Liposomal lidocaine gel for topical use at the oral mucosa: characterization, in vitro assays and in vivo anesthetic efficacy in humans

Evaluation of EMLA cream with microneedle patches in palatal anesthesia in children: a randomized controlled clinical trial

Palatal injections are considered to be one of the most painful dental procedures. As a result, it was important to find alternatives to this painful injection to improve children's cooperation. The dental literature mentioned using EMLA cream as a possible alternative to conventional injections, but its anesthetic effect was debated. Therefore, it was valuable to research the impact of microneedle patches to enhance the effectiveness of this cream. The purpose of this randomized controlled clinical trial was to compare the effectiveness of different methods of anesthesia and pain levels in children aged 7-11 years. The study compared the use of EMLA cream, EMLA with microneedles, and conventional palatal injections. A total of 90 children were randomly assigned to three groups: Group 1 received conventional palatal anesthesia (control), Group 2 received EMLA cream only, and Group 3 received EMLA with microneedles. Pain levels were assessed using the FLACC and Wong-Baker scales at three different time points: T1(during anesthesia), T2(on palatal probing), and T3(during extraction). The FLACC scale revealed a significant difference in pain between groups only at T1 (P value = 0.000). It was found that the conventional palatal injection group had a higher pain level than the EMLA cream-only group and the group using microneedle patches with EMLA cream (P value = 0.000). However, the other groups did not show significant differences in pain levels during the anesthesia (P value  = 1.00). Similarly, the Wong-Baker scale also demonstrated a statistically significant difference in pain between groups only at T1 (P value  = 0.000). It was found that the conventional palatal injection group had a higher pain level than the EMLA cream-only group and the group using microneedle patches with EMLA cream (P value  = 0.000). However, the other groups did not show significant differences in pain levels during the anesthesia (P value  = 0.091). The study concludes that both EMLA cream alone and EMLA with microneedles can be used as an alternative to conventional palatal anesthesia for children.

Toward a solid microneedle patch for rapid and enhanced local analgesic action

Analgesic creams find widespread application as adjuncts for localized anesthesia prior to surgical procedures. Nevertheless, the onset of analgesic action is protracted due to the skin barrier's inherent characteristics, which necessitates prolonged intervals of patient and clinician waiting, consequently impinging upon patient compliance and clinician workflow efficiency. In this work, a biodegradable microneedles (MNs) patch was introduced to enhance the intradermal administration of lidocaine cream to achieve rapid analgesia through a minimally invasive and conveniently accessible modality. The polylactic acid (PLA) MNs were mass-produced using a simple hot-pressing method and served the purpose of creating microchannels across the skin's surface for rapid absorption of lidocaine cream. Optical and electron microscopes were applied to meticulously scrutinize the morphology of the fabricated MNs, and the comprehensive penetration tests involving dynamometer tests, evaluation on porcine cadaver skin, artificial film, optical coherence tomography (OCT), transepidermal water loss, and analysis on rats' skins, demonstrated the robust mechanical strength of PLA MNs for successful intradermal penetration. The behavioral pain sensitivity tests on living rats using Von Frey hair filaments revealed that the MN-assisted lidocaine treatment expeditiously accelerated the onset of action from 40 to 10 min and substantially enhanced the efficacy of localized anesthesia. Furthermore, different treatment protocols encompassing the sequence of drug application relative to MN treatment, MN dimensions, and the frequency of MN insertions exhibited noteworthy influence on the resultant local anesthesia efficacy. Together, these results demonstrated that the lidocaine cream followed by diverse PLA MN treatments would be a promising strategy for rapid clinical local anesthesia with wide-ranging applications.

Polymeric Nanocapsules Loaded with Lidocaine: A Promising Formulation for Topical Dental Anesthesia

Lidocaine is the most commonly used local anesthetic worldwide, known for its rapid onset and moderate duration of anesthesia. However, it is short-lived and does not effectively promote effective topical anesthesia in the oral cavity when used alone. Our aim was to investigate whether an approximate 50% encapsulation of lidocaine in poly(ε-caprolactone) nanocapsules (LDC-Nano) would be able to increase its permeation and analgesic efficacy and reduce cytotoxicity. In this study, we characterized LDC-Nano and conducted MTT tests with HaCaT cells to assess their in vitro cytotoxicity. Additionally, in vitro permeation assays across the pig esophageal epithelium and the anesthetic efficacy of the hind paw incision model in rats were performed. Plain lidocaine (LDC) was compared with LDC-Nano and lidocaine hydrochloride plus epinephrine (LDC-Epi). The physicochemical characteristics of LDC-Nano were satisfactory (pH: 8.1 ± 0.21; polydispersity index: 0.08 ± 0.01; mean diameter (nm): 557.8 ± 22.7; and encapsulation efficiency (%): 51.8 ± 1.87) and remained stable for up to 4 months. LDC-Nano presented similar in vitro cytotoxicity to LDC but was higher than LDC-Epi (LD50: LDC = 0.48%; LDC-Nano = 0.47%; and LDC-Epi = 0.58%; p < 0.0001). Encapsulation increased the permeability coefficient about 6.6 times and about 7.5 the steady-state flux of lidocaine across the mucosal epithelium. Both encapsulation and epinephrine improved anesthesia duration, with epinephrine demonstrating superior efficacy (100% of animals were anesthetized up to 100, 30, and 20 min when LDC-Epi, LDC-nano, and LDC were used, respectively). Although LDC-Epi demonstrated superior in vivo anesthetic efficacy, the in vitro permeation and cytotoxicity of LDC-Nano indicate promising avenues for future research, particularly in exploring its potential application as a topical anesthetic in the oral cavity.

Physiology of pregnancy and oral local anesthesia considerations

Background

Safe and effective local anesthesia is a prerequisite for emergency oral surgeries and most dental treatments. Pregnancy is characterized by complex physiological changes, and increased sensitivity to pain. Pregnant women are particularly vulnerable to oral diseases, such as caries, gingivitis, pyogenic granuloma and third molar pericoronitis. Maternally administered drugs can affect the fetus through the placenta. Therefore, many physicians and patients are reluctant to provide or accept necessary local anesthesia, which leads to delays in the condition and adverse consequences. This review is intended to comprehensively discuss the instructions for local anesthesia in the oral treatment of pregnant patients.

