Correspondence

Seizure Associated with Use of Visicol for Colonoscopy

N Engl J Med 2002; 347:295-296July 25, 2002

Article

To the Editor:

Visicol has been prescribed more than 210,000 times since its introduction last year. The letter by Mackey et al. (June 27 issue)1 describes four patients with seizures after the use of Visicol for colonic cleansing and suggests that the risk of seizures may be greater with this product than with other purgatives. We take issue with this suggestion.

All four patients discussed by Mackey et al. had severe hyponatremia, which was the most likely cause of their seizures. Hyponatremia could have resulted from sodium losses through gastrointestinal mechanisms or sweating, excessive free-water ingestion, and excessive secretion of antidiuretic hormone. Potential contributing factors not identified by Mackey et al. include hypoparathyroidism, strenuous exercise during hot weather, the administration of two 20-tablet doses of Visicol two to three hours apart, and daily use of a laxative containing polyethylene glycol (PEG).

Neurologic dysfunction as a result of elevated antidiuretic hormone levels with hyponatremia has been reported after colonoscopy and the use of a PEG-containing product as a purgative.2 Also, among 40 patients who received a PEG-containing product as a purgative, 25 percent had elevated antidiuretic hormone levels just before undergoing colonoscopy and 7.5 percent had hyponatremia just after undergoing colonoscopy.3 The investigators attributed the elevated antidiuretic hormone levels to the nausea, vomiting, and abdominal hyperactivity associated with the use of PEG-containing purgatives; other possible causes include hypovolemia and hypotension.4

Neurologic symptoms of hyponatremia include confusion, somnolence, loss of consciousness, and seizures.4 The data base of the Food and Drug Administration indicates that all these adverse events, as well as others, have been attributed to the use of PEG-containing products (Table 1Table 1Selected Adverse Events in the Food and Drug Administration's Adverse Event Reporting System as of October 31, 2001, in Which a Product Containing Polyethylene Glycol Was Thought to Be a Primary Cause.). The data suggest that sodium phosphate tablets and PEG-containing purgatives can cause hyponatremia, which in rare cases may lead to seizures. The growing adoption of a regimen involving reduced doses of sodium phosphate tablets and reduced volumes that is described by Rex et al.5 may further decrease the likelihood of hyponatremia and may have contributed to the apparent absence of new cases of seizures since August 2001.

Martin Rose, M.D., J.D.
Leonard S. Jacob, M.D., Ph.D.
InKine Pharmaceutical, Blue Bell, PA 19422

5 References

1. 1

   Mackey AC, Shaffer D, Prizant R. Seizure associated with the use of Visicol for colonoscopy. N Engl J Med 2002;346:2095-2095
   Full Text | Web of Science | Medline

2. 2

   Shroppel B, Segerer S, Keuneke C, Cohen C, Schlondorff D. Hyponatremic encephalopathy after preparation for colonoscopy. Gastrointest Endosc 2001;53:527-529
   CrossRef | Web of Science | Medline

3. 3

   Cohen CD, Keuneke C, Schiemann U, et al. Hyponatraemia as a complication of colonoscopy. Lancet 2001;357:282-283
   CrossRef | Web of Science | Medline

4. 4

   Baylis PH. Vasopressin and its neurophysin. In: DeGroot LJ, Besser GM, Cahill GF Jr, et al., eds. Endocrinology. 2nd ed. Vol. 1. Philadelphia: W.B. Saunders, 1989:213-29.
   

5. 5

   Rex DK, Chasen R, Pochapin MB. Safety and efficacy of two reduced dosing regimens of sodium phosphate tablets for preparation prior to colonoscopy. Aliment Pharmacol Ther 2002;16:937-944
   CrossRef | Web of Science | Medline

Citing Articles (5)

Citing Articles

1. 1

   Sun Hwan Bae. (2010) Long-term safety of PEG 4000 in children with chronic functional constipation: A biochemical perspective. Korean Journal of Pediatrics 53:7, 741
   CrossRef

2. 2

   Jeong Hee Lee, Ran Lee, Sun Hwan Bae. (2008) Efficacy and safety of electrolytes-free polyethylene glycol (PEG) 4000 for disimpaction in children with chronic functional constipation. Korean Journal of Pediatrics 51:4, 391
   CrossRef

3. 3

   G. R. LICHTENSTEIN, L. B. COHEN, J. URIBARRI. (2007) Review article: bowel preparation for colonoscopy - the importance of adequate hydration. Alimentary Pharmacology & Therapeutics 26:5, 633-641
   CrossRef

4. 4

   So Hee Lee, Sun Hwan Bae. (2007) Maintenance dose of electrolyte free polyethylene glycol (PEG) 4000 in Korean children with chronic functional constipation. Korean Journal of Pediatrics 50:12, 1212
   CrossRef

5. 5

   Jerry Nagler, David Poppers, Meredith Turetz. (2006) Severe Hyponatremia and Seizure Following a Polyethylene Glycol-based Bowel Preparation for Colonoscopy. Journal of Clinical Gastroenterology 40:6, 558-559
   CrossRef