A Bilayer Microneedle for Modulated Sequential Release of Adrenaline and Lidocaine for Prolonged Local Anesthesia

Chronic pain emerges as a major global health issue, significantly impacting individuals' health and quality of life. In this study, we designed a bilayer microneedle loaded with lidocaine nanocomposites in the inner layer and adrenaline (Adr) in the outer layer (HCP MNs) for modulated sequential release to achieve prolonged local anesthesia. The obtained HCP MNs featured an intact structure with adequate mechanical strength for efficient skin penetration. The bilayer structure of MNs was evidenced by loading two fluorescent dyes in each layer. Furthermore, these HCP MNs were capable of inducing rapid as well as prolonged local anesthetic effects in guinea pigs. Hence, the bilayer MN coloaded with Adr and lidocaine nanocomposite serves as a promising transdermal delivery platform for chronic pain management.

An isocratic RP-HPLC-UV method for simultaneous quantification of tizanidine and lidocaine: application to in vitro release studies of a subcutaneous implant

Implantable devices have been widely investigated to improve the treatment of multiple diseases. Even with low drug loadings, these devices can achieve effective delivery and increase patient compliance by minimizing potential side effects, consequently enhancing the quality of life of the patients. Moreover, multi-drug products are emerging in the pharmaceutical field, capable of treating more than one ailment concurrently. Therefore, a simple analytical method is essential for detecting and quantifying different analytes used in formulation development and evaluation. Here, we present, for the first time, an isocratic method for tizanidine hydrochloride (TZ) and lidocaine (LD) loaded into a subcutaneous implant, utilizing reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with a UV detector. These implants have the potential to treat muscular spasticity while providing pain relief for several days after implantation. Chromatographic separation of the two drugs was accomplished using a C18 column, with a mobile phase consisting of 0.1% TFA in water and MeOH in a 58 : 42 ratio, flowing at 0.7 ml min-1. The method exhibited specificity and robustness, providing accurate and precise results. It displayed linearity within the range of 0.79 to 100 μg ml-1, with an R2 value of 1 for the simultaneous analysis of TZ and LD. The developed method demonstrated selectivity, offering limits of detection and quantification of 0.16 and 0.49 μg ml-1 for TZ, and 0.30 and 0.93 μg ml-1 for LD, respectively. Furthermore, the solution containing both TZ and LD proved stable under various storage conditions. While this study applied the method to assess an implant device, it has broader applicability for analysing and quantifying the in vitro drug release of TZ and LD from diverse dosage forms in preclinical settings.

Discovery of a Novel Lidocaine Metabolite by Human Liver Microsome and Identification of Microbial Species Which Produces the Same Metabolite

Preparation of drug metabolites at the milligram scale is essential for determining the structure and toxicity of drug metabolites. However, their preparation using recombinant proteins and human liver microsomes (HLM) is often difficult because of technical and ethical issues. Reproducing human drug metabolism in food-derived microorganisms may be useful for overcoming these challenges. In this study, we identified an unknown metabolite of the anaesthetic drug lidocaine, which is metabolised by HLM. By screening for lidocaine metabolic activity in five types of foods (blue cheese, shiitake mushroom, natto, yoghurt, and dry yeast), we found that bacteria isolated from natto reproduced the lidocaine metabolic reaction that occurs in HLM. A fraction containing the unknown lidocaine metabolite was prepared through mass cultivation of a Bacillus subtilis standard strain, ethyl acetate extraction, open column chromatography, and HPLC purification. We identified the unknown metabolite as 3-(2,6-dimethylphenyl)-1-ethyl-2-methyl-4-imidazolidinone using NMR. Our results showed that food-derived microorganisms can produce large amounts of human drug metabolites via large-scale cultivation. Additionally, food microorganisms that can reproduce drug metabolism in humans can be used to examine drug metabolites at a low cost and without ethical issues.

A simple, fast, and cost-effective smartphone-based digital imaging method for quantification of lidocaine hydrochloride in pharmaceutical formulations

OBJECTIVE

A simple, highly specific, accurate and fast method by smartphone-based digital imaging was developed for estimating lidocaine hydrochloride in pharmaceutical formulations.

MATERIAL AND METHODS

To obtain the images, a Galaxy A03 Core smartphone and an image acquisition device developed in the laboratory were used to control the incident factors in reproducibility of the measurements. The processing of the images was carried out with the Color Grab application. Finally, the absorbance values were calculated using the RGB intensity values of blank, standard, and sample solutions. The proposed method was compared with spectroscopic and chromatographic methods.

RESULTS

The reaction between copper and lidocaine hydrochloride was characterized, showing better results in an equimolar ratio and maintaining the pH of the solution above 11.5. The use of the device for the capture of digital images allowed to control those sensitive parameters for reproducibility so that the analytical measurements showed adequate precision and accuracy. Validation of the main parameters of the method showed compliance with acceptance criteria. The application of the method for the analysis of injectable samples achieved reliable results, which were statistically similar to other reference instrumental methods.

CONCLUSION

The proposed method presented figures of merit in relation to linearity, precision, selectivity, accuracy, and robustness; it was carried out by designing and manufacturing a device for capturing digital images on a smartphone, which were analyzed to obtain RGB intensity values. These data are finally used to calculate absorbance values of solutions. All these elements provide this work with innovative characteristics in the field of analysis for control of pharmaceutical formulations.

In situ drug release measuring in α-TCP cement by electrochemical impedance spectroscopy

The use of drug delivery systems is a good technique to leave the right quantity of medicine in the patient's body in a suitable dose, because the drug application is delivered directly to the affected region. The current techniques such as HPLC and UV-Vis for the drug delivery calculation has some disadvantages, as the accuracy and the loss of the sample after characterization. With the aim of reducing the amount of material used during the characterization and have a non-destructive test with instantaneous results, the present paper shows the possibility of using electrochemical impedance spectroscopy (EIS) to have a drug delivery measurement during the release phenomena for a calcium phosphate cement (CFC) delivery system with gentamicin sulfate (GS) and lidocaine hydrochloride (LH), at a ratio of 1% and 2%, respectively. The equivalent circuit and the chemical mechanism involved during the measurements have been proposed as a tool to determine the drug delivery profile. The method has been compared with the UV-Vis technique. XRD was realized to verify conditions, before and after release. It was possible to verify the potential for using EIS as an instant technique to quantify drug delivery.

Immediate Use After Reconstitution of a Biostimulatory Poly-L-Lactic Acid Injectable Implant

BACKGROUND

Poly-L-lactic acid (PLLA) is a biodegradable, synthetic polymer that stimulates collagen production and can improve skin quality, volume, and thickness. The current reconstitution procedure for Sculptra, a PLLA-containing injectable device involves 2 hours standing time before use.

OBJECTIVE

To evaluate and validate an immediate-use procedure for reconstituting a PLLA-containing injectable device.

METHODS AND MATERIALS

Three batches of the product were shaken for 1 minute immediately after reconstitution with 8 mL of sterile water. Different physicochemical tests including viscosity, concentration of excipients (sodium carboxymethylcellulose and mannitol), pH, and particle size distribution were performed for standing times 0, 2, 24, and 72 hours after immediate shaking, and compared with the standard 2 hours standing time before shaking. The recovery and stability of optional addition of 1 mL of 2% lidocaine hydrochloride was also assessed.

RESULTS

All physiochemical parameters evaluated were equivalent, regardless of reconstitution procedure, showing that shaking vigorously for 1 minute dissolves the excipients of the product properly without a required standing time and with no impact to the PLLA particles. There were no differences in lidocaine hydrochloride content of suspensions after 0 and 72 hours.

