Adrenoceptor Agonist Research Articles

Phenylephrine, an α1–adrenoceptor agonist, inhibits conditioned pain modulation in healthy humans

Phenylephrine, an α1–adrenoceptor agonist, inhibits conditioned pain modulation in healthy humans

Left ventricular systolic function after inhalation of beta-2 agonists in healthy athletes

Inhaled beta-2 adrenoceptor agonists (iβ2A) are routinely used as bronchodilators in the treatment of asthma. However, their cardiac effects in athletes are scarcely examined. Thus, the aim of this study was to evaluate the effects of iβ2A on left ventricular (LV) systolic function (SF) by echocardiography in healthy, non-asthmatic female and male endurance athletes. A randomized, double-blinded, placebo-controlled, balanced, 4-way complete block cross-over study was conducted. Twenty-four healthy athletes (12f/12m: 22.9 ± 2.7/24.4 ± 4.6 years) randomly completed 4 study arms (placebo; salbutamol; formoterol; formoterol + salbutamol). After inhalation of the study medication, the participants performed a 10-min time trial (TT) on a bicycle ergometer. After each TT an echocardiography was performed to determine LVSF. Blood samples were collected pre, post, 3 h and 24 h post TT. In females, total serum concentrations for salbutamol and formoterol were higher. LV ejection fraction (LVEF) and LV global longitudinal strain (LVendoGLS) showed a treatment effect for the whole study group (p < 0.0001) and a sex effect on LVEF (p = 0.0085). In women, there was a significant treatment effect for all medication arms (at least p ≤ 0.01) both on LVEF and LVendoGLS. In men only formoterol and formoterol + salbutamol displayed a treatment effect on LVEF (p = 0.0427, p = 0.0330; respectively), whereas on LVendoGLS only formoterol + salbutamol was significant (p = 0.0473). The iβ2A significantly influenced LVSF after an acute bout of exercise in healthy endurance athletes. These effects were even more pronounced when combining both iβ2A that supports a dose-dependent effect on cardiac function. Moreover, female athletes had higher serum concentrations of β2 agonists and stronger effects on LVSF compared to male athletes. This is mainly explained by differences in body weight and related plasma volume and may indicate a potential risk when increasing dose above the tested concentrations. Trial registration: At the European Union Drug Regulating Authorities Clinical Trials (Eudra CT) with the number 201,500,559,819 (registered prospectively on 09/12/2015) and at the German register for clinical studies (DRKS number 00010574 registered retrospectively on 16/11/2021).

FLUTICASONE FUROATE AND VILANTEROL (FF/VI) VERSUS FLUTICASONE PROPRIONATE AND FORMOTEROL (FP/FM) AS MAINTENANCE THERAPY IN STABLE ASTHMATIC PATIENTS- A COMPARATIVE STUDY

Background: Fluticasone furoate (FF) is a novel long-acting inhaled corticosteroid (ICS). Vilanterol (VI) is a long‐acting beta2‐agonist (LABA) that binds to the beta2‐adrenoceptor on the airway smooth muscle, producing bronchodilation. The corticosteroid fluticasone propionate (FP)and the long-acting β₂-adrenoceptor agonist (LABA) formoterol fumarate (FM) have been combined in a single, pressurized, metered-dose, aerosol inhaler for the maintenance treatment of patients aged ≥12 years with persistent asthma.This study evaluated the efficacy and safety of Fluticasone furoate 100 mcgandVilanterol 6 mcg versus Fluticasone proprionate 250 mcg and Formoterol 25 mcg for 12 weeks in patients with persistent asthma as maintenance therapy. Methods and Materials: A hospital based comparative study was conducted among stable asthmatic patients attended to Santhiram Medical College and General Hospital, Nandyal during January 2024 to June 2024(6months) by using convenient sampling method with sample size 60. Study tool was pre-designed, pre-tested, asthma control questionnaire5 (ACQ5),asthma control test (ACT) and Ask 12 adherence barrier survey. Results: Among 60 patients, 30 patients (Group1) were given Fluticasone furoate and Vilanterol and another 30 patients (Group 2) were given Fluticasone proprionate and Formoterol. All the patients (both the treatment groups) completed the 12 weeks treatment period. Improvements from baseline in 0- to 24-h wmFEV1 were observed with both FF/VI (376 mL) and FP/FM (353 mL) the adjusted mean treatment difference was not statistically significant. There were no differences between 0- to 4-h serial wmFEV1, asthma control test, ACQ5 and Ask 12 adherence barrier survey. There was no difference in reported exacerbations between treatments. Adverse events reported in the present study were not significant. Both treatments were well tolerated. Conclusion: The present study shows that the efficacy of once daily Fluticasone furoate and Vilanterol was not inferior as compared to the efficacy of twice daily Fluticasone proprionate and Formoterol as maintenance therapy in stable asthmatic patients. Howevertreatment with once daily FF/VI has the advantage of forgetfulness and inconvenience of inhalation.Henceonce daily FF/VI can be also useful for stable asthmatic patients as maintenance therapy as FF/VI DPI treatment.

