Tetracaine Research Articles

Topical and subconjunctival anesthesia versus topical anesthesia alone in patients with senile cataracts undergoing phacoemulsification: a double-blind randomized controlled trial

BackgroundThis study compared topical anesthesia to a combination of topical anesthesia and subconjunctival anesthesia for phacoemulsification.MethodsThis double-blinded parallel placebo-controlled randomized trial involved senile cataract patients scheduled for phacoemulsification between May and December 2022. Patients were randomly assigned to receive either topical anesthesia with 0.5% tetracaine hydrochloride and subconjunctival balanced salt solution injection (Control group) or topical anesthesia and subconjunctival injection with 2% lidocaine (Lidocaine group). Baseline parameters, cataract grades, and various outcomes were recorded, including pain scores at specific time points, patient cooperation scores, requests for additional anesthesia, and complications. Statistical methods included Fisher’s exact test, the t-test, ordinal logistic regression, and linear regression with robust standard errors.ResultsIn total, 176 patients were included in the study after excluding 33 patients. A significant reduction in immediate postoperative pain was achieved in the Lidocaine group (p < 0.001) and was maintained for 2 h (p = 0.011). Additionally, better cooperation was observed in this group (p = 0.038). However, patients in the Lidocaine group experienced more pain during the subconjunctival injection (p = 0.001) and a significant increase in subconjunctival hemorrhage related to the injection (p < 0.001). Despite this, the rates of surgical complications were comparable between the groups, and all phacoemulsification procedures were successfully completed using the assigned anesthetic technique.ConclusionsThe addition of subconjunctival lidocaine injection to topical anesthesia reduced postoperative pain and improved patient cooperation during phacoemulsification. However, the lidocaine injection was painful, and it carried a higher risk of spontaneous-relief subconjunctival hemorrhage.Trial registrationTrial Registration Number: TCTR20220804003, date of registration August 4, 2022, retrospectively registered.

Topical anesthetics for needle-related pain in adults and children (TOPIC): a mini-review.

Healthcare professionals (HCP) perform various needle procedures that can be distressing and painful for children and adults. Even though many strategies have been proven effective in reducing distress and pain, topical anesthetic use before needle procedures is uncommon. However, there are limited studies in the existing literature comparing specifically liposomal lidocaine and tetracaine hydrochloride topical creams. This systematic review analyzed studies on the use of two anesthetic creams, Liposomal Lidocaine (Maxilene®) and Tetracaine hydrochloride (Ametop™), in children and adults undergoing a needle-related procedure. Databases searched: PubMed, CINAHL, ClinicalTrials. Only randomized controlled trials (RCT) and Controlled Clinical Trials (CCT) studies were included. Cochrane Collaboration's Risk of Bias assessment tool was used. Strictly minimally invasive procedures were included to standardize different skin needle interventions. Only one study with 60 participants was available to be included in this review. No statistically significant difference was found in the mean pain score among both interventions. The outcomes of self-reported distress during cannulation and on HCP satisfaction were not reported. However, physiological characteristics associated with stress/anxiety and on cannulation success rate were reported and did not show statistical significance. Little to no evidence regarding the most efficient cream between liposomal lidocaine and tetracaine hydrochloride for pain management during needle-related procedures was found. Further studies, particularly RCT with larger sample sizes and standardized outcome measures, are needed to confirm the relative efficacy of either anesthetic cream.

Tetracaine hydrochloride induces macrophage pyroptosis through caspase‑1/11‑GSDMD signaling pathways.