Methodology

An in-depth search on Medline, Embase, and the Cochrane Library was performed to review articles concerned with maternal and fetal physiology, local anesthetic pharmacology, and their applications for oral treatment.

Results

Standard oral local anesthesia is safe throughout the pregnancy. At present, 2% lidocaine with 1:200,000 epinephrine is considered to be the anesthetic agent that best balances safety and efficacy for pregnant women. Maternal and fetal considerations must be taken into account to accommodate the physiological and pharmacological changes in the gestation period. Semi-supine position, blood pressure monitoring, and reassurance are suggested for high-risk mothers to reduce the risk of transient changes in blood pressure, hypoxemia, and hypoglycemia. For patients with underlying diseases, such as eclampsia, hypertension, hypotension, and gestational diabetes, the physicians should use epinephrine cautiously and control the dose of anesthetic. New local anesthesia formulations and equipment, which contribute to minimizing injection pain and relieving the anxiety, have and are being developed but remain understudied.

Conclusions

Understanding the physiological and pharmacological changes during pregnancy is essential to ensure the safety and efficiency of local anesthesia. Optimal outcomes for the mother and fetus hinge on a robust understanding of the physiologic alterations and the appropriate selection of anesthetic drugs and approaches.

Localized Delivery of Erlotinib Using Liposomal Gel Formulations for the Treatment of Oral Squamous Cell Carcinoma

Oral cancer accounts for more than 350000 cases worldwide with 90% of them being oral squamous cell carcinomas (OSCC). The current treatment modalities of chemoradiation have poor outcomes along with harmful effects to neighbouring healthy tissues. The present study aimed to deliver Erlotinib (ERB), locally at the site of tumor arising in the oral cavity. ERB was encapsulated in liposomal formulations (ERB Lipo) and optimized using full factorial, 3² experimental design. The optimized batch was then coated with chitosan to obtain CS-ERB Lipo and were characterized further. Both liposomal ERB formulations had size less than 200nm and PDI less than 0.4. Zeta potential was upto -50mV for ERB Lipo and upto + 25mV for CS-ERB Lipo indicating stable formulation. Liposomal formulations were freeze dried and loaded into gel to study in-vitro release and chemotherapeutic evaluation. CS-ERB Lipo showed sustained release upto 36 h from gel as compared to control formulation. In-vitro cell viability studies showed potent anti-cancer activity on KB-cells. In-vivo studies showed better pharmacological efficacy in terms of tumor volume reduction for ERB LIPO gel (49.19%) and CS-ERB Lipo gel (55.27%) as compared to plain ERB Gel (38.88%) applied locally. Histology also revealed that formulation could alleviate dysplasia condition to hyperplasia. The locoregional therapy of ERB Lipo gel and CS-ERB Lipo gel thus show promising outcome in improving pre-malignant and early-stage oral cavity cancers.

Oral Mucosa Models to Evaluate Drug Permeability

Due to its numerous advantages, such as excellent drug accessibility, rapid absorption, and bypass of first-pass metabolism, the route of drug administration that involves crossing the oral mucosa is highly favored. As a result, there is significant interest in investigating the permeability of drugs through this region. The purpose of this review is to describe the various ex vivo and in vitro models used to study the permeability of conveyed and non-conveyed drugs through the oral mucosa, with a focus on the most effective models. Currently, there is a growing need for standardized models of this mucosa that can be used for developing new drug delivery systems. Oral Mucosa Equivalents (OMEs) may provide a promising future perspective as they are capable of overcoming limitations present in many existing models.

Recent advances in pain management based on nanoparticle technologies

BACKGROUND

Pain is a vital sense that indicates the risk of injury at a particular body part. Successful control of pain is the principal aspect in medical treatment. In recent years, the advances of nanotechnology in pain management have been remarkable. In this review, we focus on literature and published data that reveal various applications of nanotechnology in acute and chronic pain management.

METHODS

The presented content is based on information collected through pain management publications (227 articles up to April 2021) provided by Web of Science, PubMed, Scopus and Google Scholar services.

RESULTS

A comprehensive study of the articles revealed that nanotechnology-based drug delivery has provided acceptable results in pain control, limiting the side effects and increasing the efficacy of analgesic drugs. Besides the ability of nanotechnology to deliver drugs, sophisticated nanosystems have been designed to enhance imaging and diagnostics, which help in rapid diagnosis of diseases and have a significant impact on controlling pain. Furthermore, with the development of various tools, nanotechnology can accurately measure pain and use these measurements to display the efficiency of different interventions.

CONCLUSIONS

Nanotechnology has started a new era in the pain management and many promising results have been achieved in this regard. Nevertheless, there is still no substantial and adequate act of nanotechnology in this field. Therefore, efforts should be directed to broad investigations.

Evaluation of the Efficacy, Biocompatibility, and Permeation of Bupivacaine-Loaded Poly(epsilon-caprolactone) Nano-Capsules as an Anesthetic

In this study bupivacaine (BVC) was encapsulated in Nano-capsules of poly-ε-caprolactone (PCL) and its cytotoxicity in HaCaT (MTT) cells, its permeability in the oesophageal epithelium of pigs, as well as its anesthetic effect in the incision model of rat's hind paw (electronic von Frey anesthesiometer) were evaluated. BVC and epinephrine-associated bupivacaine (BVC-Epi) have been compared to BVC-Nano and it was demonstrated that BVC-Nano had high physicochemical properties and remained stable for 120 days; also, encapsulation of bupivacaine did not affect its toxicity to HaCaT cells, but epinephrine reduced its toxicity. Although both methods of combination with epinephrine and encapsulation in nanocapsules resulted in an extended time of anesthesia, the efficacy of epinephrine was more favorable. The permeation evaluation indicated that encapsulation increased both the permeability coefficient and the steady-state flux of bupivacaine across the esophageal epithelium. BVC permeation was enhanced by encapsulation into Nano-capsules, as a new novel therapeutic strategy, facilitating future research as a topical anesthetic.

