Coronary flow capacity and survival prediction after revascularization: physiological basis and clinical implications.

BACKGROUND AND AIMS: Coronary flow capacity (CFC) is associated with an observed 10-year survival probability for individual patients before and after actual revascularization for comparison to virtual hypothetical ideal complete revascularization. METHODS: Stress myocardial perfusion (mL/min/g) and coronary flow reserve (CFR) per pixel were quantified in 6979 coronary artery disease (CAD) subjects using Rb-82 positron emission tomography (PET) for CFC maps of artery-specific size-severity abnormalities expressed as percent left ventricle with prospective follow-up to define survival probability per-decade as fraction of 1.0. RESULTS: Severely reduced CFC in 6979 subjects predicted low survival probability that improved by 42% after revascularization compared with no revascularization for comparable severity (P = .0015). For 283 pre-and-post-procedure PET pairs, severely reduced regional CFC-associated survival probability improved heterogeneously after revascularization (P < .001), more so after bypass surgery than percutaneous coronary interventions (P < .001) but normalized in only 5.7%; non-severe baseline CFC or survival probability did not improve compared with severe CFC (P = .00001). Observed CFC-associated survival probability after actual revascularization was lower than virtual ideal hypothetical complete post-revascularization survival probability due to residual CAD or failed revascularization (P < .001) unrelated to gender or microvascular dysfunction. Severely reduced CFC in 2552 post-revascularization subjects associated with low survival probability also improved after repeat revascularization compared with no repeat procedures (P = .025). CONCLUSIONS: Severely reduced CFC and associated observed survival probability improved after first and repeat revascularization compared with no revascularization for comparable CFC severity. Non-severe CFC showed no benefit. Discordance between observed actual and virtual hypothetical post-revascularization survival probability revealed residual CAD or failed revascularization.

Molecular Targets and Therapies for Ampullary Cancer.

Ampullary carcinomas are rare but increasing in incidence. Ampullary cancers have molecular alterations that guide choice of therapy, particularly in nonresectable cases. These alterations can be more common by subtype (intestinal, pancreaticobiliary, or mixed), and next-generation sequencing is recommended for all patients who cannot undergo surgery. In this article, we review the approach to tissue acquisition and consideration for molecular testing. Common molecular targets of interest in ampullary cancer are also discussed in this review, including HER2/ERBB2, HER3, tumor mutational burden, microsatellite instability, KRAS, and germline BRCA and ATM mutations, along with emerging and rarer alterations.

Quantitative myocardial perfusion in liver transplantation candidates: Poorly metabolized caffeine inhibition of vasodilatory stress.

BACKGROUND: Data on cardiac positron emission tomography (PET) in liver transplantation (LT) candidates are limited with no prior study accounting for poorly metabolized caffeine reducing stress perfusion. METHOD: Consecutive LT candidates (n = 114) undergoing cardiac rest/stress PET were instructed to abstain from caffeine for 2 days extended to 5 and 7 days. Due to persistently high prevalence of measurable blood caffeine after 5-day caffeine abstinence, dipyridamole (n = 41) initially used was changed to dobutamine (n = 73). Associations of absolute flow, coronary flow reserve (CFR), detectable blood caffeine, and Modified End-Stage Liver Disease (MELD) score for liver failure severity were evaluated. Coronary flow data of LT candidates were compared to non-LT control group (n = 102 for dipyridamole, n = 29 for dobutamine). RESULTS: Prevalence of patients with detectable blood caffeine was 63.3%, 36.7% and 33.3% after 2-, 5- and 7-day of caffeine abstinence, respectively. MELD score was associated with detectable caffeine (odd ratio 1.18,P < 0.001). CFR was higher during dipyridamole stress without-caffeine versus with-caffeine (2.22 ± 0.80 vs 1.55 ± 0.37,P = 0.048) but lower than dobutamine stress (2.22 ± 0.80 vs 2.82 ± 1.02,P = 0.026). Mediation analysis suggested that the dominant association between CFR and MELD score in dipyridamole group derived from caffeine-impaired CFR and liver failure/caffeine interaction. CFR in LT candidates was lower than non-LT control population in both dipyridamole and dobutamine group. CONCLUSION: We demonstrate exceptionally high prevalence of detectable blood caffeine in LT candidates undergoing stress PET myocardial perfusion imaging resulting in reduced CFR with dipyridamole compared to dobutamine. The delayed caffeine clearance in LT candidates makes dobutamine a preferred stress agent in this population.

