Bupropion sustained release: side effect profile.

Bupropion IR (immediate release) has been on the market since 1988 and is an effective and usually well-tolerated antidepressant. In late 1996, a new sustained-release formulation, bupropion SR, was approved and is now available. Compared with the IR formulation, the SR formulation demonstrates similar efficacy and has been found to have similar, but to some degree fewer, side effects. Its efficacy is similar to that of other newer antidepressants. Side effects of bupropion SR are limited and are not dissimilar to those of the serotonergic antidepressants; however, bupropion SR produces neither substantial sexual side effects nor drug interactions. Study data demonstrate that seizure incidence, which is a concern with high-dose IR, is substantially lower with the new SR formulation.