Science Backgrounder
Seizure Associated with the Use of Visicol for Colonoscopy--Additional
Information
For current informatino on Visicol, please see http://www.fda.gov/cder/drug/infopage/OSP_solution/default.htm
June 27, 2002
A letter to the Editor of the New England Journal of Medicine (Mackey
et al., 2002;346:2095) described four cases of tonic-clonic seizure
associated with the use of sodium phosphate tablets (Visicol, InKine
Pharmaceutical Co., Inc.). One of these patients had a history of
hypoparathyroidism which may be associated with electrolyte abnormalities;
it is not known if this condition played a role in his event. None of the
other cases had known risks for seizure. The FDA has received one
additional case of a 74-year-old female who experienced a tonic-clonic
seizure after initiating sodium phosphate tablets and before colonoscopy.
This patient had electrolyte abnormalities (Na=114 mmol/liter, K=3 mmol/liter,
Ca=7.7 mg/dl, Mg=1.2 mg/dl) at the time of the event. She had a history of
mild hyponatremia with use of a tricyclic antidepressant; it is unknown if
her hyponatremia was ongoing before she started taking the sodium
phosphate tablets.
These five reports should be interpreted in the context of
approximately 210,000 prescriptions for sodium phosphate tablets dispensed
from drug launch in January 2001 through June 2002, and the fact that
there is generally under reporting of adverse events associated with
prescription drug products.
FDA has not received reports of seizure associated with
over-the-counter sodium phosphate-containing preparations, however the
published literature includes three reports of seizure related to
hypocalcemia with use of these preparations. Manufacturers of
over-the-counter sodium phosphate-containing preparations are not required
to report adverse events to the FDA.
In summary, colonoscopy is a common procedure, and physicians should be
aware of the possible risks associated with the administration of sodium
phosphate-containing bowel evacuants in preparation for the procedure.
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Drug Information
FDA/Center for Drug Evaluation and Research
Last Updated: June 27, 2002
Originator: OTCOM/DLIS
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