Effects of lidocaine and the inclusion complex with 2-hydroxypropyl-ß-cyclodextrin on cell viability and proliferation of oral squamous cell carcinoma.

OBJECTIVES: Squamous cell carcinoma (SCC) is a malignant disease that affects the oral cavity. Lidocaine has shown antiproliferative and cytotoxic activity on several cell types. The rapid dispersion is a limitation issue; however, the complexation in cyclodextrin improved pharmacological features and modified the drug release. This study investigated the effects of lidocaine (lido) complexed with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD-lido) on cell viability and proliferation of human tongue squamous cell carcinoma SCC9 and SCC25. METHODS: The complex formation was confirmed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Cells SCC9 and SCC25 were exposed to lido and HP-ß-CD-lido (40-4000 µm), and the effects on cell viability (MTT) and antiproliferative activity (SRB) were tested. KEY FINDINGS: Differential scanning calorimetry and SEM results demonstrated the occurrence of host-guest interaction. Lido and HP-ß-CD-lido (4000 µm) significantly reduced the viability of SCC9 cells to 83% and 63%, respectively. The viability of SCC25 treated with lido, and HP-ß-CD-lido (4000 µm) was 71% and 44%, respectively. Lido (4000 µm) reduced the proliferation of SCC9 and SCC25 to 39.5% and 23.7%, respectively. HP-ß-CD-lido (4000 µm) was cytotoxic for both cell lines. CONCLUSIONS: HP-ß-CD was able to potentiate the in vitro cytotoxic effects of lidocaine on human squamous cell carcinoma.

Complexation of oxethazaine with 2-hydroxypropyl-ß-cyclodextrin: increased drug solubility, decreased cytotoxicity and analgesia at inflamed tissues.

OBJECTIVES: Oxethazaine (OXZ) is one of the few local anaesthetics that provides analgesia at low pH, but presents poor solubility, cytotoxicity and no parenteral formulations. To address these issues, we aimed to prepare OXZ host-guest inclusion complex with hydroxypropyl-beta-cyclodextrin (HP-ß-CD). METHODS: The inclusion complex was formed by co-solubilization, followed by a job plot analysis to determine stoichiometry of complexation and dialysis equilibrium analysis (based on UV/VIS absorption and fluorescence profiles of OXZ). Complex formation was confirmed by phase-solubility data, X-ray, Scanning Electron Microscopy and DOSY-1 H-NMR experiments. In vitro cytotoxicity was analysed by MTT test in 3T3 fibroblasts. In vivo analgesia was tested by Von Frey test (inflammatory wounds - rats). KEY FINDINGS: Oxethazaine complexed (1 : 1 molar ratio) with HP-ß-CD, as indicated by loss of OZX crystalline structure (X-ray) and strong host: guest interaction (NMR, K = 198/M), besides increased solubility. In vitro cell survival improved with the complex (IC50 OXZ = 28.9 µm, OXZ : HP-ß-CD = 57.8 µm). In addition, the complex (0.1% OXZ) promoted in vivo analgesia for the same time that 2% lidocaine/epinephrine did. CONCLUSION: Our results show that complexation improved physicochemical and biological properties of OXZ, allowing its application to inflamed tissues by parenteral routes.

Effect of 4-(N,N-dimethylamino)phenethyl Alcohol on Degree of Conversion and Cytotoxicity of Photo-Polymerized CQ-Based Resin Composites

