Switching among equivalents in chronic cardiovascular therapies: 'real world' data from Italy

Since August 2012, Italian general practitioners are required to prescribe the generic name of medicines, except for refill of chronic therapy. We evaluated the extent of switching among equivalents in chronic cardiovascular therapies, the influence of the 2012 regulatory intervention and of patient-related or drug-related factors. Prescription of off-patent antiarrhythmics, oral antidiabetics, and ACE-inhibitors dispensed from August 2011 to August 2013 within the Bologna Local Health Authority (870,000 inhabitants) were collected. The rate of actual switching among equivalents was evaluated monthly. The effect of the regulatory intervention was estimated by interrupted time series analysis. Adjusted odds ratios (aORs) of switching were calculated for: age, gender, number of different equivalents available for each drug, change in dispensing pharmacy between subsequent refills. The average monthly rates of switches were 9.6%, 16.3%, and 16.3% for antiarrhythmics, antidiabetics, and ACE-inhibitors, respectively. Values significantly increased soon after the regulatory intervention for ACE-inhibitors (+1.81%, p=0.00), antiarrhythmics (+1.46%, p=0.01) and antidiabetics (+1.09%, p=0.01), and no significant decreasing trends were observed in the following 12 months. For all drug classes, odd of switching was higher in case of change in dispensing pharmacy (up to aOR=4.31, 95CI=4.26-4.35 for ACE-inhibitors) and availability of ≥5 different equivalents (up to aOR=7.82, 95CI=7.39-8.28 for antidiabetics). Switching was lower for age ≥65 for antidiabetics and ACE-inhibitors (aOR=0.92, 95CI=0.90-0.93; 0.87, 0.86-0.88, respectively). The Italian regulatory intervention generated an immediate increase, not sustained in time, in switching among equivalents of cardiovascular therapies. Young age, high number of available equivalents and changes in dispensing pharmacy between subsequent refills were associated with switching.