CONCLUSION

The PLLA-containing product can be used immediately after reconstitution including vigorous shaking, as shown from physicochemical analyses. Optional addition of lidocaine hydrochloride is feasible. J Drugs Dermatol. 2020;19(12): doi:10.36849/JDD.2020.5228.

Topical Drug Delivery Systems Based on Bacterial Nanocellulose: Accelerated Stability Testing

Bacterial nanocellulose (BNC) membranes have enormous potential as systems for topical drug delivery due to their intrinsic biocompatibility and three-dimensional nanoporous structure, which can house all kinds of active pharmaceutical ingredients (APIs). Thus, the present study investigated the long-term storage stability of BNC membranes loaded with both hydrophilic and lipophilic APIs, namely, caffeine, lidocaine, ibuprofen and diclofenac. The storage stability was evaluated under accelerated testing conditions at different temperatures and relative humidity (RH), i.e., 75% RH/40 °C, 60% RH/25 °C and 0% RH/40 °C. All systems were quite stable under these storage conditions with no significant structural and morphological changes or variations in the drug release profile. The only difference observed was in the moisture-uptake, which increased with RH due to the hydrophilic nature of BNC. Furthermore, the caffeine-loaded BNC membrane was selected for in vivo cutaneous compatibility studies, where patches were applied in the volar forearm of twenty volunteers for 24 h. The cutaneous responses were assessed by non-invasive measurements and the tests revealed good compatibility for caffeine-loaded BNC membranes. These results highlight the good storage stability of the API-loaded BNC membranes and their cutaneous compatibility, which confirms the real potential of these dermal delivery systems.

Saline vs. dextrose for local anesthetic dilution in brachial plexus block: A randomized study

Higher sodium ions in saline diluted local anesthetic may reduce the anesthetic action of the drug as injected around the nerves. However, the impact of local anesthetic dilution agents on the quality of peripheral nerve blockades has not yet been widely investigated. This study was aimed at evaluating the impact of lidocaine dilution with normal saline vs dextrose 5% on onset time of supraclavicular approach to brachial plexus block. Sixty American Society of Anesthesiologists class 1or2 patients, scheduled for elective upper extremity surgeries under sono-guided supraclavicular block were randomly assigned to receive lidocaine 2% diluted with either dextrose 5% or normal saline. At the end of lidocaine injection, sensory and motor blocks were evaluated at 5 min intervals for 30 min in the areas innervated by median, radial, ulnar and musculocutaneous nerves. Block onset time and number of patients with complete sensory or motor blockade were similar in both groups. Lidocaine diluted with either normal saline or dextrose 5% produces comparable sensory and motor block onset time and success rate in ultrasound guided supraclavicular block.

Effect Of Lignocaine Addition On The Properties Of Irreversible Hydrocolloid Impression Material

BACKGROUND

Irreversible hydrocolloid impression materials have been a staple in dentistry and useful for the fabrication of dental prosthesis. Gagging is most commonly experienced during maxillary impression making, which may affect the clinical management of the patient. Different techniques have been described to alleviate this problem. One of them is mixing lignocaine local anesthetic solution in irreversible hydrocolloid impression material before making the impression. The objective of this study was to evaluate the effect of lignocaine addition in irreversible hydrocolloid impression on the properties of irreversible hydrocolloid impression materials.

METHODS

Irreversible hydrocolloid was mixed with water (Control group) or water and adrenalin (Lidocaine hydrochloride) (Experimental group). Compressive strength, tear strength and setting time were measured according to ISO1567 and ANSI/ADA specifications 18. The structural analysis of both groups was also evaluated by Fourier Transform Infrared Spectroscopy (FTIR).

RESULTS

In the experimental group, insignificant decrease was observed in compressive and tear strength of irreversible hydrocolloid (p>0.05). There was significant (p<0.05) increase in setting time of irreversible hydrocolloid impression material. FTIR analysis indicated no change in chemistry of irreversible hydrocolloid before and after setting.

CONCLUSIONS

Addition of lignocaine in irreversible hydrocolloid impression material may result in control of gag reflex without affecting its mechanical and chemical properties.

A novel lidocaine hydrochloride mucoadhesive films for periodontal diseases

Periodontal diseases are inflammatory disorders caused primarily by dental plaque microorganisms that even may need surgery to remove damaged tissue. Adhesive biocompatible films may be an adequate form in order to improve drug retention or prevent microbial infections by covering the surgical site. In recent years, much attention has been focused on biocompatible inexpensive polymers, for biomedical and pharmaceutical potential applications. The objective of this research is the development of a film for mucosal application containing lidocaine hydrochloride (5%, w/w) as anesthetic drug. Lidocaine films were prepared with three biopolymers: hydroxypropylmethylcellulose (HPMC), chitosan (CH), or xanthan gum (XG). Their thickness and uniformity content were characterized. Rheological behavior of the hydrated films was studied using flow curves, creep and recovery tests and dynamic oscillatory measurements with a rheometer. The mucoadhesive assays were carried out with cheeks of Wistar rat using a universal tensile tester to know their adhesiveness. Finally, lidocaine delivery through the films was investigated in Franz cells. All films (n = 3 for each polymer) showed flexibility, a drug content of 0.015 ± 0.001 g/cm² and a thickness of 0.25 ± 0.01 mm. The results of the maximum detachment force in tensile tests and work adhesion indicated that XG is the polymer that showed greater power of mucoadhesion (p < 0.05). These properties show a good correlation with the rheological characteristics. In all cases, the lidocaine amount released at 30 min is around 4 mg/cm². This amount could be considered sufficient to guarantee the anesthetic effect.

Open-Label, Post-Marketing Study to Evaluate the Performance and Safety of Calcium Hydroxylapatite With Integral Lidocaine to Correct Facial Volume Loss

Background: Calcium hydroxylapatite (CaHA, Radiesse®) with integral 0.3% lidocaine (CaHA(+)) has recently been approved for use in aesthetic medicine. This study assessed the performance of CaHA(+) in subjects undergoing treatment for facial volume loss and evaluated subject and physician satisfaction. Methods: In a prospective, open-label, post-marketing study, 25 women seeking treatment for age-related facial volume loss received CaHA(+) injections in 1–3 facial areas including the cheeks, marionette lines, prejowl sulcus, and jawline. Subjects returned for follow-up at 14 and 120 days, with the option of touch-up injections at day 14 if required to achieve optimal correction. Filler performance was assessed using the Merz Aesthetics Scales (MAS) and subject satisfaction using the Global Impression of Change Scale (GICS). Physician satisfaction was assessed in terms of CaHA(+)-related properties (eg, ease of injection, distribution, positioning) and aesthetic outcomes. Adverse events were recorded. Results: Mean MAS scores at baseline were ~2 corresponding to moderate facial volume loss/sagging in the treated area. At day 14, the mean score had improved to ≤1.4 for all treated areas, indicating mild volume loss. At day 120, mean scores had further improved to ≤1.1. At both follow-up visits, mean GICS scores were ≥2 indicating facial appearance was ‘much improved’ compared with baseline. All subjects reported willingness to repeat treatment and recommend it to family/friends. Physician ratings were high for ease of CaHA(+) injection, distribution, positioning, sculpturing outcome, and effect on skin tension. Compared to CaHA without lidocaine, the physician rated CaHA(+) as better or similar in performance. Adverse events were mostly mild and expected with CaHA and filler injections in general. Conclusion: The well-established efficacy and safety profile of CaHA appears unchanged by the addition of integral lidocaine. CaHA(+) was effective for volume enhancement in a number of facial areas and associated with high subject and physician satisfaction. J Drugs Dermatol. 2019;18(1):86-91.