Does financial hardship associate with abnormal quantitative myocardial perfusion and major adverse cardiovascular event?

BACKGROUND: Data on impact of financial hardship on coronary artery disease (CAD) remain incomplete. METHODS: Consecutive subjects referred for clinical rest/stress cardiac positron emission tomography (PET) were enrolled. Financial hardship is defined as patients' inability to pay for their out-of-pocket expense for cardiac PET. Abnormal cardiac PET is defined as at least moderate relative perfusion defects at stress involving > 10% of the left ventricle or global coronary flow reserve ≤ 2.0. Patients were followed for major adverse cardiovascular event (MACE) comprised of all-cause mortality, non-fatal myocardial infarction, and late coronary revascularization. RESULTS: We analyzed a total of 4173 patients with mean age 65.6 ± 11.3 years, 72.2% men, and 93.6% reported as having medical insurance. Of these, 504 (12.1%) patients had financial hardship. On multivariable analysis, financial hardship associated with abnormal cardiac PET (odds ratio 1.377, p = 0.004) and MACE (hazard ratio 1.432, p = 0.010) and its association with MACE was mostly through direct effect with small proportion mediated by abnormal cardiac PET or known CAD. CONCLUSION: Among patients referred for cardiac rest/stress PET, financial hardship independently associates with myocardial perfusion abnormalities and MACE; however, its effect on MACE is largely not mediated by abnormal myocardial perfusion or known CAD suggesting distinct impact of financial hardship beyond traditional risk factors and CAD that deserves attention and intervention to effectively reduced adverse outcomes. Having medical insurance does not consistently protect from financial hardship and a more preventive-oriented restructuring may provide better outcomes at lower cost.

Design and rationale of the randomized trial of comprehensive lifestyle modification, optimal pharmacological treatment and utilizing PET imaging for quantifying and managing stable coronary artery disease (the CENTURY study).

BACKGROUND: The literature reports no randomized trial in chronic coronary artery disease (CAD) of a comprehensive management strategy integrating intense lifestyle management, maximal medical treatment to specific goals and high precision quantitative cardiac positron emission tomography (PET) for identifying high mortality risk patients needing essential invasive procedures. We hypothesize that this comprehensive strategy achieves greater risk factor reduction, lower major adverse cardiovascular events and fewer invasive procedures than standard practice. METHODS: The CENTURY Study (NCT00756379) is a randomized-controlled-trial study in patients with stable or at high risk for CAD. Patients are randomized to standard of care (Standard group) or intense comprehensive lifestyle-medical treatment to targets and PET guided interventions (Comprehensive group). Comprehensive Group patients are regularly consulted by the CENTURY team implementing diet/lifestyle/exercise program and medical treatment to target risk modification. Cardiac PET at baseline, 24-, and 60-months quantify the physiologic severity of CAD and guide interventions in the Comprehensive group while patients and referring physicians of the Standard group are blinded to PET results. The primary end-point is the CENTURY risk score reduction during 5 years follow-up. The secondary endpoint is a composite of death, non-fatal myocardial infarction, stroke, and coronary revascularization. CONCLUSIONS: The CENTURY Study is the first study in stable CAD to test the incremental benefit of a comprehensive strategy integrating intense lifestyle modification, medical treatment to specific goals, and high-precision quantitative myocardial perfusion imaging to guide revascularization. A total of 1028 patients have been randomized, and the 5 years follow-up will conclude in 2022.

Treatment Approach to Adenocarcinoma of the Ampulla of Vater.

