March 1998

Dear Doctor,

This letter is intended to inform you that Tegretol® Suspension (carbamazepine USP) should not be administered simultaneously with other liquid medicinal agents or diluents.

Novartis has submitted to the FDA a report of a patient who passed an orange rubbery mass in his stool the day after ingesting Tegretol Suspension immediately followed by Thorazine® (chlorpromazine) solution. Subsequent testing has shown that mixing Tegretol Suspension and chlorpromazine solution (both generic and brand name) as well as Tegretol Suspension and liquid Mellaril® (thioridazine HCI USP) results in the precipitation of a rubbery orange mass. It is not known if the formation of this precipitate results in decreased bioavailablility of Tegretol or of either of the other two medications tested.

The extent to which this interaction occurs, if at all, with other liquid medications is not known.

Systematic testing is underway to determine the cause and nature of this interaction.

Please inform your patients and their caregivers of the above administration information which has been included in the Dosage and Administration and Drug Interactions sections of the package insert for Tegretol Suspension. We appreciate your support in informing your patients for whom you have prescribed or will prescribe Tegretol Suspension. Pharmacists are being sent a similar letter and will be asked to advise patients as well. Thank you for your attention to this matter.

For information regarding any product manufactured by Novartis Pharmaceuticals Corporation, please call 1-800-742-2422.

Sincerely,

Rama Seshamani, M.D.
Director, Medical Affairs

Please see enclosed complete prescribing information

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