Potential for patient confusion with generic substitution of medication

Brand substitution with generic forms of medication is common in patients being treated with statins, calcium channel blockers (CCBs), and selective serotonin reuptake inhibitor (SSRI) antidepressants, according to research published in the Medical Journal of Australia.

Dr Michael Ortiz, Pricing and Reimbursement Manager of Solvay Pharmaceuticals and Conjoint Senior Lecturer at the University of NSW, and his co-authors assessed 935,334 prescriptions for 122,000 patients (long-term concession cardholders) claimed on the Pharmaceutical Benefits Scheme between 1 August 2007 and 31 July 2008.

They found that a substantial proportion of prescriptions filled were for the original brand products. However, the study also showed that brand substitution, where a patient switched from one brand to another at least once during the study year, was common (43 per cent of patients with statins, 40 per cent with CCBs and 37 per cent with SSRI antidepressants).

Multiple switching (two or more brand switches during the study period) was recorded for 24 per cent of patients with statins, 19 per cent with CCBs and 21 per cent with SSRIs.

“The extent of multiple switches indicates the potential to create confusion if not adequately monitored by doctors and pharmacists,” Dr Ortiz said.

“However, there is little hard evidence that confusion is actually occurring on any large scale, nor are we aware of any major dataset describing any relationship between generic substitution, patient confusion and rates of hospitalisation.”

Dr Ortiz said a significant relationship was observed between multiple switching and age in all drug classes, with more switching at younger ages.

“Multiple switching was recorded for 28 per cent of those aged less than 50 years compared with 18 per cent of those aged 80 years or older,” he said.

“We might speculate that older patients are less willing to accept a brand switch, and this could mitigate potential confusion.”

Dr Ortiz said that although the study did not identify any major extent of brand switching, this might change following the recent introduction of incentives for generic dispensing in pharmacy reimbursement arrangements.

In an accompanying editorial, Professor Andrew McLachlan, from the Faculty of Pharmacy at the University of Sydney and Concord Hospital, emphasised the importance of effective communication and information from health care professionals to help consumers avoid confusion between branded and generic medicines. 

Professor McLachlan also stated that, due to the risk of double dosing, generic substitution might need to be avoided unless patients fully understand both the similarities and the differences between various brands of the same medicine.

The Medical Journal of Australia is a publication of the Australian Medical Association.

^{The statements or opinions that are expressed in the MJA  reflect the views of the authors and do not represent the official policy of the AMA unless that is so stated.}

CONTACT:   
Dr Michael Ortiz                     0401 618 050 / 02 9497 9727
Prof Andrew McLachlan            0402 281 725 / 02 9767 7373