β-Adrenoceptor Agonists Attenuate Thrombin-Induced Impairment of Human Lung Endothelial Cell Barrier Function and Protect the Lung Vascular Barrier during Resuscitation from Hemorrhagic Shock.

β-adrenoceptor (β-AR) agonists are known to antagonize thrombin-induced impairment (TII) of bovine and ovine lung endothelial barrier function. The effects of adrenoceptor agonists and other vasoactive agents on human lung microvascular endothelial cell (HULEC-5a) barrier function upon thrombin exposure have not been studied. Furthermore, it is unknown whether the in vitro effects of adrenoceptor agonists translate to lung protective effects in vivo. We observed that epinephrine, norepinephrine, and phenylephrine enhanced normal and prevented TII of HULEC-5a barrier function. Arginine vasopressin and angiotensin II were ineffective. α1B-, α2A/B-, and β1/2-ARs were detectable in HULEC-5a by RT-PCR. Propranolol but not doxazosin blocked the effects of all adrenoceptor agonists. Phenylephrine stimulated β2-AR-mediated Gαs activation with 13-fold lower potency than epinephrine. The EC50 to inhibit TII of HULEC-5a barrier function was 1.8 ± 1.9 nM for epinephrine and >100 nM for phenylephrine. After hemorrhagic shock and fluid resuscitation in rats, Evans blue extravasation into the lung increased threefold (p < 0.01 vs. sham). Single low-dose (1.8 μg/kg) epinephrine administration at the beginning of resuscitation had no effects on blood pressure and reduced Evans blue extravasation by 60% (p < 0.05 vs. vehicle). Our findings confirm the effects of β-adrenoceptor agonists in HULEC-5a and suggest that low-dose β-adrenoceptor agonist treatment protects lung vascular barrier function after traumatic hemorrhagic shock.

Cilostazol attenuates mirabegron-induced hepatic and renal toxicity in rats: regulation of metabolic, oxidative, and inflammatory pathways

Background Mirabegron (MIRG) is a type of β3 adrenoceptor agonist that is considered an alternative therapy for the treatment of overactive bladder (OAB) symptoms. Cilostazol (CITZ) is a selective inhibitor of phosphodiesterase (III) that has various pharmacological effects. Objectve The current study aimed to highlight the regulatory effects of CITZ on MIRG-induced toxicity. Materials and Methods Male rats were divided into six groups. Blood samples were collected to determine different hepatic and kidney function levels along with serum protein electrophoresis and inflammatory factor levels. Histopathological studies and oxidative stress (OS) were also assessed. Kidney and hepatic damage were detected following the administration of MIRG, especially at high doses, due to elevated OS, inflammation, and apoptotic marker levels. Results Rats receiving CITZ exhibited significant improvements in both hepatic and kidney functions, with decreased inflammation and OS. Conclusion CITZ administration plays a beneficial role in alleviating hepatic and nephrotoxicity induced by MIRG by inhibiting OS and inflammation.

Comparison of the Genomic Activity of an EP4-Receptor and β2-Adrenoceptor Agonist in BEAS-2B Human Bronchial Epithelial Cells: In Search of Compartmentalized, cAMP-Dependent Gene Expression.

