Effects of Age and Exposure Duration on the Sensitivity of Early Life Stage Fathead Minnow (Pimephales promelas) to Waterborne Propranolol Exposure.

Propranolol is a heavily prescribed, nonspecific beta-adrenoceptor (bAR) antagonist frequently found in wastewater effluents, prompting concern over its potential to adversely affect exposed organisms. In the present study, the transcriptional responses of 4, 5, and 6 days postfertilization (dpf) ±1 h fathead minnow, exposed for 6, 24, or 48 h to 0.66 or 3.3 mg/L (nominal) propranolol were characterized using RNA sequencing. The number of differentially expressed genes (DEGs) was used as an estimate of sensitivity. A trend toward increased sensitivity with age was observed; fish >7 dpf at the end of exposure were particularly sensitive to propranolol. The DEGs largely overlapped among treatment groups, suggesting a highly consistent response that was independent of age. Cluster analysis was performed using normalized count data for unexposed and propranolol-exposed fish. Control fish clustered tightly by age, with fish ≥7 dpf clustering away from younger fish, reflecting developmental differences. When clustering was conducted using exposed fish, in cases where propranolol induced a minimal or no transcriptional response, the results mirrored those of the control fish and did not appreciably cluster by treatment. In treatment groups that displayed a more robust transcriptional response, the effects of propranolol were evident; however, fish <7 dpf clustered away from older fish, despite having similar numbers of DEGs. Increased sensitivity at 7 dpf coincided with developmental milestones with the potential to alter propranolol pharmacokinetics or pharmacodynamics, such as the onset of exogenous feeding and gill functionality as well as increased systemic expression of bAR. These results may have broader implications because toxicity testing often utilizes fish <4 dpf, prior to the onset of these potentially important developmental milestones, which may result in an underestimation of risk for some chemicals. Environ Toxicol Chem 2024;43:807-820. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Revisiting the mutagenicity and genotoxicity of N-nitroso propranolol in bacterial and human in vitro assays.

Propranolol is a widely used ß-blocker that can generate a nitrosated derivative, N-nitroso propranolol (NNP). NNP has been reported to be negative in the bacterial reverse mutation test (the Ames test) but genotoxic in other in vitro assays. In the current study, we systematically examined the in vitro mutagenicity and genotoxicity of NNP using several modifications of the Ames test known to affect the mutagenicity of nitrosamines, as well as a battery of genotoxicity tests using human cells. We found that NNP induced concentration-dependent mutations in the Ames test, both in two tester strains that detect base pair substitutions, TA1535 and TA100, as well as in the TA98 frameshift-detector strain. Although positive results were seen with rat liver S9, the hamster liver S9 fraction was more effective in bio-transforming NNP into a reactive mutagen. NNP also induced micronuclei and gene mutations in human lymphoblastoid TK6 cells in the presence of hamster liver S9. Using a panel of TK6 cell lines that each expresses a different human cytochrome P450 (CYP), CYP2C19 was identified as the most active enzyme in the bioactivation of NNP to a genotoxicant among those tested. NNP also induced concentration-dependent DNA strand breakage in metabolically competent 2-dimensional (2D) and 3D cultures of human HepaRG cells. This study indicates that NNP is genotoxic in a variety of bacterial and mammalian systems. Thus, NNP is a mutagenic and genotoxic nitrosamine and a potential human carcinogen.

LogD-based modelling and ΔlogD as a proxy for pH-dependent action of ionizable chemicals reveal the relevance of both neutral and ionic species for fish embryotoxicity and possess great potential for practical application in the regulation of chemicals.

