Prilocaine Research Articles

Assessing α-Bisabolol as a Transmucosal Permeation Enhancer of Buccal Local Anesthetics.

Needle-free buccal anesthesia improves dental treatment outcomes for both patients and dentists. In this study, we report on an assessment of the enhancement effects of α-bisabolol on the in vitro transmucosal permeation of prilocaine hydrochloride (PCl) and lidocaine hydrochloride (LCl) from needleless buccal films. We also evaluated the mechanical properties of the film, which consisted of Methocel™ K100 LV as the film-forming polymer (3% m·m-1), PEG 400 as a cosolvent (15% m·m-1 based on drug loading), α-bisabolol (15 and 30% m·m-1 based on drug loading), and the drugs combined at a 1:1 ratio (15 mg·unit-1). The porcine esophageal epithelium was used as a membrane barrier, and artificial saliva was the release medium. After a 1 h experiment at 25 ± 2 °C, α-bisabolol significantly decreased, rather than enhanced, the permeation fluxes (five-fold), permeability coefficients (seven-fold), and retentions (two-fold) of both PCl and LCl through the epithelium, regardless of the concentration. Moreover, the resistance and flexibility of the films markedly decreased compared to those without α-bisabolol. Therefore, under the experimental conditions, using α-bisabolol as a buccal permeation enhancer for the hydrophilic local anesthetics PCl and LCl from buccal films is not feasible.

Molecular interactions of hydrated co-amorphous systems of prilocaine and lidocaine

It is generally accepted that water as a plasticizer can decrease the glass transition temperatures (Tgs) of amorphous drugs and drug excipient systems. However, previous studies suggest that water, as an anti-plasticizer, can increase the Tgs of co-amorphous systems of prilocaine (PRL) and lidocaine (LID). In order to investigate the intermolecular interactions between water and co-amorphous PRL-LID systems, Fourier transform infrared spectroscopy (FTIR) and principal component analysis (PCA) were conducted. Water was found to bind with the carbonyl groups of PRL and LID molecularly evenly in the hydrated co-amorphous PRL-LID systems. Quantum chemical simulations visually confirmed the interactions between water and co-amorphous PRL-LID systems. Furthermore, the physical stability of hydrated co-amorphous PRL-LID systems was improved due to the anti-plasticizing effect of water, compared with the anhydrous samples. The preference of water to interact with the carbonyl groups of PRL and LID as binding sites could be associated with the anti-plasticizing effect of water on the co-amorphous PRL-LID systems.

Anti-plasticizing effect of water on prilocaine and lidocaine - the role of the hydrogen bonding pattern.

It is generally accepted that water, as an effective plasticizer, decreases the glass transition temperatures (Tgs) of amorphous drugs, potentially resulting in physical instabilities. However, recent studies suggest that water can also increase the Tgs of the amorphous forms of the drugs prilocaine (PRL) and lidocaine (LID), thus acting as an anti-plasticizer. To further understand the nature of the anti-plasticizing effect of water, interactions with different solvents and the resulting structural features of PRL and LID were investigated by Fourier transform infrared spectroscopy (FTIR) and quantum chemical simulations. Heavy water (deuterium oxides) was chosen as a solvent, as the deuterium and hydrogen atoms are electronically identical. It was found that substituting hydrogen with deuterium showed a minimal impact on the anti-plasticization of water on PRL. Ethanol and ethylene glycol were chosen as solvents to compare the hydrogen bonding patterns occurring between the hydroxyl groups of the solvents and PRL and LID. Comparison of the various Tgs showed a weaker anti-plasticizing potential of these two solvents on PRL and LID. The frequency shifts of the amide CO groups of PRL and LID due to the interactions with water, heavy water, ethanol, and ethylene glycol as observed in the FTIR spectra showed a correlation with the binding energies calculated by quantum chemical simulations. Overall, this study showed that the combination of weak hydrogen bonding and strong electrostatic contributions in hydrated PRL and LID could play an important role in inducing the anti-plasticizing effect of water on those drugs.

