OBJECTIVES: Anticholinergic medications are used to manage drug-induced extrapyramidal reactions (EPR), or movement disorders caused by antipsychotics and antidepressants. Long-term anticholinergic drug use is associated with increased cognitive impairment and dementia. An alternative to anticholinergics is amantadine hydrochloride, an N-methyl-D-aspartate antagonist receptor. This survey sought to gain psychiatrists’ insights on current therapeutic management of EPR, including amantadine immediate-release (IR) use, and the potential role of an amantadine extended-release (ER) formulation.

METHODS: This double-blind, quantitative survey of 98 US board-certified psychiatrists, mostly in private practice, who use amantadine IR to treat drug-induced EPR in adults was conducted between March and April 2018. Respondents were presented with amantadine ER pharmacokinetic data, reimbursement information, and a product profile. Respondents rated their views of amantadine IR in clinical use and their impression on the clinical utility of an amantadine ER formulation.

RESULTS: Approximately 17% of patients treated by this group of psychiatrists experienced drug-induced EPR; patients with schizophrenia and schizoaffective disorder were most likely to be affected. Overall, 57% of patients who experience drug-induced EPR were treated with medication. Benztropine (44%) and amantadine (17%) were most commonly used to treat drug-induced EPR. Approximately 50% of patients started on amantadine IR experienced a benefit and remained on the therapy. When shown a product profile and attributes for amantadine ER, 93% of respondents anticipated prescribing the product. A majority of respondents would consider use of product in patients who could benefit from once daily dosing.

CONCLUSIONS: Potential limitations of this survey include a limited number of respondents, underpowered for statistical significance, and a specific focus on amantadine-prescribing psychiatrists. The results of this survey reveal a majority of surveyed psychiatrists anticipate increased clinical utility of an amantadine ER formulation to treat drug-induced EPR. Of those who did not see clinical utility, cost was a common shared concern.