September 06, 2005

Switching to Atypicals Reduces Anti-Parkinsonian Drug Use

A new study suggests that switching from typical antipsychotics to atypicals may reduce the need for anti-parkinsonian drugs. The results were found to differ depending on which atypical agent was used. The researchers mentioned that the reduction in the need of such medication was substantial in this study which looked just at community practices, but it was not as much of a difference as has been seen in past randomized controlled trials.

"Between 1994 and 1998, switching from typical to atypical antipsychotics was associated with a sudden 9.2% drop in the prescribing of anti-parkinsonian drugs and a decreasing trend of 0.5% per quarter thereafter. In contrast, when individuals switched from one typical antipsychotic to another, there was a sudden 12.9% increase in the rate of anti-parkinsonian drug use, although the rate did decrease by 0.7% per quarter afterwards" (

The effects of switching from a typical to an atypical antipsychotic was studied in 209 individuals with schizophrenia. This was compared to the effects of switching from one typical antipsychotic to another typical in 261 people with schizophrenia.

The type of atypical antipsychotic prescribed had a large effect on whether or not there was a change in anti-parkinsonian drug use. Switching to olanzapine decreased anti-parkinsonian drug use by 19.2% whereas switching to risperdal did not result in any change.

Original Source: Switching to atypical antipsychotics reduces anti-parkinsonian drug use. August 4, 2005.

This research study was published in Br J Psychiatry 2005; 187: 137–142


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