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The ability of anaesthetists to identify generic medications from trade names.

As a component of quality perioperative care it is expected that an anaesthetist undertake a review of all medications that his or her patient may be taking (1). The names of any medications would usually be ascertained at the preoperative assessment, as this provides the anaesthetist with valuable information and enables appropriate anaesthetic planning. Clues to the medical condition of the patient, potential drug interactions, medication side-effects and biochemical abnormalities may be gleaned and optimal perioperative management of medication is facilitated.

Correctly identifying these medications may, however, be more difficult than expected. Patients often present with no written record of prescriptions or may remember medications only by their trade or brand names. These are usually simpler than corresponding generic or chemical names, as they are designed to be memorable for the purpose of marketing (2). Unfortunately, they do not always give an indication of therapeutic grouping or chemical composition. At this point the anaesthetist is expected to recognise or identify the generic medication from the provided trade name, but with several hundred drugs and several thousand brand names registered in Australia, this is not always possible. An alternative approach is to refer to an appropriate reference (e.g. MIMS, Pharmaceutical Benefits Scheme Schedule, Australian Medicines Handbook), but in the busy preoperative setting access to such resources may be limited.

A large body of literature exists that examines medication errors relating to confusion with similar sounding (phonological) or similar looking (orthographic) drug names (3-5) and prescription errors due to illegible handwriting and abbreviations (6). A recent review7 and an analysis of data from the Australian Incident Monitoring Study present information on errors in medication administration and preparation in both anaesthesia and critical care (8). No data exists specifically addressing the problem anaesthetists face in simply identifying medications accurately when only trade names are provided. This study was designed with the following aims:

* to measure the extent to which difficulty in identifying medications is perceived to be a clinical problem for anaesthetists,

* to assess whether access to drug reference material is perceived as being adequate, and

* to examine the ability of anaesthetists to correctly identify generic medications from their respective trade names.

METHODS

A literature search was conducted using MEDlINE and EMBASE to identify articles on medication errors in anaesthesia, drug naming strategies and drug name confusion. These articles were examined for mention of drug name recognition and recall as a component of the issues discussed. Additional internet-based research was conducted using the search engines Google[TM] and Google Scholar[TM]. Statistical information concerning patterns of medication usage in Australia was obtained from the Department of Health and Ageing publications and the Australian Bureau of Statistics.

A two-part survey was developed utilising existing guidelines and advice on appropriate construction and administration of questionnaires in medicine (9,10). respondents were asked to rate their attitudes to the importance of knowing generic medicines and estimate the frequency with which they encountered problems in recognising trade names. Subsequent questions assessed the use of reference material for identifying medications, access to this material and its perceived usefulness. A final question asked whether they were aware of any adverse events occurring due to failure to identify a medication. A closed response format (11) was selected for questions assessing attitudes, with respondents asked to select the most appropriate option on a five-point rating scale from 'strongly disagree' (1) to 'strongly agree' (5). Questions estimating the frequency of an occurrence were also measured on a five-point scale from 'never' (1) to 'always' (5).

The second component was a theoretical test that presented the respondents with the trade names of 25 separate drugs. They were asked to write the generic name in a blank space. For each trade name they were also asked to identify the chemical or therapeutic group. This was designed to assess the anaesthetists' ability to describe the clinical use of a drug, even if they were unable to recall the generic name. Answers were considered to be correct if a corresponding generic name was identified. Minor spelling mistakes, where no misidentification of the drug would occur, were accepted as correct. The chemical or therapeutic group was marked as correct if either was successfully identified as described in the World Health Organization Anatomical Therapeutic Chemical classification. Table 1 presents an example.

To ensure relevance, 22 of the 25 generic drug substances represented were selected from the top 100 Pharmaceutical Benefits Schedule (PBS) prescribed drugs by volume for the year ending June 2005 (12) (Table 2). The remaining three drugs were chosen for potential significance to anaesthesia. Trade names for these drugs were selected from those listed as available on the PBS. After an initial pilot run, the survey was distributed by internal mail to all specialist anaesthetists, anaesthetic fellows and anaesthetic registrars at two major teaching hospitals in Melbourne, Victoria (n = 86). The author was employed at both hospitals during the study period, enabling ready distribution and collection of the responses. Each survey form had a covering letter outlining the aims of the project, instructions for completion and the expected time required to complete the task. Participants were encouraged to return completed surveys, either to sealed collection boxes located in the respective anaesthetic departments or directly to the investigator. responses were anonymous and numbered only for subsequent reference and analysis.