Tetracaine hydrochloride (TTC) is a long-lasting local anesthetic commonly used for topical anesthesia. Inappropriate dosage or allergic reactions to TTC can lead to local anesthetic toxicity. TTC exerts cytotoxic effects on certain cell types by inducing apoptosis and necrosis; however, the effects of TTC on macrophages are currently unclear. In the present study, the RAW 264.7 and BV2 cell lines, and murine peritoneal macrophages, were used to evaluate the cytotoxicity of TTC. The present study demonstrated that TTC caused a decrease in cell viability according to a Cell Counting Kit-8 assay, increased lactate dehydrogenase and IL-1β secretion according to ELISA, and induced morphological changes characteristic of pyroptosis according to western blotting. Moreover, TTC-induced macrophage pyroptosis was mediated by gasdermin (GSDM)D, and the cleavage of GSDMD was modulated by both caspase-1 and caspase-11. These results were experimentally validated using caspase-1 and caspase-11 inhibitors. Furthermore, it was observed that TTC and lipopolysaccharide (LPS) exerted similar effects on macrophages. However, the mechanism of induction of pyroptosis by TTC was different from that of LPS. The present study demonstrated that TTC alone could induce macrophage pyroptosis mediated by canonical and non-canonical inflammatory caspases. Therapies targeting pyroptosis may potentially provide a promising future strategy for the prevention and treatment of local anesthetic toxicity induced by TTC.

In situ enrichment and determination of 6 kinds of caine-type anesthetics in cosmetics and rat serum by thin layer chromatography-Raman spectroscopy

A simple, economical and selective method has been established for simultaneous detection of 6 kinds of caine-type anesthetics in cosmetics and rat serum by in situ enrichment thin layer chromatography (TLC) and Raman spectroscopy. The target caine-type anesthetics, procaine hydrochloride (Pro), tetracaine hydrochloride (Tet), dibucaine (Dib), mepivacaine hydrochloride (Mep), lidocaine hydrochloride (Lid) and ropivacaine hydrochloride (Rop), were separated by TLC. The original spots (or position of Rf equal to that of the standard) of anesthetics on TLC plates were in situ enriched into much smaller ones driven by solvent from different directions, and followed by Raman measurement for quanlitative and quantitative analysis, resulting in the improvement of sensitivity and selectivity. Optimization and standardization of the experimental conditions, the composition and proportion of developing solvent, were conducted. Thus a robust and reliable approach which enabled effective separation, accurate identification and quantification has been developed with the lowest detectable amounts of 0.4, 0.2, 1.2, 1, 1 and 1 μg for Pro, Tet, Dib, Mep, Lid and Rop, respectively. The established method was successfully applied in anesthetics analysis in cosmetics (essence, cream and gel) and rat serum without complex sample pretreatment processes, and the results were verified by HPLC. It turned out that the in situ enrichment TLC-Raman technique was feasible and effective for separation and determination of 6 caine-type anesthetics in biological samples and cosmetics, and would have good prospects for on-site qualitative screening of prohibited goods and adulterants.

Effect of the Clinical Usage of Tetracaine Hydrochloride Ophthalmic Solution on Multiple Antibiotic Resistant Staphylococcus Aureus

Background: The emergence of resistant strain bacteria is rendering many antibiotics ineffective in the management of infectious diseases.&#x0D; Objective: The purpose was to investigate the effect of Tetracaine hydrochloride usage on the emergence of a resistant strain of bacteria.&#x0D; Materials and methods: A total of fifteen New Zealand White rabbits of either sex weighing between 1400-2700 grams were used for this study. Infectious agents of Ophthalmia neonatorum were cultured, isolated and identified. Their susceptibility to various antibiotics was assessed. A resistant strain was picked up and inoculated on the conjunctiva of the rabbits to induce bacterial conjunctivitis. Rabbits were divided into three groups of five rabbits each. Group A received Tetracaine as treatment, group B received 0.3% Ciprofloxacin as treatment and group C received normal saline as a treatment for 14 days. Outcome measures included bacterial colony count, clinical signs and post-antibiotic susceptibility test.&#x0D; Results: The tetracaine significantly reduced clinical signs (P=0.012) compared to normal saline (control) and 0.3% Ciprofloxacin reduced clinical signs (P =0.003) compared to normal saline (control). This means there was a significant decrease in clinical scores with the interventions as compared to the normal saline which showed minimal change in clinical score. Tetracaine hydrochloride significantly reduced bacteria load (P≤0.0001). It decreased multiple antibiotic-resistant index by 20%.&#x0D; Conclusion: Tetracaine has a supplemental antibiotic effect on resistant strain of bacteria and does not worsen antibiotic resistance of bacteria. Clinical usage of tetracaine ophthalmic solution should therefore be applied after conjunctival swaps or corneal scrapping have been taken.