Simultaneous Determination of Dexpanthenol, Lidocaine Hydrochloride, Mepyramine Maleate and their Related Substances by a RP-HPLC Method in Topical Dosage Forms

The pharmaceutical combination of dexpanthenol (DPA), lidocaine hydrochloride (LIH) and mepyramine maleate (MAM) is used for their anti-allergic, anti-inflammatory, anti-pruritic, anesthetic and antiseptic properties. The present study was aimed to develop and validate a new, first and rapid high performance liquid chromatographic method for simultaneous determination of DPA, LIH and MAM in the presence of their stress-induced degradation products in pharmaceutical gel/fluigel formulations. The chromatographic separation was performed on an Inertsil ODS-3 V, 250 × 4.6 mm (5 μm) column using a gradient mobile phase of an aqueous solution of ammonium acetate (0.01 M) and methanol mixture at gradient flow rates of 1.3 mL/min and 1.5 mL/min with detection at 230 nm. The retention times for DPA, LIH and MAM were ~3.28 min, 11.67 min and 12.99 min, respectively. The method was validated in accordance with International Conference on Harmonisation guidelines. Calibration curves were linear in the ranges of 9-54 μg/mL for MAM and LIH and 30-180 μg/mL for DPA with satisfactory correlation coefficients (R2 > 0.999). The mean % recoveries obtained were found to be 99.9% for MAM, 100.3% for LIH and 99.3% for DPA. Precision % RSD was <2. Robustness results were uniform, there were no marked changes, so method is highly validated. All drugs were subjected to stress conditions and degradation products were separated with acceptable peak tailing (T ≤ 2) and good resolution (Rs > 2). The validated method therefore can be adapted for quality control procedures of the drugs in pharmaceutical dosage forms and their stability studies.

Nanohybrid hydrogels designed for transbuccal anesthesia

BACKGROUND

Local anesthesia in dentistry is by far the most terrifying procedure for patients, causing treatment interruption. None of the commercially available topical formulations is effective in eliminating the pain and phobia associated to the needle insertion and injection.

MATERIALS AND METHODS

In this work we prepared a nanostructured lipid-biopolymer hydrogel for the sustained delivery of lidocaine-prilocaine (LDC-PLC) for transbuccal pre-anesthesia. The lipid was composed of optimized nanostructured lipid carriers (NLC) loaded with 5% LDC-PLC (NLC/LDC-PLC). The biopolymer counterpart was selected among alginate, xanthan (XAN), and chitosan matrices. The XAN-NLC hydrogel presented the most uniform aspect and pseudoplastic rheological profile, as required for topical use; therefore, it was selected for subsequent analyses. Accelerated stability tests under critical conditions (40°C; 75% relative humidity) were conducted for 6 months, in terms of drug content (mg/g), weight loss (%), and pH.

RESULTS

In vitro LDC-PLC release profile through Franz diffusion cells revealed a bimodal kinetics with a burst effect followed by the sustained release of both anesthetics, for 24 hours. Structural analyses (fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy) gave details on the molecular organization of the hybrid hydrogel, confirming the synergic interaction between the components. Safety and efficacy were evaluated through in vitro cell viability (3T3, HaCat, and VERO cells) and in vivo antinociceptive (tail-flick, in mice) tests, respectively. In comparison to a control hydrogel and the eutectic mixture of 5% LDC-PLC cream (EMLA®), the XAN-NLC/LDC-PLC hybrid hydrogel doubled and quadrupled the anesthetic effect (8 hours), respectively.

CONCLUSION

Considering such exciting results, this multifaceted nanohybrid system is now ready to be further tested in clinical trials.

Rheological Properties of Several Hyaluronic Acid-Based Gels: A Comparative Study

BACKGROUND

Adding lidocaine to hyaluronic acid (HA)-based gels appeared to modify their rheological properties, in the view of the first author.

OBJECTIVE

This paper sought to compare the rheological properties of three CE-marked and FDA-approved gels, administered with and without lidocaine, along with two other newly FDA-approved gels.

METHODS

The tested gels were as follows: NASHA® Restylane® with and without lidocaine; CPM®; Belotero® Balance with and without lidocaine; 3-D Matrix®; Surgiderm® 30XP (without lidocaine) and Juvederm® Ultra 3- Juvederm® Ultra Plus XC (with lidocaine); Preserved Network® RHA®2 (with lidocaine); Vycross® Volbella® (with lidocaine). For rheological analyses, viscoelastic data were collected with plate-plate geometry of 25mm, temperature regulated by a Peltier-effect plate, and the following assessed: Strain sweep from 0.01% to 3000% strain at 1Hz over frequency sweep from 0.1 to 100 Hz.

RESULTS

NASHA Restylane gels with and without lidocaine exhibited similar viscoelastic characteristics, with very similar tan δ values, but the elastic modulus G' proved significantly higher when the gel was injected with lidocaine vs without. 3D-Matrix Surgiderm 30XP gel without lidocaine and Juvéderm Ultra 3 with lidocaine exhibited similar viscoelastic characteristics, as well as tan δ values, yet the elastic modulus G' of Surgiderm 30XP proved significantly higher than that of Juvederm Ultra 3-Juvederm Ultra Plus XC. CPM Belotero Balance gels with and without lidocaine exhibited similar G' and G'' values. tan δ was somewhat higher when the gel was administered without lidocaine. VYCROSS Volbella gel exhibited a higher elastic modulus G' than the other Allergan gels, roughly nearing the NASHA gel values. Preserved Network RHA 2 gel exhibited values that were close to its partially cohesive "competitors", except for Vycross.

CONCLUSION

Adding lidocaine to HA gels does modify their rheological properties yet this, to a variable extent depending on the product. J Drugs Dermatol. 2018;17(9):948-954.

Fluorescent Imaging Evaluation of Lidocaine Distribution Following Bier Block in the Upper Extremity

INTRODUCTION

Bier block regional anesthesia has been used as an alternative to general anesthesia for years. Despite multiple theories and multiple techniques to delineate the location of the action of lidocaine during Bier block anesthesia, there has not been a consensus on the location of action. The purpose of this study was to use fluorescent imaging to further investigate the site of action of lidocaine during Bier block.

MATERIALS AND METHODS

Three patients with carpal tunnel syndrome underwent open carpal tunnel release with Bier block anesthesia performed in the standard fashion with 1cc of Indocyanine green (IcG) mixed with lidocaine. Fluorescent images were obtained at the time of injection and after 10 minutes to allow patients to reach the level of surgical anesthesia. Repeated imaging was obtained at the time of completion of the procedure or at 30 minutes of tourniquet time.

RESULTS

At time 0, IcG was distributed along the superficial venous system of the hand and forearm. At 10 minutes, the distribution of IcG was within the capillary system and infiltrating the dermis. The distribution later saturated the capillary beds and remained present until release of the tourniquet.

CONCLUSIONS

The authors demonstrate that some lidocaine action occurs at the cutaneous level during the administration of a Bier block. Due to limited field depth of view provided by the SPY® Elite System (Novadaq Technologies Inc., Mississauga, Canada), we are unable to draw any conclusions as to the distribution of the IcG or lidocaine at the level of the larger nerves at the site of the tourniquet.

