Enema Products: Uses and Cautions
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Enema Products: Uses and Cautions

W. Steven Pray, Ph.D., R.Ph.


Nonprescription enemas are recommended by physicians for certain patients with special problems. Used appropriately, they are safe and effective. However, if they are used inappropriately or in situations in which their use is not warranted, they can cause considerable patient injury.

Enemas are solutions of certain ingredients introduced rectally to induce laxation or for other medical reasons (e.g., corticosteroid enemas for ulcerative colitis).1 They have various mechanisms of action. Tap water works simply by distending the bowel.2 The Food and Drug Administration recognizes several categories of active ingredients as effective for the treatment of constipation.3 They include: Probably the most commonly used enemas are the sodium phosphate/biphosphate solutions, which are widely available as ready-to-use enemas, e.g., Fleet and several generic competitors. The Fleet enema adult package contains 19 g of monobasic sodium phosphate and 7 g of dibasic sodium phosphate per 118 mL of fluid, yielding 4.4 g of sodium per adult dose. The pediatric package contains half the amount of the adult enema dose, for a dose of 2.2 g of sodium per 66.6 mL bottle.

Mineral oil enemas and glycerin ready-to-use enemas are also available.

Colace Microenema
is a newly introduced product containing 5 mL of docusate sodium per container. While the FDA initially approved only docusate potassium as the sole stool softener for enema use, the agency acknowledged that the substitution of sodium should not significantly affect the biological activity of the docusate.4 Nevertheless, the agency asked manufacturers to submit data to prove that the other docusate salts would be safe and effective in enema form.

Uses of Enemas

• Constipation: Constipation is the complaint that commonly prompts the use of enemas, and that topic has been previously covered in this column (July 1992). Enemas are often seen as a method for treating both childhood and adult constipation.5,6

• Bowel Retraining: Patients may be constipated through failure
to heed the defecatory reflex until it is lost. Then, physicians may suggest the use of a small-volume enema (e.g., one pint of warm tap water) to distend the lower bowel and stimulate the vestigial defecatory reflex.7 The optimal administration time is after a meal, when the postprandial defecatory reflex is maximal, especially
following breakfast.
Further enemas may be necessary to fully retrain the bowel, but they should be discontinued after several days to allow the patient’s own body to resume normal activity. Enemas may also be helpful in the same manner to allow retraining of the laxative-dependent colon.8

• Fecal Impaction: Fecal impaction results from prolonged retention of the stool in the distal bowel, allowing the body to absorb moisture from the fecal mass.9 If the mass continues to harden, it becomes progressively more difficult for the patient to eliminate. Thus, the patient complains of constipation. The problem is further compounded by the fact that the patient continues to eat and pass material through the colon proximal to the impaction. This material is blocked by the accumulated fecal mass and is added to the mass. Eventually, the impaction blocks the section of bowel that is active in water absorption, and fluid feces accumulate behind the impaction. Luminal pressure eventually may force the liquid stool to pass around the impaction, producing what has been termed a "ball-valve effect," also known as paradoxical diarrhea. In children, this overflow diarrhea is also called encopresis.10

Fecal impaction cannot be treated with oral laxatives, which are ineffective for this condition and worsen abdominal discomfort and pain.9 Effective treatments are topical doasge forms, either suppositories or enemas, although this indication is not part of the FDA-suggested nonprescription labeling.3 However, at least one manufacturer has placed on the label, "For the relief of fecal impaction."

While mineral oil
enemas are indeed effective for preliminary softening of the fecal impaction, before selling the product it is preferable to ask the patient if a physician has diagnosed impaction.2,11,12 If a physician has diagnosed impaction, the pharmacist should ascertain if a mineral oil enema was specifically recommended by the physician. Should the enema fail to relieve the impaction, manual fragmentation and extraction are the next steps to be undertaken. Following this procedure, mineral oil enemas are helpful in lubricating the distal rectum and they facilitate expulsion of any residual mass.9

• Pre-Procedure Preparation: Enemas often are a component of kits used for bowel preparation prior to such procedures as barium enema, proctosigmoidoscopy, colonoscopy, etc.13 However, some kits contain ingredients that allow creation of a soapsuds enema, which could be dangerous.

Hazards

Enemas may cause trauma due to the method by which they are introduced into the body. A 55-year-old female was given a sodium phosphate enema, but the tip of the rectal enema tube produced a mucosal laceration, which allowed enema solution to enter the submucosal plane, causing mucosal necrosis.14

• Sodium Phosphate/ Biphosphate Enemas

When sodium phosphate enemas are used as directed, they are quite safe. However, in a fraction of patients they may produce adverse reactions, especially when misused. Some cases deserve discussion to emphasize the cautions that should be observed in their administration.

Tissue Damage: Sodium phosphate/biphosphate enemas may alter the appearance of rectal tissue upon proctoscopic examination and produce tissue necrosis.9 One paper related the courses of three patients who received phosphate enemas and subsequently experienced rectal gan-grene.15 Each patient had decreased ability to combat inflammation; two had advanced
malignancy, and the other was elderly and debilitated. The authors implicated trauma
from the nozzle tip,
but they also indicated that this hazard seems to be more pronounced with phosphate-containing enema solutions.

Phosphate Imbalance: Patients with renal insufficiency may experience hyperphospha-temia with use of these products, as may neonates, small children and patients with Hirschsprung’s disease, imperforate anus and rectal atresia.9 In one such case, an 81-year-old male was given a single sodium phosphate enema, but passed little of it.16 Retention allowed absorption, and the patient’s mild chronic renal insufficiency reduced its elimination, leading to hyperphosphatemia.