Investigation of an anaesthetic drug (tetracaine hydrochloride) in the presence of ionic fluid and surfactant: Mixed micellization & spectroscopic studies

The effect of ionic liquid and cationic surfactant on the physicochemical characteristic of an anaesthetic drug (tetracaine hydrochloride, TCH) has been studied in the current task. The ionic fluid (1-hexadecyl-3-methyl imidazolium chloride, SAIL) and cationic surfactant (cetylpyridinium chloride, CPC) used in this study are of the same hydrophobic chain length. Tensiometric and absorption spectroscopic methods have been castoff to study the interaction of TCH with SAIL/CPC. The critical micelle concentration (cmc) values of single and mixed amphiphiles were computed by the surface tension method. In addition to cmc, maximum surface excess concentrations (Γmax), minimum surface areas per surfactant molecule (Amin), surface tension at the cmc (γcmc), surface tension reduction efficiency (πcmc), and several thermodynamic parameters of mixed micellization were measured. The calculated average value for the interaction parameter (βRub) suggests TCH show higher synergistic interaction with SAIL compared to CPC. The better attractive interaction (synergism) between SAIL and TCH is also confirmed by UV–visible spectroscopy. The absorption spectra of the drug show increase in the absorption with increasing the concentration of surfactants without any shift confirming the formation of a new complex. The binding constant value is more for the TCH + SAIL mixture.

Characterization of seven new related impurities and forced degradation products of tetracaine hydrochloride and proposal of degradation pathway by UHPLC-Q-TOF-MS

A rapid and highly sensitive method was developed for separation and identification of the related impurities and degradation products in tetracaine hydrochloride by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). The chromatographic separation was achieved on an Agilent Infinity Lab Poroshell 120 EC-C18 column (4.6 ×100 mm, 2.7 µm) using gradient elution with mobiles phase of A (10 mM ammonium acetate buffer containing 0.1% formic acid) and B (acetonitrile) at a flow rate of 1.0 mL/min. Forced degradation experiments were also performed under acidic, alkaline, thermal, photolytic, and oxidative stress conditions following ICH guidance. The result revealed that tetracaine hydrochloride is extremely sensitive to oxidation condition and highly sensitive to alkaline/acidic hydrolysis, and susceptible to light condition. In total, five related impurities and seven degradation products were successfully detected in the positive mode of electrospray ionization. The structures of all these impurities were characterized based on the high-resolution MS data and manufacture process, and the fragmentation pathways of tetracaine and these impurities were constructed and discussed. Seven of them have not been reported before, and two of them were specified impurities described in various pharmacopoeias. The fragmentation pathways and plausible mechanisms for the formation of these impurities were proposed.

Molecular interactions of local anesthetics in aqueous MgCl2 solutions: A volumetric, acoustic and spectroscopic analysis