Depending on the ambient pH, ionizable substances are present in varying proportions in their neutral or charged form. The extent to which these two chemical species contribute to the pH-dependant toxicity of ionizable chemicals and whether intracellular ion trapping has a decisive influence in this context is controversially discussed. Against this background, we determined the acute toxicity of 24 ionizable substances at up to 4 different pH values on the embryonic development of the zebrafish, Danio rerio, and supplemented this dataset with additional data from the literature. The LC50 for some substances (diclofenac, propranolol, fluoxetine) differed by a factor of even >103 between pH5 and pH9. To simulate the toxicity of 12 acids and 12 bases, six models to calculate a pH-dependant logD value as a proxy for the uptake of potentially toxic molecules were created based on different premises for the trans-membrane passage and toxic action of neutral and ionic species, and their abilities to explain the real LC50 data set were assessed. Using this approach, we were able to show that both neutral and charged species are almost certainly taken up into cells according to their logD-based distribution, and that both species exert toxicity. Since two of the models that assume all intracellular molecules to be neutral overestimated the real toxicity, it must be concluded, that the toxic effect of a single charged intracellularly present molecule is, on the average, lower than that of a single neutral molecule. Furthermore, it was possible to attribute differences in toxicity at different pH values for these 24 ionizable substances to the respective deltas in logD at these pH levels with high accuracy, enabling particularly a full logD-based model on the basis of logPow as a membrane passage descriptor to be used for predicting potential toxicities in worst-case scenarios from existing experimental studies, as stipulated in the process of registration of chemicals and the definition of Environmental Quality Standards (EQS).

Propranolol hydrochloride induces neurodevelopmental toxicity and locomotor disorders in zebrafish larvae.

Propranolol hydrochloride is the first-line drug for the clinical treatment of hypertension, arrhythmia, and other diseases. However, with the increasing use of this drug, its safety and environmental health have received more and more attention. In this study, aquatic vertebrate zebrafish were used as a model to study the toxic effects and mechanisms of propranolol hydrochloride. It was revealed that zebrafish larvae exposed to propranolol hydrochloride showed aberrant head nerve development and locomotor disorders. Additionally, exposure to propranolol hydrochloride could induce oxidative stress, alter the activities of AChE and ATPase, and disrupt the expression of genes involved in neurodevelopment and neurotransmitter pathways. More interestingly, the expression of Parkinson's disease-related genes was altered in zebrafish treated with propranolol hydrochloride. We detected the expression of genes related to the Wnt signaling pathway and found that their expression appeared to be down-regulated. The phenotype of nerve developmental defects and locomotor disorders can be effectively rescued by astaxanthin and Wnt activators. Collectively, the results suggest that propranolol hydrochloride may induce neurotoxicity and abnormal movement behavior with PD-like symptoms in zebrafish larvae.

Photodegradation of propranolol in surface waters: An important role of carbonate radical and enhancing toxicity phenomenon.

Antihypertensive propranolol (PRO) is frequently detected in surface waters and has adverse effects on aquatic organisms. In this study, its photochemical fate in surface water with the aspect of kinetics, products and toxicity were investigated employing steady-state photochemistry experiments and ecotoxicity tests. The results showed that photodegradation of PRO was enhanced in river water than that in phosphate buffer where dissolved organic matter (DOM), NO3-, and HCO3- played important roles. DOM accelerated the photodegradation mainly through generation of excited triplet-state DOM while NO3- played dual roles in the photodegradation. The reaction between excited triplet-state PRO and HCO3- can generate carbonate radical (CO3·-) to promote the photodegradation. The second-order reaction rate constant between PRO and CO3·- was determined to be (3.4 ± 0.8) × 108 M-1 s-1. Eight photodegradation products were identified in the studied river water sample. Finally, the toxicity evaluated by Vibrio fischeri increased after photodegradation and three photodegradation products were responsible for the increasing toxicity, which was concluded from the significant correlation between toxicity parameters and quantity of the photodegradation products.

The use of Gammarus pulex as a model organism for ecotoxicological assessment of ibuprofen and propranolol at environmental relevant concentrations.

The aim of this study is to assess the toxicity of ibuprofen (IBU) and propranolol (PRO) drugs usingGammarus pulex as a model organism. Firstly, the 96 h LC50 values of IBU and PRO were determined and then three sublethal concentrations of the drugs were exposed to G. pulex. The activities of superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) were evaluated. SOD activity decreased in G. pulex exposed to IBU and PRO compared to control. In all groups exposed to IBU, CAT activity increased at different concentrations at 24 and 96 h. In the groups exposed to different PRO concentrations, CAT activities increased after 24 h compared to the control group (p < 0.05). AChE activities increased in all application groups exposed to IBU for 96 hours (p < 0.05). In conclusion, exposure to IBU and PRO resulted in increased oxidative damage. PRO has been found to cause neurotoxicity.