Calcium Imbalance: Calcium binds with phosphate, so that a rise in serum phosphate produces a reciprocal fall in serum calcium.17 This mechanism produced iatrogenic hypocalcemic tetany after a series of three adult sodium phosphate enemas were given to a 4-year-old boy with chronic constipation over a period of two to three days.18 It also caused life-threatening hypocalcemic tetany in an adult female who was given six sodium phosphate enemas over a 12-hour period.19 This patient was at higher risk for renal failure since she had an atonic dilated colon and acute renal failure. A dilated atonic colon can allow the retention of an enema solution in a large volume facilitating its absorption by the body. Coupled with renal failure, which hampers elimination, the results are potentially fatal.

Potassium Imbalance:
A 2-year-old girl with chronic constipation secondary to subacute neuropathic Gaucher’s disease was given daily saline enemas.20 Upon hospitalization for a respiratory infection, she was given two pediatric enemas, both of which were retained. She experienced hypokalemia at this time (coupled with rising phosphate) and during a later rechallenge, in spite of having no other electrolyte abnormalities.

Failure to Observe Age Warnings: The sodium phosphate enemas are not to be recommended by the pharmacist for self-therapy of patients under the age of 2. They are still dangerous when used under medical supervision. In one case, an 11-month-old child was given four adult sodium phosphate enemas to remove residual debris remaining in the distal colon following lavage.21 The enemas were apparently retained and the overdose resulted in hypernatremia, acidemia, hyperphosphatemia, hypocalcemia and death. In another case, a 4-month-old child was given one-half of a pediatric sodium phosphate enema, which was not retained yet produced hypocalcemia, hyperphosphatemia, and dehydration.22

• Soapsuds Enemas

Soapsuds (SS) enemas were once quite popular. Supposedly, their action was due to the irritant effect of soap on mucous membranes. They were made either by addition of soap to an enema bag, or with a commercially available product that included a small packet of castile soap for dilution and subsequent enema use. However, the use of soapsuds
enemas was found to be associated with adverse reactions caused by its irritant effects, including ulcerative colitis, anaphylaxis, rectal gangrene, excessive serosanguinous fluid loss and death.6,9,23-25

• Enemas in
Alternative Medicine

Certain branches of alternative medicine advise frequent enemas, evidently subscribing to the theory that the bowel must be periodically cleaned. Unfortunately, these regimens may include strange substances such as coffee enemas, which have caused morbidity and death. Hydrogen peroxide, also used in some alternative medicine regimens, also
irritates mucosa to cause bleeding.9,25 Other homemade

enemas such as milk and molasses have not been assessed for safety or efficacy.25

Cautions to Patients

Enemas of any kind (even plain water enemas) must never be administered when the patient is suffering abdominal pain. If insertion of the enema nozzle causes pain, the patient should not insert the nozzle any further and should not use the product.


1. Campieri M, et al. Role of rectal formulations: Enemas. Scan J Gastroent Suppl. 1990; 172:63-65. 2. Donatelle EP. Constipation: Pathophysiology and treatment. Am Fam Physician. 1990;42: 1335-1442. 3. Fed Reg. 1985;50: 2124-2158. 4. Fed Reg. 1993;58: 46589-46596. 5. Gleghorn EE, Heyman MB, Rudolph CD. No-enema therapy for idiopathic constipation and encopresis. Clin Pediatr. 1991;30: 669-672. 6. Rousseau P. Treatment of constipation in the elderly. Postgrad Med. 1988;83: 339-340, 343-345, 349. 7. Marshall JB. Chronic constipation in adults. Postgrad Med. 1990;88: 49-51, 54, 57-59, 63. 8. Tremaine WJ. Chronic constipation: Causes and management. Hosp Pract. 1990;25: 89-92, 95-96, 99-100. 9. Wrenn K. Fecal impaction. N Engl J Med. 1989;321:658-662. 10. Pettei MJ. Chronic constipation. Pediatr Ann. 1987;16:796-800, 804-806, 811-813. 11. Castle SC. Constipation: Endemic in the elderly? Med Clin N Am. 1989;73:1497-1509. 12. Murray Fe, Bliss CM. Geriatric constipation: Brief update on a common problem. Geriatrics. 1991;46:64-68. 13. Binder HJ. Use of laxatives in clinical medicine. Pharmacology. 1988;36(suppl 1):226-229. 14. Bell Am. Colonic perforation with a phosphate enema. J R Soc Med. 1900;83:54-55. 15. Sweeney JL, et al. Rectal gangrene: A complication of phosphate enema. Med J Aust. 1986;144:374-375. 16. Biberstein M, Parker BA. Enema-induced hyperphosphatemia. Am J Med. 1985;79:645-646. 17. Grosskopf I, et al. Hyperphosphatemia and hypocalcemia induced by hypertonic phosphate enema-An experimental study and review of the literature. Hum Exp Toxicol 1991;10:351-355. 18. Edmondson S, Almquist TD. Iatrogenic hypocalcemic tetany. Ann Emerg Med. 1990;19:938-940. 19. Korzets A, et al. Life-threatening hyperphosphatemia and hypocalcemic tetany following the use of Fleet enemas. J Am Ger Soc. 1992;40:620-621. 20. Forman J, Baluarte J, Gruskin AB. Hypokalemia after hypertonic phosphate enemas. J Pediatr. 1979;94:149-151. 21. Martin RR, et al. Fatal poisoning from sodium phosphate enema. JAMA. 1987;257:2190-2192. 22. Davis RF, et al. Hypocalcemia, hyperphosphatemia, and dehydration following a single hypertonic phosphate enema. J Pediatr. 1977;90:484-485. 23. Anon. Soapsuds Enemas. U.S. Pharmacist. 1988;13(9):24. 24. Anon. No soapsuds enemas! Am Pharm. 1988; NS28(9):14