It has been proposed that inhaled E-prostanoid 4 (EP4)-receptor agonists could represent a new class of bronchodilators for the treatment of asthma that are as effective as β 2-adrenoceptor agonists. However, the genomic impact of such drugs is unknown despite being potentially deleterious to respiratory health. Herein, we used mRNA-seq to compare the transcriptomic responses produced by 2-[3-[(1R,2S,3R)-3-hydroxy-2-[(E,3S)-3-hydroxy-5-[2-(methoxymethyl)phenyl]pent-1-enyl]-5-oxo-cyclopentyl]sulphanylpropylsulphanyl] acetic acid (ONO-AE1-329; an EP4-receptor agonist) and vilanterol (a β 2-adrenoceptor agonist) in BEAS-2B human airway epithelial cells. We also determined if an increase in cAMP mediated by different G protein-coupled receptors (GPCRs) promoted distinct transcriptional signatures by expanding this inquiry to include the adenosine A2B- and I-prostanoid receptor agonists, 2-[[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]-2-pyridinyl]thio]-acetamide (Bay60-6583) and taprostene, respectively. Maximally-effective concentrations of ONO-AE1-329 and vilanterol significantly regulated (q ≤ 0.05; ≥1.5-/≤0.67-fold) 232 and 320 genes, respectively of which 217 were shared. Spearman analysis showed these gene expression changes to be highly rank order correlated, indicating that the functional overlap between the two interventions should be considerable. Unexpectedly, the genomic effects of ONO-AE1-329, vilanterol, Bay 60-6583, and taprostene were also highly rank order correlated. This finding suggests that cAMP generated by any GPCR would initiate the same transcriptional program. Nevertheless, relative to vilanterol, ONO-AE1-329 typically behaved as a partial agonist that varied across transcripts. These data indicate that each ONO-AE1-329-regulated gene differs in sensitivity to cAMP and is defined by a unique receptor occupancy-response relationship. Moreover, if this relatively modest genomic response in BEAS-2B cells is retained in vivo, then inhaled EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators. SIGNIFICANCE STATEMENT: The genomic consequences of β 2-adrenoceptor agonists in asthma are often overlooked despite being potentially harmful to lung health. We determined that ONO-AE1-329, an EP4-receptor agonist and effective bronchodilator, produced gene expression changes in BEAS-2B cells that were typically modest relative to the β 2-adrenoceptor agonist vilanterol. Furthermore, ONO-AE1-329 behaved as a partial agonist that varied across transcripts. If this genomic activity is reproduced in vivo, then EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators.

Protective Effects of Beta-3 Adrenoceptor Agonism on Mucosal Integrity in Hyperoxia-Induced Ileal Alterations.

Organogenesis occurs in the uterus under low oxygen levels (4%). Preterm birth exposes immature newborns to a hyperoxic environment, which can induce a massive production of reactive oxygen species and potentially affect organ development, leading to diseases such as necrotizing enterocolitis. The β3-adrenoreceptor (β3-AR) has an oxygen-dependent regulatory mechanism, and its activation exerts an antioxidant effect. To test the hypothesis that β3-AR could protect postnatal ileal development from the negative impact of high oxygen levels, Sprague-Dawley rat pups were raised under normoxia (21%) or hyperoxia (85%) for the first 2 weeks after birth and treated or not with BRL37344, a selective β3-AR agonist, at 1, 3, or 6 mg/kg. Hyperoxia alters ileal mucosal morphology, leading to increased cell lipid oxidation byproducts, reduced presence of β3-AR-positive resident cells, decreased junctional protein expression, disrupted brush border, mucin over-production, and impaired vascularization. Treatment with 3 mg/kg of BRL37344 prevented these alterations, although not completely, while the lower 1 mg/kg dose was ineffective, and the higher 6 mg/kg dose was toxic. Our findings indicate the potential of β3-AR agonism as a new therapeutic approach to counteract the hyperoxia-induced ileal alterations and, more generally, the disorders of prematurity related to supra-physiologic oxygen exposure.

Heightened SAM- and HPA-axis activity during acute stress impairs decision-making: A systematic review on underlying neuropharmacological mechanisms

Individuals might be exposed to intense acute stress while having to make decisions with far-reaching consequences. Acute stress impairs processes required for decision-making by activating different biological stress cascades that in turn affect the brain. By knowing which stress system, brain areas, and receptors are responsible for compromised decision-making processes, we can effectively find potential pharmaceutics that can prevent the deteriorating effects of acute stress. We used a systematic review procedure and found 44 articles providing information on this topic. Decision-making processes could be subdivided into 4 domains (cognitive, motivational, affective, and predictability) and could be referenced to specific brain areas, while mostly being impaired by molecules associated with the sympathetic-adrenal-medullar and hypothalamic-pituitary-adrenal axes. Potential drugs to alleviate these effects included α1 and β adrenoceptor antagonists, α2 adrenoceptor agonists, and corticotropin releasing factor receptor1/2 antagonists, while consistent stress-like effects were found with yohimbine, an α2 adrenoceptor antagonist. We suggest possible avenues for future research.

