Drug-drug interactions and their predictors: Results from Indian elderly inpatients
Background: In view of the multiple co-morbidities, the elderly patients receiving drugs are prone to suffer with drug interactions since they receive a greater number of drugs.
Objective: The study was undertaken to determine the prevalence of drug interactions, as well as their predictors.
Method: The prescriptions of a total of 1510 inpatients were collected prospectively for 1.5 years from inpatients wards of public tertiary care teaching hospital. All the prescriptions were checked for drug interactions using the Micromedex® Drug-Reax database-2010 and Stockley’s Drug Interactions. Regression analyses sought to determine predictors for the drug interaction.
Results: The patients, with the average age of 67.2 ±0.2 years, were prescribed an average of 9.15 ±0.03 medications. It was found that out of 1510 prescriptions of inpatients, 126 (8.3%) prescriptions had one or more than one drug interaction. All the identified interactions were severe in nature.
The top most interacting drugs were acetylsalicylic acid and anticoagulant (n=59). The second top most interacting drug combination was clopidogrel and proton pump inhibitors (n=51). The most commonly involved drugs in interactions were C (cardiovascular system) and A (alimentary tract and metabolism). Using multivariate binary logistic regression, multiple drugs (Odds Ratio=4.5; 95% Confidence Interval: - 2.38 -9.47) and multiple diagnoses (Odds Ratio=2.6; 95%CI: -1.40 -5.57) were found to be significant predictors for drug interaction.
Conclusion: The results of this study substantiate the occurrence of severe drug interactions among Indian elderly inpatients. In order to provide safer pharmaceutical care, the active involvement of clinical pharmacists is a potential option.
2. Mendes-Netto RS, Silva CQV, Oliveira Filho A, Rocha CE, Lyra DP Jr. Assessment of Drug Interactions in elderly patients of a family health care unit in Aracaju (Brazil): A pilot study. Afr J Pharm Pharmacol 2011;5(7):812-818.
3. Juurlink DN, Mamdani M, Kopp A, Laupacis A, Redelmeier DA. Drug drug interactions among elderly patients hospitalized for drug toxicity. JAMA. 2003;289(13):1652-1658.
4. International classification of disease, in: International Statistical Classification of Diseases and Related Health Problems 10th Revision. 2007 version.
5. WHO collaborating centre for drug statistic methodology. Anatomical Therapeutic Chemical (ATC) classification index with Defined Daily Dose. Geneva: WHO; 2003.
6. DRUG-REAX (Micromedex), version 2010: Thomson MICROMEDEX; Greenwood Village, Colorado.
7. Stockley IH editor. Stockley’s Drug Interactions. 7th edition. London: Pharmaceutical Press; 2006.
8. Roughead EE, Kalisch LM, Barratt JD, Gilbert AL. Prevalence of potentially hazardous drug interactions amongst Australian veterans. Br J Clin Pharmacol. 2010 Aug;70(2):252-257. doi: 10.1111/j.1365-2125.2010.03694.x
9. Braga TB, Pfaffenbach G, Weiss DP, Barros MB, Bergsten-Mendes G. Point prevalence of drug prescriptions for elderly and non-elderly inpatients in a teaching hospital. Sao Paulo Med J. 2004;122(2):48-52.
10. Locatelli J. Drug interactions in hospitalized elderly patients. Einstein 2007;5(4):343-346.
11. Bista D, Saha A, Mishra P, Palaian S, Shankar PR. Impact of educational intervention on the pattern and incidence of potential drug-drug interactions in Nepal. Pharm Pract (Granada). 2009;7(4):242-247.
12. Manchon ND, Bercoff E, Lemarchand P, Chassagne P, Senant J, Bourreille J. Incidence and severity of drug interactions in the elderly: a prospective study of 639 patients. Rev Med Interne. 1989;10(6):521-525.
13. Doubova SV, Reyes-Morales H, Torres-Arreola LP, Suárez-Ortega M. Potential drug-drug and drug-disease interactions in prescriptions for ambulatory patients over 50 years of age in family medicine clinics in Mexico City. BMC Health Serv Res. 2007;7:147.
14. Robert-Ebadi H, Le Gal G, Righini M. Use of anticoagulants in elderly patients: practical recommendations. Clin Interv Aging. 2009;4:165-177.
15. Bajorek B. A review of the safety of anticoagulants in older people using the medicines management pathway. Ther Adv Drug Saf. 2011;2(2):45-58.
16. Juurlink DN, Gomes T, Ko DT, Szmitko PE, Austin PC, Tu JV, Henry DA, Kopp A, Mamdani MM. A population-based study of the drug interaction between proton pump inhibitors and clopidogrel. CMAJ. 2009;180(7):713-718. doi: 10.1503/cmaj.082001
17. Lau WC, Gurbel PA. The drug-drug interaction between proton pump inhibitors and clopidogrel. CMAJ. 2009;180(7):699-700. doi: 10.1503/cmaj.090251
18. Allen MJ, McLean-Veysey P. Interaction between clopidogrel and proton pump inhibitors. CMAJ. 2009;180(12):1228-1229.
19. Siller-Matula JM, Spiel AO, Lang IM, Kreiner G, Christ G, Jilma B. Effects of pantoprazole and esomeprazole on platelet inhibition by clopidogrel. Am Heart J. 2009;157(1):148.e1-e5. doi: 10.1016/j.ahj.2008.09.017
20. Sibbing D, Morath T, Stegherr J, Braun S, Vogt W, Hadamitzky M, Schömig A, Kastrati A, von Beckerath N. Impact of proton pump inhibitors on the antiplatelet effects of clopidogrel. Thromb Haemost. 2009;101(4):714-719.
21. Small DS, Farid NA, Payne CD, Weerakkody GJ, Li YG, Brandt JT, Salazar DE, Winters KJ. Effects of the proton pump inhibitor lansoprazole on the pharmacokinetics and pharmacodynamics of prasugrel and clopidogrel. J Clin Pharmacol. 2008;48(4):475-84. doi: 10.1177/0091270008315310
22. Bhatt DL, Cryer BL, Contant CF, Cohen M, Lanas A, Schnitzer TJ, Shook TL, Lapuerta P, Goldsmith MA, Laine L, Scirica BM, Murphy SA, Cannon CP; COGENT Investigators. Clopidogrel with or without omeprazole in coronary artery disease. N Engl J Med. 2010;363(20):1909-1917. doi: 10.1056/NEJMoa1007964
23. Momary K, Cavallari LH. Clopidogrel and proton pump inhibitors: between a rock and a hard place. Pharmacotherapy. 2010;30(8):762-765. doi: 10.1592/phco.30.8.762
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