Drug–Drug and Drug–Nutrients Interactions: From Theory to Clinical Relevance

Abstract

Several changes in pharmacokinetics (PK) and pharmacodynamics (PD) are associated with ageing, complicating therapeutic management in older patients. Furthermore, older patients often suffer from multiple chronic diseases generating prescription of a growing number of drugs. Age-related changes in PK/PD, polypharmacy and multimorbidity play an important role in the prevalence of drug–drug interactions (DDIs) and drug–nutrient interactions (DNIs) in older people, which increases the risk of reduced drug efficacy and adverse drug events. This chapter first describes different mechanisms of DDIs and DNIs on a pharmacokinetic and pharmacodynamic level. Second, age-related changes in PK/PD are discussed, where changes in distribution, renal elimination and susceptibility to certain drug classes are of highest importance. Finally, this chapter provides an overview of commonly clinically relevant DDIs and DNIs in older people. Most clinically relevant DDIs are of pharmacodynamic origin and often include cardiovascular, antithrombotic and centrally acting drugs. The most common DNI is a pharmacokinetic interaction, where a nutrient or enteral feed affects the absorption of a drug.