Intrathecal Fentanyl versus Intrathecal Dexmedetomidine as an Adjuvant to Isobaric Levobupivacaine 0.5% in Elective Cesarean Sections: A Randomized Control Trial

Background: When a cesarean section is performed, it is crucial to have access to good postoperative analgesia. To achieve this, adjuvants are added along with local anesthetics as it has a synergistic action to improve its duration and quality. Alpha-2 adrenoceptor agonists and opioids such as dexmedetomidine and fentanyl, respectively, are used for their sedative, analgesic, and perioperative sympatholytic and cardiovascular stabilizing effects with reduced anesthetic requirements. The purpose of this research is to evaluate the effects of intrathecal fentanyl versus dexmedetomidine combined with levobupivacaine on postoperative analgesia and hemodynamic changes. Materials and Methods: This is a prospective randomized control trial, among 50 patients undergoing elective cesarean section. Group 1 will receive 0.5% levobupivacaine 2 ml + fentanyl 25 mcg and Group 2 will receive 0.5% levobupivacaine + dexmedetomidine 5 mcg. Duration of analgesia and onset and duration of sensory-motor block, perioperative analgesic requirements, sedation, and hemodynamic stability were compared. The data were entered into Microsoft Excel and analyzed using SPSS 16. Results: The baseline characteristics such as age and gender, weight, height, and body mass index were not statistically significant in both the groups. Duration of analgesia was significantly longer in the dexmedetomidine group than the fentanyl group. The mean time of onset of motor block in the group, for which dexmedetomidine was 14.23 ± 1.85 min and it was found to be much earlier than the local anesthetic group. All the patients in the dexmedetomidine group had a Visual Analog Scale (VAS) score of 0 (no pain) at the end of 4 h. In contrast, only 21 patients in the fentanyl group had a VAS score of 0, and four patients had a VAS score of 2, indicating mild pain requiring no treatment. Conclusion: The study showed that both fentanyl and dexmedetomidine as an adjuvant to levobupivacaine in cesarean section showed a longer duration of analgesia with increased sedation score and lesser pain score. When comparing the both, dexmedetomidine to the levobupivacaine has a more effective effect on postoperative pain management than fentanyl.

The Use of Guanfacine to Mediate Anxiety-related Reactivity and Reduce Associated Agonistic Behavior in Two Pigtail Macaques (Macaca nemestrina).

Guanfacine, an α ₂adrenoceptor agonist, has been used to successfully treat self-injurious behavior in nonhuman primates, including macaques (Macaca mulatta) and baboons (Papio anubis). It does so by facilitating a correction to the dopaminergic system that mediates a reduction in impulsivity and reactivity. Given this, we assessed the potential efficacy of guanfacine to treat socially directed agonistic behavior in primates with an apparent reactive behavioral phenotype. We present data from 2 pigtail macaques (Macaca nemestrina): an intact adult male housed in a breeding group, and an experimentally naive adult female living in a research setting with her social partner. Baseline behavioral assessments suggested that both macaques showed extreme responses to external stressors that triggered them to aggress social partners often leading to wounding that required veterinary intervention. Both animals were tracked during the course of 1 y. Once treated regularly with guanfacine, both animals showed significant reduction in their agonistic behavior and the rate at which they wounded other animals. Indeed, in the year since the female has been treated with guanfacine she has never wounded her cagemate. By collecting regular and detailed behavioral observations on the male in the breeding colony, we were able to identify triggers for his aggression and to track the behavioral changes evidenced after guanfacine treatment. These data supported our hypothesis that his aggression reflected extreme reactivity to external stressors, rather than general anxiety. Importantly, we saw only a limited and short-lived reduction in the male's affiliative behavioral rates, and thus guanfacine had no sedative effect, but did successfully reduce his reactivity and resultant agonism and wounding.

Dexmedetomidine, an alpha-2 adrenoceptors agonist, provides a neuroprotective effect for dopaminergic neurons in the substantia nigra and attenuates glucose imbalance in the 6-hydroxydopamine animal model of Parkinson’s disease

