Reviews for Primary Care - Fall 2007 - (Page 27) Chronic Constipation and Functional Bowel Disorders lubiprostone would have any action on CFTR because lubiprostone’s structure is very specific to the ClC-2 receptor. Exactly how lubiprostone acts on ClC-2 is unknown. Question: Please describe what is included in biofeedback. What is the process that patients are actually going to go through? Panel: Basically, normal defecation involves the increase of intrarectal pressure and intra-abdominal pressure with valsalva. There should be a coordinated relaxation of the striated muscles—that is, the puborectalis, which forms the anorectal angle, and the external anal sphincter, which of course can enhance or decrease the pressure of the anal canal. In biofeedback you do not measure the puborectalis, so the external sphincter becomes the surrogate for that muscle. So when you bear down with a manometry catheter in place you should see the intrarectal pressure rise, and you should see the anal canal pressures fall. When you see the opposite (ie, when you see the anal canal pressures rise), we can presume that the puborectalis is also contracting and narrowing the anorectal angle. Now you have this kind of back-and-forth thing. What the technician or the therapist will do is point this out to the patient and ask the patient through trial and error to attempt to make the needle or the pressure go in the appropriate direction. The biofeedback process allows them to come to an idea of what they are doing wrong and to learn how to relax it. Once they can do that, then you can remove the visual or the auditory feedback and they can continue to self-reinforce over time. That is basically why manometry is so important, because it identifies what may be going wrong and provides a mode to correct that. Question: Are there any prokinetic agents available that help in patients with constipation? Panel: Prokinetic agents such as metoclopramide and erythromycin are most effective in the upper gut and have very little, if any, effect on the colon. Question: Is there any way to predict which patients are going to respond to standard medical therapies? Panel: It is really just trial and error. The important thing in terms of dissatisfaction of patients is that we as clinicians are often not using treatments that we do have correctly. Treatments we use are often episodic or inadequate regarding dosing and we are gathering very little feedback from the patients. There will always be patients who will be unhappy, and they will be unhappy with any drug that you come up with, but if we take the time to work with patients we can get a better outcome. Of course it does take time and follow-up. Panel: There is a wealth of data—the lubiprostone data for example—but most of it is still not published. Eventually when we can actually look at those data we may get some idea of what the individual predictors are or at least possible predictors of response. Certainly you could do a pooled analysis to find that out, but that has not been done. Conclusion and Summary Chronic constipation and IBS-C are common overlapping multisymptom disorders. In patients without alarm symptoms, the diagnosis of chronic constipation or IBS-C is relatively straightforward and can be accomplished through judicious application of the Rome criteria, a thorough physical, and a digital rectal exam followed by empiric treatment. Exclusionary diagnostic testing is rarely needed to confirm a diagnosis of chronic constipation or IBS-C. In a small subset of patients with alarm symptoms or abnormal physical findings, further diagnostic testing may be warranted because it may affect therapy and outcomes. Most traditional treatment options are indicated for occasional constipation and not chronic constipation. These treatments include: • Bulk laxatives (psyllium, calcium polycarbophil, methylcellulose, and wheat dextrin) • Stool softeners (docusate sodium and docusate calcium) • Osmotic laxatives (lactulose, PEG 3350, sorbitol, and milk of magnesia) Treatment options for chronic constipation include: • Lubiprostone • PEG 3350 (at physician discretion) • Tegaserod (restricted use) • Pelvic floor retraining • Nonpharmacologic approaches for those with abnormal anorectal testing and evidence of pelvic floor dysfunction • Surgical therapy for a very small subset of patients There is increasing evidence of safety and efficacy of lubiprostone and PEG 3350 in the adult and elderly populations as well as lactulose in the pregnant population. Clinical studies and experience are providing more insights and significant promise for improved outcomes in our patients with constipation and IBS-C, especially with respect to some of the newer agents including probiotics, antibiotics, and lubiprostone. VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE 27
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.