Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 Jan;8(1):50-5.
doi: 10.4321/s1886-36552010000100006. Epub 2010 Mar 15.

Drugs with narrow therapeutic index as indicators in the risk management of hospitalised patients

Hege S Blix  1 , Kirsten K Viktil  2 , Tron A Moger  3 , Aasmund Reikvam  4
Affiliations

Drugs with narrow therapeutic index as indicators in the risk management of hospitalised patients

Hege S Blix et al. Pharm Pract (Granada). 2010 Jan.

Abstract

Drugs with narrow therapeutic index (NTI-drugs) are drugs with small differences between therapeutic and toxic doses. The pattern of drug-related problems (DRPs) associated with these drugs has not been explored.

Objective: To investigate how, and to what extent drugs, with a narrow therapeutic index (NTI-drugs), as compared with other drugs, relate to different types of drug-related problems (DRPs) in hospitalised patients.

Methods: Patients from internal medicine and rheumatology departments in five Norwegian hospitals were prospectively included in 2002. Clinical pharmacists recorded demographic data, drugs used, medical history and laboratory data. Patients who used NTI-drugs (aminoglycosides, ciclosporin, carbamazepine, digoxin, digitoxin, flecainide, lithium, phenytoin, phenobarbital, rifampicin, theophylline, warfarin) were compared with patients not using NTI-drugs. Occurrences of eight different types of DRPs were registered after reviews of medical records and assessment by multidisciplinary hospital teams. The drug risk ratio, defined as number of DRPs divided by number of times the drug was used, was calculated for the various drugs.

Results: Of the 827 patients included, 292 patients (35%) used NTI-drugs. The NTI-drugs were significantly more often associated with DRPs than the non-NTI-drugs, 40% versus 19% of the times they were used. The drug risk ratio was 0.50 for NTI-drugs and 0.20 for non-NTI-drugs. Three categories of DRPs were significantly more frequently found for NTI-drugs: non-optimal dose, drug interaction, and need for monitoring.

Conclusion: DRPs were more frequently associated with NTI-drugs than with non-NTI-drugs, but the excess occurrence was solely related to three of the eight DRP categories recorded. The drug risk ratio is a well-suited tool for characterising the risk attributed to various drugs.

Keywords: Clinical Pharmacy Information Systems; Drug Toxicity; Inpatients; Norway.

PubMed Disclaimer

Conflict of interest statement

CONFLICT OF INTEREST

None to declare.

The study was carried out at the University of Oslo and partly funded by The Norwegian Community Pharmacy Foundation and The Norwegian Pharmacy Associations’ Foundation. Both are nonprofit organisations.

Figures

Figure 1
Figure 1
Frequencies of various types of drug-related problems (DRPs) related to drugs with a narrow therapeutic index (NTI-drugs, N = 376) and to other drugs (non-NTI-drugs, N = 6778) among 827 hospitalised patients. Differences between NTI-drugs and non-NTI-drugs are shown by p values
Figure 2
Figure 2
Times used and drug risk ratio for drugs with a narrow therapeutic index (NTI-drugs)a and other drugs (non-NTIdrugs) among 827 hospitalised patients a Drugs used less than 5 times are not included in the figure. In the following, number of times used and number of DRPs are shown in brackets: ciclosporin (2/4), digoxin (1/0), flecainide (1/1), gentamicin (3/4), lithium (3/7), phenobarbital (3/3), phenytoin (1/0), rifampicin (3/1). In total, those drugs were used 17 times and were associated with 20 DRPs, which equals a drug risk ratio of 1.2.
See this image and copyright information in PMC

References

    1. Ernst FR, Grizzle AJ. Drug-related morbidity and mortality: updating the cost-of-illness model. J Am Pharm Assoc. 2001;41:192–199. - PubMed
    1. Winterstein AG, Sauer BC, Hepler CD, Poole C. Preventable drug-related hospital admissions. Ann Pharmacother. 2002;36:1238–1248. - PubMed
    1. Patel P, Zed PJ. Drug-related visits to the emergency department: how big is the problem? Pharmacotherapy. 2002;22:915–923. - PubMed
    1. Goodman, Gilman's . Pharmacokinetics and Pharmacodynamics. 11. Ed. Chapter 1. The McGraw-Hill Companies, Inc; 2005. The Pharmacological Basis of Therapeutics. ISBN:0-07-142280-3.
    1. Budnitz DS, Shehab N, Kegler SR, Richards CL. Medication use leading to emergency department visits for adverse drug events in older adults. Ann Intern Med. 2007;147:755–765. - PubMed

LinkOut - more resources