ABSTRACT Introduction Studies have shown that dexmedetomidine (DEX, an a2-adrenoceptors agonist) provides a neuroprotective effect and influences blood glucose levels. Here, we evaluated the effect of prolonged treatment with low doses of DEX on the survival rate of dopaminergic (DAergic) neurons in the substantia nigra and also serum glucose levels in 6-hydroxydopamine (6-OHDA) – induced Parkinson’s disease (PD) in the rat. Material and Methods The neurotoxin of 6-OHDA was injected into the medial forebrain bundle by stereotaxic surgery. DEX (25 and 50 µg/kg, i.p) and yohimbine, an a2-adrenoceptor antagonist (1 mg/kg, i.p) were administered before the surgery to the 13 weeks afterward. Apomorphine-induced rotational tests and blood sampling were carried out before the surgery and multiple weeks after that. Thirteen weeks after the surgery, the rats’ brain was transcardially perfused to assess the survival rate of DAergic neurons using the tyrosine hydroxylase (TH) immunohistochemistry. Results DEX remarkably attenuated the severity of rotational behavior and reversed the progress of the PD. It also increased the number of TH-labeled neurons by up to 60%. The serum glucose levels in 6-OHDA-received rats did not change in the third and seventh weeks after the surgery but decreased significantly in the thirteenth week. Treatment with DEX prevented this decrement in glucose levels. On the other hand, Treatment with yohimbine did not affect PD symptoms and glucose levels. Conclusion Our data indicate that DEX through neuroprotective activity attenuates the severity of 6-OHDA-induced PD in rats. DEX might also prevent hypoglycemia during the progress of the PD.

Integrated approach of white analytical chemistry and design of experiments to microwave-assisted sensitive and eco-friendly spectrofluorimetric estimation of mirabegron using 4-chloro-7-nitrobezofuran as biosensing fluorescent probe

The USFDA recently approved mirabegron, a novel once-daily β-3 adrenoceptor agonist for oral administration, as a transformative treatment for overactive bladder. Despite the existence of numerous analytical methods for the assay and bioanalysis of mirabegron, it’s perplexing that none have explored the domain of microwave-assisted sensitive spectrofluorimetric method for mirabegron estimation, even after extensive literature review. Adding to the enigma is the insistence of current analytical methods on using expensive and harmful organic solvents, posing a threat to marine life and the broader environment. Recently, the white analytical chemistry approach has been introduced to develop analytical methods that are cost-effective, environmentally friendly, and user-friendly. Consequently, a white analytical chemistry-based, sensitive, and eco-friendly spectrofluorimetric estimation of mirabegron has been initiated, using 4-Chloro-7-nitrobenzofurazan as a fluorescent biosensing probe. The development of this robust method involved a series of experiments designed to minimize solvent and time wastage. Through a combination of fractional factorial and Box-Behnken designs, researchers identified the critical variables and optimized the method to perfection. This method was validated according to the stringent ICH Q2 (R2) and USFDA guidelines, ensuring its reliability and accuracy. Once approved, this sensitive spectrofluorimetric method was tested, accurately estimating mirabegron levels in commercial formulations and rat plasma samples. To further enrich the study, a comprehensive evaluation of existing analytical methods was conducted alongside the proposed spectrofluorimetric method, using advanced tools like the AGREE calculator, GAPI software, and RGB model to assess their eco-friendliness and effectiveness in mirabegron estimation.

Cardio-protective and Antioxidant Potential of Pterocarpus marsupium heartwood extract on Isoproterenol induced heart failure in rats

