Atypical neuroleptics/antipsychotics tardive dyskinesia

Tardive dyskinesia can occur in manic patients on neuroleptics alone, the frequency may be greater than in schizophrenics who are more likely to be on continuous medication. One possible explanation for this lies in the fact that neuroleptics are often administered to manic patients for short periods only, sufficient to abort the active episode, and then abruptly stopped. Thus high doses of neuroleptics are separated by drug-free periods, leading to a situation most likely to precipitate tardive dyskinesia. The recent increase in prescribing high potency neuroleptics such as haloperidol instead of low potency drugs such as chlorpromazine or thioridazine has undoubtedly increased the frequency of tardive dyskinesia. Clearly, use of the atypical antipsychotics with the very low frequency of EPS makes them the treatments of choice. 

The main indications for atypical antipsychotics are the acute and maintenance treatment of schizophrenic disorders, with an emphasis on the treatment of refractory and chronic disorders. However, because of the lower risk of EPS and in particular of tardive dyskinesia, there is a tendency toward a wider range of indications for some of the atypical neuroleptics. Favorable effects in drug-induced psychoses have been demonstrated for olanzapine. Clozapine seems effective in the treatment and relapse prevention of manic episodes and bipolar disorders, and risperidone has been shown to have good efficacy in conduct disorders and in the pervasive developmental disorders. 

Atypical neuroleptics. Because of the limited effectiveness and safety of conventional neuroleptics in TS, clinicians have turned to a new generation of neuroleptics that have been introduced for the treatment of schizophrenia. Risperidone, a member of a class of antipsychotics that blocks both DA and serotonin receptors, has been established as superior to placebo and equal, or superior, to haloperidol in the treatment of schizophrenia (Chouinard et al. 1993 Marder and Meibach 1994]. Risperidone has a more favorable side-effect profile than that of conventional neuroleptics and may have less potential for producing tardive dyskinesia. Compared with haloperidol, fewer extrapyramidal side effects are observed with risperidone in doses of 6 mg/ day or less. As encouraging reports appear in the literature (Lombroso et al. 1995 Stamenkovic et al. 1994 van der Linden et al. 1994], risperidone is currently being widely used by clinicians to treat tic disorders. 

EPS include acute dystonic reactions, parkinsonian syndrome, akathisia, tardive dyskinesia, and neuroleptic mahgnant syndrome. Although high-potency conventional antipsychotics are more hkely than low-potency conventional antipsychotics to cause EPS, all first-generation antipsychotic drugs are equally hkely to cause tardive dyskinesia. The atypical antipsychotics cause suhstantially fewer EPS, which is one reason that they are recommended as first-line agents. 

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