A comprehensive aquatic risk assessment of the beta-blocker propranolol, based on the results of over 600 research papers.

A comprehensive aquatic environmental risk assessment (ERA) of the human pharmaceutical propranolol was conducted, based on all available scientific literature. Over 200 papers provided information on environmental concentrations (77 of which provided river concentrations) and 98 dealt with potential environmental effects. The median concentration of propranolol in rivers was 7.1 ng/L (range of median values of individual studies 0.07 to 89 ng/L), and the highest individual value was 590 ng/L. Sixty-eight EC50 values for 35 species were available. The lowest EC50 value was 0.084 mg/L. A species sensitivity distribution (SSD) provided an HC50 value of 6.64 mg/L and an HC5 value of 0.22 mg/L. Thus, there was a difference of nearly 6 orders of magnitude between the median river concentration and the HC50 value, and over 4 orders of magnitude between the median river concentration and the HC5 value. Even if an assessment factor of 100 was applied to the HC5 value, to provide considerable protection to all species, the safety margin is over 100-fold. However, nearly half of all papers reporting effects of propranolol did not provide an EC50 value. Some reported that very low concentrations of propranolol caused effects. The lowest concentration reported to cause an effect - in fact, a range of biochemical and physiological effects on mussels - was 0.3 ng/L. In none of these 'low concentration' papers was a sigmoidal concentration-response relationship obtained. Although inclusion of data from these papers in the ERA cause a change in the conclusion reached, we are sceptical of the repeatability of these 'low concentration' results. We conclude that concentrations of propranolol present currently in rivers throughout the world do not constitute a risk to aquatic organisms. We discuss the need to improve the quality of ecotoxicology research so that more robust ERAs acceptable to all stakeholders can be completed.

Penicillin causes non-allergic anaphylaxis by activating the contact system.

Immediate hypersensitivity reaction (IHR) can be divided into allergic- and non-allergic-mediated, while "anaphylaxis" is reserved for severe IHR. Clinically, true penicillin allergy is rare and most reported penicillin allergy is "spurious". Penicillin-initiated anaphylaxis is possible to occur in skin test- and specific IgE-negative patients. The contact system is a plasma protease cascade initiated by activation of factor XII (FXII). Many agents with negative ion surface can activate FXII to drive contact system. Our data showed that penicillin significantly induced hypothermia in propranolol- or pertussis toxin-pretreated mice. It also caused a rapid and reversible drop in rat blood pressure, which did not overlap with IgE-mediated hypotension. These effects could be countered by a bradykinin-B2 receptor antagonist icatibant, and consistently, penicillin indeed increased rat plasma bradykinin. Moreover, penicillin not only directly activated contact system FXII-dependently, but also promoted bradykinin release in plasma incubated-human umbilical vein endothelial cells. In fact, besides penicillin, other beta-lactams also activated the contact system in vitro. Since the autoactivation of FXII can be affected by multiple-factors, plasma from different healthy individuals showed vastly different amidolytic activity in response to penicillin, suggesting the necessity of determining the potency of penicillin to induce individual plasma FXII activation. These results clarify that penicillin-initiated non-allergic anaphylaxis is attributed to contact system activation, which might bring more effective diagnosis options for predicting penicillin-induced fatal risk and avoiding costly and inappropriate treatment clinically.

Untargeted metabolomics changes on Gammarus pulex induced by propranolol, triclosan, and nimesulide pharmaceutical drugs.

