients to get up and move around. So increase their mobility because that can also help to stimulate peristalsis.

First up, we have our stool softeners, which includes docusate sodium and docusate calcium. These medications are used to prevent constipation. They work by drawing water into the stool, which helps to soften the stool. Side effects can include mild cramping, as well as diarrhea. We want to encourage our patient to take this medication with a full glass of water. And our cool chicken hint for remembering these medications is the doc said if you ate more fiber, you wouldn't need docusate to soften your stool.

All right. Next we have our bulk forming laxative, which include psyllium and methylcellulose. So these medications are used for constipation, as well as the management of chronic watery diarrhea. The mode of action of these bulk forming laxatives is that they combine with water in the intestines to soften the stool and increase the bulk of the stool. Side effects can include mild cramping, as well as nausea or vomiting. In terms of administration of this medication, we want to encourage the patient to take psyllium or methylcellulose with a full glass of water and then drink another glass of water after that.

Next we have our stimulant laxatives, which include bisacodyl and sennosides. These medications are used for constipation, as well as bowel prep prior to a surgery or procedure. They work by stimulating peristalsis. Side effects can include cramping, as well as nausea and vomiting. We want our patient to take their medication with a full glass of water. Our cool chicken hint for remembering at least one of these medications is bisacodyl will help you do your business. So your BM.

All right. Next let's talk about osmotic laxatives, which include magnesium hydroxide, magnesium citrate, and polyethylene glycol, which is Miralax. These medications are used for constipation, as well as bowel prep prior to a surgery or procedure. They work by drawing water into the intestine, as well as stimulating peristalsis. Side effects can include cramping, bloating, and diarrhea. And if we're talking about administration of magnesium hydroxide or magnesium citrate, then it can actually cause hypermagnesemia, so elevated magnesium levels. So as the nurse, you need to monitor your patient's magnesium levels if they're on one of these two medications. There's another osmotic laxative, which is a lactulose, which I've always pronounced as lactalose, but apparently it's lactulose. Lactulose is used for the treatment of hepatic encephalopathy due to a buildup of ammonia in the body. So this occurs when a patient has liver dysfunction and the body's not getting rid of toxins, including ammonia, and that ammonia goes up to the brain and causes confusion. So we would give the patient lactulose, which helps to lower the PH in the colon, which in turn promotes excretion of ammonia. So it helps to bring those ammonia levels down.

So our little cool chicken hint here for remembering lactulose is that lactulose will cause you to lose stool as it gets rid of excess ammonia. So when you look at the spelling of lactulose, it ends in that L-O-S-E, which will help you to remember that it will help you lose stool and get rid of that ammonia.

All right. That is it for osmotic laxatives. Time for a quiz. Question number one, what instructions should you provide your patient who is taking psyllium? You should tell them to take it with a full glass of water and then drink another glass of water after that. Question number two, what laxatives can cause hypermagnesemia? The answer is magnesium hydroxide and magnesium citrate. Question number three, what laxative is used to treat hepatic encephalopathy? The answer is lactulose. All right. I hope this quiz has been helpful. Hopefully, the whole video was helpful. If so, be sure to leave me a comment. I would love to hear from you. Take care and good luck with studying.


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