Chapter 46: Gastrointestinal Medications

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Welcome to the Deep Dive.

Today we're tackling a really important area,

gastrointestinal medications.

We're using Chapter 46 from the Saunders Comprehensive Review for the NCLE XPN Examination Seventh Edition as our roadmap.

It's a great resource.

Yeah.

Think of this as like your shortcut to understanding these drugs, whether you're in healthcare or maybe just curious about treatments for common, you know, tummy troubles.

Exactly.

And it covers such a wide range, doesn't it?

From the stuff you grab over the counter to more specialized prescription drugs.

Right.

So our mission today is to really pull out the must -know info, make it easy to grasp, maybe even have a few aha moments along the way.

Let's do it.

All right.

Let's start with something really common, antacids.

I think most people have used these at some point.

What's the basic idea behind them?

Well, at their core, antacids just neutralize stomach acid.

Simple as that, really.

Think of them as a quick fix for heartburn or indigestion.

Just neutralizing the acid.

Mostly, yeah.

They also dampen down pepsin activity that's a digestive enzyme and can give the stomach lining a bit of extra protection.

But, and this is key, they don't actually heal ulcers.

Okay.

So they're more for immediate relief, creating a less harsh environment.

That makes sense for things like peptic ulcers and GERD.

Precisely.

By cutting down the acidity, they help manage the symptoms.

Big time.

Now taking them, it's not just whenever you feel like it, is it?

The timing seems important.

Oh, definitely.

For some, a regular schedule is best like an hour and three hours after meals, maybe again at bedtime.

Why so specific?

The goal is to keep the stomach pH above five.

You want to maintain that less acidic state for longer stretches.

Ah, okay.

And how you take them physically, tablets versus liquids.

Yeah, that matters too.

Chewable tablets.

You really need to chew them thoroughly.

Helps them mix better.

Then follow with water or milk.

And liquids?

Liquids need a good shake first.

Make sure everything's mixed up properly before you pour your dose.

Okay, here's something that really stood at that one hour gap.

You need to separate antacids from other meds by an hour.

Why is that?

Interactions.

That's the big reason.

Antacids can seriously interfere with how your body absorbs lots of other drugs.

Reducing their effectiveness.

Exactly.

So waiting at least an hour gives those other meds a chance to get absorbed properly before the antacid changes the stomach's environment.

Super important.

Right.

The chapter then gets into the different types of antacids.

And they're not all the same, are they?

Let's start with aluminum compounds.

Okay.

Aluminum hydroxide, for example.

It's actually used sometimes to lower high phosphate levels.

That's hyperphosphatemia.

But because it binds phosphate, it can cause the opposite.

Low phosphate, hypophosphatemia.

It also messes with absorbing things like tetracycline antibiotics, warfarin, digoxin.

And watch the sodium content if you have high blood pressure or heart failure.

Oh, and the most common side effect,

constipation.

Aluminum tends to back things up.

Okay.

Aluminum equals constipation risk.

Got it.

What about magnesium compounds?

They kind of have the opposite rep, right?

They do.

Magnesium hydroxide, for instance.

It's a saline laxative.

It pulls water into the gut, so diarrhea is pretty common.

Which is why you often see aluminum and magnesium combined in one product, trying to balance out the effects.

Makes sense.

But you absolutely cannot use magnesium compounds if there's a bowel obstruction, appendicitis, or, you know, undiagnosed belly pain.

And critically, if your kidneys aren't working well, magnesium can build up to toxic levels.

Really need to be careful there.

Okay.

So magnesium can speed things up maybe too much, and kidney function is a big watch out.

Next,

calcium compounds.

What's their story?

Calcium carbonate, like Tums.

One thing with these is potential acid rebound.

Acid rebound.

Yeah.

After the initial relief, your stomach might actually pump out more acid later.

They work fast, release carbon dioxide gas.

Leading to?

Belching, flatulence.

Fun times.

And constipation is also common with calcium, plus there's a risk of something called milk alkali syndrome, so avoid tons of milk or vitamin D with these.

Good to know.

Belching and rebound.

Okay.

Lastly, sodium bicarbonate.

Baking soda, basically.

Pretty much.

It works fast, also releases CO2 gas, so you get that increased abdominal pressure, maybe flatulence.