The presence of pharmaceuticals and personal care products (PPCPs) in natural water resources due to incomplete removal in Wastewater Treatment Plants (WWTPs) is a serious environmental concern at present. In this work, the effects of three pharmaceuticals (propranolol, triclosan, and nimesulide) on Gammarus pulex metabolic profiles at different doses and times of exposure have been investigated by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). The complex data sets generated in the different exposure experiments were analyzed with the ROIMCR procedure, based on the selection of the MS regions of interest (ROI) data and on their analysis by the Multivariate Curve-Resolution Alternating Least Squares (MCR-ALS) chemometrics method. This approach, allowed the resolution and identification of the metabolites present in the analyzed samples, as well as the estimation of their concentration changes due to the exposure experiments. ANOVA Simultaneous Component Analysis (ASCA) and Partial Least Squares Discriminant Analysis (PLS-DA) were then conducted to assess the changes in the concentration of the metabolites for the three pharmaceuticals at the different conditions of exposure. The three tested pharmaceuticals changed the concentrations of metabolites, which were related to different KEGG functional classes. These changes summarize the biochemical response of Gammarus pulex to the exposure by the three investigated pharmaceuticals. Possible pathway alterations related to protein synthesis and oxidative stress were observed in the concentration of identified metabolites.

Drug response analysis for scaffold-free cardiac constructs fabricated using bio-3D printer.

Cardiac constructs fabricated using human induced pluripotent stem cells-derived cardiomyocytes (iPSCs-CMs) are useful for evaluating the cardiotoxicity of and cardiac response to new drugs. Previously, we fabricated scaffold-free three-dimensional (3D) tubular cardiac constructs using a bio-3D printer, which can load cardiac spheroids onto a needle array. In this study, we developed a method to measure the contractile force and to evaluate the drug response in cardiac constructs. Specifically, we measured the movement of the needle tip upon contraction of the cardiac constructs on the needle array. The contractile force and beating rate of the cardiac constructs were evaluated by analysing changes in the movement of the needle tip. To evaluate the drug response, contractile properties were measured following treatment with isoproterenol, propranolol, or blebbistatin, in which the movement of the needle tip was increased following isoproterenol treatment, but was decreased following propranolol or blebbistain, treatments. To evaluate cardiotoxicity, contraction and cell viability of the cardiac constructs were measured following doxorubicin treatment. Cell viability was found to decrease with decreasing movement of the needle tip following doxorubicin treatment. Collectively, our results show that this method can aid in evaluating the contractile force of cardiac constructs.

In-plate toxicometabolomics of single zebrafish embryos.

Toxicometabolomic studies involving zebrafish embryos have become increasingly popular for linking apical endpoints to biochemical perturbations as part of adverse outcome pathway determination. These experiments involve pooling embryos to generate sufficient biomass for metabolomic measurement, which adds both time and cost. To address this limitation, we developed a high-throughput toxicometabolomic assay involving single zebrafish embryos. Incubation, microscopy, embryo extraction, and instrumental metabolomic analysis were all performed in the same 96-well plate, following acquisition of conventional toxicological endpoints. The total time for the assay (including testing of 6 doses/n = 12 embryos per dose plus positive and negative controls, assessing conventional endpoints, instrumental analysis, data processing and multivariate statistics) is <14 days. Metabolomic perturbations at low dose were linked statistically to those observed at high dose and in the presence of an adverse effect, thereby contextualizing omic data amongst apical endpoints. Overall, this assay enables collection of high resolution metabolomic data in a high throughput manner, suitable for mode of action hypothesis generation in the context of pharmaceutical or toxicological screening.

Toxicity of Atenolol and Propranolol on Rat Heart Mitochondria.

Propranolol and atenolol are known as ß receptor blocker drugs. These drugs are used to treat some heart diseases. There are controversies in the relationship between the use of beta-blocker drugs and the level of reactive oxygen species (ROS). Mitochondria as one of the most important sources of ROS are considered as one of the targets of drug-induced cardiotoxicity. The aim of this study was to evaluate the effects of propranolol and atenolol on mitochondria isolated from the heart. To achieve this aim, several markers of mitochondrial and cellular toxicity were evaluated. The key results of this study are the increased ROS level, collapse in mitochondrial membrane potential (MMP), mitochondrial swelling and cytochrome c release as well as disruption of respiratory chain complex II in mitochondria in isolated heart mitochondria after exposure to propranolol and atenolol. The results indicate an increase in caspase-3 activity and a decrease in the ATP level in cardiomyocytes after exposure to propranolol and atenolol. The underlying mechanisms of propranolol and atenolol induced cardiotoxicity may be associated with alterations in mitochondrial function, oxidative stress, and changes in the mitochondrial membrane.

