Archived – Important Safety Information Regarding Sodium Phosphates Oral Solution – Pharmascience Inc.

Important Safety Information Regarding Phosphates Solution (Sodium Phosphates Oral Solution - DIN 02230399)

Pharmascience Inc.

March 18, 2002

Dear Health Care Professional:

Following discussions with Health Canada, Pharmascience would like to highlight the following important safety information related to use of Phosphates Solutions:

• Electrolyte shifts may occur in patients with or without risk factors for electrolyte shifts if the maximum recommended dose of 45 ml (contains 5760 mg of phosphorus) in a 24-hour period is exceeded. Hypocalcermia, hyperphosphatemia, hypernatremia, hypokalemia, and acidosis can occur with the use of oral sodium phosphates solutions. These conditions are more likely to occur when more than one dose (45 ml) of sodium phosphates is given in a 24-hour period. Physicians should counsel patients on the recommended dose.
• The recommended maximum total daily dose for any indication for adults is 45 ml of sodium phosphates oral solution in a 24-hour period (contains 5760mg of phosphorus).
• Do not use the product in patients with congenital megacolon, bowel obstruction, ascites or congestive heart failure.
• Use the product with caution in patients with impaired renal function, heart disease, acute myocardial infarction, unstable angina, preexisting electrolyte disturbances (such as may occur in dehydration or secondary to the use of diuretics, diarrhea, GI bleeding), the elderly, or people taking drugs that may affect electrolyte levels, or with debilitated patients.
• Treatment of electrolyte imbalance may require immediate medical intervention with appropriate electrolyte and fluid replacement.

Phosphates Solution is an oral solution, which has been marketed in Canada since 1993 and is used as a laxative for the relief of occasional constipation. The product is also used as a purgative as part of a bowel-cleansing regimen in preparing patients for surgery or for preparing the colon for x-ray or endoscopic examination.

Serious electrolyte disturbances (hypocalcaemia, hyperphosphatemia, hypernatremia, hypokalemia), dehydration, renal failure, and tetany have been observed:

• In patients ingesting more than the 45 ml dose of sodium phosphates oral solution as a bowel preparation for colonoscopy surgery, or barium enema at a physician's instruction.
• In patients at medical risk.
• In patients using multiple purgatives for bowel preparation.

These observations were identified through a review of adverse drug reactions associated with sodium phosphates oral solutions received by the Canadian Adverse Drug Reaction Monitoring Program from 1987 up to October 31, 2001. A search of the database revealed 10 domestic Canadian reports with 9 of these reports involving one or more of these risk factors. Reporting rates determined on the basis of spontaneously reported post-marketing adverse events may underestimate the risks associated with drug treatments. For more information refer to the FDA Science Background document "Safety of sodium phosphates oral solution" found at the following internet address: http//www.fda.gov/cder/drug/safety/sodiumphospate.htm.

Changes in hematocrit, serum sodium, blood urea nitrogen, serum osmolality, and body weight after ingesting sodium phosphate oral solution suggest that a contraction of intravascular volume can occur. In patients without risk factors, shifts in serum calcium, serum phosphorus, serum sodium, and serum potassium can be statistically significant when compared to baseline values, but generally electrolyte values remain within the normal range without significant clinical sequelae and return to normal values rapidly. The clinical significance of any changes in electrolyte values will be influenced by individual patient risk factors for electrolyte shifts and concurrent medical conditions such as those noted above.

If administration of sodium phosphates oral solution is being considered for patients at risk of electrolyte imbalances or if more than 45 ml of the product is to be used in a 24-hour period, it is advisable to obtain baseline electrolyte levels prior to administration and to ensure sufficient fluid replacement to prevent dehydration and serious electrolyte problems.

The identification, characterization, and management of drug-related adverse events is dependent on the active participation of health care professionals in adverse drug reaction reporting programmes. Health care professionals are asked to report any suspected adverse reactions in patients receiving oral sodium phosphates solution (Phosphates Solution) directly to Pharmascience Inc., or to the Bureau of Licensed Product Assessment at the following addresses:

Medical Scientific Information Department
Pharmascience Inc.
6111 Royalmount Ave.
Bureau 100
Montreal, (Que), H4P 2T4

medinfo@pharmascience.com
Tel: 1 888 550-6060
Fax: 1 514 340-9920

Your professional commitment in this regard has an important role in protecting the well being of your patients by contributing to early signal detection and informed drug use.

Should you require any additional information, please don't hesitate to contact our Medical Information Department at the telephone numbers mentioned above.

Yours sincerely,

original signed by

Pharmascience Inc.
Len Neirinck, Ph.D.
Vice President Scientific Affairs
Tel: (514) 340-5085
Fax: (514) 340-9920
Email: lneirinc@pharmascience.com

Any suspected adverse reactions can also be reported to:

Canadian Adverse Drug Reaction Monitoring Program (CADRMP)
Bureau of Licensed Product Assessment
Health Canada
Address Locator: 0201C2
Ottawa, Ontario, K1A 1B9
Tel: (613) 957-0337 or Fax: (613) 957-0335
Toll free for consumers and health professionals:
Tel: 866 234-23.45, Fax: 866 678-6789
cadrmp@hc-sc.gc.ca

The ADR Reporting Form can be found in The Canadian Compendium of Pharmaceuticals and Specialties, or on the TPD website, along with the ADR Guidelines.