Treating IBS: Antispasmodics and Neuromodulators

JULY 02, 2019
MD Magazine

Mark Pimentel, MD: Let’s go to antispasmodics.

William D. Chey, MD: There is evidence to suggest that antispasmodics can help with abdominal pain, but my own personal preference is to use it in patients with postprandial abdominal pain. And the reason for that is because the traditional antispasmodics or anticholinergics—and the gastrocolic reflex, which is hyperactive in IBS-D [irritable bowel syndrome with diarrhea] patients, for example, and is associated with the development of pain and is at least partially cholinergically mediated. So it makes sense to use an anticholinergic in that setting.

What I would also say, though, is that it doesn’t make any sense to me to use anticholinergics for chronic abdominal pain. I can’t envision a reason why that would work, and I would discourage people from doing that.

Mark Pimentel, MD: Why not put everybody on a titrating dose of Imodium, Brennan, and save money?

Brennan Spiegel, MD: Well, I think Imodium is good for slowing the bowel down, but it’s not at all clear that it affects the sensory experience of IBS [irritable bowel syndrome]. What I mean by that is we have to distinguish the sensory symptoms—pain, bloat, fullness, tightness—from the bowel symptoms—diarrhea, incontinence, constipation. Loperamide is perfectly good at changing the speed at which the colon moves, but it’s not at all helpful for chronic abdominal pain.

Mark Pimentel, MD: Bloating and distension are among the most common and most bothersome of complaints in IBS-D. Is that going to be in the Rome V criteria?

William D. Chey, MD: You know, this is a complicated discussion. We certainly looked at that really carefully for Rome III and Rome IV. The problem is that virtually every patient with IBS has bloating. So the sensitivity is off the charts. The problem is the specificity. Because if you look across the functional GI [gastrointestinal] disorders, a significant proportion of patients have bloating. So the difficulty is in the specificity. That being said, I absolutely, 100% of the time in IBS patients, regardless of whether it’s part of the criteria or not, ask about bloating. I completely agree with you. I think it’s 1 of the most bothersome complaints for patients with IBS.

Mark Pimentel, MD: Antidepressants, Tony?

Anthony J. Lembo, MD: There are a lot of data on antidepressants, although most of the studies are small.

Mark Pimentel, MD: Should we be calling them antidepressants in this use?

Anthony J. Lembo, MD: Well, they’re neuromodulators. That’s how I present it to patients. I explain to them that it’s in the class of antidepressants because, of course, they’re going to see that when they pick up the prescription. But I explain exactly how we think they work. I usually walk them through some of the data. We often will use a low dose of a tricyclic antidepressant, where most of the data are, particularly in patients who have IBS with diarrhea. And I start the dose relatively low. There are data suggesting that in people with IBS with diarrhea, that 10 mg of amitriptyline will be helpful. And then I will titrate the dose up, oftentimes going to 50 mg. But if they don’t tolerate it, I would switch to 1 with less of an anticholinergic effect. Desipramine would be another 1, or nortriptyline. 

And sometimes for patients who have IBS with constipation, the data are not as good for SSRIs [selective serotonin reuptake inhibitors] and SNRIs [serotonin-norepinephrine reuptake inhibitors], although we believe that the SNRIs are probably helpful for pain. But I will sometimes use those as well. I’ll also start by lowering the dose and gradually increase with it. So I think there is a role for them.

Mark Pimentel, MD: I was at a talk recently and 1 of the speakers said that they combine an SNRI with mirtazapine. Where’s the data for that? That’s not evidence-based medicine. So I guess there’s a lot of experiential medicine here. And Brennan is probably the best expert on this panel to talk about evidence-based medicine. Obviously, we need more evidence. What’s your thought on this area?

Brennan Spiegel, MD: There’s evidence-based and then there’s eminence-based medicine. Sometimes we don’t have evidence for a lot of what we do, and it’s worthwhile hearing from experts who have a lot of experience and can speak to it. But obviously, there’s a fine line, and we need to try, wherever possible, to rely on the evidence that we have. When we talk about antidepressants—or neuromodulators, or however we want to discuss them—I think it’s an important distinction. I tell my patients, “Listen, I’m not a psychiatrist. I’m not here to manage your mental health directly. That’s not what I’m trained to do. But it does look like the brain and the gut talk to each other.”

And in fact, this idea that the brain and the gut—or the brain and the body—even are separate…is a very old concept from the mid-1600s, from René Descartes. And it still, to this day, affects the way we think about the human body. The apparatus in our body—the sensory apparatus, the neuromuscular apparatus—is all an extracranial extension of the brain that just happens to be in the skull up top to be protected, because we’re doing a lot of processing up there. But we need a body to know anything. Literally, to think. So there’s really fascinating neuroscience behind that. But when you kind of pose it that way, say, “Listen, I’m going to try to modulate the way the 2 sides, the neurovisceral polls, are communicating with each other.” And there’s pretty reasonable evidence that using neuromodulators can help both with the pain, and to some degree, when relevant, the visceral anxiety that goes along with it.

Mark Pimentel, MD: Would you agree that most of these things are blunt tools, still, though?

William D. Chey, MD: Oh yeah, absolutely blunt tools. But I totally agree with the approach Brennan just outlined. I really think if you explain to patients this interaction between the brain in your head and the brain in your gut, they get that. And I also completely have changed to really talk about neuromodulators rather than antidepressants. I think it’s really important because it helps the patient understand that you’re not giving them the medication for its antidepressant properties. By the way, I also think it’s important to tell the patients that when they go to the pharmacy. I prepare them for the fact that a lot of times the pharmacist will tell them, “Oh, I see your doctor started you on an antidepressant,” which can be quite upsetting to people. So it’s good to just prepare them for that possibility.

Transcript edited for clarity.

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