UV-LED/chlorine degradation of propranolol in water: Degradation pathway and product toxicity.

This study reports on the propranolol (PRO) degradation performance and product toxicity of an ultraviolet light-emitting diode (UV-LED)/chlorine process. The effects of experimental parameters including solution pH, chlorine dosage, and water matrix constituents on PRO removal were evaluated. Up to 94.5% of PRO could be eliminated within 15 min at a PRO-to-chlorine molar ratio of 1:4. The overall removal efficiency of PRO was non-pH dependent in the range of 5-9, while the initial rate was accelerated under alkaline conditions. The presence of Cl-/HCO3- had little influence on the PRO degradation, whereas either humic acid or NO3- had an obvious inhibitory effect. Radical scavenger experiments showed that both HO and Cl primarily contributed to the PRO degradation, and electron paramagnetic resonance data demonstrated the generation of 1O2. The transformation of PRO during this process led to five detected products, which exhibited a higher acute toxicity than the parent compound according to the bright luminescent bacillus T3 method. It is worth mentioning that under the same ultraviolet illumination intensity, the degradation of PRO under UV-LED/chlorine gave a better performance than UV254/chlorine, but the EEO of the former is obviously higher than the latter. So further research is required on improving the electric current to photon conversion efficiency for UV-LED. Additionally, the UV-LED/chlorine system was effective in the degradation of other drugs including sulfamethoxazole, oxytetracycline hydrochloride, and gatifloxacin, suggesting the possible application of the UV-LED/chlorine process for the removal of pharmaceuticals during wastewater treatment.

Use of a non-hepatic cell line highlights limitations associated with cell-based assessment of metabolically induced toxicity.

Metabolically induced drug-toxicity is a major cause of drug failure late in drug optimization phases. Accordingly, in vitro metabolic profiling of compounds is being introduced at earlier stages of the drug discovery pipeline. An increasingly common method to obtain these profiles is through overexpression of key CYP450 metabolic enzymes in immortalized liver cells, to generate competent hepatocyte surrogates. Enhanced cytotoxicity is presumed to be due to toxic metabolite production via the overexpressed enzyme. However, metabolically induced toxicity is a complex multi-parameter phenomenon and the potential background contribution to metabolism arising from the use of liver cells which endogenously express CYP450 isoforms is consistently overlooked. In this study, we sought to reduce the potential background interference by applying this methodology in kidney-derived HEK293 cells which lack endogenous CYP450 expression. Overexpression of CYP3A4 resulted in increased HEK293 proliferation, while exposure to four compounds with reported metabolically induced cytotoxicity in liver-derived cells overexpressing CYP3A4 resulted in no increase in cytotoxicity. Our results indicate that overexpression of a single CYP450 isoform in hepatic cell lines may not be a reliable method to discriminate which enzymes are responsible for metabolic induced cytotoxicity.

Neurotoxic and respiratory effects of human use drugs on a Neotropical fish species, Phalloceros harpagos.

Pharmaceutical drugs are usually and continuously carried to the aquatic environment in different ways. Thus, they are pseudo-persistent in the environment, and they may exert deleterious effects on aquatic organisms. The objective of the present study was to investigate the acute and chronic effects of two widely used pharmaceutical drugs, paracetamol (analgesic and antipyretic) and propranolol (ß-blocker) on the activity of specific biomarkers (namely cholinesterase enzymes and lactate dehydrogenase) of the neotropical fish Phalloceros harpagos. The obtained results indicate an inhibition of the activity of the enzyme lactate dehydrogenase (LDH) after acute exposure to paracetamol, and an increase in cholinesterase activity in acutely propranolol-exposed fish. Chronic exposure to both drugs did not modify the enzymatic activities. Such short-term changes in enzymatic activities may be harmful to organisms, altering the preferential pathway of energy metabolism, and may induce behavioral changes that may compromise prey capture and predator escape, and in the longer term may induce population declines.