The aim of this study was to evaluate the degree of conversion (DC) and the cytotoxicity of photo-cured experimental resin composites containing 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH) combined to the camphorquinone (CQ) compared with ethylamine benzoate (EDAB). The resin composites were mechanically blended using 35 wt% of an organic matrix and 65 wt% of filler loading. To this matrix was added 0.2 wt% of CQ and 0.2 wt% of one of the reducing agents tested. 5x1 mm samples (n=5) were previously submitted to DC measurement and then pre-immersed in complete culture medium without 10% (v/v) bovine serum for 1 h or 24 h at 37 °C in a humidifier incubator with 5% CO2 and 95% humidity to evaluate the cytotoxic effects of experimental resin composites using the MTT assay on immortalized human keratinocytes cells. As a result of absence of normal distribution, the statistical analysis was performed using the nonparametric Kruskal-Wallis to evaluate the cytotoxicity and one-way analysis of variance to evaluate the DC. For multiple comparisons, cytotoxicity statistical analyses were submitted to Student-Newman-Keuls and DC analysis to Tukey's HSD post-hoc test (=0.05). No significant differences were found between the DC of DMPOH (49.9%) and EDAB (50.7%). 1 h outcomes showed no significant difference of the cell viability between EDAB (99.26%), DMPOH (94.85%) and the control group (100%). After 24 h no significant difference were found between EDAB (48.44%) and DMPOH (38.06%), but significant difference was found compared with the control group (p>0.05). DMPOH presented similar DC and cytotoxicity compared with EDAB when associated with CQ.

O objetivo deste estudo foi avaliar o grau de conversão (GC) e a citotoxicidade de resinas compostas experimentais utilizando o álcool 4-(N,N-dimetilamino) fenil etílico (DMPOH) associado à canforoquinona (CQ) como sistema fotoiniciador (SF) comparado à versão comercial utilizando o benzoato de etilamina (EDAB). Para tanto, as resinas compostas experimentais foram mecanicamente misturadas utilizando (em peso): 35% de matriz orgânica e 65% em peso de partículas de carga. Posteriormente, foram adicionados 0,2% de CQ e 0,2% de um dos agentes redutores testados. Amostras de 5 x 1 mm (n=5) foram previamentes submetidas à análise de GC e posteriormente, esterilizadas e colocadas no meio de cultura completo sem soro fetal bovino estéril por 1 h ou 24 h a 37 °C em encubadora com 5% de CO2 and 95% de umidade para avaliar os efeitos citotóxicos das resinas compostas experimentais utilizando o método MTT emcélulas células humanas imortalizadas de queratinócitos. Os dados de citotoxicidade foram submetidos à análise estatística de Kruskal-Wallis e de GC à análise de variância com um fator. Em virtude da ausência de normalidade, a análise estatística da citotoxicidade foi realizada utilizando-se o teste não-paramétrico de Kruskal-Wallis. Para o GC, os dados foram submetidos à análise de variaância de 1 fator. Posteriormente para múltiplas comparações, os dados de citotoxicidade foram submetidos ao teste Student-Newman-Keuls e o GC ao teste de Tukey's HSD post-hoc (=0.05). Não foi observada diferença estatística entre o GC de DMPOH (49,9%) e EDAB (50,7%). Para os resultados de 1 h não houve diferença na viabilidade celular entre EDAB (99,26%), DMPOH (94,85%) e o grupo controle (100%). Após 24 h, nenhuma diferença estatística foi encontrada entre EDAB (48,44%) e DMPOH (38,06%), entretanto, diferença significativa foi encontrada em relação ao grupo controle (p>0,05). O DMPOH apresentou GC e citotoxicidade semelhante à EDAB quando associado à CQ.

Effect of 4-(N,N-dimethylamino)phenethyl alcohol on degree of conversion and cytotoxicity of photo-polymerized CQ-based resin composites.

The aim of this study was to evaluate the degree of conversion (DC) and the cytotoxicity of photo-cured experimental resin composites containing 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH) combined to the camphorquinone (CQ) compared with ethylamine benzoate (EDAB). The resin composites were mechanically blended using 35 wt% of an organic matrix and 65 wt% of filler loading. To this matrix was added 0.2 wt% of CQ and 0.2 wt% of one of the reducing agents tested. 5x1 mm samples (n=5) were previously submitted to DC measurement and then pre-immersed in complete culture medium without 10% (v/v) bovine serum for 1 h or 24 h at 37 °C in a humidifier incubator with 5% CO2 and 95% humidity to evaluate the cytotoxic effects of experimental resin composites using the MTT assay on immortalized human keratinocytes cells. As a result of absence of normal distribution, the statistical analysis was performed using the nonparametric Kruskal-Wallis to evaluate the cytotoxicity and one-way analysis of variance to evaluate the DC. For multiple comparisons, cytotoxicity statistical analyses were submitted to Student-Newman-Keuls and DC analysis to Tukey's HSD post-hoc test (=0.05). No significant differences were found between the DC of DMPOH (49.9%) and EDAB (50.7%). 1 h outcomes showed no significant difference of the cell viability between EDAB (99.26%), DMPOH (94.85%) and the control group (100%). After 24 h no significant difference were found between EDAB (48.44%) and DMPOH (38.06%), but significant difference was found compared with the control group (p>0.05). DMPOH presented similar DC and cytotoxicity compared with EDAB when associated with CQ.