2.5% EMLA Versus 2% Lignocaine with Adrenaline Injection in Small Oral Mucosal Biopsies: A Parallel Group Randomized Controlled Trial

Trial Design

The study was designed as an open label randomized comparative parallel group design with a 1:1 allocation ratio.

Methods

All consecutive patients reporting for small biopsies (incisional or excisional) who gave written informed consent were included in the study between October 2018 and October 2019. They were randomized into two groups, Group A and Group B both receiving intervention in the form of 2.5% EMLA cream and 2% Lignocaine with 1:80,000 Adrenaline injection respectively, to anaesthetise tissue for small mucosal biopsies in the oral cavity.

Results

EMLA was found to be as effective as lignocaine infiltration with a completely painless application and higher satisfaction for overall comfort during procedure. The duration required to achieve anaesthesia was however more. A particular subgroup of pathology was found to be completely resistant to anaesthesia by EMLA.

Conclusion

We recommend the use of EMLA as a sole anaesthetic in small mucosal biopsies and shavings in all patients. We suggest it as a higher and first line recommendation for anaesthesia in needle phobic patients and children.

Mucoadhesive, Thermoreversible Hydrogel, Containing Tetracaine-Loaded Nanostructured Lipid Carriers for Topical, Intranasal Needle-Free Anesthesia

Recent advances have been reported for needle-free local anesthesia in maxillary teeth by administering a nasal spray of tetracaine (TTC) and oxymetazoline, without causing pain, fear, and stress. This work aimed to assess whether a TTC-loaded hybrid system could reduce cytotoxicity, promote sustained permeation, and increase the anesthetic efficacy of TTC for safe, effective, painless, and prolonged analgesia of the maxillary teeth in dental procedures. The hybrid system based on TTC (4%) encapsulated in nanostructured lipid carriers (NLC) and incorporated into a thermoreversible hydrogel of poloxamer 407 (TTCNLC-HG4%) displayed desirable rheological, mechanical, and mucoadhesive properties for topical application in the nasal cavity. Compared to control formulations, the use of TTCNLC-HG4% slowed in vitro permeation of the anesthetic across the nasal mucosa, maintained cytotoxicity against neuroblastoma cells, and provided a three-fold increase in analgesia duration, as observed using the tail-flick test in mice. The results obtained here open up perspectives for future clinical evaluation of the thermoreversible hybrid hydrogel, which contains TTC-loaded NLC, with the aim of creating an effective, topical, intranasal, needle-free anesthesia for use in dentistry.

Should local drug delivery systems be used in dentistry?

In dentistry, the use of biomaterial-based drug delivery systems (DDS) aiming the release of the active compounds directly to the site of action is slowly getting more awareness among the scientific and medical community. Emerging technologies including nanotechnological platforms are offering novel approaches, but the majority are still in the proof-of-concept stage. This study critically reviews the potential use of DDS in anesthesiology, oral diseases, cariology, restorative dentistry, periodontics, endodontics, implantology, fixed and removable prosthodontics, and orthodontics with a special focus on infections. It also stresses the gaps and challenges faced. Despite numerous clinical and pharmacological advantages, some disadvantages of DDS pose an obstacle to their widespread use. The biomaterial's biofunctionality may be affected when the drug is incorporated and may cause an additional risk of toxicity. Also, the release of sub-therapeutic levels of drugs such as antibiotics may lead to microbial resistance. Multiple available techniques for the manufacture of DDS may affect drug release profiles and their bioavailability. If the benefits outweigh the costs, DDS may be potentially used to prevent or treat oral pathologies as an alternative to conventional strategies. A case-by-case approach must be followed.

Overcoming barriers by local drug delivery with liposomes

Localized or topical administration of drugs may be considered as a potential approach for overcoming the problems caused by the various biological barriers encountered in drug delivery. The combination of using localized administration routes and delivering drugs in nanoparticulate formulations, such as liposomes, may have additional advantages. Such advantages include prolonged retention of high drug loads at the site of action and controlled release of the drug, ensuring prolonged therapeutic effect; decreased potential for side-effects and toxicity (due to the high topical concentrations of drugs); and increased protection of drugs from possible harsh environments at the site of action. The use of targeted liposomal formulations may further potentiate any acquired therapeutic advantages. In this review we present the most advanced cases of localized delivery of liposomal formulations of drugs, which have been investigated pre-clinically and clinically in the last ten years, together with the reported therapeutic advantages, in each case.

Lidocaine Hydrochloride Nanoparticles Preparation using Multiple Emulsions and its Physicochemical Evaluation

Lidocaine is a primary local anesthesia that blocks the ionic fluxes required for the beginning and operation of impulses in the neuronal membrane. The benefits of local anesthetics, such as enhancing patient acceptance, prohibiting systemic toxicity and delivering continuous drug delivery, make them the attracting field for pharmaceutical researchers. The nanoparticles were prepared by solvent evaporation W1/O/W2 emulsion method and in the ratios of 1 to 1, 1 to 2 and 1 to 3 drug to polymer. The production yield, loading efficiency, particle size, poly dispersity index and zeta potential of selected formulation were 84.30%, 80.60%, 192[Formula: see text]nm, 0.18[Formula: see text]mV and [Formula: see text][Formula: see text]mV, respectively. DSC and FTIR studies showed that no chemical interactions between drug and polymer Formulations showed an initial burst release, which is a reason for the good capacity of the polymer to maintain the drug in it and lead to a primary slow release.

