Correspondence to: Ms Lisa Kalisch, Quality Use of Medicines and Pharmacy Research Centre, Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, GPO Box 2471, Adelaide, SA 5001. Fax: (08) 8302 1087; e-mail: firstname.lastname@example.org
Background: In Australia, brand substitution by pharmacists has been possible since 1994. There is no limit to the number of substitutions per prescription. Doctors have expressed concern that patients may receive a different product each time their prescription repeats are dispensed, which has the potential to confuse patients. It is unknown how often multiple substitutions per prescription occur.
Objectives: We aimed to identify the number of switches per prescription for a range of medicines and to determine the number of different brand and generic products supplied on each prescription.
Methods: Repatriation Pharmaceutical Benefits Scheme prescription claims between 1 January 2001 and 28 February 2006 were identified for atenolol, citalopram, enalapril, metformin, omeprazole, ramipril, and simvastatin. Original prescriptions with five repeats and all supplies dispensed were included. Switches were identified if a different product was supplied on consecutive repeat dispensings.
Results: 533,279 original prescriptions were included. 488,735 (92%) had no switches on repeats and 37,513 (7%) had only one switch. Only 1% of all prescriptions had more than one switch identified on repeats, and in most cases only two different products were supplied. None of the prescriptions had a different product supplied on each dispensing.
Conclusion and Implications: Multiple switches per prescription are uncommon and multiple different products are rarely supplied on repeats of the same prescription. The rules of the brand substitution policy appear to be adequate in allowing brand choice for patients, without leading to multiple switches per prescription.
In Australia, brand substitution of Pharmaceutical Benefits Scheme (PBS) and Repatriation Pharmaceutical Benefits Scheme (RPBS) medicines has been possible since December 1994, when the brand substitution policy was introduced. Pharmacists can dispense a brand or generic product other than the one prescribed provided the patient agrees to the switch, the substituted products are bioequivalent and the prescriber has not specified that substitution cannot occur. At present, the policy does not limit the number of substitutions that can occur on repeats of an individual prescription. In 2003, the Australian Divisions of General Practice highlighted this and expressed concerns about the potential for patients to receive a different brand of medicine each time their prescription was dispensed, equating to six different brands over the life of a script.1 They suggested that a limit of one switch per prescription should be enforced.1 Their concerns about multiple substitutions per prescription arose from the different names and appearance of the various brand and generic alternatives available.
Generic drugs in Australia are marketed under a unique trade name rather than the generic name of the drug. For drugs with multiple brand and generic products, patients are faced with multiple different trade names, and in many cases the product appearance also differs. Qualitative Australian research has found that patients may become confused when products are substituted.2,3 Between 1998 and 2000, the Pharmaceutical Health and Rational Use of Medicines (PHARM) committee held discussions with representatives from more than 100 consumer groups for a range of chronic conditions, including patients from non-English-speaking backgrounds. It found that patients may not realise that substituted brand and generic products are actually the same drug and problems such as double dosing (i.e. taking both products at the same time) or poor compliance may result.2 Concerns about multiple switches per prescription and the potential for patient confusion are also held by general practitioners.3,4 Hassali and colleagues interviewed a convenience sample of 10 Australian general practitioners (GPs) about their views of generic medicines.3 Some GPs in their sample expressed concerns about the potential for patient confusion when substitution occurred, and some were also critical of the brand substitution policy not preventing multiple switches by pharmacists.3 In another Australian study 70 GPs were surveyed.4 Many of the GPs expressed concerns that generic substitution had the potential to confuse patients and some suggested that there should be limits to the number and frequency of brand substitutions.4 The small sample sizes of these studies limit the generalisability of results; however, there appears to be a perception among Australian prescribers and consumers that brand substitution can cause confusion. The actual extent of the problem is unknown.
Since 1997, the Pharmaceutical Society of Australia (PSA) has had brand substitution guidelines for pharmacists.5 These guidelines state that the health and safety of the patient should be the foremost concern when substitution occurs, and that whenever possible the same product should be supplied to patients on chronic therapy.5 The extent to which pharmacists follow these guidelines is unknown. A survey of 312 pharmacists conducted by the PSA in mid-2006 found that 94% of respondents regularly offered brand substitution to their patients, and more than 70% of respondents reported that less than 20% of prescriptions they dispensed had substitution prohibited by the doctor.6 Opportunities for patients to be switched are great; however, the extent to which this translates into multiple switches per prescription and multiple different products being supplied is unknown.
We aimed to identify the number of switches on the repeats of an individual prescription and to determine how often there were multiple switches and multiple products supplied on the same prescription.
