Nitrosamine drug impurities, including both small-molecule nitrosamines and nitrosamine drug substance-related impurities (NDSRIs), are members of a cohort of concern for pharmaceutical safety assessment. As the toxicity of most nitrosamine impurities requires metabolic activation by cytochrome P450 enzymes, this study used human HepaRG cells, which have metabolic activity similar to that of human hepatic cells, to evaluate methods for nitrosamine safety assessment. The genotoxicity of four small-molecule nitrosamines, N-bis(2,2-diethoxyethyl) nitrous amide (BDEA), N-nitrosodiphenylamine, N,N-nitroso-N-ethylaniline (NEPA), and 1-methyl-4-nitrosopiperazine (MNP), and five NDSRIs, N-nitroso-bumetanide, N-nitroso-ciprofloxacin, N-nitroso-dabigatran etexilate, N-nitroso-desmethyl-diphenhydramine, and N-nitroso-sertraline, was evaluated in two-dimensional (2D)/attached and three-dimensional (3D)/spheroid HepaRG cell cultures using two high-throughput genetic toxicity assays, the CometChip DNA damage assay and the flow-cytometric micronucleus (MN) assay. These test substances exhibited a range of responses in other genotoxicity assays, including strong positive, negative, and inconclusive results. Following a 24-h treatment, two NDSRIs, N-nitroso-desmethyl-diphenhydramine and N-nitroso-sertraline, and two small-molecule nitrosamines, BDEA and MNP, induced DNA damage, with the small-molecule nitrosamines positive only in 3D HepaRG spheroids. MN formation was detected only in spheroids exposed to N-nitroso-desmethyl-diphenhydramine. Benchmark concentration (BMC) values derived from the DNA damage data were lower for the genotoxic NDSRIs compared to the genotoxic small-molecule nitrosamines, which correlated with higher cytotoxicity for the NDSRIs. These results show that, while HepaRG spheroids were a more sensitive model for the hazard identification of small-molecule nitrosamines, the responses produced by NDSRIs were more complex, with NDSRIs tested producing similar levels of DNA damage in 2D and 3D cultures and inducing MN formation only in 3D spheroids.

ORAI channels are store-operated Ca[2+] channels, which play important roles in physiology and pathophysiology. ORAI channel modulators are useful for developing pharmacological interventions. Here, we aimed to investigate the benzhydryl-derived analogues as novel ORAI channel blockers. The effects of benzhydryl-derived analogues TH1177, clemastine, cloperastine, and diphenhydramine were investigated in HEK-293 cells overexpressing individual ORAI isoforms and STIM1. The ORAI currents were recorded by patch-clamp, and cytosolic Ca[2+] was measured by a fluorescent Ca[2+] dye. TH1177 inhibited ORAI1, ORAI2, and ORAI3 currents with IC50 values of 18.3 μM, 4.8 μM, and 35.6 μM, respectively. Clemastine inhibited ORAI1 and ORAI2, but showed no effect on ORAI3. Both cloperastine and diphenhydramine, without a pyrrolidine ring structure, only showed minimal inhibition of ORAI1. Intracellular application of TH1177 and outside-out patch demonstrated that TH1177 blocked ORAI3 currents via the extracellular surface. TH1177 did not affect cytosolic STIM1 clustering and movement. Moreover, TH1177 potently inhibited cell proliferation with IC50 values of 2.6 µM for HAEC, 5.2 µM for EA.hy926, and 29.4 µM for HK-2 cells and induced apoptotic cell death. It is concluded that TH1177 is a pan-inhibitor for ORAI1-3 channels, while clemastine inhibits ORAI1 and ORAI2 but shows little effect on ORAI3. The pyrrolidine ring structure in the compounds of TH1177 and clemastine is critical for their inhibitory activity. The two benzhydryl derivatives (cloperastine and diphenhydramine) without the pyrrolidine ring only showed minimal inhibition of ORAI1. Our findings give a new pharmacological profile of ORAI channels.