Development of a local anesthetic lidocaine-loaded redox-active injectable gel for postoperative pain management

Although local anesthesia is commonly applied for pain relief, there are several issues such as its short duration of action and low effectiveness at the areas of inflammation due to the acidic pH. The presence of excessive amount of reactive oxygen species (ROS) is known to induce inflammation and aggravate pain. To resolve these issues, we developed a redox-active injectable gel (RIG) with ROS-scavenging activity. RIG was prepared by mixing polyamine-b-poly(ethylene glycol)-b-polyamine with nitroxide radical moieties as side chains on the polyamine segments (PMNT-b-PEG-b-PMNT) with a polyanion, which formed a flower-type micelle via electrostatic complexation. Lidocaine could be stably incorporated in its core. When the temperature of the solution was increased to 37°C, the PIC-type flower micelle transformed to gel. The continuous release of lidocaine from the gel was observed for more than three days, without remarkable initial burst, which is probably owing to the stable entrapment of lidocaine in the PIC core of the gel. We evaluated the analgesic effect of RIG in carrageenan-induced arthritis mouse model. Results showed that lidocaine-loaded RIG has stronger and longer analgesic effect when administered in inflamed areas. In contrast, while the use of non-complexed lidocaine did not show analgesic effect one day after its administration. Note that no effect was observed when PIC-type flower micelle without ROS-scavenging ability was used. These findings suggest that local anesthetic-loaded RIG can effectively reduce the number of injection times and limit the side effects associated with the use of anti-inflammatory drugs for postoperative pain management.

STATEMENT OF SIGNIFICANCE

1. We have been working on nanomaterials, which effectively eliminate ROS, avoiding dysfunction of mitochondria in healthy cells. 2. We designed redox injectable gel using polyion complexed flower type micelle, which can eliminates ROS locally. 3. We could prepare local anesthesia-loaded redox injectable gel (lido@RIG). 4. Drug release could be extended by local administration of lido@RIG. 5. Deprotonation of lidocaine improved anesthetic effect because ROS were eliminated locally by RIG. 6. Local inflammation could be also suppressed by lido@RIG.

Development and Application of a High-Performance Liquid Chromatography Stability-Indicating Assay for Beyond-Use Date Determination of Compounded Topical Gels Containing Multiple Active Drugs

Topical gels compounded by pharmacists are important clinical tools for the management of pain. Nevertheless, there is often a dearth of information about the chemical stability of drugs included in these topical formulations, complicating the assignment of beyond-use dating. The purpose of this study was to develop a high-performance liquid chromatography photodiode array-based stability-indicating assay that could simultaneously resolve six drugs (amitriptyline, baclofen, clonidine, gabapentin, ketoprofen, lidocaine) commonly included in topical gels for pain management and their potential degradation products. Furthermore, this method was applied to the determination of beyond-use dating of combinations of these drugs prepared in commonly utilized bases (Lipobase, Lipoderm, Pluronic organogel). Gabapentin was determined to be the least stable component in all formulations tested. Measured stability ranged between 7 to 49 days depending on the base and other active drugs present in the formulation. In the absence of gabapentin, baclofen was the next least stable component, lasting for 120 days, regardless of the type of formulating base used.

Survey of topical oral solutions for the treatment of chemo-induced oral mucositis

Purpose. The objectives of this study were (1) to describe the usage of topical oral solutions in patients experiencing chemotherapy-induced oral mucositis (CIOM); and (2) to survey the care of oral mucositis provided to patients by clinical oncology pharmacists in institutional settings.

Methods. Surveys were distributed to institutional pharmacists in the US, who were asked to provide the components of their ‘magic mouthwash’. Other questions included whether an institutional mucositis management guideline is available and what is the involvement of clinical pharmacy in mucositis care.

Results. Forty institutions returned surveys during the study period. The top five ingredients used to compound the magic mouthwash are diphenhydramine, viscous lidocaine, magnesium hydroxide/aluminum hydroxide, nystatin and corticosteroids. Most institutions administer the mouthwash every 4 hours (36%) or every 6 hours (36%). Of the surveyed institutions, 33% currently possess guidelines for the management of CIOM.

Conclusions. Most institutions in the country formulate their topical solution, or magic mouthwash, with a variety of ingredients. There is a need to standardize the ingredients used to compound the magic mouthwash, in order to fully evaluate the efficacy of the solution to manage CIOM.

Rheological Properties of Calcium Hydroxylapatite With Integral Lidocaine

BACKGROUND

Calcium hydroxylapatite with integral lidocaine, CaHA (+), received FDA approval in 2015 and CE mark approval in 2016. This formulation has been associated with significant pain reduction compared to CaHA. In a previous rheometry study, CaHA without lidocaine demonstrated higher viscosity and elasticity when compared with hyaluronic acid fillers.

STUDY OBJECTIVE

To compare the rheological properties of CaHA (+) lidocaine to CaHA without lidocaine and to compare the rheological measures of CaHA (+) to 5 cross-linked hyaluronic acid (HA) fillers with integral 0.3% lidocaine.<br/>

MATERIALS AND METHODS

The rheological properties of complex viscosity (&eta;*) and elastic modulus (G') were measured for 2 types of CaHA fillers [CaHA without lidocaine and CaHA (+) with integral 0.3% lidocaine] and 5 HA fillers using an oscillation frequency sweep at a sheer stress of 5 pascal tau (Pa) and an interpolation of 0.7 Hz.<br/>

RESULTS

CaHA with and without integral lidocaine demonstrate similar &eta;* and G' measurements. CaHA with and without integral lidocaine demonstrates higher &eta;* and G' compared with HA fillers with integral lidocaine.<br/>

CONCLUSION

CaHA with integral lidocaine has a similar rheological profile to CaHA without lidocaine: the highest &eta;* and G' compared with available HA fillers with integral lidocaine. <br /><br /> <em>J Drugs Dermatol.</em> 2016;15(9):1107-1110.

Development of an ANN optimized mucoadhesive buccal tablet containing flurbiprofen and lidocaine for dental pain

A novel mucoadhesive buccal tablet containing flurbiprofen (FLB) and lidocaine HCl (LID) was prepared to relieve dental pain. Tablet formulations (F1-F9) were prepared using variable quantities of mucoadhesive agents, hydroxypropyl methyl cellulose (HPMC) and sodium alginate (SA). The formulations were evaluated for their physicochemical properties, mucoadhesive strength and mucoadhesion time, swellability index and in vitro release of active agents. Release of both drugs depended on the relative ratio of HPMC:SA. However, mucoadhesive strength and mucoadhesion time were better in formulations, containing higher proportions of HPMC compared to SA. An artificial neural network (ANN) approach was applied to optimise formulations based on known effective parameters (i.e., mucoadhesive strength, mucoadhesion time and drug release), which proved valuable. This study indicates that an effective buccal tablet formulation of flurbiprofen and lidocaine can be prepared via an optimized ANN approach.

Effect of Local and General Anesthetics on Interfacial Water

Background

Water undergoes structural change as it interfaces with hydrophilic surfaces, including the many hydrophilic surfaces within the cell. This interfacial water has become known as “Exclusion Zone (EZ) water” or “fourth-phase water” [1].

Methods

We tested the hypothesis that anesthetics diminish the amount of EZ water, and that this change may correlate with functional changes in anesthesia. By using the local anesthetics Lidocaine and Bupivacaine as well as a general inhalational anesthetic, Isoflurane, we tracked the EZ size as these anesthetics were introduced.

Results

All three anesthetics diminished EZ size in a concentration-dependent manner at concentrations of 0.18 mM and greater for Bupivacaine, 0.85 mM and greater for Lidocaine, and 0.2% for Isoflurane. At extremely low (micromolar) concentrations, however, all three anesthetics increased EZ size.

Conclusions

The sharp increase of EZ size associated with micromolar anesthetic concentrations follows a similar pattern to induction of general anesthesia, from the excitation stage (Stage II) to the depression and overdose stages of surgical anesthesia (Stages III and IV). The results are consistent with the hypothesis that anesthetics may act on water, a fundamental organizational component common to all cells.

NaHCO3-Buffered Lidocaine Gel for Outpatient Rigid Cystoscopy in Men

PURPOSE

The purpose of this study was to explore the effect of NaHCO3-buffered lidocaine gel as a topical anesthetic agent for pain relief for rigid cystoscopy.

