Last week’s post covered controversial enema claims and unproven treatments. There are, however, several uses for enemas that are supported by evidence-based medicine. Enemas can be used in procedural preparation, as part of a post-operative regime, and as a medical delivery mechanism. Their use is more frequent in distal Crohn’s disease effecting the large intestine and rectum and in left-sided Ulcerative Colitis and Ulcerative Proctitis, due to the fact that enemas generally only effect those locations in the GI tract. A few of the evidence supported medical uses are covered below.
Drug delivery directly to the colon is done for three primary reasons – to decrease systemic absorption of specific drugs, to increase bioavailability of targeted drugs, and to provide direct application of drugs to effected areas.
Many drugs used to treat IBD have a negative systemic impact. Chief among these are corticosteroids, which can cause high blood pressure, eye problems, osteoporosis, unusual fat deposition, and increased risk of infection. Because of this, targeted delivery of these drugs through the use of an enema reduces overall systemic absorption. Both budesonide and prednisone, two key anti-inflammatory drugs used in IBD treatment, have been successfully delivered via enema. The enemas can be liquid or foam-based, and have been shown to have fewer systemic side effects than oral use of the same drugs. (1,2)
A corollary to the systemic side effects is related to bioavailability. There digestive system is complex, and everything from saliva to the inhospitable pH from stomach acids to pancreatic enzymes can degrade or render inert medicines. Drug companies spend almost as much time engineering how to get a drug to the area of the body where it will be absorbed (and even better, time released) as they do in the basic research for the drug. While injections are possible with certain drugs, others can be absorbed through the intestinal mucosal layer by being inserted into the other end – bypassing the digestive process.
The final reason is the direct delivery of drugs to the affected area. Just like a topical treatment on the skin, direct delivery allows for a high dose of drugs to be brought to bear on the area of concern itself. Drugs like mesalamine (Canasa ™) and hydrocortisone (Cortenema™) can be delivered directly to inflamed areas through enemas.(3)
For a lower-GI series, a barium enema is delivered through a tube into the rectum prior to taking X-rays of the large intestines. The lower GI series allows for detailed imaging and review of the large intestine, and is an alternative mechanism to the colonoscopy. The lower-GI barium series has generally been shown to be a less effective diagnostic technique than colonoscopy in most cases, and has fallen out of general favor as a primary diagnostic tool and is used only in very specific circumstances (e.g. severe stenosis).(4)
For preparation of the large intestine before a sigmoidoscopy, enemas are often used. A single over-the-counter enema has been shown to be effective in cleaning out the lower parts of the GI tract for the procedure (and was more effective than suppositories). Some rectal surgeries and prostate procedures use enemas as well for prep.(5)
Other preparatory uses have fallen out of favor. For example, enemas were previously recommended for those having endourological surgery. The theory was that the enema would prevent future urinary tract infections and other complications due to fecal contamination. For the most part, there was no clinical difference between patients preparing with the enemas and those who did not in post-operative infection rates. (6)
Finally, enemas have been put forth as a delivery mechanism for fecal transplant operations. The data on their effectiveness as a delivery mechanism is preliminary, but early studies show promise for getting the transplanted bacteria delivered to the distal small intestine.(7)
· Enemas have multiple medical uses in treating IBD, with new uses appearing and others being removed from common use.
1. Danielsson, Å., et al. "A steroid enema, budesonide, lacking systemic effects for the treatment of distal ulcerative colitis or proctitis." Scandinavian journal of gastroenterology 27.1 (1992): 9-12.
2. McIntyre, P. B., et al. "Therapeutic benefits from a poorly absorbed prednisolone enema in distal colitis." Gut 26.8 (1985): 822-824.
3. Chourasia, M. K., and S. K. Jain. "Pharmaceutical approaches to colon targeted drug delivery systems." J Pharm Pharm Sci 6.1 (2003): 33-66.
4. Rockey, D. C., et al. "Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison." The Lancet 365.9456 (2005): 305-311.
5. Underwood, D., et al. "A prospective randomized single blind trial of Fleet phosphate enema versus glycerin suppositories as preparation for flexible sigmoidoscopy." Irish journal of medical science 179.1 (2010): 113-118.
6. Utrera, N. Miranda, et al. "An analysis of the value of bowel preparation for preventing postoperative complications in endoscopic surgery." actas urol esp34.3 (2010): 278-281.
7. Silverman, Michael S., Ian Davis, and Dylan R. Pillai. "Success of Self-Administered Home Fecal Transplantation for Chronic Clostridium difficile Infection." Clinical Gastroenterology and Hepatology 8.5 (2010): 471-473.