Drug-induced liver injury (DILI) may occur after exposure to prescription medications, supplements, or non-standardized cosmetic preparations. Cosmetic "liquid lipo" injections are increasingly used for localized fat reduction, but systemic hepatic complications are rarely reported. A 31-year-old woman with no prior liver disease presented with nausea, vomiting, jaundice, and generalized pruritus shortly after receiving a cosmetic "liquid lipo" injection containing deoxycholic acid, phosphatidylcholine, and L-carnitine. Initial laboratory evaluation showed severe hepatocellular liver injury with aspartate aminotransferase 1901 U/L, alanine aminotransferase 2227 U/L, alkaline phosphatase 213 U/L, total bilirubin 6.2 mg/dL, and an R ratio of 6.6. Abdominal imaging showed no biliary obstruction or hepatic mass. Viral, HIV, Epstein-Barr virus, cytomegalovirus, and autoimmune workup were unrevealing. Intravenous N-acetylcysteine (NAC) was initiated for suspected severe DILI, but the patient developed an acute anaphylactic reaction requiring discontinuation of the infusion and treatment with epinephrine, diphenhydramine, and methylprednisolone. She remained hemodynamically stable without encephalopathy or progression to acute liver failure. Liver tests improved with supportive management, and biochemical recovery was documented on outpatient follow-up. Cosmetic liquid lipo injection may be associated with severe hepatocellular DILI. Clinicians should obtain a detailed cosmetic procedure exposure history in unexplained acute liver injury and remain alert to hypersensitivity reactions during intravenous NAC therapy.

A naive Bayesian classifier (NBC) combined with principal component analysis (PCA) effectively differentiates the dose-dependent effects of certain groups of psychoactive drugs based on their impact on the amplitude-spectral characteristics of electrocorticograms (ECoG) in rats. This approach has been shown to be useful for pharmacological screening of agents with unknown or poorly understood activity. Despite previously obtained optimistic results, classification determination for some drugs was inaccurate, necessitating the search for possible ways to improve the predictive effectiveness of the proposed algorithm. One possible approach would be to use as input quantitative data not only the impact of the psychoactive drugs studied on the amplitude-spectral characteristics of ECoG but also connectivity changes, including the average coherence power of different pairs of leads. The aim of this study was to compare the accuracy of NBC in classifying the pharmacological mechanism of action of agents with well-known mechanisms (test set) using pharmaco-EEG data on changes in the amplitude-spectral characteristics of ECoG, coherence, and the combined use of two data sets. Materials and methods. Experiments were performed on Wistar rats with chronically implanted ECoG electrodes. The training set, relative to which the effects of the pharmacological agents from the test set were classified, were the matrices of effects of 12 pharmacological agents: the NMDA antagonist dizocilpine, the D2/D3 antagonists haloperidol and sulpiride, the M-anticholinergic tropicamide, the H1/5HT2A receptor blocker hydroxyzine, the acetylcholinesterase inhibitor galantamine, the alpha-2 adrenergic agonist dexmedetomidine, the alpha-2 adrenergic antagonist atipamezole, the adenosine receptor blocker caffeine and the GABA-mimetics aminophenylbutyric acid (phenibut), bromdihydrochlorophenylbenzodiazepine (phenazepam) and 5-ethyl-5-phenyl-2,4,6(1H,3H,5H)-pyrimidinetrione. The test set included various drugs with tropism for the targets of the training set drugs: dopamine receptor antagonists chlorpromazine, droperidol, tiapride and raclopride, H1-histamine blockers diphenhydramine and promethazine, 5-HT2-receptor blockers ritanserin and glemenserin, acetylcholinesterase inhibitor ipidacrine, alpha2-adrenergic receptor antagonist yohimbine, alpha2-adrenergic agonists medetomidine and xylazine, GABA-mimetics 5-ethyl-5-(1-methylbutyl)-2,4,6(1H,3H,5H)-pyrimidinetrione and chloral hydrate. The analysis of the ECoG signal included the calculation of 132 amplitude-spectral characteristics and 75 coherence indicators, which, using the PCA, led to new integrative indicators used for further classification of the NBC. Results and discussion. For each drug in the test set, the median similarity probability with a particular group from the training set was calculated, which was used to assess the classification quality. It was found that, when using the amplitude-spectral characteristics of ECoG, the proposed methodological approach allows for the identification of the ECoG effects of several groups of psychoactive drugs, including D2/D3-dopamine, M-cholinergic, H1-histamine, and 5-HT2-serotonin receptor blockers, AChE inhibitors, GABA-mimetics, and alpha-2-adrenergic receptor agonists and antagonists. This approach enabled the correct classification of 18 of 24 groups in the test set. When using changes in coherence indices as the initial data, the classification accuracy also amounted to 18 of 24 groups. When combining the two data sets, the number of correctly identified NBC groups was 20 of 24 groups. When comparing the classification during training (confusion matrix), it was found that coherence data or adding coherence data to the data based on changes in amplitude-spectral characteristics leads to a statistically significant (p < 0.01 in both cases) increase in accuracy. Conclusions. The obtained data demonstrated high accuracy in classifying the pharmacological activity of the test sample drugs using any of the three compared approaches. Despite the lack of statistically significant differences between them, classification based on the combined dataset demonstrated a higher number of "correct" similarities. This allows us to recommend the approach based on combined data of drug effects on amplitude-spectral characteristics and coherence as the most promising for further studies using pharmaco-EEG screening.