DESIGN

Prospective randomized controlled trial.

METHODS

ASA I-II male patients undergoing rigid cystoscopy randomly received 10 mL 2% Carbocaine lidocaine gel with 1 mL 0.9% saline (group 1) or 1 mL 5% NaHCO3 solution (group 2). After 3 minutes exposure, the cystoscope was inserted into the urethra. On receiving the gel, cystoscope insertion, and intravesical observation, pain score was recorded using the visual analog scale.

FINDINGS

The gel pH with or without NaHCO3 was 7.20 and 6.41, respectively. The concentration of soluble lidocaine in the gel was stable for 24 hours or more. The visual analog scale score in group 2 was significantly lower (1.3 ± 0.9) than in group 1 (5.28 ± 1.99). No adverse effects were recorded.

CONCLUSION

Alkalized lidocaine gel resulted in successful analgesia for rigid cystoscopy in men without adverse effects.

A NEW APPROACH TO THE STUDY OF MUCOADHESIVENESS OF POLYMERIC MEMBRANES USING SILICONE DISCS

The introduction of new test methods and the modification of existing ones are crucial for obtaining reliable results, which contributes to the development of innovative materials that may have clinical applications. Today, silicone is commonly used in medicine and the diversity of its applications are continually growing. The aim of this study is to evaluate the mucoadhesiveness of polymeric membranes by a method that modifies the existing test methods through the introduction of silicone discs. The matrices were designed for clinical application in the management of diseases within the oral cavity. The use of silicone discs allows reliable and reproducible results to be obtained, which allows us to make various tensometric measurements. In this study, different types of polymeric matrices were examined, as well as their crosslinking and the presence for the active pharmaceutical ingredient were compared to the pure dosage form. The lidocaine hydrochloride (Lid(HCl)) was used as a model active substance, due to its use in dentistry and clinical safety. The results were characterized by a high repeatability (RSD < 10.6%). The advantage of silicone material due to its mechanical strength, chemical and physical resistance, allowed a new test method using a texture analyzer to be proposed.

Ionisation effects on the permeation of pharmaceutical compounds through silicone membrane

Silicone membrane is frequently used as an in vitro skin mimic whereby experiments incorporate a range of buffered media which may vary in pH. As a consequence of such variability in pH there is a corresponding variability in the degree of ionisation which in turn, could influence permeation through the mainly hydrophobic-rich membrane structure. This study reports the effect of pH on the permeation of five model compounds (benzoic acid, benzotriazole, ibuprofen, ketoprofen and lidocaine). For the five compounds analysed, each at three distinct percentages of ionisation, it was found that the greater extent of permeation was always for the more 'neutral', i.e. more greatly unionised, species rather than the anionic or cationic species. These findings fit with the theory that the hydrophobic membrane encourages permeation of 'lipid-like' structures, i.e. the more unionised form of compounds. However, results obtained with an Inverse Gas Chromatography Surface Energy Analyser (iGC SEA) indicate the membrane surface to be an electron dense environment. In the knowledge that unionised forms of compounds permeate (rather than the charged species) this negatively charged surface was not anticipated, i.e. the basic membrane surface did not appear to affect permeation.

Galanin-Mediated Behavioural Hyperalgesia from the Dorsomedial Nucleus of the Hypothalamus Involves Two Independent Descending Pronociceptive Pathways

Activation of the dorsomedial nucleus of the hypothalamus (DMH) by galanin (GAL) induces behavioural hyperalgesia. Since DMH neurones do not project directly to the spinal cord, we hypothesized that the medullary dorsal reticular nucleus (DRt), a pronociceptive region projecting to the spinal dorsal horn (SDH) and/or the serotoninergic raphe-spinal pathway acting on the spinal 5-HT3 receptor (5HT3R) could relay descending nociceptive facilitation induced by GAL in the DMH. Heat-evoked paw-withdrawal latency (PWL) and activity of SDH neurones were assessed in monoarthritic (ARTH) and control (SHAM) animals after pharmacological manipulations of the DMH, DRt and spinal cord. The results showed that GAL in the DMH and glutamate in the DRt lead to behavioural hyperalgesia in both SHAM and ARTH animals, which is accompanied particularly by an increase in heat-evoked responses of wide-dynamic range neurons, a group of nociceptive SDH neurones. Facilitation of pain behaviour induced by GAL in the DMH was reversed by lidocaine in the DRt and by ondansetron, a 5HT3R antagonist, in the spinal cord. However, the hyperalgesia induced by glutamate in the DRt was not blocked by spinal ondansetron. In addition, in ARTH but not SHAM animals PWL was increased after lidocaine in the DRt and ondansetron in the spinal cord. Our data demonstrate that GAL in the DMH activates two independent descending facilitatory pathways: (i) one relays in the DRt and (ii) the other one involves 5-HT neurones acting on spinal 5HT3Rs. In experimental ARTH, the tonic pain-facilitatory action is increased in both of these descending pathways.

Human Serum Modifies Aggregation Properties of Commonly Used Epidural Steroids

BACKGROUND

Case reports of catastrophic neurological sequelae during ESIs have questioned the safety of this procedure. A proposed mechanism is particulate steroid embolization resulting in neuralischemia. Previous reports have described steroid clumping in common epidural injection mixtures. We demonstrate that physiologic medium can also modify aggregation.

OBJECTIVE

To inspect and compare aggregative properties of steroid preparations with and without human serum.

SETTING

Academic tertiary care center.

HYPOTHESIS

Particulate steroids display different aggregation characteristics in serum compared to non-physiologic solutions.

DESIGN

Solutions were inspected under light microscopy: betamethasone sodium phosphate/betamethasone acetate, methylprednisolone, and dexamethasone were each mixed in lidocaine 1%, bupivacaine 0.5%, or sterile water in a 1:1 ratio. All preparations were inspected under light microscopy with 100x and 400x magnifications by a pathologist blinded to our expectations and hypothesis. Five random viewing fields were selected within each slide and the number of aggregates per field and the number of particles per aggregate was evaluated.

RESULTS

The addition of serum had a significant effect on steroid particle aggregation and number of particles per aggregate.

LIMITATIONS

This study was limited by sample size as only 2 sets of human serum samples were tested with each preparation against one non-serum control. Additionally, as steroid preparations were evaluated under light microscopy, the ex vivo setting must be considered in the interpretation of results. Finally, mixing preparations with human serum as opposed to whole blood was necessary to allow for improved visibility on light microscopy despite the fact that whole blood may be necessary to more closely emulate in vivo coagulation setting.

CONCLUSIONS

Overall, the presence of serum resulted in fewer large steroid particle aggregates when compared to non-serum control samples. Amongst particulate steroids, betamethasone with bupivacaine 0.5% demonstrated the fewest and smallest particle aggregates, suggesting that preparation may reduce the risk of embolic infarction. Methylprednisolone formed significantly larger particles in bupivicaine 0.5% with serum compared to non-serum controls.

WITHDRAWN: Adjusting the pH of lidocaine for reducing pain on injection

May 2015

This review was originally published in 2010 and at that time complied with Cochrane’s Commercial Sponsorship Policy. The Commercial Sponsorship policy was updated in 2014 (http://community.cochrane.org/organisational‐policy‐manual/appendix‐5‐commercial‐sponsorship‐policy ). This review is no longer compliant with that policy.

The non conflicted members of the original team of authors have decided not to update the review. We have therefore decided to withdraw the review and seek new authors to update it

The editorial group responsible for this previously published document have withdrawn it from publication.

