Abstract Introduction Phenibut is a GABA B receptor agonist that is approved in Russia for the management of PTSD, generalized anxiety disorder, social anxiety and insomnia. It is not approved by the FDA but is commercially available for purchase as a supplement; it is increasingly used as a cognitive enhancer. Phenibut is not detected by urine drug screening and may be absent from medication lists. Sudden withdrawal is life- threatening and can manifest as marked anxiety, psychosis, movement disorders or seizures. Case A 45-year-old male with past medical history of heart failure with reduced ejection fraction, substance use disorder (benzodiazepines, anabolic steroids, and opioids) was admitted with a diagnosis of multi-lobar pneumonia with sepsis with acute kidney injury. He was started on intravenous vasopressors, noninvasive ventilation (NIV), renal replacement therapy and antibiotics however, in the setting of ongoing agitation and multiple vomiting episodes, he was intubated for airway protection He was successfully weaned off vasopressors and made complete renal recovery. He followed commands during spontaneous breathing trials, but had significant restlessness and spontaneously self-extubated. He was given a trial of NIV, but in view of continuous agitation and increased respiratory secretions he required reintubation. Diagnosis of gabapentin toxicity (despite renally-adjusted dosing) and ICU delirium were considered; dexmedetomidine and ziprasidone were started and the dose of gabapentin was further modified after discussion with pharmacy, but these measures failed to control the agitation and tremors. Repeat head imaging was negative for any acute findings, and EEG showed a normal awake pattern. Collateral history later revealed daily consumption of approximately 10 g of phenibut, with recent increase in intake . Toxicology was consulted, and the patient was started on oral baclofen. Following trial of baclofen, agitation and tremors resolved and the patient was subsequently extubated within 48 hours. Discussion Delirium management is central to the ICU ABCDEF bundle and is associated with prolonged ventilation, length of stay, mortality, and cognitive dysfunction. In this patient, unrecognized phenibut withdrawal mimicked refractory ICU delirium, prolonging the ICU stay despite recovery from sepsis. This case underscores the importance of thorough history-taking and medication reconciliation, including supplements and nootropics which may not appear on standard drug screens. Refractory ICU delirium is often a diagnostic and therapeutic challenge, consideration of alternative etiologies is essential for early recognition and targeted therapy, thereby preventing unnecessary interventions and improving outcomes. This abstract is funded by: none
Gupta et al. (Fri,) studied this question.