Diphenhydramine hydrochloride was determined through a newly developed turbidimetric method on a home-designed continuous-flow injection analysis (CFIA) system. The principle of the method is based on the precipitation-induced signal enhancement, using potassium hexacyanoferrate (III) as a selective precipitating agent. The CFIA manifold uses a flow-through detection cell that consists of 12 white light-emitting diodes and three solar cells placed at 0, 90 and 180 degrees in order to track cumulative light scattering over a range of angles. The systematically optimized chemical and instrumental parameters were the reagent concentration, flow rate and sample volume to attain optimal sensitivity and reproducibility. The technique had good linearity (correlation coefficient, R = 0.9975) and per cent linearity (R [2]% = 99.49). The limit of detection was 255.325 ng/sample, calculated from serial dilution within the calibration range. Very high accuracy was achieved with a relative standard deviation (r.s.d.% < 0.4) of six replicates at 5 and 12 mmol l[-1]. Diphenhydramine hydrochloride in pharmaceutical tablets was successfully determined using the method. The method was found to be accurate, reliable and suitable for pharmaceutical quality control, as demonstrated by statistical comparisons with a conventional spectrophotometric technique using a paired t-test and a one-way ANOVA at the 95% confidence level.

Feature-based molecular networking (FBMN) can support prioritization of library-absent features in high-resolution mass spectrometric screening, but parameter choices may create chemically misleading links, particularly for data-independent acquisition (DIA) spectra. We developed a structure-guided multi-metric parameter-optimization framework using 51 authenticated antihistamines assigned to structural classes independently of retention time, MS/MS similarity, and network topology. Across 595 GNPS-FBMN parameter combinations, the selected application-specific setting P264 (minimum cosine similarity, 0.475; matched ions, 8; MAX_SHIFT, 150 Da) gave an adjusted Rand index of 0.216, a same-class edge ratio of 0.697, and a cross-class edge ratio of 0.303, compared with 0.101, 0.621, and 0.379, respectively, for the controlled GNPS edge-default setting. In 120 commercial cosmetics, in-house library screening detected diphenhydramine in one sample; authentic-standard comparison confirmed the retention time, precursor ion, and MS/MS evidence, and post-confirmation measurement gave 3.28 mg kg[-1]. Independent 51-target triple-quadrupole MRM analysis produced no discordant known-target result in the evaluated commercial-sample set. In a separate library-absent proof-of-concept experiment, buclizine fortified into blank cream satisfied the predefined three-anchor prioritization rule, ranked first with SIRIUS/CSI:FingerID, and was subsequently confirmed with an authentic standard. These results support the optimized FBMN as a complementary approach for structural-context assessment and library-absent candidate prioritization under the evaluated DIA-HRMS conditions.

Ayahuasca is a psychoactive botanical brew originating from Amazonian ceremonial traditions, containing monoamine oxidase inhibitors (MAOIs) derived from Banisteriopsis caapi and N,N-dimethyltryptamine from Psychotria viridis or Diplopterys cabrerana. Its use has expanded globally for perceived antidepressant and anti-addictive effects. However, the MAOI content of ayahuasca predisposes users to serotonergic toxicity when combined with other serotonergic agents. We present the case of a 46-year-old man who developed severe serotonin syndrome (SS) complicated by acute respiratory failure after ingesting ayahuasca over three days, followed by over-the-counter dextromethorphan (DXM) and diphenhydramine. He required emergent intubation and intensive care unit (ICU) admission. Management with intravenous benzodiazepines, oral cyproheptadine, and supportive care led to rapid clinical improvement, with extubation on ICU day 2 and discharge on hospital day 3. Severe SS attributable to ayahuasca is rarely documented, and to our knowledge this is the first report of ayahuasca combined with over-the-counter DXM and diphenhydramine producing SS severe enough to cause acute respiratory failure. This case highlights the life-threatening potential of combining ayahuasca with commonly available serotonergic medications and underscores the need for clinician awareness of these interactions.