Environmental risk assessment of propranolol in the groundwater bodies of Europe.

A growing concern for contamination due to pharmaceutical compounds in groundwater is expanding globally. The ß-blocker propranolol is a ß-adrenoceptors antagonist commonly detected in European groundwater bodies. The effect of propranolol on stygobiotic species (obligate groundwater dweller species) is compelling in the framework of environmental risk assessment (ERA) of groundwater ecosystems. In fact, in Europe, ERA procedures for pharmaceuticals in groundwater are based on data obtained with surrogate surface water species. The use of surrogates has aroused some concern in the scientific arena since the first ERA guideline for groundwater was issued. We performed an ecotoxicological and a behavioural experiment with the stygobiotic crustacean species Diacyclops belgicus (Copepopda) to estimate a realistic value of the Predicted No Effect Concentration (PNEC) of propranolol for groundwater ecosystems and we compared this value with the PNEC estimated based on EU ERA procedures. The results of this study showed that i) presently, propranolol does not pose a risk to groundwater bodies in Europe at the concentrations shown in this study and ii) the PNEC of propranolol estimated through the EU ERA procedures is very conservative and allows to adequately protect these delicate ecosystems and their dwelling fauna. The methodological approach and the results of this study represent a first contribution to the improvement of ERA of groundwater ecosystems.

Phenotypical and molecular changes induced by carbamazepine and propranolol on larval stages of Mytilus galloprovincialis.

The possible impact of carbamazepine (CBZ) and propranolol (PROP), two widespread pharmaceuticals in the aquatic environment, were investigated on morphology and gene transcription of early larvae of Mytilus galloprovincialis. Pharmaceuticals were first tested in a wide concentration range (from 0.01 to 1000 µg/L) through the 48-hpf embryotoxicity assay. The results showed that both compounds significantly affected embryo development from environmental concentrations. Although similar EC50 were obtained, (≅ 1 µg/L) CBZ induced a progressive increase in embryo malformations, whereas PROP apparently showed greater impacts in terms of arrested development and embryo mortality at higher concentrations (>10 µg/L). Transcriptional analyses of 17 genes involved in different physiological functions in mussels and/or in their response to environmental contaminants, were performed at 24 and 48 h pf at two selected concentrations of CBZ and PROP (0.01 and 1 µg/L). Both compounds induced down-regulation of shell-specific and neuroendocrine related transcripts, while distinct effects were observed on antioxidant, lysosomal, and immune-related transcripts, also depending on the larval stage investigated. The results demonstrate that CBZ and PROP can affect development and gene transcription in mussel early larvae at environmental concentrations.

Novel chiral metal organic frameworks functionalized composites for facile preparation of optically pure propranolol hydrochlorides.

Two novel sorbents based on polydopamine (PDA)-coated magnetic graphite oxide-metal organic frameworks nanoparticles [Cu(L-mal)(bpy)]·H2O (MGO-CuLBH) and [Cu(D-mal)(bpy)]·H2O (MGO-CuDBH) possessing of both magnetic property and excellent enantioselective ability were prepared and characterized. Solutions of racemic propranolol hydrochloride (Rac-PRO) were chosen to investigate the enantioselective performance of MGO-CuLBH and MGO-CuDBH by dispersive magnetic nanoparticle solid phase extraction (d-MNSPE). The results showed that the nanocomposites have excellent enantioselectivity to PROs with enantiomeric excess (ee) values reaching up to 98%. The entire process with PROs by the d-MNSPE method was fast, convenient and the collected composites could be easily recycled. Multi-stage operations using MGO-CuLBH and MGO-CuDBH were scaled up to obtain milligram quantities of R-propranolol hydrochloride (R-PRO) and S-propranolol hydrochloride (S-PRO). Furthermore, on the basis of the successful preparations, the differences in the cytotoxicity of Rac-PRO, R-PRO and S-PRO on A549 cells in vitro were all evaluated.

