Sub-Lingual Dexmedetomidine in Agitation Associated With Dementia

Inclusion Criteria: * Male and female patients 65 years and older. * Patients who have dementia and a history of acute agitation. * History of agitation that requires intervention or impairs social or daily activities * Patients who meet International Psychogeriatric Association (IPA) diagnostic criterion for agitation. * Patients with a total score of ≥ 8 on the Pittsburgh Agitation Scale (PAS). * Patients who have a score of ≥ 2 on at least 1 of the 4 items on the Pittsburgh Agitation Scale (PAS). * Patients who read, understand and provide written informed consent, or who have a Legally Authorized Representative (LAR). * Patients who are in good general health. Exclusion Criteria: * For Part B: Patients with dementia associated with Parkinson's disease and/or Lewy Body Disease, if etiology of dementia is known. * Patients with agitation caused by acute intoxication. * Patients treated within 4 hours prior to study drug administration with benzodiazepines, other sedatives, hypnotics or oral or short-acting intramuscular antipsychotics must be excluded. * Treatment with alpha-1 noradrenergic blockers, alpha adrenergic antagonists within 8 hours prior to dosing. * No new chronic medications initiated in the past 14 days prior to screening excluding over-the-counter products taken sporadically. * Patients at significant risk of harm to themselves or others * Patients considered medically unstable or in recovery * Patients with history of clinically significant syncope or sy…