August 23, 1996

Dear Doctor:

Pharmacia & Upjohn Company would like to inform you about recent changes to the prescribing information for HALCION Tablets (triazolam tablets) C-IV and XANAX Tablets (alprazolam tablets) C-IV. Triazolam and alprazolam are metabolized via the cytochrome P450 3A (CYP 3A) pathway and may interact with other drugs and foods that use this pathway. Please review the Contraindications, Warnings, and Precautions sections of the complete prescribing information (updated text also enclosed).

HALCION is contraindicated with ketoconazole, itraconazole, and nefazodone, medications that significantly inhibit oxidative metabolism mediated by CYP 3A, and caution is recommended for other drugs and substances. A more complete list of possible drug interactions can be found in the updated Warnings and Precautions sections of the prescribing information for HALCION.

XANAX is contraindicated with ketoconazole and itraconazole, and caution is recommended for other drugs and substances. Again, a more complete list of possible drug interactions can be found in the updated Warnings and Precautions sections of the prescribing information for XANAX.

Pharmacia & Upjohn Company is dedicated to providing important new information about our products to health-care providers. The safety and efficacy of HALCION and XANAX have been demonstrated when they are used in accordance with the enclosed full prescribing information.

The medical community can further our understanding of these events by reporting all cases to Pharmacia & Upjohn Company at 1-800-253-8600, ext 9-8777, or to the FDA MEDWATCH Program by phone 1-800-FDA-1088; by fax 1-800-FDA-0178; by modem 1-800-FDA-7737; or by mail to MEDWATCH, HF-2, FDA, 5600 Fishers Lane, Rockville, Maryland 20857.

If any questions arise about the content of this communication, please call our Medical & Drug Information Unit at 1-800-253-8600, ext 9-8244.

Sincerely,

David L. Keck, RPh

Enclosures