Micro and nanosystems for delivering local anesthetics.

INTRODUCTION: One of the most common strategies for pain control during and after surgical procedures is the use of local anesthetics. Prolonged analgesia can be safely achieved with drug delivery systems suitably chosen for each local anesthetic agent. AREAS COVERED: This review considers drug delivery formulations of local anesthetics designed to prolong the anesthetic effect and decrease toxicity. The topics comprise the main drug delivery carrier systems (liposomes, biopolymers, and cyclodextrins) for infiltrative administration of local anesthetics. A chronological review of the literature is presented, including details of formulations as well as the advantages and pitfalls of each carrier system. The review also highlights pharmacokinetic data on such formulations, and gives an overview of the clinical studies published so far concerning pain control in medicine and dentistry. EXPERT OPINION: The design of novel drug delivery systems for local anesthetics must focus on how to achieve higher uploads of the anesthetic into the carrier, and how to sustain its release. This comprehensive review should be useful to provide the reader with the current state-of-art regarding drug delivery formulations for local anesthetics and their possible clinical applications.

Efficacy of liposome-encapsulated mepivacaine for infiltrative anesthesia in volunteers.

This blinded crossover study evaluated the efficacy and pain sensitivity evoked by a previously reported liposome-encapsulated mepivacaine formulation (Araujo et al., 2004). Thirty healthy volunteers received an intraoral injection (1.8 mL), at four different sessions, of the following formulations: 2% mepivacaine with 1:100,000 epinephrine (MVC(2%EPI)), 3% mepivacaine (MVC(3%)), and 2 and 3% liposome-encapsulated mepivacaine (MVC(2%LUV) and MVC(3%LUV)). Latency period and duration of anesthesia were assessed by an electrical pulp tester and injection discomfort by a visual analog scale (VAS). Data were analyzed with Tukey-Kramer and Friedman tests (P < 0.05). No significant difference was found regarding latency period (in minutes) among the formulations (P > 0.05). The duration of anesthesia after the injection of MVC(3%LUV) was higher than the one obtained after the infiltration of MVC(2%LUV) and of MVC(3%) (P < 0.05). However, the duration of anesthesia obtained with MVC(3%) did not differ from the one obtained with MVC(2%LUV) (P > 0.05). MVC(3%LUV) showed lower VAS median values than MVC(2%EPI) (P < 0.05), and there were no significant differences among the others formulations. Liposome-encapsulated 3% mepivacaine showed longer duration of anesthesia, in comparison to the commercial formulation of MVC(3%). MVC(2%LUV) was able to produce a similar duration of anesthesia as the 3% commercial formulation, despite the 50% decrease in the anesthetic concentration. Thus, the encapsulation of mepivacaine increased the duration of anesthesia and reduced the injection discomfort caused by vasoconstrictor-associated formulations in healthy volunteers.

Liposome-encapsulated ropivacaine for intraoral topical anesthesia.