This study aimed to integrate in vitro dissolution testing, in vivo pharmacokinetic (PK) studies, and computational simulation to develop a physiologically based biopharmaceutics model (PBBM) for fixed-dose combination ibuprofen/diphenhydramine citrate tablets, thereby evaluating bioequivalence (BE) and establishing a dissolution safe space. Initially, a PBBM model was constructed using B[2]O Simulator software. Subsequently, an integrated approach was employed, combining dissolution profiles with physiological parameters to develop a virtual bioequivalence (VBE) model. Through simulations involving virtual batches exhibiting diverse dissolution characteristics, the safe dissolution range was determined. Consequently, the PBBM models for ibuprofen and diphenhydramine were successfully validated. Furthermore, the VBE model demonstrated favorable bioequivalence, with an absolute average fold error (AAFE) of less than 1.5 between predicted and observed values for key PK parameters (Cmax and AUC). Scenario analyses supported a formulation- and medium-specific dissolution criterion of no less than 85% dissolution within 30 min for both APIs in pH 6.5 phosphate buffer. Additionally, scenario analyses suggested that, within the simulated two-treatment, two-period crossover settings evaluated in this study, a sample size of approximately 40 subjects may represent a practical lower bound for obtaining stable BE conclusions. In conclusion, this study provides a product-specific, model-informed workflow for bioequivalence risk assessment of ibuprofen/diphenhydramine citrate tablets. The application of PBBM and VBE modeling offers guidance for quantitative BE risk assessment, thereby holding promise to accelerate the development process while reducing associated costs. (The bioequivalence study in healthy subjects was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the Second Affiliated Hospital of Anhui Medical University [ChiCTR registration number: ChiCTR2500106504; approved: March 12, 2023].).

This article reviews the role of outpatient dental sedation in managing patients with dental anxiety or phobia. Sedation helps reduce pain, fear, and memory of procedures while improving patient cooperation and treatment outcomes. The article discusses commonly used sedative and adjunct medications, including midazolam, remimazolam, propofol, ketamine, opioids such as fentanyl and remifentanil, and supportive drugs like dexmedetomidine, diphenhydramine, atropine, glycopyrrolate, and ondansetron. Newer agents such as remimazolam and ketofol combinations may offer improved safety and recovery profiles. Overall, the article emphasizes individualized patient care and thorough pharmacologic knowledge to ensure safe and effective outpatient dental sedation.

Gadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging (MRI) and are generally considered safe, with immediate hypersensitivity reactions being rare. While anaphylaxis typically presents with classic skin reactions, respiratory distress, or cardiovascular collapse, exposure to a known allergen can cause single-system respiratory or laryngeal variants. An 83-year-old male with multiple chronic medical conditions underwent a diagnostic brain MRI with contrast. Immediately after receiving 8.5 mL of gadobutrol, the patient developed hoarseness and a sporadic cough. Notably, he had no skin reactions, dyspnea, tachypnea, drop in oxygen saturation, or hypotension. Instead, his blood pressure remained stable but elevated. Due to the rapid onset of these isolated upper airway symptoms, a rapid response was triggered. He was treated proactively with epinephrine, diphenhydramine, and methylprednisolone, and transferred to the intensive care unit (ICU) for close monitoring. Bedside flexible laryngoscopy confirmed only minimal right arytenoid edema and a patent glottis. He completely recovered within 24 hours without further clinical progression. This case underscores a highly atypical presentation of GBCA-induced anaphylaxis localized entirely to the upper airway, manifesting solely as hoarseness and coughing. As an isolated respiratory reaction to a known non-inhaled allergen, this case shows how the absence of classic multisystem involvement can easily mask a severe allergic reaction.

