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Journal of Liposome Research Sep 2021We have previously developed ammonium sulphate gradient loaded liposomes to encapsulate dibucaine. Thus, the purpose of this study was to evaluate the pre-clinical...
We have previously developed ammonium sulphate gradient loaded liposomes to encapsulate dibucaine. Thus, the purpose of this study was to evaluate the pre-clinical safety and effectiveness of this novel ionic liposomal formulation of dibucaine (DBC), as described in previous work. Effectiveness was evaluated on Wistar rats (n = 8) that received plain DBC or liposomal DBC (DBC). Control empty liposomes (without DBC) or saline were also used as control. Sciatic nerve block was performed using the formulations or controls (0.4 mL). A hindpaw incision-based postoperative pain model was used to evaluate mechanical hypersensitivity with von Frey filaments. To verify antiinflamatory activity protein levels of TNF-α, IL-1β, substance P and CGRP were measured by ELISA in the hindpaw tissue after 1 and 6 hours of the incision. To corroborate drug safety, sciatic nerve Schwann cell cultures were treated with the aforementioned formulations and assessed for cell viability (MTT assay) and death (flow cytometry assay). Histopathology of the tissues surrounding the sciatic nerve region was also assessed 2 and 7 days after treatment. All animals presented post incisional hypersensitivity and DBC showed longer analgesic effect ( < 0.001). DBC reduced TNF-α and CGRP levels ( < 0.05). Histopathological evaluation showed greater inflammatory reaction after the administration of control liposomes when compared to DBC ( < 0.05). There was no difference in Schwann cell viability and death between plain and encapsulated DBC. DBC was safe and enhanced anaesthesia duration due to slow release of dibucaine from ammonium sulphate gradient loaded liposomes.
Topics: Analgesia; Anesthetics, Local; Animals; Dibucaine; Liposomes; Rats; Rats, Wistar
PubMed: 32567452
DOI: 10.1080/08982104.2020.1785494 -
Pharmaceutics Nov 2018Dibucaine (DBC) is among the more potent long-acting local anesthetics (LA), and it is also one of the most toxic. Over the last decades, solid lipid nanoparticles (SLN)...
Dibucaine (DBC) is among the more potent long-acting local anesthetics (LA), and it is also one of the most toxic. Over the last decades, solid lipid nanoparticles (SLN) have been developed as promising carriers for drug delivery. In this study, SLN formulations were prepared with the aim of prolonging DBC release and reducing its toxicity. To this end, SLN composed of two different lipid matrices and prepared by two different hot-emulsion techniques (high-pressure procedure and sonication) were compared. The colloidal stability of the SLN formulations was tracked in terms of particle size (nm), polydispersity index (PDI), and zeta potential (mV) for 240 days at 4 °C; the DBC encapsulation efficiency was determined by the ultrafiltration/centrifugation method. The formulations were characterized by differential scanning calorimetry (DSC), electron paramagnetic resonance (EPR), and release kinetic experiments. Finally, the in vitro cytotoxicity against 3T3 fibroblast and HaCaT cells was determined, and the in vivo analgesic action was assessed using the test in rats. Both of the homogenization procedures were found suitable to produce particles in the 200 nm range, with good shelf stability (240 days) and high DBC encapsulation efficiency (~72⁻89%). DSC results disclosed structural information on the nanoparticles, such as the lower crystallinity of the lipid core vs. the bulk lipid. EPR measurements provided evidence of DBC partitioning in both SLNs. In vitro (cytotoxicity) and in vivo () experiments revealed that the encapsulation of DBC into nanoparticles reduces its intrinsic cytotoxicity and prolongs the anesthetic effect, respectively. These results show that the SLNs produced are safe and have great potential to extend the applications of dibucaine by enhancing its bioavailability.
PubMed: 30441802
DOI: 10.3390/pharmaceutics10040231 -
Chemico-biological Interactions Nov 2016Butyrylcholinesterase (BChE) activity assay and inhibitor phenotyping can help to identify individuals at risk of prolonged paralysis following the administration of...
