Brian Lacy, MD, and Greg Sayuk, MD on Chronic Abdominal Pain: Part 2

In the second part of their podcast, Drs Lacy and Sayuk discuss treatment options available for patients with chronic abdominal pain.

Brian Lacy, MD, is a professor of medicine and gastroenterologist at the Mayo Clinic in Jacksonville, Florida. Gregory Sayuk, MD is an associate professor of medicine and psychiatry at Washington University School of Medicine in St Louis, Missouri.

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TRANSCRIPT:

Thank you for joining us for part two of this podcast from the Gastroenterology Learning Network as doctors Brian Lacy and Greg Sayuk continue their conversation on chronic abdominal pain with a discussion of treatment options.

Dr. Lacy:

That's a perfect segue to talk about treatment options for chronic abdominal pain. We now use the term neuromodulator. What is a neuromodulator and why might they be beneficial?

Dr. Greg Sayuk:

Right. Neuromodulators are a group of agents, really, that derive from largely other areas of medicine that we've borrowed and found to be effective for the management of chronic abdominal pain in our specialty. One of the major classes of agents that we use as neuromodulators are the antidepressants, particularly the tricyclic antidepressants. We also use, in some cases, atypical anti-psychotic agents, contemporary anti-epileptic medications.

There's a variety of different agents that we regard as neuromodulators. The commonality with all of these neuromodulator agents is that in essence, they hold the potential to change, to down-regulate the communication of these pain signals from the gut to the brain, and as a result, hold the potential to improve that chronic abdominal pain experience for the patient.

Dr. Lacy:

Many experts for the treatment of chronic abdominal pain recommend a tricyclic antidepressant, also called TCA, but a lot of patients are resistant to this because you just said it's a tricyclic antidepressant and they believe you're treating their depression, not your pain. How do you get around this issue? How do you explain that to a patient?

Dr. Greg Sayuk:

This can be a challenge and it's an important one to take and address head on when you're considering prescribing one of these agents. If you circumvent this discussion, the likelihood is that your patient may get the prescription and read a little bit about the medication and then be turned off from its use because they're presuming that you're treating their mood and just didn't clarify that that was the purpose of this agent. It's important to explain, I think, to the patient that though these medications may have been initially developed as antidepressant agents, in reality, for example, in the case of the tricyclic antidepressants, we rarely, if ever, use these medications for the purpose of treating mood disorders in the contemporary era.

These medications are effective, we believe, because of their potential to alter, to change the levels of neurotransmitters, receptor levels for these neurotransmitters within the gut and the central nervous system. I tell the patients that we're basically using a medication once developed for a specific indication in mood for a new purpose now, and we're just taking advantage of the effects of these medications on neurotransmitters and receptors.

Dr. Lacy:

Wonderful. Focusing a little bit more on the TCAs, the tricyclic antidepressants, sometimes we talk about tertiary amines and secondary amines. Can you help guide us through that? Why might you choose a tertiary amine such as imipramine or amitriptyline over a secondary amine?

Dr. Greg Sayuk:

That's an important point because it gets at the potential for undesired side effects, off-site receptor effects that we are perhaps less interested in with regard to the use of these agents. The tertiary amines, as you mentioned, amitriptyline, imipramine, these medications have, in general, a greater potential for muscarinic cholinergic effects, for antihistaminergic effects, and these tend to be the effects that lead to the greater potential for side effects.

Dry mouth, sedation, dizziness and so forth, to a greater degree with the tertiary amines. That being said, many of us prefer to start with the use of a secondary amine. Examples here would include nortriptyline or desipramine with lesser potential for these side effects tend to be better tolerated by patients and as a result, generally easier to start and use in the majority of our patients where we're considering using one of these agents.

Dr. Lacy:

Great, great. Thank you. As you alluded to, usually starting at a low dose and going slowly as we work our way up. As we wind down here, let's talk about SNRI, serotonin. Norepinephrine reuptake inhibitors such as duloxetine. This agent is oftentimes used to treat chronic abdominal pain or centrally mediated abdominal pain syndrome, CAPS. You mentioned that earlier. Do you find that beneficial and do you use this medication in your practice?

Dr. Greg Sayuk:

I do. These medications have the advantage of, again, being in comparison to the tricyclic agents, overall better tolerated. You also have the advantage with the SNRIs, such as duloxetine, of using them at more of a typical therapeutic dose. In the event, for example, that a patient has overlapping depression, you may truly get an antidepressant effect with these agents, whereas as I mentioned earlier, the tricyclics were using them at subtherapeutic doses in terms of their typical use for mood.

One important point to make here is that we feel that the effect of these agents, these neuromodulators on their potential to modulate norepinephrine is important, and so the SNRIs that do have a norepinephrine effect are probably superior to other agents such as the SSRIs or the selective serotonin reuptake inhibitors that don't have as much of a norepinephrine effect. As a result, we tend to preferentially select SNRIs over SSRIs in our practice if we're moving beyond the tricyclics as a neuromodulator.

One other important point is that, of course, not all of these agents are created equally, and it's worth as a provider who is intending to use these medications to become somewhat familiar with their effects, noting that duloxetine, for example, has more of an SNRI effect than say, perhaps, venlafaxine, where at lower doses venlafaxine, though regarded as an SNRI does have more of a pure SSRI effect at lower doses.

Dr. Lacy:

Wow, great teaching points. Thank you very much. Now I think our listeners should be much more comfortable using these classes of agents. Greg, this has really been a wonderful conversation. I can't thank you enough. Any last thoughts for our listeners?

Dr. Greg Sayuk:

I think one other point that I would just raise is that stay tuned in this field because there's a lot of exciting development going on right now, moving beyond for the use of neuromodulators, these antidepressant agents, these anti-seizure medications into other areas, including exploration in the cannabinoid system, for example, which is exciting. Also, bear in mind that when we think about neuromodulation, we become very focused on, of course, medications.

But there's a whole literature and a whole experience with the use of behavioral therapies, which we didn't have time to get into detail on today, but also shown to have very effective benefit in the management of these chronic abdominal pain symptoms for patients as well.

Dr. Lacy:

Greg, wonderful. We've been listening today to this expert in the field, Dr. Greg Sayuk, professor of Medicine at Washington University in St. Louis, Missouri. Thank you so much. For our listeners today, we hope you can tune into another Gastroenterology Learning Network podcast in the future. Thank you so much.

Dr. Greg Sayuk:

Thank you.

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