Methylphenidate, neuroleptics and dyskinesia-dystonia.

Methlyphenidate is one of two stimulant drugs used in the management of the Hyperkinetic Reaction in children. It has been known to have side effects such as dyskinesia, but this case details the emergence of dystonia and dyskinesia when the simultaneous use of methylphenidate and a phenothiazine was followed by withdrawal of the phenothiazine. It is postulated that the use of phenothiazine resulted in a post-synaptic supersensitivity which precipitated dystonia and dyskinesia when phenothiazine was withdrawn and methylphenidate reinstituted. It is also suggested that the phenothiazine dopamine-blocking action may necessitate the use of larger quantities of stimulant in order to produce the desired effect.