Inflammatory signal transduction pathways induced by prilocaine toxicity in cultured ARPE-19 cells.

Prilocaine (PRL) is a common local anesthetic. Despite the successful use of regional anesthesia for intraocular surgery, there are associated side effects that may affect the retina in case of accidental intravitreal injection. This study examined the signal transduction pathways activated by PRL toxicity and determined the protective role of nitric oxide synthase-2 (NOS2) inhibition in cultured human-derived retinal pigment epithelial cells (ARPE-19). Toxicity analysis was performed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay to detect the toxic dose of PRL and protective effectiveness of asperglaucide (ASP), an NOS2 inhibitor. Nuclear factor kappa B p65 (NF-κB p65), phosphorylated NF-κB p65, phospho-protein kinase B (AKT), NOS2, nitrotyrosine, and cleaved caspase-3 protein levels were evaluated by immunofluorescence staining and/or western blot analysis. Interleukin-6 (IL-6) and nitrated protein levels were quantified using an immunoassay, whereas caspase-3 activity and nitrite/nitrate levels were measured using a fluorometric method. A significant increase in NF-κB p65, and phosphorylated NF-κB p65 and AKT levels due to PRL toxicity was observed. Similarly, IL-6, NOS2, nitrite/nitrate, and nitrotyrosine levels were significantly higher in PRL-treated cells than in control cells. Application of ASP to PRL-treated cells reduced NF-κB p65, and phosphorylated NF-κB p65 and AKT to basal levels. IL-6, NOS2, nitrite/nitrate, and nitrotyrosine levels also considerably decreased following ASP treatment in cells experiencing PRL-induced toxicity. Moreover, the caspase-3-dependent apoptotic pathway was not activated. Our results indicate that ASP could ameliorate PRL-induced activation of NF-κB p65 that led to inflammation in cultured ARPE-19 cells.

Thermal investigation on hydrated co-amorphous systems of nicotinamide and prilocaine

It is generally recognized that water, acting as a plasticizer, increases molecular mobility, leading to a decrease of the glass transition temperature (Tg) in amorphous systems. However, an anti-plasticizing effect of water was recently observed on prilocaine (PRL). This effect might be used in co-amorphous systems to moderate the plasticizing effect of water. Nicotinamide (NIC) can form co-amorphous systems with PRL. In order to investigate the effect of water on these co-amorphous systems, the Tgs and molecular mobility of hydrated co-amorphous NIC-PRL systems were compared with those of the respective anhydrous systems. Molecular mobility was estimated by considering the enthalpic recovery at the Tg using the Kohlrausch-Williams-Watts (KWW) equation. At molar ratios of NIC above 0.2, a plasticizing effect of water on co-amorphous NIC-PRL systems was observed with increasing the NIC concentration. In contrast, at molar ratios of NIC of 0.2 and below, water had an anti-plasticizing effect on the co-amorphous NIC-PRL systems, with increased Tgs and reduced mobility upon hydration.

Influence of Water on Amorphous Lidocaine.

Water is generally regarded as a universal plasticizer of amorphous drugs or amorphous drug-containing systems. A decrease in glass-transition temperature (Tg) is considered the general result of this plasticizing effect. A recent study exhibits that water can increase the Tg of amorphous prilocaine (PRL) and thus shows an anti-plasticizing effect. The structurally similar drug lidocaine (LID) might show similar interactions with water, and thus an anti-plasticizing effect of water is hypothesized to also occur in amorphous LID. However, the influence of water on the Tg of LID cannot be determined directly due to the very low stability of LID in the amorphous form. It is possible to predict the Tg of LID from a co-amorphous system of PRL-LID using the Gordon-Taylor equation. Interactions were observed between PRL and LID based on the deviations between the experimental Tgs and the Tgs calculated by the conventional use of the Gordon-Taylor equation. A modified use of the Gordon-Taylor equation was applied using the optimal co-amorphous system as a separate component and the excess drug as the other component. The predicted Tg of fully hydrated LID could thus be determined and was found to be increased by 0.9 ± 0.7 K compared with the Tg of water-free amorphous LID. It could be shown that water exhibited a small anti-plasticizing effect on LID.