Investigations of the physicochemical properties of drugs in the presence of co-solutes in aqueous solutions have always been a keen interest of the researchers. Such properties are very important to derive the information about solute–solute and solute–solvent type interactions. Therefore, in this communication, various physicochemical properties of two local anesthetics viz. Procaine hydrochloride (PC) and Tetracaine hydrochloride (TC) in aqueous and in aqueous solutions of MgCl2 (mB = 0.024, 0.047, 0.070 mol kg−1) have been studied using density and sound velocity measurements at different temperatures (288.15, 298.15, 308.15, and 318.15 K) along with 1H NMR spectroscopy. Various parameters like apparent molar volume (V) and isentropic compressibility (Ks) of solutes, apparent molar volume (V°) and isentropic compressibility (Ks°) of solutes at infinite dilution, apparent molar expansibility (E°) and their double derivatives (∂2V°/∂T2)P have been evaluated using density and sound velocity data. The transfer volumes (ΔtrV°) of PC and TC drugs from water to aqueous MgCl2 solutions and the various acoustical parameters like acoustic impedance (Z), intermolecular free length (Lf), and relative association (RA) have also been computed. All these parameters have been used to throw light on the effect of temperature as well as the effect of co-solute (MgCl2) concentration on the various solute–solvent/co-solute interactions with the help of co-sphere overlap model. The structure breaker/or maker ability of both local anesthetics in the presence of MgCl2 has also been analyzed. The spectroscopic results indicate the presence of hydrophobic–ionic interactions at higher concentrations of co-solute.

Lethal intoxications of medical staff with substances used in the profession – Presentation of a group of cases

The access medical staff has to special drugs through the nature of the job can lead to undesirable situations (illicit consumption, abuse and addiction, accidental overdoses, suicide, homicide). We focus on identifying situations of lethal intoxication of the medical staff with substances used within the profession and we propose a forensic approach to these types of cases. We made a review of the literature using MEDLINE, EMBASE, Scopus, Cochrane and internet search data of deaths among nurses and doctors due to intoxication with special regime drugs used in the profession. Five cases of autopsies performed at INML “Mina Minovici” Bucharest and Ilfov Medical-Legal Service, Romania, are presented (a veterinarian, a nurse and three anesthesiologist doctors). A 27-year-old female, a veterinarian, was found dead in bed, in her apartment, next to a 10-mL syringe with an attached branch, containing 4 ml of transparent liquid. It's a case of intravenous self-administration of T61, with a suicidal intention. T61 is a solution used for animal euthanasia, a mixture of 3 substances: embutramide (opioid analgesic), mebezonium iodide (curare-compound) and tetracaine hydrochloride (local anesthetic). A 38-year-old man, a male nurse, was found dead in his home, surrounded by several empty containers of Fentanyl and Mialgin. A bag with partially empty containers of medicines was found in his car: Enalapril, Telmisartan, Mialgin, Diazepam, Fentanyl, Acupan (nefopan chloridate), Dormicum (Midazolam), syringes and needles, used, but also sealed. The cause of death was an acute intoxication with a cocktail medication (opioid analgesics and benzodiazepines), stolen from the workplace. A 37-year-old man, an anesthesiologist doctor, was found by a colleague, at 7.00 a.m, in the on call room of the hospital, at the end of his shift. The cause of death was the acute intoxication with morphine (0.448 μg/mL). A 34-year-old woman, anesthesiologist doctor, was found dead by her father, on the bathroom floor of her apartment. Next to the body were found: a 5 mL syringe with 3 mL liquid content and 2 ampoules of tramadol hydrochloride (Mabron). In the trash, there was an empty bottle of ketamine hydrochloride (Ketamidor, for veterinary use) and fragments of ampoules of Midazolam and Calypsol. More than 150 ampoules labeled with various substances used in anesthesia were found in the house. In the last period, the woman doctor was exhausted as she had been working both in the public and private system. Female, 51 years old, anesthesiologist doctor, known as a consumer of analgesic substances for about 3 years, was found dead at home by her husband, on the bedroom floor. Cause of death was acute pulmonary edema, the consequence of an acute intoxication with drugs (pethidine > 2/mL μg/mL and nordazepam 0.03 μg/mL). The paper analyzes all the findings: the on-site investigations (extremely important to gather information), the necropsy data and the results of the histopathological, toxicological, tanatochemical and serological examinations. The analytical methods currently used for highlighting and dosing the identified substances are also presented. Autopsy findings were nonspecific, except for the stigma of chronic injectable drug use. That is why an algorithm for step by step approaching these types of cases could be very useful in order not to go beyond the possibility of an acute drug intoxication of medical staff. Nurses and doctors are vulnerable to chemical dependence due to the high work-related stress associated with easy access to medicines. This must always be suspected by the forensic doctors when they perform an autopsy of a medical staff person and they must follow a special algorithm in such cases.