Atenolol, citalopram, enalapril, metformin, omeprazole, ramipril, and simvastatin were selected for study (see Table 1). These drugs were chosen as they are all commonly dispensed on the PBS and RPBS,7 cover a range of therapeutic classes, and are generally used in the treatment of long-term conditions. All study drugs have bioequivalent brand and generic alternatives available. Strengths and formulations studied are listed in Table 1.
Table 1. Study drugs.
Strengths and forms studied
Number of brand/generic products
Therapeutic category and uses
(a) Single brand and generic products were added or deleted at certain times over the study period. Therefore, the number of products available for the majority of the study period has been shown.
50 mg tablets
Beta blocking agent used in the treatment of cardiovascular conditions including hypertension
20 mg tablets
5 mg, 10 mg and 20 mg tablets
Angiotensin converting enzyme inhibitor used in the treatment of cardiovascular conditions including hypertension
500 mg and 850 mg tablets
Biguanide oral hypoglycaemic agent, used in the treatment of type 2 diabetes
20 mg tablets
2 (3 from Dec 2004 onwards)
Proton pump inhibitor used in the treatment of acid-related gastrointestinal disorders such as gastroesophageal reflux disease and peptic ulcer disease.
1.25 mg, 2.5 mg and 5 mg tablets
Angiotensin converting enzyme inhibitor used in the treatment of cardiovascular conditions including hypertension
5 mg, 10 mg, 20 mg, 40 mg and 80 mg tablets
4 until August 2005, then 10
HMG CoA-reductase inhibitor used to lower cholesterol
RPBS prescription claims for all study drugs were identified. The first citalopram generic became available on 1 August 2001, and the first simvastatin generic became available on 1 November 2004. For these two drugs, claims were included from the date the first generic became available until the end of February 2006. For all other study drugs, claims identified between 1 January 2001 and 28 February 2006 were included. Each claim record includes a patient identifier, date of prescription, a prescriber identifier, the number of repeats on the prescription, whether the original prescription or a repeat was dispensed, the manufacturer code and the date of supply. Doctors can write PBS prescriptions for each of the study drugs valid for up to six supplies (the original dispensing, plus a maximum of five repeat dispensings); and can only write one PBS or RPBS prescription for each strength of study drug per patient per day.8 Following these rules, we determined that when the claim record showed the same patient identifier, prescriber identifier, date of prescribing and was for the same strength of drug, repeats of the same prescription had been used at those dispensings. Individual prescriptions were identified and original and repeat dispensings were sorted by date of supply. The total number of dispensings per prescription was calculated.
Inclusion and exclusion criteria
Original prescriptions written for five repeats with all six supplies dispensed within the study period were included.
Data errors were identified if there was more than one claim for an original prescription written by the same doctor on the same day for any patient, or if there were more claims identified for a prescription than allowed by the number of repeats ordered. This led to 16,175 dispensings being excluded (0.3% of identified dispensings).
The manufacturer code in each claim record was used to identify the brand or generic product dispensed. We assumed that the original dispensing was for the brand or generic product prescribed; switches were then identified if different brand or generic products were supplied on consecutive repeat dispensings of the same prescription. When the manufacturer code was not recorded for a given dispensing (3% of claims), we assumed that it was the same as the previous supply. We calculated the number of switches per prescription and the number of different brand or generic products dispensed over the life of the prescription. Using this method, we could identify a maximum of five switches per prescription and six different products supplied over the life of the prescription.
Overall, 533,279 original prescriptions with five repeats prescribed and all supplies dispensed were identified and included in the study.
Number of switches per prescription
Ninety-two per cent of prescriptions studied had no switches (see Figure 1). When switches were identified on repeats of the same prescription, in the majority of cases there was only one switch per prescription (7% of all prescriptions). Only 1% of all prescriptions identified had more than one switch.
Prescriptions with multiple switches
Ramipril and omeprazole, the drugs with the fewest brand and generic products, had the lowest proportions of prescriptions with more than one switch (0.7%), while citalopram had the highest (3%). Only 1% (n=7,031) of the 533,279 prescriptions studied had more than one switch, and the majority of these (n=5,822) had two switches. Only 0.2% (1,026) of all prescriptions had three switches and 0.03% (161) had four switches. Of the 533,279 prescriptions studied, only 22 had a switch on every repeat dispensing (i.e. five switches per prescription).
Number of different products supplied per prescription
Our definition of switching means that prescriptions with no switches had the same product supplied on each repeat, and prescriptions with one switch had two different products supplied over the life of the prescription. In most cases, prescriptions with more than one switch also had only two different products dispensed over the life of the prescription (see Table 2). None of the prescriptions included in the study had a different product supplied with each dispensing.
Table 2. Number of products dispensed on prescriptions with multiple switches.
