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PAGES FOR HEALTHCARE PROVIDERS

bulb.pngClinically Important, Common Drug-Drug Interactions (DDIs)

 

A clinically relevant Drug-Drug Interaction (DDI) occurs when the effectiveness or toxicity of one medication is altered by the administration of another medicine or a substance that is administered for medical purposes (to be distinguished from drug-food interactions). Adverse consequences of DDIs may result from either diminished therapeutic effect or toxicity. Among the various types of medical errors, the occurrence of adverse DDIs is one that is usually preventable. It is therefore essential that health professionals be able to evaluate the potential for DDIs and, when detected, to determine appropriate prevention or management strategies.

The potential for clinically important DDIs can often be predicted based on the drug properties, method of drug administration, and patient-specific parameters.1Consequently, adverse outcomes resulting from DDIs can be prevented by making patient- and situation-specific assessments and, if appropriate, avoiding concomitant administration by implementing alternative therapeutic strategies, or taking precautionary measures such as dosage adjustments and increased monitoring.

The table below describes potential management strategies for 16 DDIs. It is intended to serve as an educational tool and is not intended to be a guide for medical practice. The table lists the effect (e.g., pharmacokinetic, pharmacokinetic, clinical) and mechanism of the potential DDIs in addition to the propensity for related drugs to interact and options for clinical management. Click on a object-precipitant interacting drug pair to expand the table for relevant information on the interaction.

 

 

info.pngNotes About the Table:

 

This Table is for educational purposes only and is not intended to be a solitary guide for medical decisions. It was posted on May 21, 2010 and, to the best of our knowledge, is accurate and current as of that date. However, previous or future sources of information may be relevant and the reader should consider the Table in the context of other information that they have available to them. The authors will make their best efforts to maintain the accuracy of the Table but the reader should assume that additional information may have become available after May 21, 2010 that affects the accuracy of the information in the Table. 
The DDIs in the table are arranged alphabetically by object drug (the drug whose action is altered by the interaction) and precipitant drug (the drug causing the altered action of the other drug). Drugs are listed with up to 2 common brand names. There are several brand names for some of the common drugs, such as erythromycin. It is also important to consider the active drugs that are in combination products such as Simcor®, which contains niacin and simvastatin.

The interactions were selected based on previous research,2-4 with an emphasis on cardiovascular medications (e.g., warfarin), and with consideration of more recent evidence on DDIs. References for the interactions included in the table are provided upon request. Possible options typically include using an alternative, non-interacting object or precipitant drug or increased monitoring of the patient's response. These options, listed as "avoid," "usually avoid," or "take precautions," are loosely adapted from the Operational Classification of Drug Interactions.5 Although using non-interacting alternatives is frequently preferred in order to avoid adverse drug interactions, monitoring is often a reasonable option because very few drug combinations are absolutely contraindicated. Determining the most appropriate alternative medication requires careful consideration of patient-specific risks and benefits. This table focuses specifically on DDIs although drug-disease, drug-food, and drug-herbal interactions are also important considerations.

 

ref.pngReferences



1. Dresser GK, Bailey DG. A basic conceptual and practical overview of interactions with highly prescribed drugs. Can J Clin Pharmacol. Winter 2002;9(4):191-198.
2. Malone DC, Abarca J, Hansten PD, et al. Identification of serious drug-drug interactions: results of the partnership to prevent drug-drug interactions. J Am Pharm Assoc (2003). Mar-Apr 2004;44(2):142-151.
3. Malone DC, Hutchins DS, Haupert H, et al. Assessment of potential drug-drug interactions with a prescription claims database. Am J Health Syst Pharm. Oct 1 2005;62(19):1983-1991.
4. Murphy JE, Malone DC, Olson BM, Grizzle AJ, Armstrong EP, Skrepnek GH. Development of computerized alerts with management strategies for 25 serious drug-drug interactions. Am J Health Syst Pharm. Jan 1 2009;66(1):38-44.
5. Hansten PD, Horn JR, Hazlet TK. ORCA: OpeRational ClassificAtion of drug interactions. J Am Pharm Assoc (Wash). Mar-Apr 2001;41(2):161-165.

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