I think I’ve seen this scenario play out more times than I would like. A patient is prescribed both a laxative, Senna, and Questran (cholestyramine), a medication used to manage diarrhea symptoms. This example of the prescribing cascade often presents slowly over the course of months to years and may be exacerbated by other medications.
Here’s the scenario…
HS had been dealing with chronic watery diarrhea for over six months. His provider initiated cholestyramine (Questran) 4 g twice daily, which significantly improved his diarrhea. However, at a recent visit, he reported that over the past two weeks, he had not had a bowel movement in three days and was feeling increasingly bloated and uncomfortable. He also reports that he has been taking diphenhydramine twice daily for seasonal allergies and to help him sleep at night. In response, his nurse practitioner instructs him to take Senna 1 tablet twice daily to deal with his constipation.
In managing medications, we must review the entire medication list and ensure that adverse effects are not causing the problem. The Questran and/or the diphenhydramine should be reduced in this situation before adding a laxative to the patient’s regimen, which can counteract what we are trying to do with the Questran. I can’t encourage you enough to review the medication list when a new concern or symptom arises.
In patients taking cholestyramine for diarrhea, adding a stimulant laxative like senna can create a therapeutic conflict if not carefully managed. Senna and Questran work against each other in the gut, leading to unpredictable results and patient frustration. Pharmacists must play an active role in identifying these examples of the prescribing cascade, educating patients and providers, and recommending alternatives or medication reduction and discontinuation where appropriate to avoid polypharmacy.
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