Synergistic Interaction and Binding Efficiency of Tetracaine Hydrochloride (Anesthetic Drug) with Anionic Surfactants in the Presence of NaCl Solution Using Surface Tension and UV-Visible Spectroscopic Methods.

Surfactants are ubiquitous materials that are used in diverse formulations of various products. For instance, they improve the formulation of gel by improving its wetting and rheological properties. Here, we describe the effects of anionic surfactants on an anesthetic drug, tetracaine hydrochloride (TCH), in NaCl solution with tensiometry and UV–visible techniques. Various micellar, interfacial, and thermodynamic parameters were estimated. The outputs were examined by using different theoretical models to attain a profound knowledge of drug–surfactant mixtures. The presence of attractive interactions among drug and surfactant monomers (synergism) in mixed micelle was inferred. However, it was found that sodium dodecyl sulfate (SDS) showed greater interactions with the drug in comparison to sodium lauryl sarcosine (SLS). The binding of the drug with surfactants was monitored with a spectroscopic technique (UV–visible spectra). The results of this study could help optimize the compositions of these mixed aggregates and find the synergism between monomers of different used amphiphiles.

Rapid and sensitive simultaneous separation and electrochemical detection of tetracaine hydrochloride and oxymetazoline hydrochloride in pharmaceutical formulations via core-shell reversed-phase liquid chromatography

Tetracaine hydrochloride (TCH) is a nasal anesthetic and oxymetazoline hydrochloride (OZH) is a nasal decongestant. A moderate to acute overdosage of OZH and TCH can lead to mydriasis, nausea, cyanosis, tachycardia, dyspnoea, cardiovascular failure, disorientation, seizures, and even death. Liquid chromatography (LC) has been mainly utilized for the individual determination of either TCH or OZH; however, there is a need for rapid and efficient methods for simultaneous analysis in pharmaceutical formulations and aqueous samples. This study highlights the use of the fast and efficient separation capabilities of core-shell silica particles in liquid chromatography (LC) for the simultaneous determination of TCH and OZH using UV detection and the enhanced selectivity afforded by electrochemical detection at a boron-doped diamond (BDD) electrode. Rapid reversed-phase (RP) separation and detection of OZH and TCH in nasal spray and eye drops was achieved within 45 s using a poroshell 120 EC-C18 column, by adjusting the ratio of organic solvent, mobile phase pH, detection potential and mobile phase flow rate. Sensitivity was compared using ultraviolet (UV) detection at 280 nm, and ECD at + 1.3 V with detection limits of 40 and 70 nM for TCH and OZH, respectively. The developed rapid method was utilized successfully in the analysis of pharmaceutical formulations, where the estimated levels of TCH and OZH in these formulations are in agreement with the specified values outlined by the manufacturers.

Mixed Micellization, Thermodynamic and Adsorption Behavior of Tetracaine Hydrochloride in the Presence of Cationic Gemini/Conventional Surfactants.

