Psychiatric Drug Interactions: Strategies to Minimize Adverse Outcomes From Unintended DDIs

Sheldon H. Preskorn, MD
David Flockhart, MD, PhD

Dr. Preskorn is Professor, Chair, Department of Psychiatry and Behavioral Sciences, University of Kansas Shool of Medicine, CEO, Clinical Research Institute

Dr. Flockhart is Professor of Medicine, Genetics, and Pharmacology; Chief, Division of Clinical Pharmacology, Indiana University School of Medicine

A Personal Formulary: Concept and Criteria

While all physicians are taught pharmacology in medical school, many, if not most, of the drugs that the average prescriber uses were not available during their training. For this reason, the value of a personal formulary in an era of polypharmacy and pervasive and potent marketing cannot be overemphasized. Such a formulary should consist of 10–15 drugs that are used virtually every day in the clinician’s practice and that he/she is intimately familiar with.

The physician should truly be an expert on these medications. That includes their generic and brand names, pharmacokinetics, pharmacodynamics, adverse effects, and potential DDIs.

It should not be easy for a drug to enter a personal formulary. Diligent study of the drugs in question, careful evaluation of the literature pertaining to them, and ongoing checks of new developments should be a routine habit for the prescriber.

This foundation of knowledge can then serve as a basis for the evaluation of new drugs as they appear.

Generic Names

At a minimum, a prescriber should be aware of the generic name of a medication on their personal formulary. As medicine becomes more international and the world becomes smaller, the physician must be aware that medications have different brand names in different countries, and frequently have multiple brand names. For example, there are 18 different brand names for fluoxetine in Italy.

The use of the generic name in prescriptions allows cheaper generic drugs to be used when they are available.

Lastly, persistent confusion over the similarity of drug names, either written or spoken, accounts for ~25% of all reports to the US Pharmacopeia Medication Errors Reporting Program, and the case for the use of both a generic name and brand name in legible handwriting on prescriptions is strong.

Although many have made the case that a switch to e-prescribing may obviate this problem, incorrect selection of a drug name from a computerized list has already been shown to be a significant problem; thus, there is one more argument making the case for routinely using both the generic and the brand names as a means of ensuring quality in prescribing.

Disclosure: Dr. Preskorn is a consultant to Bristol-Myers Squibb, Cyberonics, Eli Lilly, Johnson&Johnson, Memory, Otsuka, Pfizer, Shire, Somerset, and Wyeth; is on the speaker’s bureaus of Bristol-Myers Squibb, Cyberonics, Forest, Otsuka, and Pfizer; and receives grant support from Brtistol-Myers Squibb, Cyberonics, Johnson&Johnson, Memory, Merck, The National Instute of Mental Health, Novartis, Organon, Otsuka, Pfizer, Predix, Sepracor, and Somerset.

Disclosure: Dr. Flockhart is a consultant to Hoffman-La-Roche.