The conformational stability, solvation and the assignments of the experimental infrared, Raman, (1)H and (13)C NMR spectra of the local anesthetic drug lidocaine

The structure, vibrational and (1)H and (13)C NMR spectra of the local anesthetic drug lidocaine were investigated by the B3LYP/6-311G(∗∗) calculations. The molecule was predicted to have the non-planar cis (NCCN∼0°) structures being about 2-6kcal/mol lower in energy than the corresponding trans (NCCN∼180°) forms. The calculated NCCN (9.6°) and CNCC (-132.2°) torsional angles were in a good qualitative agreement with the reported X-ray angles (3.1 and 13.0°, -102.67 and -77.9°, respectively, for H-bonded dimers). The Gibbs energy of solution of lidocaine in formamide, water, dimethylsulfoxide, acetonitrile, methanol, ethanol and chloroform solutions was estimated at the B3LYP level. The predicted affinity of lidocaine toward the alcohols, acetonitrile and chloroform solutions was in excellent agreement with the reported experimental solubility of the drug in organic solvents. The analysis of the observed vibrational spectra is consistent with the presence of lidocaine in only one conformation at room temperature. The (1)H and (13)C NMR spectra of lidocaine were interpreted by experimental and DFT calculated chemical shifts of the drug. The RMSD between experimental and theoretical (1)H and (13)C chemical shifts for lidocaine is 0.47 and 8.26ppm, respectively.

Engineered heart slices for electrophysiological and contractile studies

A major consideration in the design of engineered cardiac tissues for the faithful representation of physiological behavior is the recapitulation of the complex topography and biochemistry of native tissue. In this study we present engineered heart slices (EHS), which consist of neonatal rat ventricular cells (NRVCs) seeded onto thin slices of decellularized cardiac tissue that retain important aspects of native extracellular matrix (ECM). To form EHS, rat or pig ventricular tissue was sectioned into 300 μm-thick, 5 to 16 mm-diameter disks, which were subsequently decellularized using detergents, spread on coverslips, and seeded with NRVCs. The organized fiber structure of the ECM remained after decellularization and promoted cell elongation and alignment, resulting in an anisotropic, functional tissue that could be electrically paced. Contraction decreased at higher pacing rates, and optical mapping revealed electrical conduction that was anisotropic with a ratio of approximately 2.0, rate-dependent shortening of the action potential and slowing of conduction, and slowing of conduction by the sodium channel blocker lidocaine. Reentrant arrhythmias could also be pace-induced and terminated. EHS constitute an attractive in vitro cardiac tissue in which cardiac cells are cultured on thin slices of decellularized cardiac ECM that provide important biochemical, structural, and mechanical cues absent in traditional cell cultures.

Validation of data on the use of twin mix in minor oral surgery: comparative evaluation of efficacy of twin mix versus 2 % lignocaine with 1:200000 epinephrine based on power analysis and an UV spectrometry study for chemical stability of the mixture

INTRODUCTION

There is convincing evidence supporting the addition of dexamethasone to lignocaine and its administration as an intra-space injection to achieve benefit of a single dose steroid after third molar surgery. This study was undertaken to validate the existing data on the use of twin mix in minor oral surgery based on power analysis, statistical sample size estimation and an ultraviolet (UV) spectrometry study for chemical stability of the mixture.

MATERIAL AND METHODS

A prospective, randomized, double-blind trial was designed to validate the pilot study on the efficacy of twin mix and 2 % lignocaine with 1:200,000 epinephrine in the surgical removal of impacted mandibular third molars. Clinical parameters of anaesthetic latency, anaesthetic duration, efficacy of twin mix as an anaesthetic and post-operative patient discomfort were assessed. The stability of active ingredients in the solution was assessed using a double beam UV-visible spectrophotometery.

RESULTS

The results of the study showed better post-operative outcome with administration of dexamethasone and lignocaine as an intra-space injection in decreasing the post-operative patient discomfort. The anaesthetic efficacy of the twin-mix admixture was found statistically similar to the control solution of 2 % lignocaine with 1:200,000 epinephrine. The λmax recorded for dexamethasone and local anaesthetic individually was obtained with the twin-mix solution, which indicated no change in the active pharmacological compounds.

DISCUSSION

Clinical anaesthetic efficacy of twin mix is comparable to 2 % lignocaine with 1:200,000 epinephrine when administered in the pterygomandibular space with the additional advantage of a single prick co-administration of dexamethasone with local anaesthetic, lesser sting of the local anaesthetic injection, shorter anaesthetic latency, prolonged duration of the soft tissue anaesthesia and decrease in post-operative discomfort after the oral surgical procedure.

A comparative study of novel spectrophotometric resolution techniques applied for pharmaceutical mixtures with partially or severely overlapped spectra

Simultaneous determination of mixtures of lidocaine hydrochloride (LH), flucortolone pivalate (FCP), in presence of chlorquinaldol (CQ) without prior separation steps was applied using either successive or progressive resolution techniques. According to the concentration of CQ the extent of overlapping changed so it can be eliminated from the mixture to get the binary mixture of LH and FCP using ratio subtraction method for partially overlapped spectra or constant value via amplitude difference followed by ratio subtraction or constant center followed by spectrum subtraction spectrum subtraction for severely overlapped spectra. Successive ratio subtraction was coupled with extended ratio subtraction, constant multiplication, derivative subtraction coupled constant multiplication, and spectrum subtraction can be applied for the analysis of partially overlapped spectra. On the other hand severely overlapped spectra can be analyzed by constant center and the novel methods namely differential dual wavelength (D(1) DWL) for CQ, ratio difference and differential derivative ratio (D(1) DR) for FCP, while LH was determined by applying constant value via amplitude difference followed by successive ratio subtraction, and successive derivative subtraction. The spectra of the cited drugs can be resolved and their concentrations are determined progressively from the same ratio spectrum using amplitude modulation method. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures and were successfully applied for the analysis of pharmaceutical formulations containing the cited drugs with no interference from additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the official or reported methods; using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

[Evaluation of the pharmaceutical stability of polaprezinc/sodium alginate gargle solution containing lidocaine]

OBJECTIVE

A gargle solution(L-P/AG)for the treatment of painful stomatitis was prepared by adding lidocaine to a polaprezinc/sodium alginate gargle solution(P/AG), and its pharmaceutical stability was evaluated.

METHODS

L-P/AG was stored at 5, 25, and 40°C. The strengths of polaprezinc and lidocaine were determined. The viscosity and pH of L-P/AG were also determined, and its appearance was evaluated.

RESULTS

When stored at 5 or 25°C in a dark place, L-P/AG showed neither reduction in the strength of either drug nor did it show a change in the viscosity, pH, or appearance. When stored exposed to light at 40°C, L-P/AG showed reductions in the strength of both drugs, as well as in viscosity and pH; furthermore, a change in appearance was noted.

DISCUSSION

L-P/AG prepared for the treatment of painful stomatitis remains pharmaceutically stable for 28 days when stored at 25°C in a dark place.

Guest:host interactions of lidocaine and prilocaine with natural cyclodextrins: spectral and molecular modeling studies

Inclusion complex formation of two local anesthetics drugs (lidocaine (LC) and prilocaine (PC)) with α- and β-cyclodextrins (CDs) in aqueous solution were studied by absorption, fluorescence, time-resolved fluorescence and molecular modeling methods. The formation of inclusion complexes was confirmed by 1H NMR, FTIR, differential scanning calorimetry, SEM, TEM and X-ray diffractometry. Both drugs formed 1:1 inclusion complex and exhibit biexponential decay in water whereas triexponential decay in the CD solution. Nanosized self-aggregated particles of drug: CD complexes were found by TEM. Both experimental and theoretical studies revealed that the phenyl ring with the amide group of the drug is encapsulated in the hydrophobic CD nanocavity. Investigations of energetic and thermodynamic properties confirmed the stability of the inclusion complexes. van der Waals interactions are mainly responsible for enthalpy driven complex formation of LC and PC with CDs.