A Swine Model of Severe Propranolol Toxicity Permitting Direct Measurement of Brain Tissue Oxygenation.

INTRODUCTION: High-dose insulin (HDI) therapy has been used successfully for beta-blocker toxicity, but needs further study when hypotension persists despite HDI. The objective was to develop a model of propranolol toxicity with persistent hypotension despite HDI and to develop means to measure cerebral oxygen tension (PbrO2). METHODS: Eight anesthetized Yorkshire pigs were instrumented with a tracheostomy, Swan-Ganz catheter, arterial catheter, and intra-cerebral pressure and oxygen monitor. Intravenous propranolol was given until the initial point of toxicity (POT); 25% reduction from baseline mean arterial pressure (MAP) × heart rate (HR). At the initial POT, normal saline (NS) bolus and infusion along with HDI infusion were started. The propranolol infusion was titrated up slowly to induce hypotension. Group 2 pigs received a norepinephrine (NE) infusion after a secondary POT defined as a MAP < 50 mmHg. NE was titrated to maintain subsequent MAPs > 50 mmHg. Cardiac output, HR, MAP, PbrO2, and intracranial pressure were then recorded every 5 min until death or 4 h. Systemic vascular resistance, potassium, and glucose were also measured. Surviving pigs were euthanized. RESULTS: Two pigs received unique doses for protocol development. One pig developed a tachyarrhythmia prior to protocol, one failed to reach secondary POT, leaving 2 pigs in each group reaching secondary POT. The range of PbrO2 recordings for group 1 was 12.7-48.5 mmHg and 9.2-26.2 mmHg for group 2. CONCLUSION: We report a pilot study swine model of propranolol toxicity with hypotension despite HDI, in which physiologic measures including PbrO2 are achieved. Our toxicity model can be used in the future, and the hemodynamic and brain monitoring model may prove important for subsequent research in various contexts.

A randomized controlled study comparing high-dose insulin to vasopressors or combination therapy in a porcine model of refractory propranolol-induced cardiogenic shock.

Context: Although cerebral perfusion (CP) is preserved across a wide range of mean arterial pressures (MAP) through cerebral-vascular autoregulation, the relationship between MAP and CP in refractory poison-induced cardiogenic shock (PICS) has never been studied. We compared the effects of therapies used in PICS: high-dose insulin (HDI), HDI plus norepinephrine (NE), and vasopressors alone (NE plus epinephrine (Epi)) on cerebral tissue oxygenation (PtO2). Methods: Fifteen swine were randomized to either HDI, HDI + NE, or NE + Epi. All animals received a propranolol infusion using an established model of toxicity. At primary toxicity (P1), defined as a 25% reduction in heart rate (HR) multiplied by MAP, the HDI and HDI + NE groups received HDI and the NE + Epi group received NE. Once a sustained MAP < 55 mmHg was reached (P2), the HDI group received saline (NS), the HDI + NE group received NE and the NE + Epi group received Epi until death or censoring. PtO2 and hemodynamic parameters including MAP, cardiac output (CO) and central venous pressure (CVP) were measured every 10 minutes. Glucose and potassium were measured at predetermined intervals. Results: Animals treated with HDI + NE maintained PtO2 over time more than the HDI-alone group. Due to rapid hemodynamic collapse, we were unable to analyze PtO2 data in the vasopressor only animals. Mean survival time was 1.9, 2.9 and 0.1 hours for the HDI, HDI + NE and NE + Epi groups, respectively. Survival time from P2 (sustained MAP <55 mmHg) to death or censoring was not different between HDI and HDI + NE groups. Conclusions: HDI + NE treatment was superior to HDI-alone at preserving PtO2 when MAP < 55 mmHg. We were unable to compare the PtO2 between the NE + Epi to the HDI or HDI + NE due to rapid decline in CO and death. If MAP is sustained at < 55 mmHg after maximizing HDI, adjunctive treatment with NE should be considered to preserve PtO2.