Statistical analysis was carried out utilising Microsoft Excel 2003 spreadsheet and statistical software package Stata 8.0 (Stata Corporation, TX, USA).

RESULTS

Questionnaire

A response was obtained from 52 of the 86 anaesthetists surveyed (response rate 60%) with one respondent failing to complete the questionnaire component and another the theoretical test. These were excluded from subsequent analysis leaving 50 complete responses. Fourteen respondents identified themselves as being either a registrar or provisional fellow (i.e. trainees) and the remaining 36 as consultants (specialists). All respondents stated that adult anaesthesia was the principal component of their anaesthetic practice. However, two respondents indicated that they also undertook paediatric anaesthesia.

When asked if they felt it was important to know the generic medicines their patients were taking, 20% (n = 10) 'agreed' and 62% (n = 31) indicated they 'strongly agreed', which is consistent with existing expectations for anaesthetic care. However, unfamiliar trade names were encountered 'often' or 'always' by the same number of respondents (82%, n = 41). Unfamiliar names were researched 'often' or 'always' by 78% (n = 39) of respondents, but there was a broad spread of opinion as to whether access to appropriate reference material was perceived as being adequate in the workplace. For example, 38% (n = 19) 'disagreed' or 'strongly disagreed' that access was adequate, with the same number indicating the opposite response. The remaining 24% neither agreed nor disagreed. The responses from each hospital were similar.

Only 18% (n = 9) of respondents always carried a reference source for checking drug information, with 54% (n = 27) indicating they 'never' did. When asked if they felt there would be a benefit in being provided with such reference material the response was strongly positive, with 86% either 'agreeing' or 'strongly agreeing'.

Seven respondents (14%) were aware of adverse events occurring as a result of failure to correctly identify medication. One respondent described excessive intra-operative bleeding and three discussed cancellation of elective procedures or 'near misses' with regional anaesthesia as a result of failure to recognise the trade names of clopidogrel (Plavix or Iscover) in the pre-assessment clinic. One respondent described "problematic interactions with older mono-amine oxidase inhibitors". The other two remaining positive answers did not provide details.

Theoretical test

The mean number of generic drugs correctly identified from their trade names without using reference material was 7.4 (29%). The mean number of drugs where the chemical or therapeutic group was successfully identified was 13.7 (54%). The highest number of generic drugs correctly identified by a respondent was 23 (92%) and the least was zero (although this candidate successfully identified the therapeutic group for 13 drugs). Trade names that were commonly not identified included Talam (citalopram) and Avandia (rosiglitazone), with only one correct answer each. There were 12 drugs where fewer than 20% of respondents correctly identify the generic name. Drugs that were best recognised were Cartia (aspirin) and Iscover (clopidogrel), which were identified correctly by 90% and 76% respectively.

Many respondents were successfully able to identify the chemical or therapeutic group of a drug even if they were unable to recall the generic name. Of those trade names where the generic drug was not identified, on average 40% were able to name the therapeutic group. This was particularly so if the trade name gave some indication of the use of a medication. For example, Diabex was correctly identified as metformin by 56% of respondents, whereas 100% were able to describe it as an oral hypoglycaemic agent. A similar effect was seen with Coversyl, where only 46% identified perindopril, but 96% correctly described it as an angiotensinconverting enzyme inhibitor or antihypertensive agent. The angiotensin-converting enzyme inhibitor family of drugs are associated with the suffix '-pril' alluded to in the brand name by the similar sounding '-syl'. There was also a suggestion that brand names could be misleading, with several respondents incorrectly identifying the novel antipsychotic risperdal (risperidone) as a bronchodilator and others describing the benzodiazepine Murelax (oxazepam) as a laxative.

DISCUSSION

The results demonstrate that anaesthetists in at least two major teaching hospitals have difficulty with identifying generic medication from trade names without access to appropriate reference material, with less than one-third (29%) of the trade names tested being identified correctly. This supports the hypothesis that the large number of trade names on the Australian market leads to problems with recognition and identification for anaesthetists. The results of the theoretical test are consistent with the observation that unfamiliar trade names are encountered 'often' or 'always' in the course of normal practice.

At the same time, anaesthetists in these hospitals recognised the importance of knowing these medications and a large number used reference material to check drug names. Perceptions of access to such reference material were varied. In the hospitals studied, written references such as MIMS were gradually being replaced by online versions of the same material. This has the advantage of ensuring that all information is up to date. Drugs can be searched rapidly and more detail is available if required. However, this relies on the adequate provision of computer terminals, functional internet access and assumes a basic level of computer literacy. It is possible that the latter requirements are not being met, as indicated by the positive response to the suggestion that the provision of portable versions of this information would be beneficial.

