Generic substitution by pharmacists of commonly used medications in Australia

January 01, 0001

Generic substitution by pharmacists of commonly used medications in Australia

The aim of this study by researchers from Australia was to study the extent of brand substitution and switching in three commonly used classes of drugs available on the Pharmaceutical Benefits Scheme (PBS), involving assessment of PBS claim records for a 1-year period from 1 August 2007 to 31 July 2008 for long-term concession cardholders drawn from a 10% random sample of the Australian population. The target drug classes were: statins (pravastatin, simvastatin), calcium channel blockers (CCBs) (amlodipine, felodipine, nifedipine), and selective serotonin reuptake inhibitor (SSRI) antidepressants (fluoxetine, fluvoxamine, paroxetine, sertraline). The researchers retrieved information relating to 935,334 prescriptions for 122,000 patients.

Of those patients filling at least four prescriptions for a product, 41,174 patients received statins, 27,230 received CCBs and 21,342 received SSRIs. More than half the patients received only one brand during the study period: 57% for statins, 60% for CCBs, and 63% for SSRIs. Multiple switching was recorded for 24% of patients with statins, 19% with CCBs, and 21% with SSRIs, with smaller proportions receiving three or more brands: 14% for statins, 10% for CCBs, and 12% for SSRIs. Multiple switching was more common among younger patients for all drug classes (28% for those aged less than 50 years v 18% for those aged = 80 years).

The researchers concluded: "Generic substitution with multiple switches is occurring in a small proportion of patients being treated with statins, CCBs or SSRIs. The potential for patient confusion appears to be relatively small, but this may change with recent incentives included in pharmacy reimbursement arrangements."

This can confuse patients and pharmacists appear to be influenced by incentives.

For the full abstract, click here.

MJA 192 (7):370-373, 5 April 2010
© The Medical Journal of Australia 2010
Generic substitution of commonly used medications: Australia-wide experience, 2007-2008. Michael Ortiz, Leon A Simons and Gordon Calcino. Correspondence to Leon Simons:

Category: HSR. Health Services Research. Keywords: generic, substitution, medications, Australia, assessment of claims records, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 23 April 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.