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

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

Resistivity Technique for the Evaluation of the Integrity of Buccal and Esophageal Epithelium Mucosa for In Vitro Permeation Studies: Swine Buccal and Esophageal Mucosa Barrier Models

Permeation assays are important for the development of topical formulations applied on buccal mucosa. Swine buccal and esophageal epithelia are usually used as barriers for these assays, while frozen epithelia have been used to optimize the experimental setup. However, there is no consensus on these methods. In transdermal studies, barrier integrity has been evaluated by measuring electrical resistance (ER) across the skin, which has been demonstrated to be a simple, fast, safe, and cost-effective method. Therefore, the aims here were to investigate whether ER might also be an effective method to evaluate buccal and esophageal epithelium mucosa integrity for in vitro permeation studies, and to establish a cut-off ER value for each epithelium mucosa model. We further investigated whether buccal epithelium could be substituted by esophageal epithelium in transbuccal permeation studies, and whether their permeability and integrity were affected by freezing at -20 °C for 3 weeks. Fresh and frozen swine buccal and esophageal epithelia were mounted in Franz diffusion cells and were then submitted to ER measurement. Permeation assays were performed using lidocaine hydrochloride as a hydrophilic drug model. ER was shown to be a reliable method for evaluating esophageal and buccal epithelia. The esophageal epithelium presented higher permeability compared to the buccal epithelium. For both epithelia, freezing and storage led to decreased electrical resistivity and increased permeability. We conclude that ER may be safely used to confirm tissue integrity when it is equal to or above 3 kΩ for fresh esophageal mucosa, but not for buccal epithelium mucosa. However, the use of esophageal epithelium in in vitro transmucosal studies could overestimate the absorption of hydrophilic drugs. In addition, fresh samples are recommended for these experiments, especially when hydrophilic drugs are involved.

Levobupivacaine-Loaded Liposome Associated with Thermogel for Prolonged Analgesia

Pain is a phenomenon present in the majority of the population, affecting, among others, the elderly, overweight people, and especially recently operated patients, analgesia being necessary. In the specific case of relief of postoperative pain, different kinds of anesthetics are being used, among them bupivacaine, a widely used drug which promotes long-lasting analgesic effects. However, cardiotoxicity and neurotoxicity are related to its repetitive use. To overcome these shortcomings, Novabupi® (a racemic mixture) was developed and is marketed as an injectable solution. This formulation contains an enantiomeric excess of the levogyre isomer, which has reduced toxicity effects. Seeking to rationalize its use by extending the duration of effect and reducing the number of applications, the objectives of this work were to develop and evaluate liposomes containing Novabupi (LBPV), followed by incorporation into thermogel. Liposomes were prepared using the lipid hydration method, followed by size reduction using sonication, and the developed formulations were characterized by hydrodynamic diameter, polydispersity index (PDI), surface zeta potential, and encapsulation efficiency. The selected optimal liposomal formulation was successfully incorporated into a thermogel without loss of thermoresponsive properties, being suitable for administration as a subcutaneous injection. In the ex vivo permeation studies with fresh rodent skin, the thermogel with liposomes loaded with 0.5% LBPV (T-gel formulation 3) showed higher permeation rates compared to the starting formulation, thermogel with 0.5% LBPV (T-Gel 1), which will probably translate into better therapeutic benefits for treatment of postoperative analgesia, especially with regard to the number of doses applied.

Promising potential of articaine-loaded poly(epsilon-caprolactone) nanocapules for intraoral topical anesthesia

To determine whether the permeation capacity and analgesic efficacy of articaine (ATC) could be increased and cytotoxicity decreased by encapsulation in poly(ɛ-caprolactone) nanocapsules (ATC_nano), aiming at local or topical anesthesia in dentistry. Cellular viability was evaluated (using the MTT test and fluorescence microscopy) after 1 h and 24 h exposure of HaCaT cells to ATC, ATC_nano, ATC with epinephrine (ATC_epi), and ATC in nanocapsules with epinephrine (ATC_nanoepi). The profiles of permeation of 2% ATC and 2% ATC_nano across swine esophageal epithelium were determined using Franz-type vertical diffusion cells. Analgesic efficacy was evaluated with a von Frey anesthesiometer in a postoperative pain model in rats, comparing the 2% ATC, 2% ATC_nano, 2% ATC_epi, and 2% ATC_nanoepi formulations to 4% ATC_epi (a commercially available formulation). We show that use of the nanocapsules decreased the toxicity of articaine (P<0.0001) and increased its flux (P = 0.0007). The 2% ATC_epi and 4% ATC_epi formulations provided higher analgesia success and duration (P<0.05), compared to 2% ATC, 2% ATC_nano, and 2% ATC_nanoepi. Articaine-loaded poly(ɛ-caprolactone) nanocapsules constitute a promising formulation for intraoral topical anesthesia (prior to local anesthetic injection), although it is not effective when injected in inflamed tissues for pain control, such as irreversible pulpitis.

Manufacturing and characterisation of a novel composite dosage form for buccal drug administration

The potential of alternative routes of application compared to the traditional oral route is constantly growing. Especially in transmucosal applications for the oral cavity, easy accessibility is an attractive feature with many new opportunities. The combination of a minitablet and a buccal mucoadhesive carrier film has been shown to enable safe and accurate drug administration compared to semi-solid formulations currently available on the market. In order to investigate these so-called composite dosage forms in more detail, two different manufacturing methods were compared within this study to investigate the resulting properties. The formulation development of the minitablets containing lidocaine, complying with the compendial requirements, resulted in immediate release using both manufacturing methods (more than 80% lidocaine release after 3-4 min using direct incorporation, 7-8 min by the gluing method). Differences in morphology and drug migration behaviour could be observed. The directly incorporated minitablets revealed a twofold higher drug migration (1.5 mm) into the mucoadhesive shielding film within two weeks compared to the glued minitablets (0.8 mm). These findings enable a further optimization of the formulation depending on the duration of the application and the feasibility for the addressed patient population.

Hybrid Pectin-Liposome Formulation against Multi-Resistant Bacterial Strains

This work describes the development of a gastroresistant antimicrobial formulation composed of two carriers, pectin and liposomes, intended to improve the efficiency of norfloxacin (NOR) against multi-resistant bacterial strains. The formulations showed physicochemical stability for 180 days (4 °C) in terms of size, polydispersity, and zeta potential of the vesicles, prolonging the in vitro release of NOR for 11 h. The hybrid nanocarriers improved the in vitro antimicrobial activity against different multidrug-resistant bacterial strains, such as Salmonella sp., Pseudomonasaeruginosa, E. coli and Campylobacterjejuni, in comparison to commercial NOR and liposomal suspensions. The in vivo toxicity assay in chicken embryos revealed that the hybrid systems were not toxic in any of the different parameters analyzed, a result also corroborated by the analyses of biochemical biomarkers of the chicken-embryos liver function.

