Effects of Generic Exchange of Levodopa Medication in Patients With Parkinson Disease

Generic exchange is common practice in most healthcare systems. This study investigated how patients with Parkinson disease (PD) perceived a switch of their levodopa medication and the resulting effects on their PD symptoms.

A questionnaire was developed, piloted, and finally distributed to 13,857 members of the national PD patient support group. It was designed to be completed by patients and their pharmacies. χ 2 tests for independence statistics with or without Monte Carlo simulation were performed. Cramér φ and Cramér V were calculated. McNemar test was used to investigate whether a generic switch of a levodopa-containing medication had an impact on PD symptoms.

Analyses were done with 410 finalized respondents of 13,857 distributed questionnaires. More than half of the responders were 75 years or older and rated themselves Hoehn and Yahr stages 3 to 5. Most patients were confused by a change of their medication. A total of 54.7% of the switchers (n = 148) reported swallowing difficulties with medication, which was significantly more frequent than with nonswitchers (37.3% of 204, P = 0.001). Adverse effects related to the switch were reported by 26.6% of all switchers (switchback rate, 20.5%). The patients at higher Hoehn and Yahr stages were affected to a greater extend.

Patients, who experienced any brand switch of their levodopa medication, frequently expressed distrust and confusion. Swallowing difficulties and negative effects on their symptoms were problems, which were more pronounced in advanced disease stages. It remains unclear whether the detrimental impact on therapy was caused by the brand switch or by a nocebo effect.