In this approach, tensiometry and UV-visible techniques are used to determine the effect of cationic gemini and conventional surfactants on tetracaine hydrochloride (TCH), an anesthetic drug. We have estimated micellar, interfacial, and energetic constraints. To gain a deep understanding of their mixed association behavior, the outputs were examined using different theoretical models. The critical micelle concentration for single and mixed amphiphiles was estimated. The cmc values of mixed amphiphiles were found between the individual amphiphiles due to strong attractive interaction (synergism) between the components after mixing. The non-ideal behavior of mixtures was confirmed by the larger values of ideal cmc than the experimental cmc values. The negative values of interaction parameter (β) and values of activity coefficients less than unity indicate strong synergistic interaction between drug and surfactant. The stability of the mixed systems is demonstrated by the negative Gibbs free energy of micellization and excess free energy of micellization. In contrast to a single chain surfactant, a double chain surfactant (gemini) exhibits better interactions with the drug. Spectral measurements (UV-visible spectra) were used to monitor the binding of the drug with surfactant (conventional as well as gemini). Studying these mixed aggregates could help to optimize their compositions and find synergistic properties between TCH monomers and surfactants.

Characterization of the Salt and Free Base of Active Pharmaceutical Ingredients Based on NMR Relaxometry Measured by Time Domain NMR.

NMR relaxometry measurement by time domain NMR (TD-NMR) is a promising technique for characterizing the properties of active pharmaceutical ingredients (APIs). This study is dedicated to identifying the salt and free base of APIs by NMR relaxometry measured by the TD-NMR technique. Procaine (PC) and tetracaine (TC) were selected as model APIs to be tested. By using conventional methods including powder X-ray diffraction and differential scanning calorimetry, this study first confirmed that the salt and free base of the tested APIs differ from each other in their crystalline form. Subsequently, measurements of T1 and T2 relaxation were performed on the tested APIs using TD-NMR. The results demonstrated that these NMR relaxometry measurements have sufficient capacity to distinguish the difference between the free base and salt of the tested APIs. Furthermore, quantification of the composition of the binary powder blends consisting of salt and free bases was conducted by analyzing the acquired T1 and T2 relaxation curves. The analysis of the T1 relaxation curves provided a partly acceptable estimation: a good estimation of the composition was observed from PC powders, whereas for TC powders the estimation accuracy changed with the free base content in the binary blends. For the analysis on T2 relaxation curves, a precise estimation of the composition was observed from all the samples. From these findings, the NMR relaxometry measurement by TD-NMR, in particular the T2 relaxation measurement, is effective for evaluating the properties of APIs having different crystalline forms.

Tetracaine hydrochloride induces cell cycle arrest in melanoma by downregulating hnRNPA1

Recent evidence suggests potential benefits of applying local anesthetics in cancer patients. Specifically, tetracaine has a potent antitumor effect in diverse cancers, including neuroblastoma, breast cancer, and melanoma; however, the underlying molecular mechanisms remain unclear. Here, we reported that tetracaine hydrochloride inhibited the growth of melanoma cells and arrested melanoma cells in the G0/G1 phase. Tetracaine hydrochloride treatment resulted in translocation of hnRNPA1 from the nucleoplasm to the nuclear envelope and reduced the protein stability of hnRNPA1 possibly by disrupting the dynamic balance of ubiquitination and neddylation. Elevated hnRNPA1 upregulated cyclin D1 to promote cell cycle in melanoma. The hnRNPA1 overexpression attenuated the effect of tetracaine hydrochloride on melanoma cell growth suppression and cell cycle arrest. Furthermore, melanoma homograft experiments demonstrated that tetracaine hydrochloride suppressed melanoma growth, while hnRNPA1 overexpression alleviated tetracaine's antitumor effect on melanoma. Taken together, our findings suggest that tetracaine hydrochloride exerts a potent antitumor effect on melanoma both in vitro and in vivo, and the effect involves cell cycle arrest induction via downregulation of hnRNPA1.

Age and Sex Variation in the Duration of Action and Corneal Touch Threshold (CTT) following Instillation of 0.5% Topical Ophthalmic Proparacaine and Tetracaine Hydrochlorides.