Physicochemical characterization and cytotoxicity of articaine-2-hydroxypropyl-β-cyclodextrin inclusion complex

Articaine (ATC) is one of the most widely used local anesthetics in dentistry. Despite its safety, local toxicity has been reported. This study aimed to develop an ATC-2- hydroxypropyl-β-cyclodextrin inclusion complex (ATC HPβCD) and to assess its toxicity in vitro. The inclusion complex was performed by solubilization, followed by a fluorimetric and job plot assay to determine the complex stoichiometry. Scanning electron microscopy, DOSY- 1 H-NMR, differential scanning calorimetry (DSC), and sustained release kinetics were used to confirm the inclusion complex formation. In vitro cytotoxicity was analyzed by MTT assay and immunofluorescence in HGF cells. Fluorimetric and job plot assay determined the inclusion complex stoichiometry (ATC:HPβCD = 1:1) and complex formation time (400 min), as indicated by a strong host/guest interaction (Ka = 117.8 M - 1), complexed fraction (f = 41.4%), and different ATC and ATC HPβCD melting points (172 °C e 235 °C, respectively). The mean of cell viability was 31.87% and 63.17% for 20-mM ATC and 20-mM ATC HPβCD, respectively. Moreover, remarkable cell toxicity was observed with free ATC by immunofluorescence. These results indicate the ATC HPβCD complex could be used to improve the safety of ATC. Further research are needed to establish the anesthetic safety and effectiveness in vivo .

Palatal needle-free anesthesia for upper molars extraction. A randomized clinical trial

BACKGROUND

The aim of this study was to compare the ability of liposomal and non-liposomal lidocaine and prilocaine in hydrogel formulations to promote topical anesthesia in palatal mucosa during upper molar extractions.

METHODS

In this randomized, cross over, triple-blinded clinical trial, a liposomal and a non-liposomal formulation of the eutectic mixture of local anesthetics, 2.5% lidocaine and 2.5% prilocaine, were used to promote palatal anesthesia without the local anesthetic infiltration during bilateral upper molars extractions.

RESULTS

From the total of 40 patients included in this study, the non-liposomal eutectic lidocaine-prilocaine formulation failed in 40% of cases, unlike the liposomal formulation, which was effective for all patients (Fisher's exact test, p < 0.0001). Furthermore, the liposomal formulation (26.75 ± 7,47 min) induced longer anesthesia duration (t-test, p < 0.0001) than the non-liposomal formulation (16.78 ± 4.75 min). No mucosal ulceration or discomfort was reported for both formulations.

CONCLUSION

The liposomal formulation was able to induce adequate anesthesia in palatal mucosa during dental extraction, avoiding the local anesthetic infiltration. For the first time, a topical formulation allowed upper molars surgical removal without injection of any local anesthetic agent into palatal mucosa in adults.

Nanomedicine: a new paradigm to overcome drug incompatibilities

OBJECTIVES

Drug incompatibilities may compromise the safety and effectiveness of combined drugs and result in mild-to-serious clinical complications, such as catheter obstruction, loss of drug efficacy, formation of toxic derivatives and embolism. Various preventive strategies have been implemented to overcome drug incompatibilities with limited success. This review presents an innovative approach to prevent drug incompatibilities via isolating the incompatible drugs into nanostructures.

KEY FINDINGS

Several examples of incompatible drugs may be loaded separately into nanostructures of various types. Physicochemical characteristics and biocompatibility of the nanomaterials that are being utilized to prevent physicochemical incompatibilities should be carefully considered.

CONCLUSIONS

There is a new era of exploiting nanomaterials in overcoming various types of physicochemical incompatibilities, with additional benefits of further improvements in pharmacokinetic profiles and pharmacological actions of the administered drugs.

The effect of ethanol evaporation on the properties of inkjet produced liposomes

Background

Inkjet method has been used to produce nano-sized liposomes with a uniform size distribution. However, following the production of liposomes by inkjet method, the solvent residue in the product could have a significant effect on the properties of the final liposomes.

Objective

This research paper aimed to find a suitable method to remove ethanol content and to study its effect on the properties of the final liposomal suspension.

Method

Egg phosphatidylcholine and lidocaine were dissolved in ethanol; and inkjet method at 80 kHz was applied to produce uniform droplets, which were deposited in an aqueous solution to form liposomes. Dry nitrogen gas flow, air-drying, and rotary evaporator were tested to remove the ethanol content. Liposome properties such as size, polydispersity index (PDI), and charge were screened before and after ethanol evaporation.

Results

Only rotary evaporator (at constant speed and room temperature for 2 h) removed all of the ethanol content, with a final drug entrapment efficiency (EE) of 29.44 ± 6.77%. This was higher than a conventional method. Furthermore, removing ethanol led to liposome size reduction from approximately 200 nm to less than 100 nm in most samples. Additionally, this increased the liposomal net charge, which contributed to maintain the uniform and narrow size distribution of liposomes.

Conclusion

Nano-sized liposomes were produced with a narrow PDI and higher EE compared to a conventional method by using an inkjet method. Moreover, rotary evaporator for 2 h reduced effectively the ethanol content, while maintaining the narrow size distribution.

The Oral Administration of Lidocaine HCl Biodegradable Microspheres: Formulation and Optimization

Purpose

Lidocaine (LID) is a local anesthetic that is administered either by injection and/or a topical/transdermal route. However, there is a current need to develop efficacious methods for the oral delivery of LID with optimized bioavailability.

Methods

We developed oral LID biodegradable microspheres that were loaded with alginate-chitosan with different mass ratios, and characterized these microspheres in vitro. We also developed, and utilized, a simple and sensitive HPLC-tandem mass spectrometry (LC-MS-MS) method for assaying LID microspheres.

