Stomach Ulcer (Peptic Acid Disease) Medication

00:01 Welcome to Pharmacology by Lecturio.

00:04 I'm Dr. Pravin Shukle.

00:05 We're going to be covering GI pharmacology today.

00:10 The drugs used for gastrointestinal order spend a huge range of medications.

00:15 We have drugs for peptic acid disease, drugs for pro-motility, drugs for irritable bowel disease, drugs for inflammatory bowel disease, and anti-emetics.

00:27 We have a whole host of other agents as well for various ailments.

00:32 Let's look at peptic acid disease.

00:35 We have the antacids, the H2 blockers, the PPIs, the mucosal protective agents, and the antibiotics.

00:45 Let's start off with the antacids.

00:48 Now, antacids are weak bases that neutralize the low pH environment of the stomach.

00:53 These can include many agents such as magnesium hydroxide which is better known as Milk of Magnesia.

00:59 Milk of Magnesia is a mainstay of antacid therapy and it's probably the first line agent that we use in most cases.

01:07 It has a strong laxative effects so it's very good for patients who are also constipated.

01:12 Another agent that we use is aluminum hydroxide, commonly known as Maalox.

01:17 It has a strong constipating effects so it's better for people who have diarrhoea.

01:22 And calcium carbonate and sodium bicarbonate are just plain antacids.

01:27 They are absorbed by the gut unlike the other agents.

01:31 The first two agents that I mentioned tend to stay in the gut, these agents are actually get absorbed.

01:36 Let's move on to the H2 receptor antagonists.

01:40 These agents block histamine at the H2 receptor inside the gastric mucosa, specifically the parietal cells.

01:48 You can see that they inhibit stomach acid production directly, especially at night, so this is a particularly good agent for people who have night time GERD symptoms.

01:59 They are relatively nontoxic agents, they are actually sold over the counter now, we don’t even prescribe them.

02:06 Cimetidine was the original and prototypical drug in this drug class.

02:11 But we actually don't use it because there are multitude of drug interactions that we get from this particular medication.

02:17 Interestingly enough, some of these agents, in particular cimetidine, do have an antiandrogen effect as well at high doses.

02:26 These are the agents that are commonly sold.

02:28 These agents are sold over the counter, they’re extensively used all around the world.

02:34 Let's move on to the PPIs or the proton pump inhibitors.

02:38 These are lipophilic weak bases.

02:39 So the agents themselves are not antacids.

02:44 What they do is they become protonated, and they work inside the parietal cells and they get concentrated in these areas up to 1,000 times.

02:53 They irreversibly inactivate the hydrogen-potassium-ATPase pump.

02:59 What this does is that it ends up causing less acid secretion, substantially less.

03:04 Now they are rapidly metabolized.

03:06 They may take 3 to 4 days to actually have an effect because of this reason.

03:11 They are far more effective than the H2 antagonists that I spoke about earlier but they last, and they work well, and they are the mainstay of anti-ulcer therapy.

03:23 There are some toxicity issues associated with the PPIs.

03:26 You can get diarrhoea, abdominal pain and headache.

03:30 And you can get hypergastrinemia if you use them for a long time.

03:36 They may also decrease the ability of drugs that require higher acid levels.

03:40 So for example, ketoconazole requires a high acid environment within the stomach to become particularly activated and absorbed, if you give a PPI the same time as you give ketoconazole, you're going to reduce the availability of ketoconazole to the body for it to do its job.

03:56 The same thing will happen with drugs like digoxin.

04:00 Now, a small increase in respiratory and enteric infections are associated with PPI use.

04:06 We have many brands out on the market today, prototypical drug is omeprazole, but you have a whole list of other ones that I've given you here.

04:15 Let's move on to the mucosal protective agents.

04:18 Now the prototypical example of this is sucralfate.

04:21 It's a very poorly soluble molecule.

04:24 It polymerizes inside the stomach.

04:26 And when I say polymerize what I mean is is that it forms chains of molecules.

04:31 This polymer will bind to the injured tissue inside the patient stomach.

04:36 And it forms a protective coating over those ulcers and prevents further damage from occuring.

04:43 The down side of this medication is it has to be taken 4 times a day.

04:47 And that's really the main reason why we don't use it as much as we used to, simply because of the inconvenience.

04:53 It's a very low toxicity agent.

04:55 It has a very low solubility.

04:57 It's quite effective, unfortunately it's inconvenient.

05:01 These medications are great for patients who are very adherent to their schedule and so if you know these patients are going to follow their instructions, it's a great choice.

05:14 Let's move on to other agents.

05:15 Misoprostol is an analogue of prostaglandin E.

05:19 It works at almost the same point in the system as the PPIs.

05:24 You get increased mucosal protection because it directly inhibits acid secretion.

05:29 And it reduces ulcers in NSAID users as well.

05:33 The adverse event rate is quite high because it's poorly tolerated.

05:38 There's lots of GI upset and diarrhoea associated with this agent.

05:42 And for this particular reason, it's not used much anymore.

05:45 It is an agent however that you should be aware of because it is going to be on pharmacology portion of your exam.

05:54 Let's move on to agents like colloidal bismuth.

05:57 So, bismuth subsalicylate, also called Pepto-Bismol, gives a protecting coating on ulcerated tissue much like sucralfate.

06:07 It stimulates mucosal protective systems as well, so it goes a little bit further than sucralfate in that sense.

06:13 It actually has direct antimicrobial effects.

06:17 And you actually have some sequestration of enterotoxins.

06:21 So if there are toxins within the gut, it actually binds those toxins and renders them biologically unavailable.

06:29 It reduces stool frequency in infectious diarrhoea.

06:33 And unfortunately, there is a cosmetic side effect of this medication, it causes a black tongue.

06:40 Now the other important issue that you have to remember is it also causes black stools.

06:44 And many times, people who have melena type stools from Pepto-Bismol are misdiagnosed as having GI bleeds.

06:52 That is not the case.

06:53 So be aware that if you have a patient who presents with melena type stools ask first if they were taking this agent.