Sodium is in the name.

Right.

So caution again with high blood pressure and heart failure.

And in people with kidney issues, there's a risk of the body becoming too alkaline systemic alkalosis.

But it has other uses.

It does.

It can be used to treat acidosis, and sometimes in overdoses, it helps the body get rid of certain acidic drugs by making the urine more alkaline.

So antacids.

Yeah.

Definitely not simple.

Lots of differences.

Okay.

Moving on.

Gastric protectants.

Misoprostol and sucralpate.

Let's take misoprostol first.

Misoprostol's interesting.

It kind of does two things.

It reduces acid secretion a bit, but it also ramps up the smex defenses.

Oh.

By maintaining good blood flow to the stomach lining, its big use is preventing ulcers caused by long -term NSAI or aspirin use.

Okay.

How do you take it?

Side effects.

Usually with meals.

Diarrhea and abdominal pain are pretty common side effects.

And a huge safety point.

Absolutely contraindicated in pregnancy.

Must not be used.

Got it.

Critical point.

Now, sucralpate.

Sounds like it works totally differently.

Yeah.

Sucralpate is more like a protective patch.

It forms a sticky barrier over ulcerated or irritated areas.

Shielding it from acid.

Exactly.

Shields it from acid and pepsin.

Needs to be taken orally on an empty stomach to work best.

Constipation can be a side effect.

And interactions.

Like antacids.

Yes.

Very important.

It can block the absorption of warfarin, phenytoin, theophiline, digoxin, antibiotics.

You need at least a two -hour gap between sucralpate and those meds.

Wow.

Two hours.

Timing is crucial again.

All right.

Let's shift to histamine H2 receptor antagonists.

H2 blockers.

What's their main job?

They're acid reducers too.

They work by blocking histamine signals that tell the stomach to produce acid.

So the result is?

Less acid.

Which means relief from heartburn, help preventing peptic ulcer complications, preventing stress ulcers in very ill patients, reducing ulcer recurrence, promoting GER healing.

Lots of uses.

Contraindications.

Well, hypersensitivity, obviously.

And use with caution if you have kidney or liver problems.

Okay.

The chapter gets into specific ones.

Starting with cementidine.

This one seems to have more baggage.

A bit, yeah.

Cementidine can be taken orally or given IV or IM.

Food slows down oral absorption.

If given IV, watch out for potential low blood pressure or heart rhythm issues.

And interactions.

Right.

Interacts with antacids need that one hour separation for oral cementidine.

And significantly, cementidine can cross the blood -brain barrier.

Leaving to?

CNS side effects, especially in older adults.

Things like confusion, agitation, even psychosis, depression, anxiety.

Wow.

Yeah.

You often need lower doses with kidney impairment.

And it messes with the metabolism of other drugs like warfarin, phenytoin, theophylline, lidocaine.

Their doses might

Okay.

That's a lot for cementidine.

What about ranitidine?

Is it simpler?

Generally, yes.

Ranitidine can also be oral, IM, or IV.

But side effects are less common, and importantly, it doesn't get into the brain as easily.

So fewer CNS issues.

Much fewer.

And food doesn't really affect its absorption either.

So yeah, a bit more straightforward.

Good.

Then there's femotidine and nizadidine.

Similar to ranitidine.

Pretty much.

They work similarly to reduce acid like ranitidine and cementidine.

And like ranitidine, you don't need to worry about taking them with food.

Okay.

So H2 blockers reduce acid, but with variations in side effects and interactions.

Got it.

Next class, proton pump inhibitors, PPIs.

These sound heavy duty.

They are pretty potent acid suppressors.

Yeah.

They work by blocking the final step in acid production, the proton pump.

Uses?

Active ulcers, erosive esophagitis.

That's inflammation from acid reflux, and conditions where the stomach just makes way too much acid.

Contraindications.

Side effects.

Again, hypersensitivity is the main contraindication.

Common side effects can be headache, diarrhea, abdominal pain, nausea.

Pretty common stuff.

And the chapter lists some common PPI names.

Yep.

Box 46 to 1 mentions esoprazole, lancoprazole, omrazole, pantoprazole, and rebaprazole.

Those are the big ones you'll see.