Saddle block anesthesia with 20 mg prilocaine hydrochloride 2% hyperbaric solution and intravenous fentanyl administration for transperineal MRI/US fusion-guided prostate biopsy

Introduction: MRI-Ultrasound (MRI/US) fusion-guided transperineal prostate biopsy (TPB) is gaining popularity in the diagnostic algorithm of prostate cancer. It is associated with higher pain score than the other methods of prostate biopsy. Effective analgesia is a key point for providing patient comfort and preventing his movement in response to pain with subsequent mismatch of the fused MRI/ US images. The mismatch could lead to inaccurate targeting of suspected cancer lesions. The preferred method of analgesia in an outpatient setting is topical intrarectal administration of lidocaine and periprostatic nerve block, but the pain and the discomfort from the procedure are not completely eliminated. Hypothetically, saddle block anesthesia has an expected better efficacy in relieving the pain from the MRI/US-TPB. Aim: To evaluate the efficacy and safety of saddle block anesthesia in patients undergoing MRI/US-TPB and сomparative analysis between patients who have received and have not received intravenous fentanyl Material and methods: A prospective randomized study was conducted on 12 consecutive patients undergoing MRI/US-TPB. Saddle block anesthesia was performed with 20 mg prilocaine hydrochloride 2% hyperbaric solution to all patients. 6 patients received intravenous fentanyl at a dose of 1mcg/kg (Group 1) and 6 patients did not receive intravenous fentanyl. It was examined: patient’s age, weight, height, BMI and ASA class; duration from the dural puncture to the end of the surgical intervention; taken number of prostate biopsies; presence of intraoperative pain; motor blockage; presence of a difference of more than 20%, before and after saddle block anesthesia, of non-invasively measured blood pressure and heart rate; additional medication; presence of early postoperative complications and recovery time from anesthesia Results: The comparative analysis of the preoperative characteristics of the both groups did not reveal significant statistical difference. There were comparatively similar indicators for surgical intervention and regional anesthesia in both groups. The both anesthesia techniques showed safety profile with hemodynamic stability, without additional medicine administration and lack of early post-anesthesia complications. Pain did not occur during inserting and moving the US probe into the anal canal and puncturing the perineal skin and the underlying tissues. 50% (3) of the patients in Group 2 had pain during the puncture of the prostate gland and biopsy extraction, while in Group 1 - 0% (0) of the patients reported presence of pain. There was a slightly delayed onset of the first postoperative pain in Group 1 - 113.17 ± 15.11 min. compared to Group 2 - 99.83 ± 11.51 min. Conclusion: The saddle block anesthesia with 20 mg prilocaine hydrochloride 2% hyperbaric solution in combination with intravenous fentanyl at a dose of 1 mcg/kg is a safe anesthesia technique, associated with excellent analgesic profile, low incidence of anesthesia-related complications and rapid recovery in patients undergoing MRI/US-TPB. Key words: saddle block, transperineal MRI/US fusion-guided prostate biopsy, prilocaine hydrochloride 2% hyperbaric solution

Herpes Labialis: A New Possibility for Topical Treatment with Well-Elucidated Drugs.