Purpose We investigated the effect of age and sex on corneal touch threshold (CTT) and duration of action following administration of 0.5% topical ophthalmic proparacaine and tetracaine hydrochlorides. Methods A prospective, randomized, subject-masked, crossover study design was used. Two hundred and forty human volunteers were enrolled in the study. Corneal touch threshold (CTT) was determined using a Cochet-Bonnet esthesiometer. CTT was measured every 15 seconds for the first 1-minute and at 5-minute intervals subsequently for a period of 40 minutes after the application of each anesthetic. CTT and duration of action of the ophthalmic solutions were tested for statistical significance using repeated measures ANOVA. Results The total duration of effect was 20 minutes for females and 25 minutes for males for both anesthetics. The total duration of the effect of both solutions decreased with increasing age; however, elderly participants had the longest duration (5 minutes) of the maximal effect (minimum CTT) of the two ophthalmic preparations. There was a significant influence of sex, F (2.39, 569.65) = 2.86, p=0.04; F (3.48, 828.19) = 4.41, p=0.003, and age, F (4.78, 566.18) = 8.97, p < 0.001; F (7.19, 852.56) = 20.55, p < 0.001 on CTT following application of proparacaine hydrochloride and tetracaine hydrochloride, respectively. Conclusion CTT and duration of anesthetic effect after instillation of 1 drop of 0.5% proparacaine hydrochloride and 0.5% tetracaine hydrochloride vary based on sex and age.

Effect of Carbon Chain Length, Ionic Strength, and pH on the In Vitro Release Kinetics of Cationic Drugs from Fatty-Acid-Loaded Contact Lenses.

This paper explores the use of fatty acids in silicone hydrogel contact lenses for extending the release duration of cationic drugs. Drug release kinetics was dependent on the carbon chain length of the fatty acid loaded in the lens, with 12-, 14- and 18-carbon chain length fatty acids increasing the uptake and the release duration of ketotifen fumarate (KTF) and tetracaine hydrochloride (THCL). Drug release kinetics from oleic acid-loaded lenses was evaluated in phosphate buffer saline (PBS) at different ionic strengths (I = 167, 500, 1665 mM); the release duration of KTF and THCL was decreased with increasing ionic strength of the release medium. Furthermore, the release of KTF and THCL in deionized water did not show a burst and was significantly slower compared to that in PBS. The release kinetics of KTF and THCL was significantly faster when the pH of the release medium was decreased from 7.4 towards 5.5 because of the decrease in the relative amounts of oleate anions in the lens mostly populated at the polymer–pore interfaces. The use of boundary charges at the polymer–pore interfaces of a contact lens to enhance drug partition and extend its release is further confirmed by loading cationic phytosphingosine in contact lenses to attract an anionic drug.

Binding behaviour of hydrophobic drug tetracaine hydrochloride used as organic counterion on ionic surfactants

Many excipients have been used in the formulation of medications to improve drug properties during the drug delivery process. Current research may show that hydrophobic drugs can be used as organic counterions that improve the excipients properties of the medicine formulation. We have used the anesthetic cationic drug tetracaine hydrochloride (TC) as an organic counterion and anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and sodium dodecyl sulfate (SDS) for this system. In aqueous media, TC significantly reduced the critical micelle concentration (CMC) of AOT and SDS. The counterion binding (B) and binding constant (Kb) values revealed that AOT micelles had a stronger interaction with TC than SDS micelles. Therefore, TC as an organic counterion could improve the micellization of surfactants. The UV spectroscopy experiment has also been used to estimate the TC mean ion occupancy (i0) per AOT/SDS micelles. We found that i0 values were 113.6 and 23.27 for AOT and SDS, respectively. These results indicated the i0 values were controlled by electrostatic interaction between drug and surfactants. Dynamic light scattering (DLS) and Transmission electron microscopy (TEM) measurement provided that the catanionic vesicle was formed with increased TC concentration. Finally, we concluded that the above formulation could be used to enhance interaction properties between the medicine and excipients in the pharmaceutical application.

Effect of topical 0.5% tetracaine hydrochloride on intraocular pressure in ophthalmologically normal cats.

