Drug-associated delirium: basic pharmacologic principles and clinical considerations. A narrative review

Delirium is an acute state of impaired awareness and cognition with significant implications for patient outcomes, particularly in the elderly. Its clinical features include fluctuating consciousness, disorientation, hallucinations, agitation, psychomotor changes, and speech disturbances. While delirium has a broad differential diagnosis—including dementia, acute intoxication, metabolic encephalopathies, infections, and withdrawal syndromes-drug-induced delirium warrants specific attention due to its high prevalence and reversible nature. Certain drug classes are commonly associated with delirium, including anticholinergics, benzodiazepines, opioids, corticosteroids, and anticonvulsants. These drugs precipitate delirium through mechanisms such as disrupting neurotransmitter systems, including acetylcholine, dopamine, and serotonin pathways. For instance, anticholinergics impair cognition by blocking acetylcholine, while benzodiazepines and opioids can induce sedation and confusion, especially in vulnerable populations. The pathophysiology of drug-induced delirium is multifactorial, involving neurotransmitter disruptions, inflammation, and metabolic disturbances. Preventing and managing drug-induced delirium requires a detailed review of a patient’s medication list, with a focus on minimizing high-risk drugs, identifying vulnerable patients (e.g., the elderly or those with polypharmacy), and monitoring for early symptoms. Treatment of delirium includes pharmacological and non-pharmacological strategies. Antipsychotics, such as haloperidol or atypical agents, are the primary pharmacological treatment, while non-pharmacological approaches involve environmental modifications, such as creating a calm, well-lit setting and involving family members for reassurance. Early recognition and prompt identification of the underlying cause are essential to improving outcomes.