Mucocutaneous infections caused by Herpes simplex virus (HSV-1 and HSV-2) are characterized by the appearance of vesicles that cause pain and embarrassment to the carrier. The standard treatment is based on the use of antivirals in gels or ointments, however, relapses are common. Local anesthetics decrease the pain caused by the lesion, in addition to showing antiviral properties. Semi-solid form facilitates application and its transformation into a thin film favors the maintenance of the formulation in place, with a more discreet final aspect. The objective of this study was to develop and evaluate formulations containing anesthetics for the treatment of cold sores. For this purpose, two semi-solid film-forming formulations were developed and evaluated, containing HPMC K100, lidocaine (LIDO) and prilocaine (PRILO) combined with adjuvants, in the presence (F1T) or not (F1) of the absorption promoter Transcutol®. The mixture of PRILO and LIDO resulted in the formation of a eutectic mixture (EM), essential for penetration of drugs into the skin. The quantification of drugs was performed by HPLC (High Performance Liquid Chromatography), and Transcutol® did not influence the release of drugs from the formulation. The bioadhesiveness of the formulation was evaluate and the drugs did not impair the adhesive potential of the polymers used. The formulations were evaluated in vivo for skin irritation and did not show any negative sign on macroscopic examination. The in vivo efficacy test proved the anesthetics' ability to decrease the lesions caused by HSV-1. Thus, the proposed formulations proved to be good alternatives to the treatment of oral lesions caused by HSV-1.

Use of infiltrative anesthesia in acute anterior dislocation of shoulder

BACKGROUND: To evaluate the results of infiltrative anesthesia for manual closed reduction of acute primary anterior shoulder dislocation. MATERIAL AND METHODS: A total of 55 adults with acute anterior dislocation of shoulder who were treated with Hippocratic maneuver were evaluated. Infiltrative anesthesia was applied directly to the deltoid muscle from two anatomic locations in anterolateral and posterolateral of the shoulder with prilocaine hydrochloride and bupivacaine (Citanest® + Marcaine®) was applied to all patients. All patients’ reductions were made by the same orthopaedic surgeon. Visual Analog Scale (VAS) of pain was applied to all subjects for evaluating the pain in management after the treatment. Demographic and clinical data, time of duration for reduction, and duration of hospitalization were recorded. RESULTS: Mean age was 57.9 ± 4.5 years, 22% were women. The reduction was completed with the mean duration of 1.0 ± 0.3 minutes after applying infiltrative anesthesia. The mean VAS scores of the patients used infiltrative anesthesia were 4.6 which indicated moderate pain. The treatment was completed in the emergency room so that patients could be discharged after reduction in the emergency department. No recurrence and complications were observed in the one-year follow-up period. CONCLUSION: Our study showed that infiltrative anesthesia, in addition to its easy management by orthopaedic surgeons, allows successful and fast reduction by avoiding difficulties caused by the contraction of the deltoid muscle without necessitating sedoanalgesia or general anesthesia.

Lipid nanocapsules loaded with prilocaine and lidocaine and incorporated in gel for topical application

Lipid nanocapsules (LNC) are special drug delivery system (DDS) carriers obtained by the phase-inversion temperature method (PIT). This study describes the encapsulation of the local anesthetics (LA) prilocaine (PLC) and lidocaine (LDC) in lipid nanocapsules (LNCPLC+LDC) optimized by 23 factorial design, characterized through DLS, NTA, CRYO-EM and release kinetics and incorporated in carbopol gel (GelLNC PLC+LDC) prior to in vivo anesthetic effect (in mice) evaluation. A very homogeneous population of small (50 nm; polydispersity index = 0.05) spherical nanocapsules with negative zeta potentials (−21 mV) and ca. 2.3 × 1015 particles/mL was obtained. The encapsulation efficiency was high (81% and 89% for prilocaine and lidocaine, respectively). The release rate profile was free PLC = free LDC > LNCPLC+LDC > GelLNC PLC+LDC. The hybrid system increased (4x) the anesthesia time in comparison to an equipotent gel formulation prepared without LNC. No tissue damage was detected on the tail skin of mice that received the formulations. This study shows that lipid nanocapsules are suitable carriers for PLC and LDC, promoting longer and safer topical anesthesia. GelLNC PLC+LDC is mucoadhesive and suitable for application in the mouth, where it could be used as a pre-anesthetic, to reduce pain of needle stick (infiltrative anesthesia).

Local treatment of pain in Tietze syndrome: A single-center experience.

