Fentanyl-Associated Serotonin Syndrome and Chest Wall Rigidity in an Intensive Care Unit Patient

Serotonin Syndrome After Prolonged Remifentanil and Propofol Infusion for Craniotomy: A Case Report

Serotonin syndrome (SS) is a life-threatening condition caused by serotonergic medications. We describe a unique case of SS likely caused by prolonged exposure to propofol and remifentanil alone. A young male presented for vestibular schwannoma resection. Several hours into the case, the patient demonstrated hyperthermia and hemodynamic instability, followed by clonus, rigidity, shivering, and tachycardia after emergence. SS was diagnosed using Hunter's criteria and improved with supportive measures. While the patient endorsed a history of methamphetamine use, his urine drug screen was negative. The possibility of SS should be considered when administering propofol and remifentanil, particularly with prolonged infusions.

Wooden Chest Syndrome: A Case Report of Fentanyl-Induced Chest Wall Rigidity

Wooden chest syndrome (WCS) describes a finding of fentanyl-induced skeletal muscle rigidity causing ventilatory failure. Known primarily to anesthesiology, pulmonary, and critical care fields, WCS is a rare complication that may affect patients of all ages if exposed to intravenous fentanyl, characterized by a patient’s inability to properly ventilate. Given the rise of synthetic opioid deaths across the United States in the past decade, an understanding of all of fentanyl’s effects on the body is necessary. In this article, we present a case of WCS in a patient with acute respiratory distress syndrome in a 61-year-old female.

The synthetic cathinone psychostimulant α-PPP antagonizes serotonin 5-HT2A receptors: In vitro and in vivo evidence

Synthetic cathinones (SCs) are β-keto analogs of amphetamines. Like amphetamines, SCs target monoamine transporters; however, unusual neuropsychiatric symptoms have been associated with abuse of some SCs, suggesting SCs might possess additional pharmacological properties. We performed radioligand competition binding assays to assess the affinities of nine SCs at human 5-HT_2A receptors (5-HT_2A R) and muscarinic M₁ receptors (M₁ R) transiently expressed in HEK293 cells. None of the SCs exhibited affinity at M₁ R (minimal displacement of [~K_d ] [³ H]scopolamine up to 10 μM). However, two SCs, α-pyrrolidinopropiophenone (α-PPP) and 4-methyl-α-PPP, had low μM K_i values at 5-HT_2A R. In 5-HT_2A R-phosphoinositide hydrolysis assays, α-PPP and 4-methyl-α-PPP displayed inverse agonist activity. We further assessed the 5-HT_2A R functional activity of α-PPP, and observed it competitively antagonized 5-HT_2A R signaling stimulated by the 5-HT₂ R agonist (±)-2,5-dimethoxy-4-iodoamphetamine (DOI; K_b  = 851 nM). To assess in vivo 5-HT_2A R activity, we examined the effects of α-PPP on the DOI-elicited head-twitch response (HTR) in mice. α-PPP dose-dependently blocked the HTR with maximal suppression at 10 mg/kg (P < 0.0001), which is a moderate dose used in studies investigating psychostimulant properties of α-PPP. To corroborate a 5-HT_2A R mechanism, we also tested 3,4-methylenedioxy-α-PPP (MDPPP) and 3-bromomethcathinone (3-BMC), SCs that we observed had 5-HT_2A R K_i s > 10 μM. Neither MDPPP nor 3-BMC, at 10 mg/kg doses, attenuated the DOI HTR. Our results suggest α-PPP has antagonist interactions at 5-HT_2A R in vitro that may translate at physiologically-relevant doses in vivo. Considering 5-HT_2A R antagonism has been shown to mitigate effects of psychostimulants, this property may contribute to α-PPPs unpopularity compared to other monoamine transporter inhibitors.