background Clozapine is an effective drug for treating psychosis in Parkinson’s disease (pdp) and is registered as such in the Netherlands. However, clozapine can have adverse effects, including agranulocytosis. The new drug pimavanserin was recently registered in the United States for the treatment of pdp.
aim To review the literature on pimavanserin and discuss the position it currently occupies in the Netherlands as a potential treatment for pdp.
method Systematic search of the literature.
results We found reports on four randomised controlled trials (rcts), one review and six articles about the pharmacokinetics and pharmacodynamics of pimavanserin. Pimavanserin is an effective treatment for pdp, and, like clozapine, it has very few negative effects on motor skills. However, all of the rcts were funded by the manufacturer of pimavanserin and the trials were conducted in a very selective patient population. This means that results cannot be generalised. Long-term results are not yet available. In earlier trials clozapine was shown to have a greater and faster antipsychotic effect. Many clinicians and psychiatrists have a great deal of experience with this drug. Another important point is that no-one has yet conducted a trial comparing clozapine and pimavanserin.
conclusion Given that the current second drug of choice, namely quetiapine, has not been found to be effective for pdp, we are of the opinion that – if pimavanserin is registered in the Netherlands – pimavanserin could be used when the current drug of choice, clozapine, is not completely effective or is poorly tolerated. For patients who have cognitive impairments in addition to psychosis, we advise testing the patient’s reaction to a cholinesterase inhibitor before starting the patient on a course of antipsychotics.