Potential drug interactions during a three-decade study period: a cross-sectional study of a prescription register

University College of Kalmar, Kalmar, Kalmar, Sweden
European Journal of Clinical Pharmacology (Impact Factor: 2.7). 10/2007; 63(9):851-9. DOI: 10.1007/s00228-007-0326-0
Source: PubMed

ABSTRACT The increased risk of adverse events in patients receiving potentially interacting drugs has long been recognized. The purpose of the present study was to evaluate the change in the risk of receiving potentially interacting drugs during a period covering three decades and to examine the relative risk of actual drug combinations.
The prescriptions from all individuals (about 8,000) with two or more prescriptions during three periods of 15 months, October to December 1983-1984, 1993-1994 and 2003-2004, were collected from an ongoing cohort study in the county of Jämtland, Sweden. The potential interactions were detected by a computerized system.
The relative risk (RR) of receiving potentially interacting drugs increased for type C interactions [RR: 1.177, 95% confidence interval (CI): 1.104-1.256] and decreased for type D interactions (RR: 0.714, 95% CI: 0.587-0.868) from the period 1983-1984 to 2003-2004. Polypharmacy for the participants increased by 61%, from 9.05 filled prescriptions per subject in 1983-1984 to 10.6 in 1993-1994 and 14.6 in 2003-2004. The RR was positively correlated to the pronounced increase in polypharmacy; in addition, an exponential relationship was found for the more severe type D interactions. Few interacting drug combinations were responsible for a large proportion of the risk.
We conclude that the risk of receiving potentially interacting drugs was strongly correlated to the concomitant use of multiple drugs. The pronounced increase in polypharmacy over time implies a growing reason for prescribers and pharmacists to be aware of drug interactions. Recently established national prescription registers should be evaluated for drug interaction vigilance, both clinically and epidemiologically.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Common Syndromes in Older Adults ii Minnesota Evidence-based Practice Center This report is based on research conducted by the Minnesota Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. HHSA 290-2007-10064-1). The findings and conclusions in this document are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services. The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment. This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied. This document is in the public domain and may be used and reprinted without permission, except those copyrighted materials noted for which further reproduction is prohibited without the specific permission of copyright holders.
  • Source
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aims of this study were to analyze the prescription pattern of desmopressin before and after the new indication was approved for treatment of nocturia in the elderly in Sweden in 2002 and to analyze to what extent other drugs potentially inducing hyponatremia were prescribed in combination with desmopressin. We conducted epidemiological analyzes of the Swedish Prescribed Drug Register from 2000 to March 2007. All patients older than 60 years who were prescribed desmopressin in Sweden during the study period were included. A marked increase in filled prescriptions of desmopressin in elderly patients was noticed after the new approval in 2002. The therapeutic intensity peaked in 2005 and has thereafter markedly decreased. The magnitude of concurrent treatment with any of the following drugs was assessed: diuretics, tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRI), chlorpromazine, carbamazepine, loperamide, and nonsteroid anti-inflammatory drugs. More than half of the patients on desmopressin during July 2005 and March 2007 filled a prescription of any of the potentially harmful drugs within 30 days of a filled prescription of desmopressin. The use of desmopressin in the elderly after the new approval in 2002 showed a similar prescription pattern to any newly introduced drug or after a changed indication. A large part of the elderly on desmopressin also receives other drugs that are potentially harmful in combination with desmopressin. Increased awareness of potentially interacting concomitant medication can improve medication safety in this fragile group.
    European Journal of Clinical Pharmacology 05/2008; 64(4):439-44. DOI:10.1007/s00228-007-0439-5 · 2.70 Impact Factor