Okay.

So PPIs are strong acid blockers.

Now what if the problem isn't just acid, but that bug, H.

pylori, helicobacter pylori.

Yes, H.

pylori, a major cause of ulcers.

And you can't just treat it with one antibiotic.

Why not?

Resistance.

The bacteria develops resistance easily, so you need combination therapy.

Like the triple and quadruple therapies mentioned.

Exactly.

Triple therapy is usually two antibiotics plus a PPI.

Box 46 to 2 gives examples like a PPI plus amoxicillin and clarithromycin, or maybe levofloxacin instead of clarithromycin.

That's usually if triple therapy fails.

It might involve a PPI or an H2 blocker plus bismuths subsalicylate metronidazole and tetracycline.

Complex regimens, but necessary to kill the bug.

A real multi -drug attack.

Okay.

Let's talk about a prokinetic agent.

Metoclopramide.

What does prokinetic mean here?

It means it helps move things along.

Metoclopramide stimulates motility in the upper GI tract, speeds up stomach emptying.

Without affecting acid.

Right.

It doesn't really touch secretions.

It's used for GERD sometimes and for paralytic ileus when the bowels just start moving after surgery, for instance.

Side effects.

Can cause restlessness, drowsiness, dizziness, insomnia, headache.

And importantly, it can cause extra pyramidal reactions.

Those are movement problems like muscle spasms or stiffness.

Usually taken about 30 minutes before meals and at bedtime.

Are there times you definitely shouldn't use it?

Oh yeah.

Contraindicated if there's a sensitivity, obviously, but also mechanical obstruction, perforation, GI bleeding,

and a specific one.

Pheochromocytoma, a type of tumor, because it can cause a hypertensive crisis.

Pregnancy.

Safety isn't established.

And long -term use has a risk of tardive dyskinesia or Parkinsonian reactions, which might mean stopping the drug.

Interactions.

Yep.

Anticholinergics and opioids can work against it.

Alcohol, sedatives, tranquilizers can increase the drowsiness effect.

Okay.

Useful, but needs careful consideration.

Let's switch gears to bile acid sequestrants.

We often hear about these for cholesterol.

We do.

They work by binding bile acids in the intestine, preventing their reabsorption so they get excreted.

This forces the liver to use cholesterol to make more bile acids, lowering blood cholesterol.

So why are they in the GI chapter?

Because they can also help with issues related to bile, like managing problems from blocked bile or the intense itching pruritus that can happen with some liver diseases.

The chapter mentions they aren't always easy to take.

Yeah.

The powdered forms like colostaramine and colisivellum listed in box 46 .3 can have, let's say, palatability issues,

gritty texture, taste.

How to manage that.

Mixing with juice or flavored drinks helps.

Side effects are mostly GI, nausea, bloating, constipation, even fecal compaction, or bowel obstruction in serious cases.

So you need to manage the constipation.

Definitely.

Stool softeners, fiber are often recommended, and you have to be really cautious if there's already suspected bowel obstruction or severe constipation.

These could make it worse.

Okay.

Now, lactulose for hepatic encephalopathy.

First, what is hepatic encephalopathy?

It's a decline in brain function that occurs as a result of severe liver disease.

The liver can't remove toxins, like ammonia, from the blood, effectively.

And lactulose helps how?

Lactulose is actually a type of sugar that isn't absorbed well.

It draws water into the colon and causes diarrhea,

basically.

But in doing so, it helps trap ammonia in the colon and promotes its excretion.

Lowering blood ammonia levels.

Exactly.

The goal is to lower those ammonia levels.

Normal is around 10 to 80 millisiege DL.

It also helps people with advanced cirrhosis tolerate protein better.

Can be given orally as a syrup or rectally.

Interesting.

Also used for constipation, right?

Same mechanism drawing water in, promoting bowel movements.

Okay.

Next.

Pancreatic enzyme replacements.

Pancrelipase.

Who needs these?

People whose pancreas doesn't produce enough digestive enzymes, like in chronic pancreatitis or cystic fibrosis.

What happens around them?

You can't digest food properly, especially fats.

Leads to malnutrition and fatty stool steteria.

So pancrelipase replaces those enzymes?

Yes.