It is clear that anaesthetists feel that the inability to identify generic medications is a clinical problem. While being able to identify a generic medication does not guarantee any subsequent knowledge about its safe use, it is certainly an important first step. No current data describe the true rate of subsequent adverse outcomes, but the seven (14%) respondents who were able to recall actual events or 'near misses' support the supposition that a genuine problem exists. It is not clear from this study if these answers described unique events, but the relatively high number is cause for concern.

While most respondents felt that being aware of the medications their patients were taking was important, this response was not uniform, with seven (14%) stating they 'disagreed' or 'strongly disagreed' with this assertion. This may reflect the general safety of modern anaesthesia practice and the perception that problems with medications are rare.

Medication naming is a complex process and each drug typically has three descriptive names (Table 4). The 'chemical name' specifies the chemical structure of the drug and may be lengthy and include numbers and parentheses. It is designated by the International union of Pure and Applied Chemistry and is typically used only by researchers.

'Generic name' refers to the international non-proprietary name (INN) as described by the World Health Organization. INNs identify pharmaceutical substances or active pharmaceutical ingredients. Each INN is a unique name that is globally recognised and is public property (13). The names used are generally consistent with those approved for use by the Australian Therapeutic Goods Administration (14) or in the United States of America by the United States Adopted Name Council. Confusingly, as is common in Australia, the term 'generic' may be used to refer to any drug marketed under a different proprietary name from that of the innovator product (15).

'Brand name' is used interchangeably with 'proprietary name' or 'trade name'. It refers to the name invented by the manufacturer to be associated with the product being marketed. Pharmaceutical companies want brand names that "promote brand loyalty, facilitate recognition" and "imply the drug's effects to a lay person" (16). In the European Union, limited codes provide guidance to manufacturers on appropriate selection of brand names (17). Guidelines are not yet available in the United States, but the Food and Drug Administration's Office of Post-Marketing Drug risk Assessment reviews all proposed brand names, rejecting on average one in three applications18. In Australia, suggestions for the appropriate selection of brand names are incorporated into best practice guidelines for labelling of medicines19. No international regulatory system exists and identical brand names used in different countries for separate medicines are another potential source of drug confusion (20).

There has been a proliferation of registered trade names for medications over the past decade, meaning that the task of identifying generic drug substances without the use of reference material has become increasingly difficult. In November 1995, there were an estimated 1697 trade names registered in Australia for 527 drug substances available on the PBS. By May 2002, there were 2506 names for 593 drug substances (21). This represents an increase of 12% in new drug substances but a 47% increase in brand names (Table 5).

The disproportionate increase in brand names is in part due to economic considerations, dictating an increase in 'generic prescribing'. Generic drugs are frequently less expensive than the equivalent products of the innovator brand. With PBS expenditure on pharmaceuticals exceeding A$6 billion in the 2004 to 2005 financial year and representing a rapidly increasing fraction of both the health budget and gross domestic product (22), there is significant incentive to reduce costs. Key legislation introduced to promote generic prescribing includes the Brand Premium Policy (1990), Therapeutic Group Premium Policy (1998) and the Brand Substitution Policy (1994) (23).

These have encouraged competition amongst manufacturers and permitted pharmacists to dispense bioequivalent generic medicines without reference to the prescriber. Many new brands have emerged, named according to the pharmacy chain selling them, even though they are often identical products made by the same manufacturer (15). While the economic benefits are clear, the proliferation of brand names is an unfortunate corollary.

The poor results seen in the theoretical test is evidence that identifying generic medications from trade names by memory alone is challenging. Indeed, the expectation that anaesthetists (or any group of health professionals) should be able to do this might be considered unreasonable. Potential solutions include improving access to reference material, including electronic resources and information being made available at the point of care through computer terminals with software for personal digital assistants (PDAs). An alternative strategy may be to use the design of trade names to clinical advantage, so that therapeutic use or chemical composition are apparent to the physician. This would appear valuable, but is likely to engender conflict with pharmaceutical companies who may seek to exploit naming for marketing purposes.

Limiting the use of trade names in clinical settings obviates the requirement to identify the intended generic medications in the first place and potentially reduces the rate of hospital prescribing errors (24). The use of trade names has been identified as a cause of medication related adverse events (25) and many hospital guidelines encourage generic prescribing. Utilising the international non-proprietary name ensures that only one drug substance can be intended. However, these are often more complex, likely to be misspelt and are themselves a potential source of confusion. Others have argued that using trade names is actually helpful (26,27) in certain instances, although this is likely to be the exception rather than the rule.