This case report describes a 51-year-old woman with recurrent cervical squamous cell carcinoma who developed acute anaphylactic shock within 5-10 min of initiating intravenous cadonilimab infusion. The physician's order was placed at 16:04; however, the actual bedside infusion was initiated at approximately 20:00 without routine premedication. Five minutes after infusion start, she presented with pruritus and multiple erythematous maculopapular rashes over the trunk, followed by dyspnea, generalized flushing, profound hypotension (68/40 mmHg), oxygen desaturation (SpO2 82%), and altered consciousness. The infusion was immediately discontinued. Emergency treatment included subcutaneous epinephrine 0.5 mg, intramuscular diphenhydramine 20 mg, intravenous dexamethasone 10 mg, aggressive fluid resuscitation, and supplemental oxygen. Because refractory hypotension persisted, intravenous norepinephrine (4 mg via continuous pump) was initiated and maintained for approximately 72 h. Hemodynamic stability was restored within 45 min. Comprehensive evaluation excluded infection, cardiogenic shock, pulmonary embolism, and cytokine release syndrome. The event fulfilled World Allergy Organization diagnostic criteria for anaphylaxis and was graded as Common Terminology Criteria for Adverse Events (CTCAE) v5.0 Grade 4. Causality assessment using the Naranjo scale yielded a score of 6, indicating a probable adverse drug reaction. The patient had a documented prior hypersensitivity to paclitaxel but no prior exposure to immune checkpoint inhibitors. Rechallenge was not attempted. Cadonilimab may rarely cause rapid-onset, life-threatening anaphylactic shock during the first infusion. Careful monitoring, immediate access to emergency management-including vasopressor support-and heightened awareness of bispecific antibody-associated hypersensitivity are essential.

Sleep disruption is common in Alzheimer's disease (AD). Diphenhydramine (DPH), a first-generation antihistamine with anticholinergic properties, is widely used as an over-the-counter sleep aid. We tested whether chronic DPH treatment alters sleep architecture in 5XFAD and wild-type mice. Female 5XFAD (n=16) and wild-type (WT) littermates (n=14) were implanted with wireless telemetry recording devices to measure electroencephalography (EEG), electromyography (EMG), temperature, and activity continuously. After a 24h baseline recording at 5 months of age, mice received oral DPH (10 mg/kg) or vehicle at ZT0 for one month. After this chronic treatment, sleep was recorded continuously for 48h during ongoing dosing. Sleep was scored as rapid eye movement (REM), non-rapid eye movement (NREM) 1, NREM2, or wake. A survival curve analysis was used to investigate the microarchitecture of sleep phases after chronic diphenhydramine treatment. At baseline, 5XFAD mice had more time in NREM1 than WT controls and had shorter REM and NREM2 bouts. Chronic DPH treatment fragmented NREM2 in both genotypes, reducing long NREM2 bouts. DPH increased total duration of NREM1 and REM during the active phase, which is analogous to daytime drowsiness in humans. DPH did not rescue 5XFAD sleep deficits; instead, DPH treatment exacerbated NREM2 fragmentation. Overall, chronic DPH use degrades sleep quality and increases fragmentation in both WT and AD-model mice, which questions the use of sedating anticholinergics as sleep aids, especially in AD.

First-generation H1 antihistamines have central nervous system penetration and anticholinergic activity, with potential side effects including sedation, cognitive impairment, and anterograde amnesia. First-generation antihistamines pose risks in driving under the influence of drugs (DUID) and drug-facilitated crimes (DFC) forensic casework. A liquid chromatography-tandem mass spectrometry method was developed and validated for five first-generation H1 antihistamines: chlorpheniramine, diphenhydramine, doxylamine, hydroxyzine, and promethazine. The calibration range was 1-200 ng/mL with a 1/x linear calibration model for quantitative compounds, and the limit of detection was determined to be 0.5 ng/mL for all compounds. Bias and precision were acceptable, with minor but acceptable suppression observed at low and high concentrations. No exogenous or endogenous interferences were observed. Carryover was not detected after a 400 ng/mL sample. Processed samples were determined to be stable 24 h after initial injection when stored in the refrigerated multi-sampler. Authentic forensic specimens from DUID and DFC investigations showed a wide range of concentrations for diphenhydramine. Selected case reports are presented to demonstrate the applicability of the method. The high percentage of polysubstance cases, range of concentrations, and delayed sample collection in DFC cases underscore the importance of a sensitive and reproducible method for these first-generation antihistamines, especially in human-performance casework.