Butyrylcholinesterase (BChE) activity assay and inhibitor phenotyping can help to identify individuals at risk of prolonged paralysis following the administration of neuromuscular blocking agents, like succinylcholine, pesticides and nerve agents. In this study, the activity of BChE and its sensitivity to inhibition by dibucaine and fluoride was evaluated in 1200 Polish healthy individuals. In addition, molecular analysis of all exons, exon-intron boundaries and the 3'UTR sequence of the BCHE gene was performed in a group of 72 subjects with abnormal BChE activity (<2000 U/L and >5745 U/L) or with DN (Dibucaine Number) or FN (Fluoride-Number) values outside the reference range (DN < 78 and FN < lower than wild type). In a studied group, BChE activity range was similar to those observed in other populations. BChE activity screening allowed to detect UA and UF phenotypes in 26 (2.2%) and 15 (1.2%) individuals, respectively. Observed UA or UF phenotypes were confirmed by direct sequencing and heterozygous c.293A > G or c.1253G > T substitutions were identified in all cases. Nine out of 18 (50%) individuals with BChE activity below 2000 U/L had a mutation in 5'UTR (32G/A), intron 2 (c.1518-121T/C) or exon 4 (c.1699G/A; the K variant mutation). Majority of the individuals with BChE activity ≥6000 U/L were wild type. To summarize, the range of BChE activity in a Polish population is similar to those observed in other countries. We conclude that the BChE phenotyping assay is a reliable method for identification of individuals with the UA and UF genotypes.
Topics: 3' Untranslated Regions; 5' Untranslated Regions; Adolescent; Adult; Aged; Aged, 80 and over; Butyrylcholinesterase; Child; Child, Preschool; Dibucaine; Exons; Female; Fluorides; Genotype; Humans; Introns; Male; Middle Aged; Nucleic Acid Conformation; Phenotype; Poland; Polymorphism, Genetic; Protein Binding; RNA, Messenger; White People; Young Adult
PubMed: 27109752
DOI: 10.1016/j.cbi.2016.04.030 -
Dermatologic Surgery : Official... Dec 2014Allergic contact dermatitis (ACD) to lidocaine is rising in prevalence. This is due to a growing number of over-the-counter (OTC) products containing topical amide and...
BACKGROUND
Allergic contact dermatitis (ACD) to lidocaine is rising in prevalence. This is due to a growing number of over-the-counter (OTC) products containing topical amide and ester anesthetics. The phenomenon poses a real threat to the authors' surgical anesthetic options.
OBJECTIVE
To investigate the epidemiology of topical anesthetic ACD in British Columbia, Canada and provide an approach for clinicians to deal with this problem.
MATERIALS AND METHODS
A retrospective chart review of 1,819 patients who underwent patch testing at the University of British Columbia Contact Dermatitis Clinic between January 2009 and June 2013 was completed. The authors also performed a detailed review of Canadian OTC preparations containing lidocaine in 2013.
RESULTS
The prevalence of ACD to local anesthetics is significant at 2.4%. The most common allergen is benzocaine (45%) followed by lidocaine (32%) and dibucaine (23%).
CONCLUSION
The proportion of ACD caused by lidocaine is higher than expected. This is likely secondary to an increase in OTC medicaments containing lidocaine. Patients who are patch test-positive to a local anesthetic should be challenged intradermally to confirm clinical relevance. Because ACD is a delayed Type IV hypersensitivity reaction (localized dermatitis), the risk of anaphylaxis is not a concern.
Topics: Anesthesia, Local; Benzocaine; British Columbia; Dermatitis, Allergic Contact; Drug Hypersensitivity; Female; Humans; Incidence; Lidocaine; Male; Patch Tests; Prevalence
PubMed: 25380091
DOI: 10.1097/DSS.0000000000000190 -
Biochimica Et Biophysica Acta. General... Sep 2019Because ordered membrane domains, called lipid rafts, regulate activation of ion channels related to the nerve pulse, lipids rafts are thought to be a possible target...
BACKGROUND
Because ordered membrane domains, called lipid rafts, regulate activation of ion channels related to the nerve pulse, lipids rafts are thought to be a possible target for anesthetic molecules. To understand the mechanism of anesthetic action, we examined influence of representative local anesthetics (LAs); dibucaine, tetracaine, and lidocaine, on raft-like liquid-ordered (L)/non-raft-like liquid-disordered (L) phase separation.
METHODS
Impact of LAs on the phase separation was observed by fluorescent microscopy. LA-induced perturbation of the L and L membranes was examined by DPH anisotropy measurements. Incorporation of LAs to the membranes was examined by fluorescent anisotropy of LAs. The biding location of the LAs was indicated by small angle x-ray diffraction (SAXD).