The aim of this study was to assess the effect of topical tetracaine hydrochloride 0.5% on intraocular pressure (IOP) in ophthalmologically normal cats. Twenty domestic shorthair cats (40 eyes) were used in this study. Each cat was randomly allocated to one of two groups (treatment or control). Baseline IOP (T0) was measured in each cat, and then one drop of tetracaine hydrochloride 0.5% or artificial tears was administered into a randomly chosen eye of each cat in the treatment and control groups, respectively. Repeat IOP measurements were performed at 2 mins (T2), 5 mins (T5), 15 mins (T15) and 30 mins (T30) with a rebound tonometer. Mean baseline IOP in all eyes was 20.6 ± 2.5 mmHg. After the unilateral administration of tetracaine, mean IOP decreased significantly in the treated eye at T2 (P = 0.01). Mean IOP returned to baseline values at T15. The mean IOPs in the treated eyes at T0, T2, T5, T15 and T30 were 20.6 ± 3.3 mmHg, 18.2 ± 2.5 mmHg, 18.2 ± 3.4 mmHg, 20.2 ± 3.2 mmHg and 19.8 ± 2.7 mmHg, respectively. A significant difference in IOP was found at all time points between the tetracaine and control groups (P <0.03). The results of the present study showed a statistically significant reduction in mean IOP 2 mins after the administration of tetracaine hydrochloride 0.5% in the treated eyes of the cats.

Influence of surface anesthesia of the nasal cavity on oral tissues in the anterior region - a pilot study.

Nasal surface anesthesia is a simple, non-invasive method with a not yet fully understood effect on oral tissues. Should it prove to be successful in dental medicine, it could replace or at least complement the more invasive injection anesthesia, especially in children after dental trauma. The local anesthetic Tenaphin (tetracaine hydrochloride and naphazoline nitrate) was applied to 105 patients prior to ear, nose and throat medical diagnosis or therapy. After different exposure times, the influence on the oral tissues in the anterior region was examined by a dentist in the context of a pilot study. The effect of the mucosal anesthesia increased in the canine and anterior region the further mesial the tooth was located and the longer the application time was. In the buccal and palatinal area the effect increased from apical to incisal. The pulps of the central incisors and the canines were better anesthetized than those of the lateral incisors. Nasal surface anesthesia has the potential to replace the more invasive injection anesthesia in the anterior region of the upper jaw or to complement it. Dosage and exposure time will have to be investigated in more detail.

Binding Interactions Between Tetracaine Hydrochloride and Biocompatible Imidazolium-Based Gemini Surfactants in Aqueous Solutions

The low solubility of drugs in an aqueous medium causes their precipitation before reaching the specific target sites leading to various undesirable side effects. Thus, there is a need for designing and formulating delivery agents which not only carry a drug to its site of action but also improve its solubility. The study of interactions between a drug and its carrier becomes significant. Pertinently, the present study encompasses the interactions between aqueous solutions of a local anesthetic drug, tetracaine hydrochloride (TC) and a non-cytotoxic imidazolium gemini surfactant, [CnIm-3OH-ImCn]Br2 (n = 12, 14, 16). The results were established on the basis of various parameters calculated from measurements using conductivity, fluorescence, UV–visible spectroscopy and cyclic voltammetry (CV). The parameters obtained from conductivity measurements showed attractive interactions (synergism) between TC and [CnIm-3OH-ImCn]Br2 whereas the UV–visible and CV measurements indicated a 1:1 stoichiometry in their complex formation. The binding of drug with gemini surfactants was found to decrease as the surfactant chain length increases. The hydrophobic, cation-π and H-bonding modes of interactions between drug and gemini surfactant aid in their binding process. The antibacterial activity of gemini surfactants was tested against both strains (gram-positive and gram-negative) of bacteria and found to be effective. Thus, these interaction studies offer new opportunities to bring about advancements in the biomedical and pharmaceutical fields.