It contains lipase, protease, amylase.

You take it with every meal and snack.

The goal is to improve digestion,

improve nutrition, and reduce that steteria.

Timing is key, then.

Any side effects or interactions?

Side effects can include abdominal cramps, pain, nausea, diarrhea.

And antacids containing calcium carbonate or magnesium hydroxide can interfere with how well it works.

Good to know about the antacids.

Okay.

Let's tackle inflammatory bowel disease, IBD, Crohn's, and ulcerative colitis.

Complex stuff.

Very.

Ongoing inflammation is the hallmark.

Treatment aims to control that inflammation and manage symptoms.

Several drug classes are used.

Like anti -microbials?

Sometimes, yeah.

To prevent or treat secondary infections that can pop up.

Box 46 -4 lists things like metronidazole, superfloxanin, refaximin, chlorethromycin.

Then there are five amino -cell esylates.

Five ASAs.

Right.

These, like mesalamine or sulfasalazine, also box 46 -4, directly target inflammation in the GI tract.

Side effects can include nausea, rash, joint pain, sometimes blood issues.

Corticosteroids, too.

Yep.

Potent anti -inflammatories like prednisone or butonide, box 46 -4, often used for flares but usually short -term due to systemic side effects.

And for tougher cases, immunosuppressants.

Yes.

Drugs like azithioprine or mercaptopurine, box 46 -4, they suppress the immune system to reduce inflammation, but they carry risks like pancreatitis or low white blood cells, so they're typically for people who don't respond to other therapies.

Finally, immunomodulators for IBD.

These are often biologic therapies, monoclonal antibodies that target specific inflammatory pathways.

Think adalimumab or infliximab, box 46 -4.

They help induce and maintain remission.

So a layered approach for IBD.

Now, irritable bowel syndrome, IBS,

different from IBD.

Very different.

IBS is a functional disorder characterized by abdominal pain, cramps, gloating, and changes in bowel habits, either diarrhea, constipation, or a mix.

No visible inflammation like an IBD.

And treatment depends on the main symptom.

Exactly.

Is it primarily constipation, IBS -C, or diarrhea, IBS -D?

Okay, for IBS -C.

Often start with bulk -forming laxatives, psyllium, for example, taken with plenty of water.

There's also lupiprostone, which increases fluid in the intestine, taken with food, and linaclotide, which speeds up transit time, taken before breakfast.

Box 46 -6 lists others for constipation.

And for IBS -D, diarrhea dominant.

Alistrine is an option, but it's restricted.

It's a selective serotonin receptor antagonist, but it has potentially serious side effects like severe constipation or even ischemic colitis.

So it's used cautiously.

Very.

Needs a special prescribing program.

Often, standard anti -diarrheal meds like loperamide listed in box 46 -7 are used first line.

Got it.

Treatment tailored to the pattern.

Antimetics for nausea and vomiting.

A huge category.

The choice really depends on why the person is nauseous or vomiting.

Is it chemo -induced?

Post -op.

Motion sickness.

What are the key nursing points?

Monitor vital signs, intake, and output.

Minimize strong odors.

They can be triggers.

Limit oral intake to clear liquids initially.

And a big one, safety.

These drugs often cause drowsiness, so protect from falls.

Box 46 -5 lists a ton of them.

Can you give us the highlights?

Sure.

You've got serotonin antagonists like ondansetron, very common.

Leucocorticoids like dexamethasone.

Substance P antagonists like apripetent.

Benzodiazepines like lorazepam, often for anxiety -related nausea.

Dopamine antagonists like prochlorparazine or metaclopramide.

Cannabinoids like dronabinol.

Anticholinergics like scuplamine patch for motion sickness.

And antihistamines like diamondhydrolate or meclazine.

Lots of mechanisms.

Definitely a wide array.

Okay, laxatives next.

For constipation.

Different types.

Yep.

Based on how they work.

Bulk forming like psyllium or methylcellulose.

Box 46 -6.

They absorb water.

Add bulk.

Don't use if obstructed.

Stimulants.

Like bisacodil or senna.

Box 46 -6.

They directly stimulate bowel motility.

Can cause cramping.

Mollients.

Also called stool softeners like docucate sodium.

Box 46 -6.

