Drug stability failure of a few lots of Carbolith® 150 mg capsules

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November 4, 2004

Subject: Drug stability failure of a few lots of Carbolith® 150 mg capsules

Dear Health Care Professional,

Valeant Canada Limited (formerly ICN Canada Limited) is advising consumers about a recall involving lots of Carbolith 150 mg capsules from pharmacies and wholesalers across Canada.

As a precaution, Valeant Canada Limited recommends physicians to re-evaluate patients on Carbolith 150 mg by monitoring serum lithium levels and exercising clinical and laboratory surveillance over possible side effects.

A recent report on the stability test of several lots of Carbolith (Lithium Carbonate) 150 mg capsules demonstrates failure of dissolution tests on the retained samples after eighteen months. Because of the narrow therapeutic window of lithium, i.e. its plasma concentration should fall within 0.5 to 1.2 mEq/L, patients who have been stabilized on the lower limit of the therapeutic concentrations may fall below the 0.5 mEq/L and therefore could relapse into depression or mania. Patients who are stabilized at a dosage requiring the use of 150 mg capsule should consult their physician, especially if signs of underdosing are manifested.

Potential adverse reactions to these products could include a worsening of manic-depressive illness, a serious psychiatric condition. A worsening of this condition could cause symptoms associated with mania, which may include motor hyperactivity, delusions of grandeur, poor judgement and aggressiveness. A severe bout of depression or mania, during which an individual could become a danger to himself/herself or others, can often require inpatient hospitalization. In addition, there is a potential risk that a toxic effect might occur in patients who are used to the lower than expected release of drug when exposed to the full drug dosage. Mild toxicity could result in tremors of the hands, thirst and more frequent urination, drowsiness, ringing in the ears and blurred vision. More severe toxicity could result in confusion, muscle twitching, vomiting, diarrhea, seizures, coma and death.

Valeant Canada Limited commits itself to produce a new lot of Carbolith 150 mg capsules as soon as possible. This decision is to help stabilized patients on Carbolith to keep the same treatment regimen, as any product change may lead to problems in therapeutic management.

The identification, characterization, and management of marketed health product-related adverse reactions are dependent on the active participation of health care professionals in adverse reaction reporting programmes. Any occurrences of a worsening of manic-depressive illness or other serious and/or unexpected adverse reactions in patients receiving Carbolith 150 mg capsules should be reported to Valeant Canada or Health Canada at the following addresses:

Should you need more information, please do not hesitate to contact the undersigned at 1-800-361-4261.

original signed by

Dr. Joseph Awad,
Director, Medical and Regulatory Affairs
Valeant Canada Limited