RESULTS
Fluorescent experiments showed that dibucaine eliminated the phase separation the most effectively, followed by tetracaine and lidocaine. The disruption of the phase separation can be explained by their disordering effects on the L membrane. SAXD and other experiments further suggested that dibucaine's most potent perturbation of the L membrane is attributable to its deeper immersion and bulky molecular structure. Tetracaine, albeit immersed in the L membrane as deeply as dibucaine, less perturbs the L membrane probably because of its smaller bulkiness. Lidocaine hardly reaches the hydrophobic region, resulting in the weakest L membrane perturbation.
CONCLUSION
Dibcaine perturbs the L membrane the most effectively, followed by tetracaine and lidocaine. This ranking correlates with their anesthetic potency.
GENERAL SIGNIFICANCE
This study suggests a possible mechanistic link between anesthetic action and perturbation of lipid rafts.
Topics: Anesthetics, Local; Fluorescence Polarization; Hydrophobic and Hydrophilic Interactions; Lipid Bilayers; Membrane Microdomains
PubMed: 31207252
DOI: 10.1016/j.bbagen.2019.06.008 -
Molecular Neurobiology May 2016Paraquat (PQ) as a Parkinsonian mimetic has been demonstrated to impair dopaminergic (DAergic) neurons and is highly correlated with the etiology of Parkinson's disease...
Paraquat (PQ) as a Parkinsonian mimetic has been demonstrated to impair dopaminergic (DAergic) neurons and is highly correlated with the etiology of Parkinson's disease (PD) where the death of DAergic neurons has been mainly attributed to impaired mitochondrial functioning. In this study, PQ-induced cytotoxicity focusing on mitochondrial membrane permeability (MMP), which has been implicated to play a part in neurodegeneration, was investigated. Primarily, PQ-induced cytotoxicity and reactive oxygen species (ROS) were inhibited by an inhibitor of NADPH oxidase (NOX), indicating the toxic effect of PQ redox cycling. Further, dibucaine and cyclosporin A which respectively inhibit mitochondrial apoptosis-induced channels (MAC) and mitochondrial permeability transition pores (mPTP) were used and found to prevent PQ-induced mitochondrial dysfunction, such as decreased mitochondrial membrane potential and increased MMP, mitochondrial ROS, and pro-apoptotic factor release. Knockdown of bax and/or bak blocked PQ-induced mitochondrial clusterization of Bax and/or Bak and cytotoxicity, demonstrating the significance of MAC which is composed of Bax and/or Bak. This clusterization coincided with the release of mitochondrial apoptotic factors before there was an increase in inner MMP, indicating that MAC may precede mPTP formation. Besides, NOX inhibitor but not dibucaine attenuated the earlier PQ-induced cytosolic ROS formation or Bax and/or Bak clusterization indicating PQ redox cycling may account for MAC formation. In this model, we have resolved for the first that PQ cytotoxicity through redox cycling may sequentially result in increased outer (MAC) and inner (mPTP) MMP and suggested MMP could be implicated as a therapeutic target in treating neurodegenerative diseases like PD.
Topics: Animals; Apoptosis Regulatory Proteins; Behavior, Animal; Cell Death; Cyclosporine; Dibucaine; Gene Silencing; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Permeability Transition Pore; Onium Compounds; PC12 Cells; Paraquat; Permeability; Protein Multimerization; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein
PubMed: 25947082
DOI: 10.1007/s12035-015-9198-y -
Biochimica Et Biophysica Acta.... Jun 2019Mitochondrial membranes are pointed out as the site of cardiotoxic action of local anaesthetics. Its three main phospholipids components are phosphatidylcholine,...
Mitochondrial membranes are pointed out as the site of cardiotoxic action of local anaesthetics. Its three main phospholipids components are phosphatidylcholine, phosphatidylethanolamine and cardiolipin. Cardiolipins, in eukaryotes, are only found in mitochondria and are essential for the maintenance of its integrity and dynamics. Fluorescence and nuclear magnetic resonance spectroscopy were used to study the interactions of a local anaesthetics, Dibucaine (DBC), with different mitochondrial membrane models constituted by combinations of its three main lipid components in which cardiolipin was a natural extract (CL). Both CL presence/absence and its percentage in the model membranes were evaluated. Fluorescence spectroscopy showed that DBC lowered the transition temperature of all membrane models understudy. DBC partition showed to be dependent of CL presence and phosphatidylethanolamine:CL ratio. Furthermore, the maximum emission wavelength (λ) exhibited a notorious decreased with increasing phospholipid to DBC ratio, in all the membrane models containing CL. Nevertheless, it remained approximately the same in the membrane without CL. This indicates a differential membrane localization of the anaesthetics, dependent on the membrane models used. NMR results showed that DBC interaction and location in the membrane models is mainly influenced by CL presence, and DBC can significant alter lipid systems properties e.g. percentage and type of lipid phase present. Taken all together it was shown that DBC interaction and location are largely dependent on the membrane model system. Furthermore, DBC is able to produce significant changes in the lipidic systems which might help to explain its high toxicity.