They let water penetrate the stool, making it softer.

Good for avoiding screening.

And osmotics.

These draw water into the colon.

Examples are magnesium hydroxide.

Polyethylene glycol like Miralax.

Lactulose.

Box 46 -6.

Effective but can cause electrolyte shifts sometimes.

General advice with laxatives.

Drink plenty of fluids.

Crucial to prevent dehydration.

Especially with bulk forming and osmotic types.

And avoid long -term reliance if possible.

Makes sense.

Now the flip side.

Medications to control diarrhea.

First step is always try to figure out the cause.

Then manage dehydration.

Replace fluids and electrolytes.

Relieve cramping.

And slow down the stool frequency.

Wow, they worked.

Opioids are actually very effective anti -diarrheals.

Lopramide.

Imodium is a common one.

Box 46 -7.

They slow down intestinal motility.

But a caution.

Yes.

If the diarrhea is caused by infection or toxins, slowing motility can actually be harmful because it keeps the bad stuff in longer.

So use cautiously in those cases.

Other types.

Ismuth subsalicylate.

Pepto -Bismol has anti -secretory and anti -microbial effects.

Bulk forming agents can sometimes help firm up stool.

Anti -cholinergics like dicyclomine can reduce cramping.

Right.

Box 46 -7.

I need to consider the cause.

Okay, the critical thinking scenario.

Patient with liver dysfunction getting lactulose ammonia level is 75 mcgdL.

What's the interpretation?

Well, we said normal ammonia is roughly 10 to 80 mcgdL.

And lactulose is supposed to lower ammonia.

So a level of 75, while still maybe on the higher end of normal or slightly elevated, depending on the lab, suggests the lactulose might be working as intended to bring the level down from potentially higher levels.

So the nurse should.

Report it to the RN, noting that the medication seems to be having its desired therapeutic effect, even if the level isn't perfectly normal yet.

It's movement in the right direction.

Okay, that makes sense.

Let's quickly hit those practice questions to cement some key points.

Sounds good.

Question 481.

Assessing infliximab for Crohn's.

The answer is 2.

Check bowel movement, frequency, and consistency.

Less inflammation should mean less diarrhea.

Right.

482.

Lopramide.

Answer 3.

For diarrhea.

It's an anti -diarrheal.

483.

Ondansetron.

Answer 4.

Nausea and vomiting.

Standard anti -emetic.

484.

Goal of pancreelopase.

Answer 3.

Reduction of staturia.

Helps digest fats.

485.

Common CNS side effect of semetidine in older adults.

Answer 3.

Confusion.

That blood -brain barrier issue.

486.

Identifying H2 blockers.

Answers 1, 2, 3, 4.

Usadidine, ranitidine, famitidine, simitidine.

The others are PPIs.

487.

Goal of mesoprostol with NSAIDs.

Answer 2.

Relief of epigastric pain by preventing ulcers.

488.

Main goal of omeprazole.

Answer 2.

Absence of heartburn.

The PPI reduces acid.

489.

Understanding H.

pylori triple therapy.

Answer 3.

The medications will kill the bacteria and stop the acid production.

Kills the bug.

Helps healing.

And 490.

Best timing for sucral fate.

Answer 4.

One hour before meals and at bedtime.

Needs to coat the stomach before food and acid hit.

Perfect.

And I think that thoroughly covers Chapter 46 on GI meds.

We really did cover a lot.

It's clear there's a massive range of drugs for GI issues.

They all work differently, have specific timing, side effects.

Lots to know.

Absolutely.

Understanding these is just so crucial.

Whether you're working in healthcare or just, you know, wanting to understand treatments for yourself or family, we've hit the different classes.

What they do, how to take them, what to watch for.

Yeah, it really highlights that even seemingly simple tummy troubles can involve complex treatments.

And the role of healthcare providers in choosing the right drug and monitoring it is huge.

Definitely.

Hopefully this deep dive provides a really solid foundation for understanding this whole group of

So,

maybe a final thought for everyone listening.

Now that you've got this deeper understanding of GI meds, how might that change the conversations you have with your doctor or pharmacist about your own digestive health?

Could you feel more empowered?

Definitely something to think about.

Good question.

Thanks for joining us on the Deep Dive.