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High prevalence of unknown co-medication in hospitalised patients

  • Pharmacoepidemiology and Prescription
  • Published:
European Journal of Clinical Pharmacology Aims and scope Submit manuscript

Abstract

Objective

Co-medication unknown to the treating physician, including self-medication, may compromise drug safety by increasing the risk of duplicate therapy, drug interactions and adverse drug reactions that are not recognised as such. The aim of the current study was to estimate exposure to unknown co-medication during hospitalisation by performing an analytical screening for a broad range of drugs and drug classes in urine of patients admitted to a general internal medicine ward.

Methods

Urine samples of 44 patients were analysed with REMEDiHS (high-performance liquid chromatography) and six different immunoassays. Positive results were compared with drug history and documented drug prescription. If appropriate, gas chromatographic-mass spectrometric confirmatory analyses were performed on drugs classified at least once as possible unknown co-medication.

Results

Nine (20%) of the patients tested positive for a compound detected by two independent analytical methods and 18 (41%) for a compound detected by at least one analytical method. Unknown co-medication consisted mostly of analgesics, benzodiazepines or ranitidine.

Conclusion

At least one in five patients exhibits at least once during hospitalisation exposure to drugs not documented in the patient record, which may compromise patient safety.

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Acknowledgements

This study was supported in part by BMBF grant #01EC9902 from the German Federal Ministry for Education and Research and by research grant F.203659 of the Medical Faculty of the University of Heidelberg (Juniorantrag). The experiments comply with the current laws of Switzerland.

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Authors and Affiliations

  1. Department of Internal Medicine VI, Clinical Pharmacology and Pharmacoepidemiology, Ruprecht-Karls-University, Im Neuenheimer Feld 410, 69120 , Heidelberg, Germany

    Karin Rieger, Ingeborg Walter-Sack, Walter E. Haefeli & Meret Martin-Facklam

  2. Clinical Chemical Laboratory, University Hospital, Basel, Switzerland

    André Scholer

  3. Documed AG, Basel, Switzerland

    Isabelle Arnet

  4. Department of Experimental and Clinical Toxicology, University of Saarland, Homburg/Saar, Germany

    Frank T. Peters & Hans H. Maurer

Authors
  1. Karin Rieger
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  2. André Scholer
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  3. Isabelle Arnet
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  4. Frank T. Peters
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  5. Hans H. Maurer
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  6. Ingeborg Walter-Sack
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  7. Walter E. Haefeli
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  8. Meret Martin-Facklam
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Corresponding author

Correspondence to Walter E. Haefeli.

Additional information

W.E.H., M.M.F., K.R. and I.W.S. designed the study. A.S. was responsible for analysis by REMEDiHS and the immunoassays. F.T.P. and H.H.M. were responsible for analysis using gas chromatographic-mass spectrometry. I.A. included the patients and collected the urine samples. K.R. and M.M.F. analysed the data. M.M.F. drafted the manuscript. All authors have approved the final version of the manuscript.

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Rieger, K., Scholer, A., Arnet, I. et al. High prevalence of unknown co-medication in hospitalised patients. Eur J Clin Pharmacol 60, 363–368 (2004). https://doi.org/10.1007/s00228-004-0784-6

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  • DOI: https://doi.org/10.1007/s00228-004-0784-6

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