OBJECTIVES: This study evaluated the efficacy of liposome-encapsulated 2% ropivacaine in topical anesthesia and its influence on pulpal response. STUDY DESIGN: Forty volunteers received the following topical formulations in the buccal fold of the maxillary lateral incisors region (bilaterally): liposome-encapsulated 2% ropivacaine gel (RL2); 20% benzocaine gel (B20); liposomal placebo gel (LP); and placebo gel (P). Formulations were kept in place for 30 minutes, during which time the teeth were electric pulp tested every 10 minutes. After this procedure, a dental needle was inserted until periosteum contact in the same site of topical application and pain was rated by a visual analog scale. Duration of soft tissue anesthesia was assessed by pinprick test. RESULTS: RL2 and B20 showed lower pain response to needle insertion and longer soft tissue anesthesia then P and LP (P = .0003 and P < .0001, respectively); however, RL2 was not different from B20 (P > .05) regarding those parameters. None of the formulations was able to induce pulpal anesthesia. CONCLUSION: RL2 was as effective as B20 in reducing pain during needle insertion and inducing soft tissue anesthesia; however, neither one was able to induce pulpal anesthesia after a 30-min application.

Liposomal encapsulation improves the duration of soft tissue anesthesia but does not induce pulpal anesthesia.

STUDY OBJECTIVE: To compare the topical and the pulpal anesthesia efficacy of liposomal and plain benzocaine formulations. DESIGN: Double-blinded, randomized crossover study. SETTING: University ambulatory dental center. PATIENTS: 30 ASA physical status I volunteers. INTERVENTIONS: Volunteers received, in three different sessions, topical application of liposome-encapsulated 10% benzocaine (LB10), 10% benzocaine gel (B10), and 20% benzocaine gel (B20) in the right maxillary canine mucobuccal fold. MEASUREMENTS: Pain associated with the needle insertion was rated by visual analog scale (VAS) and the duration of topical anesthesia was recorded. Pulpal anesthesia was evaluated using an electric pulp tester. MAIN RESULTS: VAS values (median, 1st - 3rd quartiles) were 17 cm (11 - 25), 14 cm (3 - 22), and 21 cm (9 - 21) for B10, LB10, and B20, respectively. No differences were noted among the groups (Friedman test; P = 0.58). Soft tissue anesthesia was also not different. The LB10 [10 (8 - 12) min] showed longer soft tissue anesthesia (Friedman test; P < 0.01) than the other agents [B10 = 8 (5 - 10) min, and B20 = 7 (6 - 9) min]. None of the topical benzocaine formulations tested induced pulpal anesthesia. CONCLUSIONS: The encapsulation of benzocaine into liposome increased the duration of soft tissue anesthesia. However, it did not induce pulpal anesthesia.

Liposome-encapsulated ropivacaine for topical anesthesia of human oral mucosa.

BACKGROUND: The elimination of pain caused by needle insertion for local anesthesia would be a significant advance in dentistry. METHODS: In this blinded cross-over study we evaluated the efficacy of liposome-encapsulated ropivacaine for topical anesthesia. Thirty healthy volunteers received 60 mg topical anesthetics: Liposome-encapsulated 1% ropivacaine, 1% plain ropivacaine, 2.5% lidocaine and 2.5% prilocaine mixture (EMLA), and 20% benzocaine gel, in the buccal fold of the upper-right canine for 2 min in different sessions. After insertion of 30-G needles, pain was rated on a visual analog scale (VAS). A pinprick test was used to measure the duration of topical anesthesia. The pulpar response was assessed by an electric pulp tester. RESULTS: VAS median and interquartile range (in cm) were 0.8 (0.4-1.5), 1.6 (0.8-2.6), 1.1 (0.3-2.7), 2.2 (0.9-2.9) for liposome-encapsulated ropivacaine, ropivacaine, EMLA, and benzocaine groups, respectively. The liposome-encapsulated ropivacaine group showed lower VAS mean values when compared with the benzocaine group (P = 0.0205). The median values and interquartile range for the duration of soft tissue anesthesia were 11 (7-14), 6.5 (4-11), 14 (11-16), and 7 (6-9) min for liposome-encapsulated ropivacaine, ropivacaine, EMLA, and benzocaine groups, respectively. EMLA and liposome-encapsulated ropivacaine were just as efficient for reducing pain, and showed longer soft tissue anesthesia when compared to the other local anesthetics (P = 0.0001). CONCLUSION: Liposomal-encapsulated 1% ropivacaine gel was equivalent to EMLA for reducing pain during needle insertion and for the duration of soft tissue anesthesia. None of the topical anesthetics was effective for inducing pulpal anesthesia.