Results

The mean particle size (MPS) of the LID microspheres ranged from 340.7 to 528.3 nm. As the concentration of alginate was reduced, there was a significant reduction in MPS. However, there was no significant change in drug entrapment efficiency (DEE), or drug yield, when the alginate concentration was either increased or decreased. DSC measurements demonstrated the successful loading of LID to the new formulations. After a slow initial release, less than 10% of the LID was released in vitro within 4 h at pH 1.2. In order to evaluate nephrotoxicity, we carried out MTT assays of LID in two types of cell line (LLC-PK1 and MDCK). LID significantly suppressed the cell toxicity of both cell lines at the concentrations tested (100, 200, and 400ng/µL).

Conclusion

Experiments involving the oral delivery of LID formulations showed a significant reduction in particle size and an improvement in dissolution rate. The formulations of LID developed exhibit significantly less toxicity than LID alone.

Liposomal anesthetic gel for pain control during periodontal therapy in adults: a placebo-controlled RCT

INTRODUCTION

Periodontal therapy usually requires local anesthesia. If effective, a non-invasive, liposomal anesthetic gel could increase the levels of acceptance of patients in relation to periodontal therapy.

OBJECTIVE

This study investigated the efficacy of liposomal anesthetic gel for pain control during periodontal therapy.

METHODOLOGY

Forty volunteers with moderate to severe chronic periodontitis were recruited, of which at least three sextants required periodontal therapy. At least one of the selected teeth had one site with a probing depth of ≥4 mm. The volunteers received the following three gels: a placebo, lidocaine/prilocaine (Oraqix®), or a liposomal lidocaine/prilocaine, which were applied to different sextants. Pain frequency was registered during treatment and the volunteers received a digital counter to register any painful or uncomfortable experiences. At the end of each session, the volunteers indicated their pain intensity using rating scales (NRS-101 and VRS-4). The volunteers had their hemodynamic parameters measured by a non-invasive digital monitor.

RESULTS

Pain frequency/intensity did not show statistical difference between intervention groups. The tested gels did not interfere with the hemodynamic indices. Dental anxiety, suppuration and probing depth could influence pain during periodontal therapy.

CONCLUSION

Our results suggest limited indications for the use of non-invasive anesthesia when used for scaling and root planing. Intra-pocket anesthetic gel could be a good option for anxious patients, or those who have a fear of needles.

Comparison of antinociceptive effects of plain lidocaine versus lidocaine complexed with hydroxypropyl-β-cyclodextrin in animal models of acute and persistent orofacial pain

Herein, it was investigated whether a complex of lidocaine with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) would present a better antinociceptive profile in vivo when compared with plain lidocaine in models of orofacial pain. Plain lidocaine (LDC) and complexed lidocaine (LDC:HP-β-CD) were initially evaluated in vitro to determine the release rate of the two formulations. Subsequently, the effect of both formulations was evaluated in independent groups of rats submitted to the orofacial formalin test, induction of facial heat hyperalgesia by capsaicin and carrageenan, and induction of facial heat and mechanical hyperalgesia by constriction of the infraorbital nerve. LDC:HP-β-CD led to a reduction in the lidocaine release assessed in the in vitro release assay compared to plain LDC. Both formulations presented an antinociceptive effect in all models, but LDC:HP-β-CD showed a better effect in the second phase of the formalin response, in carrageenan-induced heat hyperalgesia, and in the heat hyperalgesia associated to infraorbital nerve constriction. Our results show that complexation improved in vivo antinociceptive effects of LDC, but further studies are necessary to elucidate what properties contribute to the better effect of the complexed formulation on this models and/or what characteristics of the pain model facilitate the action of the complexed formulation.

Hybrid Hydrogel Composed of Polymeric Nanocapsules Co-Loading Lidocaine and Prilocaine for Topical Intraoral Anesthesia

This study reports the development of nanostructured hydrogels for the sustained release of the eutectic mixture of lidocaine and prilocaine (both at 2.5%) for intraoral topical use. The local anesthetics, free or encapsulated in poly(ε-caprolactone) nanocapsules, were incorporated into CARBOPOL hydrogel. The nanoparticle suspensions were characterized in vitro in terms of particle size, polydispersity, and surface charge, using dynamic light scattering measurements. The nanoparticle concentrations were determined by nanoparticle tracking analysis. Evaluation was made of physicochemical stability, structural features, encapsulation efficiency, and in vitro release kinetics. The CARBOPOL hydrogels were submitted to rheological, accelerated stability, and in vitro release tests, as well as determination of mechanical and mucoadhesive properties, in vitro cytotoxicity towards FGH and HaCaT cells, and in vitro permeation across buccal and palatal mucosa. Anesthetic efficacy was evaluated using Wistar rats. Nanocapsules were successfully developed that presented desirable physicochemical properties and a sustained release profile. The hydrogel formulations were stable for up to 6 months under critical conditions and exhibited non-Newtonian pseudoplastic flows, satisfactory mucoadhesive strength, non-cytotoxicity, and slow permeation across oral mucosa. In vivo assays revealed higher anesthetic efficacy in tail-flick tests, compared to a commercially available product. In conclusion, the proposed hydrogel has potential for provision of effective and longer-lasting superficial anesthesia at oral mucosa during medical and dental procedures. These results open perspectives for future clinical trials.

Full-Thickness Intraoral Mucosa Barrier Models for In Vitro Drug-Permeation Studies Using Microneedles

The use of permeation enhancers such as microneedles (MNs) to increase drug penetration across intraoral mucosa has increased in recent years. Permeation studies, commonly performed using vertical diffusion cells, are a well-established way to preview formulations and enhance their performance during the development stage. However, to our knowledge, the existing intraoral mucosa barrier models do not permit permeation using MN-pretreated mucosa due to their insufficient thickness. Therefore, the objective of this study was to develop a barrier model using thick palate tissues to perform in vitro permeation studies, with physical enhancement of the permeability of intraoral mucosa by pretreatment with MNs. The adapted Franz-type cells used in the permeation experiments were validated (cell dimensions and volume, sealing effectiveness, stirring and dissolution efficiency, temperature control, and establishment of uniaxial flux). Commercially available MNs were used in the palatal mucosa. Optical images of the mucosa were acquired to analyze the microperforations created. In vitro permeation studies were conducted with the MN-pretreated mucosa. This work presents a new in vitro method for the evaluation of MNs as permeation enhancers, with the aim of improving the absorption of drug formulations topically applied within the oral cavity.

