Antidopaminergic therapy for managing comorbidities in patients with Parkinson's disease

Purpose. A literature evaluation of antidopaminergic therapies in patients with Parkinson's disease (PD) who have developed psychosis, nausea, vomiting, and hiccups was conducted. Summary. Complications associated with the use of antiparkinsonian drugs make PD management more difficult given the need for antidopaminergic therapy, which worsens motor functioning in patients with PD. For psychosis, clozapine is the only atypical antipsychotic that has proven effective without worsening motor function in PD patients. However, its use requires the monitoring of agranulocytosis. Newer atypical antipsychotics such as quetiapine have been claimed to be safe in terms of motor functioning, but evidence about their effectiveness is not compelling. The emergency treatment of psychosis in PD would require parenteral administration, only available for olanzapine and ziprasidone. However, no randomized controlled trials have been conducted to establish the efficacy and safety in this setting. For nausea and vomiting, very little domperidone crosses the blood-brain barrier. As a result, the risk of developing extrapyramidal adverse effects is minimal. Metodopramide blocks central dopamine receptors and worsens motor parkinsonian symptoms. Chlorpromazine, the first-line treatment of intractable hiccups, is contraindicated in PD. Baclofen could be considered as a first-line alternative. Conclusion. Although clozapine can be used to treat psychosis in patients with PD, managing nausea, vomiting, hiccups, and emergent psychotic symptoms in these patients remains a challenge due to a lack of evidence for currently available options.