Coating solid dispersions on microneedles via a molten dip-coating method: development and in vitro evaluation for transdermal delivery of a water-insoluble drug

This study demonstrates for the first time the ability to coat solid dispersions on microneedles as a means to deliver water-insoluble drugs through the skin. Polyethylene glycol (PEG) was selected as the hydrophilic matrix, and lidocaine base was selected as the model hydrophobic drug to create the solid dispersion. First, thermal characterization and viscosity measurements of the PEG-lidocaine mixture at different mass fractions were performed. The results show that lidocaine can remain stable at temperatures up to ∼130°C and that viscosity of the PEG-lidocaine molten solution increases as the mass fraction of lidocaine decreases. Differential scanning calorimetry demonstrated that at lidocaine mass fraction less than or equal to 50%, lidocaine is well dispersed in the PEG-lidocaine mixture. Uniform coatings were obtained on microneedle surfaces. In vitro dissolution studies in porcine skin showed that microneedles coated with PEG-lidocaine dispersions resulted in significantly higher delivery of lidocaine in just 3 min compared with 1 h topical application of 0.15 g EMLA®, a commercial lidocaine-prilocaine cream. In conclusion, the molten coating process we introduce here offers a practical approach to coat water-insoluble drugs on microneedles for transdermal delivery.

Effect of additives on mineral trioxide aggregate setting reaction product formation

INTRODUCTION

Mineral trioxide aggregate (MTA) sets via hydration of calcium silicates to yield calcium silicate hydrates and calcium hydroxide (Ca[OH]2). However, a drawback of MTA is its long setting time. Therefore, many additives have been suggested to reduce the setting time. The effect those additives have on setting reaction product formation has been ignored. The objective was to examine the effect additives have on MTA's setting time and setting reaction using differential scanning calorimetry (DSC).

METHODS

MTA powder was prepared with distilled water (control), phosphate buffered saline, 5% calcium chloride (CaCl2), 3% sodium hypochlorite (NaOCl), or lidocaine in a 3:1 mixture and placed in crucibles for DSC evaluation. The setting exothermic reactions were evaluated at 37°C for 8 hours to determine the setting time. Separate samples were stored and evaluated using dynamic DSC scans (37°C→640°C at10°C/min) at 1 day, 1 week, 1 month, and 3 months (n = 9/group/time). Dynamic DSC quantifies the reaction product formed from the amount of heat required to decompose it. Thermographic peaks were integrated to determine enthalpy, which was analyzed with analysis of variance/Tukey test (α = 0.05).

RESULTS

Isothermal DSC identified 2 main exothermal peaks occurring at 44 ± 12 and 343 ± 57 minutes for the control. Only the CaCl2 additive was an accelerant, which was observed by a greater exothermic peak at 101 ± 11 minutes, indicating a decreased setting time. The dynamic DSC scans produced an endothermic peak around 450°C-550°C attributed to Ca(OH)2 decomposition. The use of a few additives (NaOCl and lidocaine) resulted in significantly less Ca(OH)2 product formation.

CONCLUSIONS

DSC was used to discriminate calcium hydroxide formation in MTA mixed with various additives and showed NaOCl and lidocaine are detrimental to MTA reaction product formation, whereas CaCl2 accelerated the reaction.

Simultaneous determination of psychoactive compounds in foodstuffs using micellar liquid chromatography with direct injection

Amicellar liquid chromatographic procedure was developed for the simultaneous determination of three commonly used stupefacients, lidocaine, ketamine and diazepam, using a C18 reversed-phase column. A micellar mobile phase 0.15 M sodium dodecyl sulfate and 6% (v/v) pentanol, pH 7, and UV detection at 230 nm were used to determine the three stupefacients in food samples. Using the selected mobile phase, the stupefacients were eluted in less than 10 min with linearity (r = 0.998), LOD (range: 0.004-0.03 ppm), LOQ (range: 0.004-0.03 ppm), intraday and interday precision (below 2.84%), and mean recoveries (range: 79.11-110.16%) in the different foodstuffs were in accordance with the internationally established acceptance criteria. Validation of the developed method was performed on the basis of International Conference on Harmonization validation guidelines. The optimized and validated micellar liquid chromatographic method was successfully applied in the determination of lidocaine, diazepam, and ketamine in a real food sample (mango drink) and in spiked food samples (banana, ladoo, soft drink, tea). The developed method could also be easily used by law enforcement laboratories and hospitals for routine analysis.

Continuous drug release by sea anemone Nematostella vectensis stinging microcapsules

Transdermal delivery is an attractive option for drug delivery. Nevertheless, the skin is a tough barrier and only a limited number of drugs can be delivered through it. The most difficult to deliver are hydrophilic drugs. The stinging mechanism of the cnidarians is a sophisticated injection system consisting of microcapsular nematocysts, which utilize built-in high osmotic pressures to inject a submicron tubule that penetrates and delivers their contents to the prey. Here we show, for the first time, that the nematocysts of the starlet sea anemone Nematostella vectensis can be isolated and incorporated into a topical formulation for continuous drug delivery. We demonstrate quantitative delivery of nicotinamide and lidocaine hydrochloride as a function of microcapsular dose or drug exposure. We also show how the released submicron tubules can be exploited as a skin penetration enhancer prior to and independently of drug application. The microcapsules are non-irritant and may offer an attractive alternative for hydrophilic transdermal drug delivery.

Successive spectrophotometric resolution as a novel technique for the analysis of ternary mixtures of pharmaceuticals

A novel spectrophotometric technique was developed for the simultaneous determination of ternary mixtures, without prior separation steps. This technique was called successive spectrophotometric resolution technique. The technique was based on either the successive ratio subtraction or successive derivative subtraction. The mathematical explanation of the procedure was illustrated. In order to evaluate the applicability of the methods a model data as well as an experimental data were tested. The results from experimental data related to the simultaneous spectrophotometric determination of lidocaine hydrochloride (LH), calcium dobesilate (CD) and dexamethasone acetate (DA); in the presence of hydroquinone (HQ), the degradation product of calcium dobesilate were discussed. The proposed drugs were determined at their maxima 202 nm, 305 nm, 239 nm and 225 nm for LH, CD, DA and HQ respectively; by successive ratio subtraction coupled with constant multiplication method to obtain the zero order absorption spectra, while by applying successive derivative subtraction they were determined at their first derivative spectra at 210 nm for LH, 320 nm or P(292-320) for CD, 256 nm or P(225-252) for DA and P(220-233) for HQ respectively. The calibration curves were linear over the concentration range of 2-20 μg/mL for both LH and DA, 6-50 μg/mL for CD, and 3-40 μg/mL for HQ. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs with no interference from other dosage form additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the official BP methods for LH, DA, and CD, and with the official USP method for HQ; using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision.

[Pharmakological characteristic of some amide local anesthetics, currently used in dental clinics]

Along with the brief history of amide local anesthetics development, their most important properties (from the viewpoint of use in clinical dental practice), are also reviewed. In particular, some properties of most commonly used local anesthetics, such as lidocaine, mepivacaine, prilocaine, bupivacaine and articaine are analysed. The most important data concerning pharmacological mechanisms of mentioned anesthetics' action, that cause certain features and peculiarities of their clinical application are given in condensed form. Besides, some precaution measures that must be taken into account in specific clinical cases together with the history and current status of each patient are mentioned as well.

