Effects of calcium channel blockers on tardive dyskinesia

Tardive dyskinesia (TD) is a serious iatrogenic disorder that is induced by long-term neuroleptic therapy. There are no well-established treatments for TD but a number of agents, such as calcium channel blockers and vitamin E, have shown some promise in decreasing the symptoms of TD. We reviewed the treatment outcome literature on the efficacy of the three prototypic calcium channel blockers, verapamil, diltiazem, and nifedipine, on TD. Although the outcome data were equivocal, when taken in their best light, they suggested that calcium channel blockers may be effective in decreasing the symptoms of TD. However, the studies were methodologically flawed in many respects and future research must ensure that the basic requirements for scientific validity are incorporated in the experimental design. Further, there is a need for dose-response studies of the three prototypic calcium channel blockers, as well as investigations of their comparative effects.