OPINION STATEMENT: ACs are rare tumors, and thus, there is a lack of prospective trials supporting treatment decisions. Moreover, although anatomically uniform, ACs comprise of biologically distinct entities, depending on what cell type they arise from. This makes the interpretation of limited data even more challenging. Overall, the clinical outcomes of patients with AC are better than those with pancreatic cancer. However, recurrence rates remain high after curative resection. Despite the absence of definitive evidence, we believe that these high recurrence rates are a rational justification for consideration of adjuvant therapy in resected disease, and therapy selection should take tumor biology, stage, resection margins, as well as patient comorbidities and performance status into account. Largely extrapolating from pancreas cancer, we recommend consideration of adjuvant chemotherapy with 6 months of dose-modified FOLFIRINOX in fit patients with pancreatobiliary subtype tumors. Alternative regimens include gemcitabine in combination with capecitabine. If chemoradiotherapy is being added, 6 weeks of radiotherapy in conjunction with 5-FU or capecitabine can be considered. For intestinal subtypes, we recommend 3-6 months of adjuvant FOLFOX. Future studies are needed to evaluate the role of contemporary, multi-agent chemotherapy and chemoradiotherapy in patients with resected and advanced ampullary adenocarcinoma. However, the logistics of performing large randomized trials in patients with a rare cancer is challenging, and the data collection, even in a carefully designed study, would likely take many years. As such, relying on data from basket trials and retrospective analysis will likely serve as guidance for treatment decisions in the near future. Treatment of metastatic disease should employ regimens that are typically used to treat pancreas cancer for tumors of pancreatobiliary subtype and 5-FU-based regimens for intestinal subtypes. Studies specific for patients with advanced AC are much needed. Molecular testing using next-generation sequencing and testing for microsatellite instability (MSI) should be performed on all tumors. We now have disease agnostic options based on these results. Pembrolizumab is approved for MSI-H tumors and tumors with high tumor mutational burden regardless of the primary site. Larotrectinib is approved for tumors with NTRK fusions. At a time when numerous therapeutic agents are in development, for example, those targeting specific K-RAS alterations or NRG fusions, identifying molecular aberrations can significantly impact patient outcomes as well as provide further insights into the biology of disease. In addition, based on recent data suggesting a significant prevalence of germline alterations in patients with ampullary tumors, referral to genetics counselors and germline testing is warranted in a significant proportion of patients with AC.

Motor "freezing" with oxaliplatin.

INTRODUCTION: We report the case of a patient who experienced severe neurological symptoms collectively characterized as being "frozen" following a second oxaliplatin infusion. CASE REPORT: A 52-year-old woman with metastatic colon cancer developed severe motor slowing, delayed and incomplete grip and dorsiflexion, speech difficulty, visual impairment, leg cramping and tingling after her second infusion of oxaliplatin. She was transferred from the infusion center to the emergency room and admitted to the hospital for further evaluation. Motor, verbal, and ocular symptoms gradually resolved within 24 hours, and she was discharged home without sequela.Management and outcome: Oxaliplatin dose was subsequently lowered and infusion time increased, and she tolerated future treatments without motor, verbal, or ocular disturbance. DISCUSSION: In this case report, we describe a rare form of neurological toxicity involving severe motor slowing, slurred speech, and blurry vision secondary to oxaliplatin.

Reliability and Reproducibility of Absolute Myocardial Blood Flow: Does It Depend on the PET/CT Technology, the Vasodilator, and/or the Software?

PURPOSE OF REVIEW: The COURAGE and ISCHEMIA trials showed no reduced mortality after revascularization compared to medical treatment. Is this lack of benefit due to revascularization having no benefit regardless of CAD severity or to suboptimal patient selection due to non-quantitative cardiac imaging? RECENT FINDINGS: Comprehensive, integrated, myocardial perfusion quantified by regional pixel distribution of coronary flow capacity (CFC) is the final common expression of objective CAD severity for which revascularization reduces mortality. Current lack of revascularization benefit derives from narrow thinking focused on measuring one isolated aspect of coronary characteristics, such as angiogram stenosis, its fractional flow reserve (FFR), anatomic FFR simulations, relative stress imaging, absolute stress ml/min/g or coronary flow reserve (CFR) alone, or even more narrowly on global CFR or fixed regions of interest in assumed coronary artery distributions, or in arbitrary 17 segments on bull's-eye displays, rather than regional pixel distribution of perfusion metrics as they actually are in an individual. Comprehensive integration of all quantitative perfusion metrics per regional pixel into coronary flow capacity guides artery-specific interventions for reduced mortality in non-acute CAD but requires addressing the methodologic questions in the title.

A population-based study of invitation to and participation in clinical trials among women with early-stage breast cancer.

PURPOSE: Although many studies clearly demonstrate disparities in cancer clinical trial enrollment, there is a lack of consensus on potential causes. Furthermore, virtually nothing is known about associations between patients' decision-making style and their participation in clinical trials. METHODS: Women with newly diagnosed, stage 0-II breast cancer reported to the Georgia and Los Angeles County Surveillance, Epidemiology, and End Results (SEER) registries in 2013-2014 were surveyed approximately seven months after diagnosis. We investigated two primary outcome variables: (1) invitation to participate in a clinical trial, (2) participation in a clinical trial. We evaluated bivariate associations using Chi-squared tests and used multivariable logistic regression models to investigate associations between patient variables, including decision-making style, and the primary outcomes. RESULTS: 2578 patients responded (71% response rate); 30% were > age 65, 18% were black, 18% were Latina, 29% had ≤ high school education. 10% of patients reported invitation to participate in a clinical trial; 5% reported participation in a clinical trial. After adjustment younger age, receipt of chemotherapy or radiation, disease stage, and a more rational (versus more intuitive) decision-making style were associated with a higher odds of invitation to participate. Being married was associated with a higher odds of participation; having an annual family income ≥ $40,000 was associated with a lower odds of participation. CONCLUSIONS: 10% of patients reported invitation to participate in a clinical trial, and half of these reported participation. Invitation to participate varied by age and decision-making style, and participation varied by marital status and income.

