Re: Drug Interactions

From: Robert Shore 301-443-3510 FAX 301-443-9282 <SHORER@cder.fda.gov> Subject: Re: Drug Interactions Date: 19 Dec 1997 10:34:31 -0500 Yet another point for discussion (and pardon me if it has already been brought up): Exposure to 'the other' drug is important. That is, if there is a list of concomitant medications which are going to be lumped together in groups (however this is done: class, CYP activity), there needs to be some measure of exposure to these others medications. Often, from clinical trials, lists of concomitant medications include patients that took one doseof these 'other medications' once as well as patients that took 'other medications' chronically. And there may not be PK data for those concomitant medications. If it is a specific drug-drug interaction study in which all subjects received the same doses of all medications, that may be different. But if this difference in exposure to the concomitant medication(s) is not taken into account, how reliable is the analysis? What does 'no interaction' from such an analysis mean? The opinions expressed in this Email are mine alone and do not represent the opinion of the FDA. Rob Shore