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.

Liposomal-based lidocaine formulation for the improvement of infiltrative buccal anaesthesia

This study describes the encapsulation of the local anaesthetic lidocaine (LDC) in large unilamellar liposomes (LUV) prepared in a scalable procedure, with hydrogenated soybean phosphatidylcholine, cholesterol and mannitol. Structural properties of the liposomes were assessed by dynamic light scattering, nanoparticle tracking analysis and transmission electron microscopy. A modified, two-compartment Franz-cell system was used to evaluate the release kinetics of LDC from the liposomes. The in vivo anaesthetic effect of liposomal LDC 2% (LUV_LDC) was compared to LDC 2% solution without (LDC_PLAIN) or with the vasoconstrictor epinephrine (1:100 000) (LDC_VASO), in rat infraorbital nerve blockade model. The structural characterization revealed liposomes with spherical shape, average size distribution of 250 nm and low polydispersity even after LDC incorporation. Zeta potential laid around -30 mV and the number of suspended liposomal particles was in the range of 10¹² vesicles/mL. Also the addition of cryoprotectant (mannitol) did not provoke structural changes in liposomes properties. In vitro release profile of LDC from LUV fits well with a biexponential model, in which the LDC encapsulated (EE% = 24%) was responsible for an increase of 67% in the release time in relation to LDC_PLAIN (p < 0.05). Also, the liposomal formulation prolonged the sensorial nervous blockade duration (∼70 min), in comparison with LDC_PLAIN (45 min), but less than LDC_VASO (130 min). In this context, this study showed that the liposomal formulations prepared by scalable procedure were suitable to promote longer and safer buccal anaesthesia, avoiding side effects of the use of vasoconstrictors.

Comparative evaluation of efficacy of EMLA and needleless jet anesthesia in non-surgical periodontal therapy

The treatment of periodontitis primarily consists of mechanical debridement carried out by means of thorough scaling and root planing that might sometimes be a painful procedure which requires the administration of some form of local anesthesia. The present study comparatively evaluates the anesthetic effect of three such forms, viz; eutectic mixture of 25 mg/g lignocaine plus 25 mg/g prilocaine (EMLA) and needleless jet anesthesia during SRP. 30 patients with probing depth of 5 mm or more and visual analog scale (VAS) score of ≥30 mm on probing were selected and asked to assess the pain by VAS and verbal rating scale (VRS) during SRP after application of the two agents. The difference between the visual analogue values of control, EMLA and Madajet XL is highly significant (p < 0.001). According to the VRS scores, 6.7% of the subjects in the EMLA group reported no pain, 80% mild pain, and 13.3% moderate pain. In the Madajet XL group, 46.7% reported no pain and 53.3% mild pain. In the control group 100% of the patients reported moderate pain when none of the anesthetic was administered. None reported severe pain. Thus, the data suggest that both anesthetics are able to produce anesthesia of the tissues. The needleless anesthesia was relatively superior in performance to EMLA.

Current progress and challenges of nanoparticle-based therapeutics in pain management

Pain is a widespread and growing health problem worldwide that exerts a considerable social and economic impact on both patients and healthcare systems and, therefore, on society in general. Although current treatment modalities include a wide variety of pharmacological and non-pharmacological approaches, due to the complexity of pain and individual differences in clinical response these options are not always effective in mitigating and relieving pain. In addition, some pain drugs such as non-steroidal anti-inflammatory drugs (NSAIDs), local anesthetics and opioids show several unfavorable side effects. Therefore, current research advances in this medical field are based on the development of potential treatments to address many of the unmet needs and to overcome the existing limitations in pain management. Nanoparticle drug delivery systems present an exciting opportunity as alternative platforms to improve efficacy and safety of medications currently in use. Herein, we review a broad range of nanoparticle formulations (organic nanostructures and inorganic nanoparticles), which have been developed to encapsulate an array of painkillers, paying special attention to the key advantages that these systems offer, (compared to the use of the free drug), as well as to the more relevant results of preclinical studies in animal models. Additionally, we will briefly discuss the impact of some of these nanoformulations in clinical trials.

Recent advances in nanocarrier-loaded gels: Which drug delivery technologies against which diseases?

The combination of pharmaceutical technologies can be a wise choice for developing innovative therapeutic strategies. The association of nanocarriers and gels provides new therapeutic possibilities due to the combined properties of the two technologies. Gels support the nanocarriers, localize their administration to the target tissue, and sustain their release. In addition to the properties afforded by the gel, nanocarriers can provide additional drug sustained release or different pharmacokinetic and biodistribution profiles than those from nanocarriers administered by the conventional route to improve the drug therapeutic index. This review focuses on recent (over the last ten years) in vivo data showing the advances and advantages of using nanocarrier-loaded gels. Liposomes, micelles, liquid and solid lipid nanocapsules, polymeric nanoparticles, dendrimers, and fullerenes are all nanotechnologies which have been recently assessed for medical applications, such as cancer therapy, the treatment of cutaneous and infectious diseases, anesthesia, the administration of antidepressants, and the treatment of unexpected diseases, such as alopecia.

Nanotechnology application to local anaesthesia (LA)

Several advancements have been made on the exact release of local anaesthetics formulation and its efficiency at inducing motor and sensory block for an extended time has been harnessed in clinical practice. The use of sustained release formulations delivers analgesia for a lengthier period of time with one administration, thereby reducing complications that usually arise with administration of conventional analgesia. In addition, controlled release of an anaesthetic drug is said to prevent overdosing, reduced side effects, especially cardiotoxicity, neurotoxicity and tissue lesions. The use of nanotechnology knowledge via liposomal formulation has recorded high successful results in pain control and quick patient recovery.