Clinical, genetic, and structural basis of apparent mineralocorticoid excess due to 11ß-hydroxysteroid dehydrogenase type 2 deficiency.

Mutations in 11ß-hydroxysteroid dehydrogenase type 2 gene (HSD11B2) cause an extraordinarily rare autosomal recessive disorder, apparent mineralocorticoid excess (AME). AME is a form of low renin hypertension that is potentially fatal if untreated. Mutations in the HSD11B2 gene result either in severe AME or a milder phenotype (type 2 AME). To date, ∼40 causative mutations have been identified. As part of the International Consortium for Rare Steroid Disorders, we have diagnosed and followed the largest single worldwide cohort of 36 AME patients. Here, we present the genotype and clinical phenotype of these patients, prominently from consanguineous marriages in the Middle East, who display profound hypertension and hypokalemic alkalosis. To correlate mutations with phenotypic severity, we constructed a computational model of the HSD11B2 protein. Having used a similar strategy for the in silico evaluation of 150 mutations of CYP21A2, the disease-causing gene in congenital adrenal hyperplasia, we now provide a full structural explanation for the clinical severity of AME resulting from each known HSD11B2 missense mutation. We find that mutations that allow the formation of an inactive dimer, alter substrate/coenzyme binding, or impair structural stability of HSD11B2 yield severe AME. In contrast, mutations that cause an indirect disruption of substrate binding or mildly alter intramolecular interactions result in type 2 AME. A simple in silico evaluation of novel missense mutations could help predict the often-diverse phenotypes of an extremely rare monogenic disorder.

Identification of novel azaindazole CCR1 antagonist clinical candidates.

Exploring various cyclization strategies, using a submicromolar pyrazole HTS screening hit 6 as a starting point, a novel indazole based CCR1 antagonist core was discovered. This report presents the design and SAR of CCR1 indazole and azaindazole antagonists leading to the identification of three development compounds, including 19e that was advanced to early clinical trials.

Discovery and optimization of pyrazole amides as antagonists of CCR1.

A HTS screen for CCR1 antagonists afforded a novel sub-micromolar hit 5 containing a pyrazole core. In this report the design, optimization, and SAR of novel CCR1 antagonists based on a pyrazole core motif is presented. Optimization led to the advanced candidate compounds (S)-16q and (S)-16r with 250-fold improved CCR1 potency, excellent off-target selectivity and attractive drug-like properties.

Five Alternative Myosin Converter Domains Influence Muscle Power, Stretch Activation, and Kinetics.

Muscles have evolved to power a wide variety of movements. A protein component critical to varying power generation is the myosin isoform present in the muscle. However, how functional variation in muscle arises from myosin structure is not well understood. We studied the influence of the converter, a myosin structural region at the junction of the lever arm and catalytic domain, using Drosophila because its single myosin heavy chain gene expresses five alternative converter versions (11a-e). We created five transgenic fly lines, each forced to express one of the converter versions in their indirect flight muscle (IFM) fibers. Electron microscopy showed that the converter exchanges did not alter muscle ultrastructure. The four lines expressing converter versions (11b-e) other than the native IFM 11a converter displayed decreased flight ability. IFM fibers expressing converters normally found in the adult stage muscles generated up to 2.8-fold more power and displayed up to 2.2-fold faster muscle kinetics than fibers with converters found in the embryonic and larval stage muscles. Small changes to stretch-activated force generation only played a minor role in altering power output of IFM. Muscle apparent rate constants, derived from sinusoidal analysis of the chimeric converter fibers, showed a strong positive correlation between optimal muscle oscillation frequency and myosin attachment kinetics to actin, and an inverse correlation with detachment related cross-bridge kinetics. This suggests the myosin converter alters at least two rate constants of the cross-bridge cycle with changes to attachment and power stroke related kinetics having the most influence on setting muscle oscillatory power kinetics.