Heart failure (HF) is a clinical syndrome characterised by a constellation of symptoms(dyspnea, orthopnea, lower limb swelling) and signs (elevated jugular venous pressure, pulmonary congestion) which have underlying cardiac abnormality resulting in reduced cardiac output and/or elevated intra-cardiac pressures. HF is a leading cause of mortality globally and despite major therapeutic advances, HF continues to cause substantial morbidity and mortality. Therefore, there is a need to develop new prophylactic and therapeutic strategies for HF. Isoproterenol (ISO) is a synthetic non-selective beta adrenoceptor agonist and is widely used to model toxic cardiomyopathy and heart failure. It induces myocyte damage mimicking myocardial infarction. In the present study, we used ISO to induce heart failure in Wistar rats and study the effect of Pterocarpus marsupium (PM) heartwood extract on it. PM is a well-recognised herbal drug known for its beneficial effect in diabetes with potential anti-inflammatory and anti-oxidative properties.Hypothesis: PM treatment will favourably modulate the cardiac hemodynamic, anti-oxidative stress and anti-inflammatory parameters compared to standard drug and control rats in isoproterenol induced heart failure rats.Methods &amp; Results. Animals were randomly divided into 10 groups.1: Normal control rats fed normal pellet diet, 2: Normal control rats treated with Fluvastatin (10 mg/kg; oral gavage) for 15 days 3: Normal control rats treated with PM Extract (100 mg/kg; oral gavage) for 15 days. 4: Normal control rats subcutaneously injected with ISO {Heart Failure (HF) group} 5: HF rats treated with Fluvastatin (10 mg/kg; oral gavage) for 15 days. 6: HF rats treated with PM Extract (100 mg/kg; oral gavage) for 15days 7: HF rats treated with PM Extract (200mg/kg; oral gavage) for 15 days. 8: Rats pretreated with Fluvastatin (10 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued Fluvastatin treatment for another 15 days 9: Rats pretreated with PM Extract (100 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued PM Extract treatment for another 15 days 10: Rats pretreated with PM Extract (200 mg/kg; oral gavage) for 15 days and at the 15th day subcutaneously injected with ISO and continued PM treatment for another 15 days. The groups were compared pre and post treatment for cardiac hemodynamic parameters, anti- oxidative stress parameters (superoxide dismutase, nitric oxide, malondialdehyde nitric oxide), cardiac injury markers, anti-inflammatory parameters (Interleukin-6 and Tumor Necrosis Factor-α).The results of the present study indicate that prophylactic and therapeutic treatment PM heartwood extract improved the altered hemodynamic and biochemical parameters in isoproterenol-induced HF rats suggesting its cardio-protective action. None declared. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Estrogen-receptor status determines differential regulation of α1- and α2-adrenoceptor-mediated cell survival, angiogenesis, and intracellular signaling responses in breast cancer cell lines.

Psychosocial stress promotes cancer pathogenesis involving angiogenesis through alterations in neuroendocrine-immune functions that may involve adrenoceptor (AR)-dependent signaling mechanisms in the brain, lymphoid organs, and cancerous cells. Various concentrations of α1- and α2- AR-specific agonists and antagonists were incubated in vitro with estrogen receptor-positive (ER +) MCF-7, and ER (-) MDA MB-231 cells to examine the secretions of VEGF-A, VEGF-C, and nitric oxide (NO), and expression of signaling molecules- p-ERK, p-CREB, and p-Akt on the proliferation of breast cancer cell lines. Cellular proliferation, VEGF-A and NO secretion, expression of p-ERK, p-CREB, and p-Akt were enhanced in MCF-7 cells treated with α1-AR agonist while VEGF-C secretion alone was enhanced in MDA MB-231 cells. Treatment of MCF-7 and MDA MB-231 cells with α2- AR agonist similarly enhanced proliferation and decreased NO production and p-CREB expression while VEGF-C secretion was decreased in MCF-7 cells and p-Akt expression was decreased in MDA MB-231 cells. α1-AR inhibition reversed cellular proliferation and VEGF-A secretion by MCF-7 cells while α2-AR inhibition reversed the proliferation of MCF-7 and MDA MB-231 cells and VEGF-C secretion by MCF-7 cells. Taken together, breast cancer pathogenesis may be influenced by distinct α-AR-mediated signaling mechanisms on angiogenesis and lymphangiogenesis that are dependent on estrogen receptor status.

Tizanidine: Advances in Pharmacology & Therapeutics and Drug Formulations.

Skeletal muscle relaxants (SMRs) are widely used in treating musculoskeletal conditions. All SMRs, with the exception of baclofen and tizanidine, are on the list of 2023 American Geriatrics Society Beers Criteria® for potentially inappropriate medication use in older adults. In our geriatric practice, off-label use of tizanidine as preemptive analgesia drove us to find recent advances in its pharmacology and therapeutics. An update review of tizanidine was thus presented, aiming to bring the latest knowledge to clinicians and promote further research and practical exploration. Relevant literature up to December 2023 was identified through searches of PubMed, Web of Science, and Embase. Tizanidine, a centrally acting alpha-2 adrenoceptor agonist with both antispastic and antispasmodic activity, shows efficacy in the common indications for all SMRs. From the perspective of drug safety, tizanidine has lower incidences of adverse events (injury, delirium, encephalopathy, falls, and opioid overdose) compared to baclofen, no association with risk of Alzheimer's disease as with orphenadrine, no risk of serotonin syndrome like metaxalone when comedicated with serotonergic drugs, no significant pharmacokinetic changes in CYP2C19 poor metabolizers unlike diazepam and carisoprodol, and no physically addictive or abuse properties like carisoprodol and diazepam. From the perspective of new and potential therapeutic uses, tizanidine has additional benefits (eg, gastroprotection that can improve patient tolerance to nonsteroidal anti-inflammatory agents, anti-neuropathic pain, a key component of multimodal analgesia strategy to reduce early postoperative pain, and anti-tumor effects). New delivery systems of tizanidine are developing to improve the pharmacokinetics of oral products, including buccal patches, transdermal delivery systems, nasal spray, and in situ rectal gel. Tizanidine is an SMR with unique features and may be an optimal initial choice for older adults. There would be more scientific studies, wider therapeutic applications, and new drug formulations in the future.

