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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. Key words: Generic substitution; generic drugs, pharmaceutical policy; pharmaco-epidemiology.

Abstract Background Age and life expectancy of residents in many developed countries, including Australia, is increasing. Health resource and medicine use in the very old is not well studied. The purpose of this study was to identify annual use of health services and medicines by very old Australian veterans; those aged 95 to 99 years (near centenarians) and those aged 100 years and over (centenarians). Methods The study population included veterans eligible for all health services subsidised by the Department of Veterans' Affairs (DVA) aged 95 years and over at August 1st 2006. A cohort of veterans aged 65 to 74 years was identified for comparison. Data were sourced from DVA claims databases. We identified all claims between August 1st 2006 and July 31st 2007 for medical consultations, pathology, diagnostic imaging and allied health services, hospital admissions, number of prescriptions and unique medicines. Chi squared tests were used to compare the proportion of centenarians (those aged 100 years and over) and near centenarians (those aged 95 to 99 years) who accessed medicines and health services with the 65 to 74 year age group. For those who accessed health services during follow up, Poisson regression was used to compare differences in the number of times centenarians and near centenarians accessed each health service compared to 65 to 74 year olds. Results A similar proportion (98%) of centenarians and near centenarians compared to those aged 65 to 74 consulted a GP and received prescription medicine during follow up. A lower proportion of centenarians and near centenarians had claims for specialist visits (36% and 57% respectively), hospitalisation (19% and 24%), dental (12% and 18%), physiotherapy (13% and 15%), pathology(68% and 78%) and diagnostic imaging services (51% and 68%) (p < 0.0001) and a higher proportion had claims for care plans (19% and 25%), occupational therapy (15% and 17%) and podiatry services (54% and 58%) (p < 0.0001). Compared to those aged 65 to 74, a lower proportion of centenarians and near centenarians received antihypertensives, lipid lowering therapy, antiinflammatories, and antidepressants (p < 0.0001) and a higher proportion received antibiotics, analgesics, diuretics, laxatives, and anti-anaemics (p < 0.0001). Conclusions Medical consultations and medicines are the health services most frequently accessed by Australian veteran centenarians and near centenarians. For most health services, the proportion of very old people who access them is similar to or less than younger elderly. Our results support the findings of other studies which suggest that longevity is not necessarily associated with excessive health service use.

Background: While it is well known that randomized controlled trials (RCTs) are usually designed with sufficient sample size and power to detect the efficacy but not safety of a medicine, the extent to which RCTs quantify safety has not been well ascertained., Purpose: The aim of this study was to assess the safety data available for five commonly prescribed medicines at the time of marketing., Methods: Published RCTs for five medicines risperidone, sertraline, donepezil, strontium ranelate and tramadol extended release were identified. All adverse events (AEs) in the trials were independently extracted by two clinical researchers. Using the sample size in the trials, the power to detect the observed difference in AEs rates between the treatment and placebo groups was calculated. A power of 80% or more was deemed adequate to detect AEs; studies with power of < 80% were deemed insufficiently powered to detect AEs., Results: 12 RCTs were identified. Six trials were insufficiently powered to detect any of the potential AEs reported. Of the 150 evaluated AEs, the trials were insufficiently powered to detect 81% (122/150) of the AEs reported. For the adverse events that were detected with adequate powered clinical trials, only 53% (10/19) of potentially very common AEs (≥10%) and 17% (18/106) of potentially common AEs (1%-<10%) were identified., Conclusion: Trials are insufficiently powered to detect the majority of adverse events that are reported in clinical trials, even for common adverse events. Observations other than primary efficacy endpoints such as AEs that are not prespecified with adequate power should be treated as hypothesis generating only and not justification of evidence. Claims of safety based on trial evidence not designed for the safety endpoint are often premature.