Abstract: Alzheimer’s disease (AD) is the most common type of neurodegenerative disorder; it affects around 47 million individuals worldwide (Prince et al., 2013). AD rose from the 12th most burdensome disease in the United States in 1990 to the sixth in 2016 in terms of disability-adjusted life years (Alzheimer’s Disease, Facts and Figures 2021). The burden carried by patients and their caregivers is substantially related to neuropsychiatric symptoms, notably agitation as the disease progresses. To date, there is no Food and Drug Administration (FDA)-approved treatment for agitation in AD. The American Psychiatric Association recommends pharmacotherapy in case of failure of non-pharmacological options. While antidepressants such as trazodone or citalopram can be used as first line agents, antipsychotics may be warranted in case of severe agitation. Antipsychotics carry however a black box warning regarding the increased risk of cerebrovascular events and mortality in patients with dementia. Hence, their use needs to be limited. Several agents are currently being investigated to fill the gap of finding a treatment for agitation in AD. Compounds in the pipeline include pimavanserin and brexpiprazole, both of which are antipsychotics. Newer “safer” compounds that are being studied include cannabinoid derivatives, and dextromethorphan/quinidine. Drug design is a long and expensive process. It is often associated with unexpected unfavorable tolerability and safety profile halting the development of a new product. Deuteration recently emerged as a new and cost-effective technique that aims at repurposing old medications and advancing their development in clinical trials to garner quick FDA approval. It consists of the selective replacement of hydrogen (protium) with deuterium, naturally occurring and stable isotope of hydrogen. This structural substitution increases the metabolic stability of the molecule and extends the metabolic half-life of the drug, improving its safety and tolerability (Schmidt, 2017). AVP-786 is the deuterated form of dextromethorphan/quinidine that emerges as a promising well-tolerated treatment option for agitation in AD. With two completed phase III trials investigating this compound, there is still insufficient evidence to obtain FDA approval of the deuterated form. The latest clinical evidence on dextromethorphan/quinidine and its deuterated form for this indication will be discussed herein.