The small number of anaesthetists sampled reduces the applicability of this data to the broader anaesthetic community. There are no comparative data to suggest that their performance would be reflective of other anaesthetists at different hospitals or in different states or countries. On the other hand, these hospitals in many ways could be considered typical of metropolitan teaching hospitals in Australia. The response rate of 60% introduces the risk of response bias (28) and reduces the reliability of the results. However, the attitudes expressed by the participants in this descriptive study should not be discounted for this reason. It is also noteworthy that conditions for completion of the survey were not standardised. Although the covering letter requested that the survey was undertaken independently and without using reference material, there was no means to check that this was the case. No incentive for completion of the survey was offered beyond feedback of group results upon completion of the study. At the time of distribution five of the 86 recipients were visiting international fellows whose medical and anaesthetic training would largely have been outside of Australia. It is possible that these respondents negatively skewed the results due to a lack of familiarity with local drug names. However, they are an integral part of the workforce and any difficulties they had in identifying generic medications serves to highlight the importance of the issue.

In summary, those anaesthetists at two Melbourne teaching hospitals who responded to this survey were able to identify less than a third of commonly prescribed medications when these were described only by their brand name. Just over half of these respondents were able to correctly identify the drug class or therapeutic group. The number of adverse or potential events described in this small sample is a cause for concern. respondents felt that hospitals could further improve access to pharmaceutical reference material. The use of personal digital assistants or the availability of other computer access at the point of care could also assist anaesthetists. It is likely that the problem of decoding drug brand names applies to all those in clinical care, but no group of doctors is more intimately involved with the process of prescribing, managing and administering medications as are anaesthetists. It is essential we know what we are working with.

ACKNOWLEDGEMENTS

I wish to thank Associate Professor Kate leslie for her assistance with survey design and statistical analysis.

Accepted for publication on February 24, 2009.

REFERENCES

(1.) Recommendations on the Pre-Anaesthesia Consultation. ANZCA Professional Documents: Professional Standards Melbourne, Australia 2003.

(2.) Lambert BL, Lin SJ, Tan H. Designing safe drug names. Drug Safety 2005; 28:495-512.

(3.) Rataboli PV, Garg A. Confusing brand names: nightmare of medical profession. J Postgrad Med 2005; 51:13-16.

(4.) Hampton T. Similar drug names a risky prescription. JAMA 2004; 291:1948-1949.

(5.) Aronson JK. Medication errors resulting from the confusion of drug names. Expert Opin Drug Saf 2004; 3:167-172.

(6.) Rados C. Drug name confusion: preventing medication errors. FDA Consum 2005; 39:35-37.

(7.) Wheeler SJ, Wheeler DW. Medication errors in anaesthesia and critical care. Anaesthesia 2005; 60:257-273.

(8.) Abeysekera A, Bergman IJ, Kluger MT, Short TG. Drug error in anaesthetic practice: a review of 896 reports from the Australian Incident Monitoring Study database. Anaesthesia 2005; 60:220-227.

(9.) Passmore C, Dobbie AE, Parchman M, Tysinger J. Guidelines for constructing a survey. Fam Med 2002; 34:281-286.

(10.) Boynton PM, Greenhalgh T. Selecting, designing, and developing your questionnaire. BMJ 2004; 328:1312-1315.

(11.) Jones D, Story D, Clavisi O, Jones r, Peyton P. An introductory guide to survey research in anaesthesia. Anaesth Intensive Care 2006; 34:245-253.

(12.) PBS Expenditure and Prescriptions to June 2005. Available from http://www.health.gov.au/internet/wcms/publishing.nsf/Content/ pbs-stats-pbexp-jun05-index1 Accessed March 2006.

(13.) Guidelines on the use of International Non-Proprietary Names (INN) for Pharmaceutical Substances. Division of Drug Management and Policies, World Health Organisation. Geneva (1997).

(14.) TGA Approved Terminology for Medicines--July 1999 (and amendments). Department of Health and Ageing, Commonwealth of Australia, 1999.

(15.) Birkett DJ. Generics--equal or not? Aust Prescr 2003; 26:85-87.

(16.) Berman A. Reducing medication errors through naming, labeling, and packaging. J Med Syst 2004; 28:9-29.

(17.) Guideline on the Acceptability of Invented Names for Human Medicinal Products Processed Through the Centralised Procedure. Human Medicines Evaluation unit, European Medicines Agency 2004.

