Drug-Drug Interactions (DDIs)

Drug-Drug Interactions (DDIs)

Definition

• Occurs when one or more drugs affect the pharmacokinetics and/or pharmacodynamics of other drugs.

Study Methods

• Principal way of studying health effects of DDIs: Pharmacoepidemiology

• Methodologic problems in DDI studies include:

  • Confounding by indication

  • Inability of healthcare data to validly identify study outcomes

  • Need for optimized methods for unanticipated associations

Research Designs

• Available designs for studying health effects of DDIs:

  • Cohort studies

  • Nested case-control studies

  • Self-controlled case series

  • Case-crossover designs

• Use of positive/negative control object drugs and precipitant drugs

Additional Considerations

• Importance of:

  • Order of concomitancy of object and precipitant

  • Time course of the DDI

Clinical Importance

• Factors contributing to increasing relevance of DDIs:

  • Polypharmacy

  • Aging population

• Urgent need for approaches to better incorporate DDI knowledge into healthcare systems.