PHARMACOTHERAPY OF OVERACTIVE BLADDER: A 10 YEARS SYSTEMATIC REVIEW

Background: OAB is a stigmatized condition that significantly affects quality of life. The current first-line pharmacological approach to treating OAB involves various medications, primarily antimuscarinic agents and adrenoceptor agonist. This study aims to provide a 10 year systematic review of pharmacological approach in OAB treatment. Methods: This systematic review adhered to the PRISMA 2020 standards and included full-text English literature published between 2014 and 2024. Exclusion criteria involved editorials, review articles from the same journal, and submissions lacking a DOI. Literature was gathered from online sources such as PubMed and SagePub. Result: Our search in PubMed yielded 997 articles, while SagePub produced 357 articles. Focusing on the last 10 years (2014-2024), PubMed had 667 articles and SagePub had 160 articles. Ultimately we selected 5 papers that met our criteria, 3 from PubMed and 2 from SagePub. Conclusion: Due to the the improvements in urgency, frequency, and incontinence as well as fewer treatment-related adverse events, adrenoceptor agonist mirabegron is recommended as the first-line treatment for OAB.

Clinical Use of Adrenergic Receptor Ligands in Acute Care Settings.

In this chapter, we review how ligands, both agonists and antagonists, for the major classes of adrenoreceptors, are utilized in acute care clinical settings. Adrenergic ligands exert their effects by interacting with the three major classes of adrenoceptors. Adrenoceptor agonists and antagonists have important applications, ranging from treatment of hypotension to asthma, and have proven to be extremely useful in a variety of clinical settings of acute care from the operating room to the critical care environment. Continued research interpreting the mechanisms of adrenoreceptors may help the discovery of new drugs with more desirable clinical profiles.

Novel drug treatments for pain in advanced cancer and serious illness: a focus on neuropathic pain and chemotherapy-induced peripheral neuropathy.

Drugs that are commercially available but have novel mechanisms of action should be explored as analgesics. This review will discuss haloperidol, miragabalin, palmitoylethanolamide (PEA), and clonidine as adjuvant analgesics or analgesics. Haloperidol is a sigma-1 receptor antagonist. Under stress and neuropathic injury, sigma-1 receptors act as a chaperone protein, which downmodulates opioid receptor activities and opens several ion channels. Clinically, there is only low-grade evidence that haloperidol improves pain when combined with morphine, methadone, or tramadol in patients who have cancer, pain from fibrosis, radiation necrosis, or neuropathic pain. Miragabalin is a gabapentinoid approved for the treatment of neuropathic pain in Japan since 2019. In randomized trials, patients with diabetic neuropathy have responded to miragabalin. Its long binding half-life on the calcium channel subunit may provide an advantage over other gabapentinoids. PEA belongs to a group of endogenous bioactive lipids called ALIAmides (autocoid local injury antagonist amides), which have a sense role in modulating numerous biological processes in particular non-neuronal neuroinflammatory responses to neuropathic injury and systemic inflammation. Multiple randomized trials and meta-analyses have demonstrated PEA's effectiveness in reducing pain severity arising from diverse pain phenotypes. Clonidine is an alpha2 adrenoceptor agonist and an imidazoline2 receptor agonist, which is U.S. Federal Drug Administration approved for attention deficit hyperactivity disorder in children, Tourette's syndrome, adjunctive therapy for cancer-related pain, and hypertension. Clonidine activation at alpha2 adrenoceptors causes downstream activation of inhibitory G-proteins (Gi/Go), which inhibits cyclic Adenosine monophosphate (AMP) production and hyperpolarizes neuron membranes, thus reducing allodynia. Intravenous clonidine has been used in terminally ill patients with poorly controlled symptoms, in particular pain and agitation.

Exploring Neuroprotective Effects of Topical Brimonidine in Experimental Diabetic Retinopathy.