Number of different brand or generic products supplied
with > one switch
(a) Only two ramipril products and three omeprazole products were available for substitution.
To our knowledge, this is the first study that has identified the number of brand substitutions that occur on repeats of the same prescription for any drug. The results show that multiple switches per prescription are uncommon. For 92% of prescriptions studied, the same product was supplied on each dispensing. If switches occurred, there was only one switch per prescription in the majority of cases (7% of prescriptions). Similarly, multiple products were rarely supplied over the life of a prescription, even if there were multiple switches on that prescription. None of the prescriptions studied had a different product supplied on each dispensing. Pharmacists appear to consistently supply the same product over the life of most prescriptions, which is in accordance with the PSA guidelines for brand substitution.
The rules of the brand substitution policy do not limit the number of switches per prescription, which led the Australian Divisions of General Practice (now known as the Australian General Practice Network) to express concerns that patients may receive a different product each time their prescription repeats are filled.1 These concerns have been reflected by consumers2 and general practitioners3,4 in qualitative Australian research. Research conducted with consumers using multiple medicines found that confusion from brand substitution may lead to poor compliance or ‘double dosing’ with two different brands of the same medicine.2 Our study is the first to quantitatively assess the number of products supplied on repeats of the same prescription. The results show that although the rules of the brand substitution policy do not prevent pharmacists from dispensing a different product on each repeat, this does not occur frequently.
Given the likely inconvenience that a limit of one switch per prescription would incur, and the fact that pharmacists already supply the same product on repeats of prescriptions in most cases, it does not appear necessary to change the rules of the brand substitution policy. A limit of one switch per prescription may be impractical for pharmacists and patients.9,10 Patients may have their repeats dispensed at more than one pharmacy. If there was a limit of one switch per prescription, pharmacies may need to stock every alternative in order to be able to dispense repeats in these situations.9 The number of brand and generic alternatives available for some drugs means that stocking all of them is impractical for most pharmacies.9,10 In addition, if a particular product is out of stock, a limit of one switch per prescription may mean that some patients cannot have their repeats dispensed if their product is out of stock.10
We differentiated between the number of switches per prescription and the total number of different products supplied per prescription because the study drugs had different numbers of products available to switch between. Only two ramipril products were available, however a patient could potentially alternate between each product with each repeat dispensing. Although the drugs with the fewest products available (ramipril and omeprazole) had the lowest proportion of prescriptions with multiple switches (0.7%), drugs with multiple products available also had a very small proportion of prescriptions with multiple switches. Only 3% of citalopram prescriptions, 2% of enalapril and simvastatin prescriptions and 1% of atenolol and metformin prescriptions had more than one switch, and in most cases only two different products were supplied over the life of the script. These five drugs all had seven or more products available to switch between for the majority of the study period.
Brand substitution is possible for many other PBS and RPBS medicines in addition to the seven study drugs. The study drugs were chosen because they represent a wide range of therapeutic classes on the PBS and are commonly dispensed on the RPBS. The number of brand and generic products available to switch between and the length of time multiple products have been available varied among the drugs. Despite these differences, in all cases the majority of prescriptions identified for each drug had no switches, and when switches were identified in most cases there was only one switch per prescription. Simvastatin and citalopram had the lowest proportions of prescriptions with no switches than the other medicines studied (83%). In the case of simvastatin, this difference may have been because brand substitution had only recently become possible. Patient-related factors may also have played a role.
We could not tell how many prescriptions were marked “brand substitution not permitted”, so we cannot be sure of how often switching was not possible and the influence that this had on the results. However, recent research suggests that substitution is possible for most prescriptions. A survey of Australian doctors found that the majority of prescribers marked less than a quarter of their prescriptions “brand substitution not permitted”,11 and a survey of pharmacists supported this finding.12
RPBS claims were studied, therefore only prescriptions dispensed to Department of Veterans’ Affairs (DVA) card holders were represented in the analysis. There is no evidence to suggest that pharmacists are more or less likely to substitute brand and generic products for DVA card holders than other patients. The medicines studied are available on both the PBS and RPBS, and the subsidised quantities and prices paid by PBS concession card holders are the same as those for DVA card holders. It is likely that the results are equally applicable to other members of the Australian population.
Results of this study indicate that pharmacists consistently supply the same product on each repeat of a prescription in the majority of cases. When switches occur, there is nearly always only one switch per script. Multiple switches per prescription are uncommon and multiple different products are rarely supplied on repeats of the same prescription. The present rules of the brand substitution policy appear to be adequate in allowing brand choice for patients, without leading to multiple switches per prescription.
This research was conducted as part of the Veterans' MATES project, funded through the Department of Veterans' Affairs and administered by the University of South Australia.