Background In this study, we present our experiences with local injections of triamcinolone and prilocaine in patients diagnosed with Tietze syndrome. Methods Between January 2016 and January 2019, a total of 28 patients (12 males, 16 females; median age: 33 years; range, 21 to 51 years) who were diagnosed with TS in our clinic were retrospectively analyzed. Triamcinolone hexacetonide and prilocaine hydrochloride were injected into painful joints. At first week, pain sensation of the patients was recorded using the Pain Rating Scale developed by the British Pain Society. Pain was also assessed at one, two, and three weeks after injections qualitatively and based on physical examination. Results At one week, the pain severity before the local injection treatment was above average the pain-related discomfort rates, and the response was quite favorable after the treatment (p=0.005 and p=0.001, respectively). A statistically significant rating was observed for treatment response and success (p=0.003). Totally 75% of the patients experienced more than 70% reduction in pain level after the injection. Conclusion Our treatment approach involving injection of a mixture of steroid and a local anesthetic provides a rapid relief from pain, irrespective of age, sex, or employment status in patients diagnosed with Tietze syndrome.

An evaluation of treatment options for lateral epicondylitis

Aim: Lateral pain in the elbow is a widespread problem in orthopedics and physiotherapy. There are different conservative treatment options available, but there is no consensus on their superiority to each other. The aim of this study was to evaluate the efficacy of three different treatment methods applied to patients followed up with a diagnosis of lateral epicondylitis. Methods: The study included a total of 105 patients who were diagnosed with lateral epicondylitis between 2010 and 2016 and treated conservatively. The patients were separated into three groups according to the treatment administered. In Group 1 (n:28), 1 ml betamethasone dipropionate (Diprospan®, Schering-Plough Corp., Kenilworth, NJ, ABD) was applied with the peppering method. In Group 2 (n:28), the same peppering method was used to apply 1 ml local anesthetic (prilocaine hydrochloride, Citanest®, AstraZeneca plc., London, UK). In Group 3 (n:49), extracorporeal shockwave therapy (ESWT) treatment was performed. Data were evaluated before and at one, three, and six months after treatment. Clinical scores were evaluated according to the Quick Dash (Q-DASH, Quick disabilities of arm, shoulder, and hand) scoring system and VAS (visual analog scale) scores during the daily activities of the patients. Quality of life and patient satisfaction levels were evaluated based on Quick Dash scores. Results: A significant improvement was observed in all three methods in the VAS and quality of life of the patients at one, three, and six months after treatment compared to pre-treatment values (P<0.001). A higher level of patient satisfaction was determined in Groups one and two compared to the ESWT group (P<0.001). Conclusion: Significant rates of satisfaction were determined in all three methods, and the corticosteroid treatment administered with the peppering method was not superior over local anesthetic applied with the same method. Although ESWT was beneficial, it was less effective than the other methods and cost higher.

Use of topical anaesthesia and peribulbar anaesthesia in Descemets membrane endothelial keratoplasty.

In instances where peribulbar anaesthesia (PBA) cannot be used, Descemet membrane endothelial keratoplasty (DMEK) surgery can be performed under topical anaesthesia (TA). We evaluated subjective pain and post-operative outcomes of DMEK surgeries performed under PBA and TA. Sixty pseudophakic patients without history of ocular comorbidities underwent DMEK surgery under either PBA or TA. PBA was performed with a single injection of 6 mL Prilocaine Hydrochloride 2% in combination with 1500 I.U. hyaluronidase. For TA, patients were given 0.4% Oxybuprocaine eye drops followed by a 2% Lidocain Hydrochloride-Gel and an intraoperative injection of a 2% Lidocaine Hydrochloride solution into the anterior chamber. All surgeries were performed by the same surgeon. Subjective pain was measured using a visual analog scale (VAS). Secondary outcomes (BCVA, duration of surgery, endothelial density, rebubbling rate) were recorded during a follow-up period of 3 months. The mean subjective pain of patients in the PBA group was 1.27 (95% CI 0.87-1.68) and 1.64 (95% CI 1.15-2.21) in the TA group. The mean duration of surgery was 402 s (95% CI 356-448) in the PBA group and 427 s (95% CI 371-483) in the TA group, p = 0.477. No major differences were observed in BCVA, endothelium density and rebubbling rate between the two groups. Anaesthesia-related side effects were more frequent in the PAB group than in the TA group. Although levels of subjective pain are lower under PBA than under TA, in selected patients without ocular comorbidities TA can achieve levels of pain acceptable for DMEK surgery.