Efficacy of lidocaine lontophoresis using either alternating or direct current in hairless rats

The aim of this study was to determine transport of lidocaine ions through a hairless rat skin in vivo and to compare the efficacy of alternating current (AC) with that of direct current (DC) iontophoresis (IOP). We measured the concentration of lidocaine transported through a cellophane membrane or a hairless rat dorsal skin applying either AC-IOP or DC-IOP. The results revealed that lidocaine concentration increased in a time-dependent manner in vitro in both DC-IOP and AC-IOP. However, the in vivo study showed different tendencies in lidocaine concentration. In the DCIOP group, lidocaine concentration reached its maximum 20 min after current application and then decreased rapidly; the AC-IOP group showed an increase in lidocaine concentration in a time-dependent manner. There were no side effects such as electrical burns in the rats. In conclusion, AC can be applied for long periods and DC for short periods, or their application time can be appropriately scheduled. Our study also suggests the mechanism by which voltage waveforms affect the skin when applied by IOP. In the future, these findings will be a solid foundation for developing various kinds of medical equipment such as scheduled drug delivery system that can easily deliver various types of drug.

Equilibrium and release properties of hyaluronic acid-drug complexes

With the aim to provide more rational basis about the potentiality of hyaluronic acid (or hyaluronan) as drug carrier a set of ionic complexes of its acid form (HA) and its sodium salt (NaHA) with three model drugs (D) (atenolol, propranolol and lidocaine) were prepared. Besides NaHA subjected to hyalurodinase depolimerization (NaHA(d)) was also used. Transparent dispersions were obtained. They exhibited negative electrokinetic potential and a high degree of counterionic condensation with affinity constants (log Kcc) in the range of 5.8-6.1 for propranolol complexes (pK(a) 9.45) and 4.0-4.6 for lidocaine ones (pK(a) 7.92). Delivery rates of D from the complexes were measured in a Franz-type bicompartimental device. Loaded D were slowly released from the three types of complexes, even when a neutral salt was added to the dispersion placed in the donor compartment, revealing the high affinity between the protonated drugs and the ionisable groups of the polymer. Complex dispersions based on HA or on NaHA(d) exhibited lower viscosity than those of NaHA but their complexing ability remained unaltered. The results reported on equilibrium and release properties of Hyaluronan-model D complexes contribute to expand the use of HA and NaHA as drug carriers for different routes of administration.

Degradation of lidocaine, tramadol, venlafaxine and the metabolites O-desmethyltramadol and O-desmethylvenlafaxine in surface waters

The photodegradation and biotic transformation of the pharmaceuticals lidocaine (LDC), tramadol (TRA) and venlafaxine (VEN), and of the metabolites O-desmethyltramadol (ODT) and O-desmethylvenlafaxine (ODV) in the aquatic environmental have been investigated. Photodegradation experiments were carried out using a medium pressure Hg lamp (laboratory experiments) and natural sunlight (field experiments). Degradation of the target compounds followed a first-order kinetic model. Rates of direct photodegradation (light absorption by the compounds itself) at pH 6.9 were very low for all of the target analytes (≤0.0059 h(-1) using a Hg lamp and ≤0.0027 h(-1) using natural sunlight), while rates of indirect photodegradation (degradation of the compounds through photosensitizers) in river water at pH 7.5 were approximately 59 (LDC), 5 (TRA), 8 (VEN), 15 (ODT) and 13 times (ODV) higher than the rates obtained from the experiments in ultrapure water. The accelerated photodegradation of the target compounds in natural water is attributed mainly to the formation of hydroxyl radicals through photochemical reactions. Biotic (microbial) degradation of the target compounds in surface water has been shown to occur at very low rates (≤0.00029 h(-1)). The half-life times determined from the field experiments were 31 (LDC), 73 (TRA), 51 (VEN), 21 (ODT) and 18h (ODV) considering all possible mechanisms of degradation for the target compounds in river water (direct photodegradation, indirect photodegradation and biotic degradation).

[Investigation of the influence of intracameral injection of domestic lidocaine on the corneal thickness during phacoemulsification of cataract]

Influence of intracameral injection of 0.5 % solution of lidocaine hydrochloride on the cornea was investigated. It was proved that 0.5 % solution of lidocaine hydrochloride being preservative-free, has not any adverse effect on the corneal thickness measured by keratopachimetry before and after injection of medicine.

Novel multifunctional platforms for potential treatment of cutaneous wounds: development and in vitro characterization

An original formulative/manufacturing approach for the development of a multi-composite wound dressing able to control the release of a water soluble API (lidocaine HCl) for several days was evaluated. The prepared multi-composite wound dressing is a microstructured spongy matrix, which embeds solid lipid microparticles (SLMs). The matrices were obtained by freeze drying of polyelectrolyte complexes made up two biopolymers: three different chitosan to alginate weight ratios (1:1, 3:1 and 1:3) were studied. The drug-loaded matrices were investigated as regards water uptake ability, swelling, drug loading, morphology and release profiles. SLMs were prepared at two different drug loadings (5% and 25%, w/w) by the spray congealing technology and were then incorporated in the spongy matrices. The characterization of the SLMs evidenced their spherical shape, mean dimensions lower than 20 μm, controlled release and the modification of the drug crystalline state. Comparing the release profiles of the SLMs-loaded sponges, the matrices with 1:3 chitosan/alginate ratio displayed a sustained release profile with the lower burst effect. Then hyaluronan and cysteine were embedded into the matrix to enhance the wound healing properties of the dressing. The final multi-composite platform was able to promote the growth of fibroblasts maintaining its prolonged release characteristic.

Polymeric complexes of lidocaine hydrochloride with poly(acrylic acid) and poly(2-hydroxyethyl vinyl ether)

The specific interactions of local anesthetic lidocaine hydrochloride with poly(acrylic acid) and poly(2-hydroxyethyl vinyl ether), as well as in a triple system composed of the drug and both polymers, have been studied in aqueous solutions by viscometric, turbidimetric, potentiometric, and FTIR spectroscopic methods. The mechanism of the drug binding to the polymers and the structures of the polycomplexes formed are clarified.

Occurrence and removal of lidocaine, tramadol, venlafaxine, and their metabolites in German wastewater treatment plants

PURPOSE

Some of the pharmaceuticals that are not extensively investigated in the aquatic environment are the anesthetic lidocaine (LDC), the analgesic tramadol (TRA), and the antidepressant venlafaxine (VEN). LDC metabolizes to 2,6-xylidine (2,6-DMA) and monoethylglycinexylidine (MEGX), TRA to O-desmethyltramadol (ODT), and VEN to O-desmethylvenlafaxine (ODV). Within this study, the distribution and behavior of these compounds in German wastewater treatment plants (WWTPs) were investigated.

METHODS

Samples of influents and effluents from WWTPs in Hesse, Germany were collected between January and September 2010. Analytes were extracted from wastewater samples by solid-phase extraction and from solid samples by sonication. Extracts were measured using gas chromatography/mass spectrometry.

RESULTS

LDC, TRA, VEN, ODT, and ODV were detected in all analyzed influent and effluent samples. 2,6-DMA could not be identified. MEGX was not detected. TRA and ODV were present in untreated wastewater at the highest concentrations (max, 1,129 (TRA) and 3,302 ng L⁻¹ (ODV)), while the concentrations of LDC and VEN were all significantly lower (mean, 135 (LDC) and 116 ng L⁻¹ (VEN)). All of the analytes were only partially removed in the WWTPs. The mean ratios between the concentrations of the metabolites and their respective parent compounds in influents were 4.7 (ODV/VEN) and 0.7 (ODT/TRA). These values remain approximately constant comparing influents and effluents.

CONCLUSIONS

LDC, TRA, VEN, ODT, and ODV are only partially removed from sewage water by WWTPs and thus are continuously discharged in respective recipient rivers. A further transformation of TRA and VEN into the known metabolites during treatment in the WWTPs is not observed.