We're unable to sign you in at this time. Please try again in a few minutes.
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......

Torsades de Pointes Occurring in Association With Terfenadine Use-Reply

Louis R. Cantilena Jr, MD, PhD; Clifford L. Ferguson, MD; Brian P. Monahan, MD
JAMA. 1991;266(17):2376. doi:10.1001/jama.1991.03470170063024.
Text Size: A A A
Published online


In Reply.  —We appreciate the comments from Mathews et al regarding our report of torsades de pointes in a patient taking terfenadine with ketoconazole at the recommended dosages. We suspected that an inhibition of terfenadine metabolism by ketoconazole was the mechanism underlying the presumed drug interaction. The results presented by Mathews et al support our hypothesis.We disagree with the Marion Merrell Dow Inc suggestion that our patient may have ingested terfenadine at "a higher-than-recommended dose." The data presented by Mathews et al to support this suggestion are from a single-dose terfenadine study, which may not be generalizable to more clinically relevant steady-state interactions with terfenadine. Based on pill counts and corroborative history from the patient's spouse, we believe that 60 mg of terfenadine was being taken twice daily (the recommended dosage). Further, based on data from current research in our division, with steady-state terfenadine drug interactions, we suggest that


Sign in

Purchase Options

• Buy this article
• Subscribe to the journal




Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Please click the checkbox indicating that you have read the full article in order to submit your answers.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.


Some tools below are only available to our subscribers or users with an online account.

Sign in

Purchase Options

• Buy this article
• Subscribe to the journal

Related Content

Customize your page view by dragging & repositioning the boxes below.