Anaphylaxis to lidocaine and cross-reactivity to articaine and prilocaine with tolerance to bupivacaine

Anaphylaxis to lidocaine and cross-reactivity to articaine and prilocaine with tolerance to bupivacaine

Synergy between surfactants and mucoadhesive polymers enhances the transbuccal permeation of local anesthetics from freeze-dried tablets.

We report on the advance of freeze-dried mucoadhesive orodispersible tablets (ODTs) loaded with prilocaine (PRC) and lidocaine (LDC) hydrochlorides, aiming to promote noninvasive buccal anesthesia. The influences of combining biocompatible polymers (pullulan and HPMC K100 LV) and a blend of surfactants (oleic acid, polysorbate 80 and propylene glycol) acting as chemical enhancers on the permeation of such drugs through the esophageal porcine epithelium and in vitro mucoadhesion were investigated. The ODTs were also characterized in terms of average weight, thickness, pH, drug content, in vitro release, thermal behavior and scanning electronic microscopy. A dissolution test showed fast drug release within one hour. The drug release data for all ODTs fitted first order. No significant influence of the type of mucoadhesive polymer on release was observed, while the drug release from ODTs decreased in the presence of chemical enhancers. For the ODT containing pullulan the drug release mechanism was anomalous transport, whist for all others it was case-II transport. A remarkable synergic effect between pullulan and chemical enhancers on the permeation flux, lag time, and permeability coefficient of both drugs, but mainly for PRC was observed. Pullulan together with permeation enhancers also substantially improved the work of mucoadhesion as compared to HPMC. In contrast, HPMC improved drug retention in the epithelium. The novel drug delivery platform achieved by combining a freeze-drying technique, mucoadhesive biocompatible polymers, and chemical permeation enhancers displayed an effective strategy for the transbuccal delivery of PRC and LDC that can be used to improve needle-free buccal anesthesia.

Collagen from Turkey (Meleagris gallopavo) tendon: A promising sustainable biomaterial for pharmaceutical use

Collagen is the major fibrillar component and protein in both human and animal connective tissue. It is applied in medical preparations, e.g. wound dressings and tissue engineering. Meat and poultry production industries result in large amounts of organic waste, rich in collagen. Our aim was to isolate and characterize pepsin soluble collagen from turkey tendon. Structural analysis indicated the presence of α-chains from both collagen type I and III, β-dimers and γ-trimers, consistent with the estimated molecular weight of 477.3 kDa. Circular dichroism spectroscopy confirmed an intact triple helix. The collagen demonstrated excellent thermal stability, with denaturation temperatures (Tmax) at 38.5 °C and 44.5 °C and partial refolding after extensive heating. Biocompatibility was confirmed through cell viability tests. The collagen was investigated for its potential drug carrier ability. Freeze dried collagen scaffolds containing prilocaine hydrochloride and riboflavin were prepared in the presence or absence of photo-crosslinking. Photochemical crosslinking was confirmed by SEM and enhanced mechanical properties were observed. Scaffolds had a significant slower in vitro release of the active ingredient than a reference solution. Altogether, our study suggests collagen from turkey tendon as a promising sustainable biomaterial for pharmaceutical use.

Increase in pulse pressure on administration of a dental local anesthetic solution, prilocaine hydrochloride with felypressin in male diabetic patients with coronary heart disease.