(18.) Strategies to reduce Medication Errors, FDA Consumer Magazine, May-June 2003.

(19.) Best practice guideline on prescription medicine labelling. Drug Safety and Evaluation Branch (DSEB) of the Therapeutic Goods Administration (TGA). Department of Health and Ageing, Commonwealth of Australia, November 2005.

(20.) Consumers Filling u.S. Prescriptions Abroad May Get the Wrong Active Ingredient Because of Confusing Drug Names. Food and Drug Administration Health Advisory, USA, January 2006.

(21.) Department of Health and Ageing. Available from http://www.aph.gov.au/library/intguide/SP/pbs.htm Accessed March 2006.

(22.) Australian Statistics on Medicine 2003. Department of Health and Ageing, Commonwealth of Australia, 2005.

(23.) Pharmaceutical Benefits Pricing Authority Annual Report, June 2005.

(24.) Schwab M, Oetzel C, Morike K, Jagle C, Gleiter CH, Eichelbaum M. Using trade names: a risk factor for accidental drug overdose. Arch Intern Med 2002; 162:1065-1066.

(25.) Dean B, Schachter M, Vincent C, Barber N. Causes of prescribing errors in hospital inpatients: a prospective study. Lancet 2002; 359:1373-1378.

(26.) Dickman A. Branded prescribing of strong opioids should be adopted as good practice. The Pharmaceutical Journal 2005; Vol. 275 p. 546 Available from www.pjonline.com Accessed June 2006.

(27.) Anton C, Cox Ar, Ferner rE. using trade names: sometimes it helps. Arch Intern Med 2002; 162:2636.

(28.) Myles P, Gin T. Statistical Methods in Anaesthesia and Intensive care. Butterworth Heineman, Oxford 2000.

D.E.P. BRAMLEY *

Departments of Anaesthesia and Pain Management, Royal Melbourne and Western Hospitals, Melbourne, Victoria, Australia

* M.B., B.S., F.A.N.Z.C.A.

Address for reprints: Dr D. E. P. Bramley, Department of Anaesthesia and Intensive Care, Western Hospital, Footscray, Vic. 3011.
TABLE 1

Trade name Generic name Chemical or therapeutic group

Coversyl perindopril Angiotensin converting enzyme
 inhibitor or anti-hypertensive

TABLE 2

Drug names tested (correct generic name included)

Trade name Generic name

Glyade gliclazide
Zocor simvastatin
Iscover clopidogrel
Coversyl perindopril
Talam citalopram
Murelax oxazepam
Acimax omeprazole
Tensig atenolol
Cartia aspirin
Zoton lansoprazole
Plendil felodipine
Dilatrend carvedilol
Marevan warfarin
risperdal risperidone
Avandia rosiglitazone
Mobic meloxicam
Minax metoprolol
Avanza mirtazipine
Micardis telmisartan
Temgesic buprenorphine
Isoptin verapamil
Zydol tramadol
Aropax paroxetine
Karvea irbesartan
Diabex metformin

TABLE 3

Summary of questionnaire results

Question All respondents
 (n = 50)

Do you feel it is important to know 5(1-5) [4-5]
the generic medicines your patients are taking?
How often do you encounter medication trade 4(2-5) [4-4]
names you are unfamiliar with?
How often would you look up medication trade 4(2-5) [4-4]
names you are unfamiliar with?
Do you feel access to drug reference material 3(1-5) [2-4]
at your workplace is adequate?
Do you carry a reference for checking drug 1(1-5) [1-4]
information? e.g. Pocket MIMS or PDA reference
Do you feel you would benefit from being 5(1-5) [4-5]
provided with such reference material?

Data are presented as median (range)
[interquartile range]. 1 = strongly disagree/
never to 5 = strongly agree/always.

TABLE 4

Chemical name (+/-)-2-(p-isobutyl-phenyl) propionic acid
Generic name ibuprofen
Brand name Nurofen[R]

TABLE 5

Number of brand names vs number of drug substances

Year Drug substances Item forms and Brand names
 strengths
1995 527 1207 1697
1996 548 1247 1773
1997 549 1285 1855
1998 555 1347 1968
1999 570 1380 2065
2000 587 1440 2252
2001 589 1458 2459
2002 593 1461 2506
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Title Annotation:Surveys
Author:Bramley, D.E.P.
Publication:Anaesthesia and Intensive Care
Article Type:Survey
Geographic Code:8AUST
Date:Jul 1, 2009
Words:3972
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