Polypharmacy and Drug Interaction

In days past, a basic understanding of a drug’s mechanism of action was sufficient for the purpose of prescribing a medication to treat the vast majority of patients and their conditions. Those days are long gone with 48 % of Medicare beneficiaries over the age of 65 having three or more chronic medical conditions and 21 % having five or more of these conditions (Boyd et al., JAMA. 294(6):716–24, 2005). It has been estimated that the likelihood of a drug interaction in a patient taking only two different medications is only 6 %, whereas when the number of medications increases to ten, the likelihood of drug interaction increases to 100 % (Lin, Can Alzheimer Dis Rev. 10–4, 2003). With this virtual certainty of frequently dealing with drug interaction, a physician must have a solid understanding of polypharmacy along with drug interactions.