Advances in Hybrid Polymer-Based Materials for Sustained Drug Release

The use of biomaterials composed of organic pristine components has been successfully described in several purposes, such as tissue engineering and drug delivery. Drug delivery systems (DDS) have shown several advantages over traditional drug therapy, such as greater therapeutic efficacy, prolonged delivery profile, and reduced drug toxicity, as evidenced by in vitro and in vivo studies as well as clinical trials. Despite that, there is no perfect delivery carrier, and issues such as undesirable viscosity and physicochemical stability or inability to efficiently encapsulate hydrophilic/hydrophobic molecules still persist, limiting DDS applications. To overcome that, biohybrid systems, originating from the synergistic assembly of polymers and other organic materials such as proteins and lipids, have recently been described, yielding molecularly planned biohybrid systems that are able to optimize structures to easily interact with the targets. This work revised the biohybrid DDS clarifying their advantages, limitations, and future perspectives in an attempt to contribute to further research of innovative and safe biohybrid polymer-based system as biomaterials for the sustained release of active molecules.

The efficacy of eutectic mixture of local anesthetics as a topical anesthetic agent used for dental procedures: A brief review

Dental pain management is one of the most critical aspects of modern dentistry which might affect patient's quality of life. Several methods are suggested to provide a painless situation for patients. Desensitization of the oral site using topical anesthetics is one of those methods. The improvements of topical anesthetic agents are probably one of the most important advances in dental science in the past 100 years. Most of them are safe and can be applied on oral mucosa with minimal irritation and allergic reactions. At present, these agents are various with different potent and indications. Eutectic mixture of local anesthetics (EMLA) (lidocaine + prilocaine) is a commercial anesthetic agent which has got acceptance among dental clinicians. This article provides a brief review about the efficacy of EMLA as a topical anesthetic agent when used during dental procedures.

Development and Evaluation of a Novel Mucoadhesive Film Containing Acmella oleracea Extract for Oral Mucosa Topical Anesthesia

Purpose

To develop an anesthetic mucoadhesive film containing Acmella oleracea (jambu) extract for topical use on oral mucosa.

Methods

Ethanolic extracts from aerial parts of jambu were prepared by maceration. Pigment removal was obtained by adsorption with activated carbon. Three mucoadhesive films were developed using a film casting method: 10 or 20% of crude jambu extract (10% JB and 20% JB), and 10% of crude jambu extract treated with activated carbon (10% JBC). The mucoadhesive films were characterized regarding their uniformity, thickness, pH, and spilanthol content, and their stability was evaluated during 120 days. Gas chromatography was used to quantify the amount of spilanthol. In vitro tests determined the permeation of spilanthol across pig esophageal epithelium mucosa in Franz diffusion cells. Topical anesthetic efficacy was assessed in vivo using a tail flick test in mice.

Results

The three mucoadhesive films showed physical stability and visual appearances suitable for use on oral mucosa. The permeation study revealed that the spilanthol from 10% JBC presented higher flux and permeability coefficient values, compared to 10% or 20% JB (p < 0.001). Moreover, 10% JBC showed better topical anesthetic efficacy than the other films (p < 0.01).

Conclusion

Mucoadhesive film containing crude extract of jambu treated with activated carbon is a potential alternative for oral, topical use, encouraging future clinical studies.

Influence of salivary washout on drug delivery to the oral cavity using coated microneedles: An in vitro evaluation

The objective of this study was to determine whether in buccal tissues, after insertion and removal of coated microneedles, the presence of saliva over the insertion site can lead to loss of the deposited drug, and if saliva can influence in vitro permeation of the drug across the tissue. Microneedles were coated with sulforhodamine (SRD), which was used as a model drug, and inserted in to porcine buccal mucosa in vitro. Fluorescence microscopy was used to study microneedle coating quality and the diffusion of SRD through the mucosa. Permeation experiments were conducted for simulated dynamic or static salivary flow by adding 100μL/h or 100, 200 or 300μL of phosphate buffered saline (PBS) in the donor compartment of the Franz diffusion cells, into which buccal tissue after insertion of SRD-coated microneedles was placed. Microscopy showed that microneedles were uniformly coated with SRD and that SRD was successfully delivered in to the mucosa. Some SRD remained in the tissue even after 24h, despite presence of PBS on top of the coated microneedle insertion site. It was found that salivary washout can result in loss of drug that has been deposited in oral cavity mucosal tissues using coated microneedles, and presence of fluid over the coated microneedle insertion site can increase flux across the tissue. Thus, it is advisable to include salivary flow during in vitro studies related to the use of coated microneedles for drug delivery to the oral cavity in order to not obtain misleading results.

Evaluation of different pig oral mucosa sites as permeability barrier models for drug permeation studies

The objective of the present study was to investigate the influence of preparation and storage conditions on the histology and permeability of different parts of porcine oral mucosa used for in vitro studies of transbuccal formulations. Fresh and frozen (-20°C and -80°C, with or without cryoprotectant) epithelia of porcine palatal, gingival, dorsum of the tongue, and buccal mucosa were submitted for histological analyses to determine the effects of storage conditions on barrier integrity. Permeation of lidocaine hydrochloride (used as a hydrophilic model drug) across fresh and previously frozen oral epithelium was measured in order to evaluate the barrier function. Histological evaluation demonstrated that the oral epithelium was successfully separated from the connective tissue, except for gingival mucosa. After storage under different conditions, all tissues presented desquamation of superficial layers and spherical spaces induced by the freezing process. The permeability of lidocaine hydrochloride varied among the fresh oral mucosa and generally increased after freezing. In conclusion, fresh epithelium from the buccal and dorsum of the tongue mucosa should be used for in vitro studies investigating hydrophilic drug transport when these are the desired clinical application sites. However, when the palate is the target site, both fresh and frozen (for up to 4weeks, without addition of cryoprotectant) samples could be used. The addition of glycerol as a cryoprotectant should be avoided due to increased lidocaine hydrochloride permeability.