Late-stage optimization of a tercyclic class of S1P3-sparing, S1P1 receptor agonists.

Poor solubility and cationic amphiphilic drug-likeness were liabilities identified for a lead series of S1P3-sparing, S1P1 agonists originally developed from a high-throughput screening campaign. This work describes the subsequent optimization of these leads by balancing potency, selectivity, solubility and overall molecular charge. Focused SAR studies revealed favorable structural modifications that, when combined, produced compounds with overall balanced profiles. The low brain exposure observed in rat suggests that these compounds would be best suited for the potential treatment of peripheral autoimmune disorders.

Inactivation of the nucleus reuniens/rhomboid causes a delay-dependent impairment of spatial working memory.

Inactivation of the rodent medial prefrontal cortex (mPFC) and hippocampus or disconnection of the hippocampus from the mPFC produces deficits in spatial working memory tasks. Previous studies have shown that delay length determines the extent to which mPFC and hippocampus functionally interact, with both structures being necessary for tasks with longer delays and either structure being sufficient for tasks with shorter delays. In addition, inactivation of the nucleus reuniens (Re)/rhomboid nucleus (Rh) of the thalamus, which has bidirectional connections with the mPFC and hippocampus, also produces deficits in these tasks. However, it is unknown how delay duration relates to the function of Re/Rh. If Re/Rh are critical in modulating mPFC-hippocampus interactions, inactivation of the RE/Rh should produce a delay-dependent impairment in spatial working memory performance. To investigate this question, groups of rats were trained on one of three different spatial working memory tasks: continuous alternation (CA), delayed alternation with a five-second delay (DA5), or with a thirty-second delay (DA30). The Re/Rh were inactivated with muscimol infusions prior to testing. The results demonstrate that inactivation of RE/Rh produces a deficit only on the two DA tasks, supporting the notion that the Re/Rh is a critical orchestrator of mPFC-HC interactions.

The roles of troponin C isoforms in the mechanical function of Drosophila indirect flight muscle.

Stretch activation (SA) is a fundamental property of all muscle types that increases power output and efficiency, yet its mechanism is unknown. Recently, studies have implicated troponin isoforms as important in the SA mechanism. The highly stretch-activated Drosophila IFMs express two isoforms of the Ca(2+)-binding subunit of troponin (TnC). TnC1 (TnC-F2 in Lethocerus IFM) has two calcium binding sites, while an unusual isoform, TnC4 (TnC-F1 in Lethocerus IFM), has only one binding site. We investigated the roles of these two TnC isoforms in Drosophila IFM by targeting RNAi to each isoform. IFMs with TnC4 expression (normally ~90% of total TnC) replaced by TnC1 did not generate isometric tension, power or display SA. However, TnC4 knockdown resulted in sarcomere ultrastructure disarray, which could explain the lack of mechanical function and thus make interpretation of the influence of TnC4 on SA difficult. Elimination of TnC1 expression (normally ~10% of total TnC) by RNAi resulted in normal muscle structure. In these IFMs, fiber power generation, isometric tension, stretch-activated force and calcium sensitivity were statistically identical to wild type. When TnC1 RNAi was driven by an IFM specific driver, there was no decrease in flight ability or wing beat frequency, which supports our mechanical findings suggesting that TnC1 is not essential for the mechanical function of Drosophila IFM. This finding contrasts with previous work in Lethocerus IFM showing TnC1 is essential for maximum isometric force generation. We propose that differences in TnC1 function in Lethocerus and Drosophila contribute to the ~40-fold difference in IFM isometric tension generated between these species.

What's age got to do with it? A study of the implementation of the discharge medicines service for paediatric patients.

OBJECTIVES: The discharge medicines service (DMS) was introduced as an essential service for all community pharmacies in England through the Community Pharmacy Contractual Framework (CPCF) in February 2021. This study aimed to describe the implementation of this service for paediatric patients and to identify any barriers to referrals. METHODS: The study was undertaken in a 24-bed paediatric ward in a District General Hospital from September 2022 to February 2023. All paediatric inpatients on long-term medications were eligible for inclusion. Out of 169 eligible participants, 149 were referred. Community pharmacists accessed referrals through PharmOutcomes® and could accept, complete, or reject referrals on this platform. KEY FINDINGS: Of the 149 referred patients, 24 (16.1%) were accepted but not yet actioned; 63 (42.3%) were fully or partially completed; 19 (12.8%) were rejected, and 43 (28.9%) there was no response (remained as referred). Younger children (<2 years) were more likely to have their referral rejected than older children (6 years and older). The feedback from parents was overwhelmingly positive (93.5%) and two families reported that they believed the DMS service prevented readmission to the hospital for their children. No children were involved in the community pharmacist consultation. Barriers to referrals included patients not having a nominated pharmacy and a lack of confidence in completing paediatric referrals. CONCLUSIONS: This study demonstrates the value of completing referrals for paediatric patients. More research is required to explore how community pharmacists can be supported to complete paediatric DMS referrals.