Topics: Anesthetics, Local; Binding Sites; Cardiolipins; Dibucaine; Mitochondrial Membranes; Models, Biological; Phosphatidylethanolamines; Temperature
PubMed: 30840858
DOI: 10.1016/j.bbamem.2019.02.011 -
Journal of Pharmaceutical Sciences Sep 2018Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the...
Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 μM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of DBC.
Topics: Anesthetics, Local; Animals; BALB 3T3 Cells; Cell Survival; Dibucaine; Drug Liberation; Liposomes; Male; Mice; Motor Activity; Pain Measurement; Phosphatidylcholines; Zebrafish
PubMed: 29802933
DOI: 10.1016/j.xphs.2018.05.010 -
Journal of Medicinal Chemistry Apr 2019Enterovirus D68 (EV-D68) is an atypical nonpolio enterovirus that mainly infects the respiratory system of humans, leading to moderate-to-severe respiratory diseases. In...
Enterovirus D68 (EV-D68) is an atypical nonpolio enterovirus that mainly infects the respiratory system of humans, leading to moderate-to-severe respiratory diseases. In rare cases, EV-D68 can spread to the central nervous system and cause paralysis in infected patients, especially young children and immunocompromised individuals. There is currently no approved vaccine or antiviral available for the prevention and treatment of EV-D68. In this study, we aimed to improve the antiviral potency and selectivity of a previously reported EV-D68 inhibitor, dibucaine, through structure-activity relationship studies. In total, 60 compounds were synthesized and tested against EV-D68 using the viral cytopathic effect assay. Three compounds 10a, 12a, and 12c were identified to have significantly improved potency (EC < 1 μM) and a high selectivity index (>180) compared with dibucaine against five different strains of EV-D68 viruses. These compounds also showed potent antiviral activity in neuronal cells, such as A172 and SH-SY5Y cells, suggesting they might be further developed for the treatment of both respiratory infection as well as neuronal infection.
Topics: Antiviral Agents; Cell Line, Tumor; Cell Survival; Dibucaine; Drug Design; Enterovirus D, Human; Humans; Quinolines; Structure-Activity Relationship
PubMed: 30912944
DOI: 10.1021/acs.jmedchem.9b00115 -
Frontiers in Microbiology 2022Human enterovirus infections are mostly asymptomatic and occasionally could be severe and life-threatening. The conserved non-structural 2C from enteroviruses protein is...
Human enterovirus infections are mostly asymptomatic and occasionally could be severe and life-threatening. The conserved non-structural 2C from enteroviruses protein is a promising target in antiviral therapies against human enteroviruses. Understanding of 2C-drug interactions is crucial for developing the potential antiviral agents. While functions of enterovirus 2C proteins have been widely studied, three-dimensional structure information of 2C is limited. In this study, the structures of 2C proteins from 20 enteroviruses were simulated and reconstructed using programs. Subsequent docking studies of the known 22 antiviral inhibitors for 2C proteins were performed to uncover the inhibitor-binding characteristics of 2C. Among the potential inhibitors, the compound hydantoin exhibited the highest broad-spectrum antiviral activities with binding to 2C protein. The anti-enteroviral activity of GuaHCL, compound 19b, R523062, compound 12a, compound 12b, quinoline analogs 12a, compound 19d, N-benzyladenosine, dibucaine derivatives 6i, TBZE-029, fluoxetine analogs 2b, dibucaine, 2-(α-hydroxybenzyl)-benzimidazole (HBB), metrifudil, pirlindole, MRL-1237, quinoline analogs 10a, zuclopenthixol, fluoxetine, fluoxetine HCl, and quinoline analogs 12c showed a trend of gradual decrease. In addition, the free energy with 22 compounds binding to EV 2C ranged from -0.35 to -88.18 kcal/mol. Our studies will provide important information for the development of pan-enterovirus antiviral agents based on 2C.
PubMed: 35572704
DOI: 10.3389/fmicb.2022.856574