OBJECTIVES: Here, we evaluated the effect of the Effexor (N06AX16) patent expiry in Sweden. The aim was to see if adaptations, such as generic penetration, increased new prescriptions, or switches from other SNRIs, could be seen when evaluating all dispatches in the year before (2008) and after (2009) the patent expiry. METHODS: We used the CEBRxA database, which combines data from the national Swedish drug registry, with a public claims database for the South-West region of Sweden, comprising around 1.5 million individuals. For the generic penetration analysis, all prevalent patients were selected. For the longitudinal analysis, all patients who had made at least 2 dispatches of any antidepressant (N06A*) were selected and a 6 months washout-period was applied. Subsequently, all dispatches were annotated, at the ATC level, as either new (no other antidepressants within 105 days), add-on (specific antidepressant dispatched both before and after), switch (specific antidepressant dispatched before, but not after), or continuation (dispatched same ATC-code within 105 days). RESULTS: Of all N06AX16 dispatches in 2009, 81% corresponded to generic Venlafaxin, and the remaining 19% corresponded to branded Effexor. However, the prevalent patient counts decreased from 12,467 in 2008, to 12,248 in 2009. This trend was opposite to that of other SNRIs; generic Mirtazapine (N06AX11) and branded Cymbalta (N06AX21) both increased by three and 10 percent, respectively. Amongst the incident population, only minor differences were observed when comparing the proportion of dispatches with evidence of a new treatment, switch or add-on, between 2008 and 2009 for N06AX16. CONCLUSIONS: Al though generic penetration was quite efficient, we did not observe an increased proportion of patients switching to, or new prescriptions for, generic Venlafaxin during 2009. This can to some extent be explained by the expiry date on prescriptions, extending into 2009, while the decreasing prevalent patient population suggests additional dimensionality.