Pharmacological evaluation of new generation OXIZID synthetic cannabinoid receptor agonists.

Synthetic cannabinoid receptor agonists (SCRAs) remain one the largest classes of new psychoactive substances, and are increasingly associated with severe adverse effects and death compared to the phytocannabinoid Δ9-tetrahydrocannabinol (THC). In the attempt to circumvent the rapid emergence of novel SCRAs, several nations have implemented 'generic' legislations, or 'class-wide' bans based on common structural scaffolds. However, this has only encouraged the incorporation of new chemical entities, including distinct core and linker structures, for which there is a dearth of pharmacological data. The current study evaluated five emergent OXIZID SCRAs for affinity and functional activity at the cannabinoid CB1 receptor (CB1) in HEK 293 cells, as well as pharmacological equivalence with THC in drug discrimination in mice. All OXIZID compounds behaved as agonists in Gαi protein activation and ß-arrestin 2 translocation assays, possessing low micromolar affinity at CB1. All ligands also substituted for THC in drug discrimination, where potencies broadly correlated with in vitro activity, with the methylcyclohexane analogue BZO-CHMOXIZID being the most potent. Notably, MDA-19 (BZO-HEXOXIZID) exhibited partial efficacy in vitro, generating an activity profile most similar to that of THC, and partial substitution in vivo. Overall, the examined OXIZIDs were comparatively less potent and efficacious than previous generations of SCRAs. Further toxicological data will elucidate whether the moderate cannabimimetic activity for this series of SCRAs will translate to severe adverse health effects as seen with previous generations of SCRAs.

Wound Modulations in Glaucoma Surgery: A Systematic Review.

Excessive fibrosis and resultant poor control of intraocular pressure (IOP) reduce the efficacy of glaucoma surgeries. Historically, corticosteroids and anti-fibrotic agents, such as mitomycin C (MMC) and 5-fluorouracil (5-FU), have been used to mitigate post-surgical fibrosis, but these have unpredictable outcomes. Therefore, there is a need to develop novel treatments which provide increased effectiveness and specificity. This review aims to provide insight into the pathophysiology behind wound healing in glaucoma surgery, as well as the current and promising future wound healing agents that are less toxic and may provide better IOP control.

Investigating selectivity and bias for G protein subtypes and ß-arrestins by synthetic cannabinoid receptor agonists at the cannabinoid CB1 receptor.

The cannabinoid CB1 receptor (CB1) is a G protein-coupled receptor (GPCR) with widespread expression in the central nervous system. This canonically G⍺i/o-coupled receptor mediates the effects of Δ9-tetrahydrocannabinol (THC) and synthetic cannabinoid receptor agonists (SCRAs). Recreational use of SCRAs is associated with serious adverse health effects, making pharmacological research into these compounds a priority. Several studies have hypothesised that signalling bias may explain the different toxicological profiles between SCRAs and THC. Previous studies have focused on bias between G protein activation measured by cyclic adenosine monophosphate (cAMP) inhibition and ß-arrestin translocation. In contrast, the current study characterises bias between G⍺ subtypes of the G⍺i/o family and ß-arrestins; this method facilitates a more accurate assessment of ligand bias by assessing signals that have not undergone major amplification. We have characterised G protein dissociation and translocation of ß-arrestin 1 and 2 using real-time BRET reporters. The responses produced by each SCRA across the G protein subtypes tested were consistent with the responses produced by the reference ligand AMB-FUBINACA. Ligand bias was probed by applying the operational analysis to determine biases within the G⍺i/o family, and between G protein subtypes and ß-arrestins. Overall, these results confirm SCRAs to be balanced, high-efficacy ligands compared to the low efficacy ligand THC, with only one SCRA, 4CN-MPP-BUT7IACA, demonstrating statistically significant bias in one pathway comparison (towards ß-arrestin 1 when compared with G⍺oA/oB). This suggests that the adverse effects caused by SCRAs are due to high potency and efficacy at CB1, rather than biased agonism.