Diabetic retinopathy is a leading cause of blindness worldwide, characterized by neurovascular dysfunction. This study aimed to investigate the impact of brimonidine, a selective adrenoceptor agonist, on diabetic retinal neurodegeneration, recognizing the critical role of neurodegeneration in diabetic retinopathy. Streptozotocin-induced diabetes was established in adult male Sprague-Dawley rats to mimic diabetic retinopathy. Rats, except non-diabetic control rats, received topical applications of 0.15% brimonidine tartrate (treatment group) or balanced salt solution (diabetic control group) twice daily following diabetes induction. Each group comprised six randomly assigned animals. Retinal samples were analyzed using immunofluorescence staining, apoptosis assay, and western blot. Topical brimonidine treatment reduced apoptosis of retinal ganglion cells at 8 weeks after induction of diabetes (p<0.05). Glial activation induced by diabetes was reduced by brimonidine treatment. Immunoblot and immunofluorescence assay revealed that the decrease in phospho- protein kinase B (AKT) level resulting from diabetes was also attenuated by brimonidine (p<0.05). Furthermore, brimonidine alleviated the decrease in anti-apoptotic proteins [BCL2 apoptosis regulator (BCL2) and BCL-xl] induced by diabetes (p<0.05). Elevation of phospho-p38 mitogen-activated protein kinase (p38MAPK) and p53 in diabetic rats were reduced by brimonidine (p<0.05). Additionally, brimonidine treatment attenuated the upregulation of the pro-apoptotic molecule BCL-2 associated X in retinas of diabetic rats (p<0.05). These findings suggest that topical brimonidine treatment may protect retinal ganglion cells in experimental diabetes by modulating the AKT pathway and reducing pro-apoptotic p38MAPK levels. This presents a potential neuroprotective approach in diabetes, offering the advantage of localized treatment without the added burden of oral medication.

Effect of Dexmedetomidine on Intraoperative Hemodynamics and Blood Loss in Patients Undergoing Spine Surgery: A Systematic Review and Meta-Analysis

Objective Dexmedetomidine (Dex) is a highly selective α2 adrenoceptor agonist that reduces blood pressure and heart rate. However, its ability to provide stable hemodynamics and a clinically significant reduction in blood loss in spine surgery is still a matter of debate. This study aimed to investigate the effects of Dex on intraoperative hemodynamics and blood loss in patients undergoing spine surgery.Methods The Web of Science, MEDLINE, EMBASE, and the Cochrane Library were searched up to February 2023 for randomized controlled trials (RCTs) including patients undergoing spine surgeries under general anaesthesia and comparing Dex and saline. A fixed- or random-effect model was used depending on heterogeneity.Results Twenty-one RCTs, including 1388 patients, were identified. Dex added the overall risk of intraoperative hypotension (odds ratio [OR]: 2.11; 95% confidence interval [CI]: 1.24 - 3.58; P=0.006) and bradycardia (OR: 2.48; 95%CI: 1.57 - 3.93; P=0.0001). The use of a loading dose of Dex led to significantly increased risks of intraoperative hypotension (OR: 2.00; 95%CI: 1.06 - 3.79; P=0.03) and bradycardia (OR: 2.28; 95%CI: 1.42 - 3.66; P=0.0007). For patients receiving total intravenous anesthesia, there was an increased risk of hypotension (OR: 2.90; 95%CI: 1.24 - 6.82; P=0.01) and bradycardia (OR: 2.66; 95%CI: 1.53 - 4.61; P=0. 0005). For patients in the inhalation anesthesia group, only an increased risk of bradycardia (OR: 4.95; 95%CI: 1.41 - 17.37; P=0.01) was observed. No significant increase in the risk of hypotension and bradycardia was found in the combined intravenous-inhalation anesthesia group. The incidence of severe hypotension (OR: 2.57; 95%CI: 1.05 - 6.32; P=0.04), but not mild hypotension, was increased. Both mild (OR: 2.55; 95%CI: 1.06 - 6.15; P=0.04) and severe (OR: 2.45; 95%CI: 1.43 - 4.20; P=0.001) bradycardia were associated with a higher risk. The overall analyses did not reveal significant reduction in intraoperative blood loss. However, a significant decrease in blood loss was observed in total inhalation anesthesia subgroup (mean difference [MD]: -82.97; 95%CI: -109.04 - -56.90; P<0.001).Conclusions Dex increases the risks of intraoperative hypotension and bradycardia in major spine surgery. The administration of a loading dose of Dex and the utilization of various anesthesia maintenance methods may potentially impact hemodynamic stability and intraoperative blood loss.