Relationships between prescription and non-prescription drug use in an elderly population

This paper explores, at an epidemiological level, the relationship between categories of over-the-counter (OTC) and prescribed (Rx) drugs in a communi ty-resident elderly population. A total of 2818, randomly selected, older a dults were interviewed at home about their use of prescribed and non-prescr ibed medication and other health-related factors. For comparative purposes OTC drugs were classified into 16 therapeutic groups-identical to those use d by other researchers; prescribed drugs were classified into 45 British Na tional Formulary (BNF) therapeutic sub-categories. Analyses revealed signif icant association between certain BNF categories and OTC categories, which may have a clinical explanation. These include a 3-fold increase (P < 0.01) of OTC laxative use by those prescribed an antidepressant, and a 4-fold in crease (P < 0.001) in OTC antacid use among those prescribed oral corticost eroids. Our findings may indicate an attempt by older people to control sid e effects of prescription medicines with OTC preparations. This study, in p art, supports the call by the Royal College of Physicians for further resea rch to determine the effect of interactions (be they pharmacological, behav ioural or otherwise) between OTC and prescribed medicines. (C) 1999 Elsevie r Science Ireland Ltd. All rights reserved.