This study aimed to evaluate pulse pressure fluctuation on dental local anesthetic administration in diabetic patients with and without coronary heart disease undergoing tooth extraction. This retrospective study in diabetic patients undergoing tooth extraction included 33 patients with coronary heart disease (mean age 79.3 ± 7.4, 64% male) and 49 patients without coronary heart disease (mean age 78.6 ± 6.5, 29% male). The increase in pulse pressure before and after administration of local anesthetics was compared between diabetic patients with and without coronary heart disease. Pulse pressure was increased in male diabetic patients with coronary heart disease compared with those without coronary heart disease following administration of 3% prilocaine hydrochloride with felypressin 0.03IU/mL (prilocaine) (15.6 ± 15.4mmHg in those with coronary heart disease (n = 11) versus 4.3 ± 10.9mmHg in those without coronary heart disease (n = 13), p = 0.03). Prilocaine administration increased pulse pressure in male diabetic patients with coronary heart disease compared with those without coronary heart disease. Further study is needed to reveal the mechanisms involved in the increase in pulse pressure. This is the first study of pulse pressure fluctuation in diabetic patients with and without coronary heart disease following administration of local anesthetics. Our findings can help guide the choice of local anesthetics and serve as a predictor of coronary vascular condition in diabetic patients during dental treatment.

The evaluation of the patients with methemoglobinemia due to prilocaine

The evaluation of the patients with methemoglobinemia due to prilocaine

A comparative study of different chromatographic techniques for determination of toxic impurities of some commonly used anesthetics

2,6-Dimethylaniline (DMA) and o-toluidine (TOL) are considered as toxic impurities and carcinogenic metabolites as well as hydrolytic products upon degradation process for lidocaine (LD) and prilocaine (PR), respectively. The presence of such impurities above the permutable limits can adversely affect health and cause severe complications. Three different separation techniques, namely, high-performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE), and thin-layer chromatography (TLC), were applied for the selective determination of the toxic compounds DMA and TOL and their intact drugs, LD and PR, respectively. The proposed HPLC method was carried out on Inertsil ODS 3 column (50 mm × 4.6 mm, 5 μm), utilizing a green mobile phase consisting of ethanol and 34 mM disodium hydrogen phosphate (20:80, v/v; pH = 6 adjusted using o-phosphoric acid). The flow rate was 1 mL min−1 with UV detection at 220 nm. The CZE separation was performed using 50 mM monobasic sodium phosphate (pH = 2.5), and voltage programming started with 22 kV for the first 6.7 min down to 18 kV from 6.9 min till 10 min. The suggested TLC method was achieved on TLC plates pre-coated with silica gel 60 F245 using a developing solvent containing toluene—chloroform—ethanol—triethylamine (5:5:1:0.1, by volume). These methods were validated with respect to linearity range, accuracy, precision, limit of detection, limit of quantification and robustness and were successfully applied for the determination of the two drugs in pure form and in pharmaceutical dosage form. A comparative study was held between the three chromatographic methods to evaluate the selectivity of the separation and the sensitivity, accuracy, and precision of the quantification.

Blocking ion channels induced by antifungal lipopeptide syringomycin E with amide-linked local anesthetics

The effects of the amide-linked (lidocaine (LDC), mepivacaine (MPV), prilocaine (PLC)) and ester-bound local anesthetics (benzocaine (BZC), procaine (PRC), and tetracaine (TTC)) on the pore-forming activity of the antifungal lipopeptide syringomycin E (SRE) in lipid bilayers were studied. Independently on electrolyte concentration in the membrane bathing solution the observed changes in conductance of SRE channels agreed with the altered membrane dipole potential under the action of ester-bound local anesthetics. Effects of aminoamides in diluted and concentrated solutions were completely different. At 0.1 M KCl (pH 7.4) the effects of amide-linked anesthetics were in accordance with changes in the membrane surface potential, while at 2 M KCl aminoamides blocked ion passage through the SRE channels, leading to sharp reductions in pore conductance at negative voltages and 100-fold decreases in the channel lifetimes. The effects were not practically influenced by the membrane lipid composition. The interaction cooperativity implied the existence of specific binding sites for amide-bound anesthetics in SRE channels.