Influence of Topical Anesthesia on Superficial Sensitivity: A Double-Blind, Randomized, Placebo-Controlled Study on 48 Healthy Subjects.

BACKGROUND: Topical anesthetics are used in noninvasive transdermal anesthesia to decrease the superficial pain sensation threshold during dermatologic surgery. Combined pain relief and sensitivity loss can avoid discomfort during the surgery. OBJECTIVE: The aim of this placebo-controlled study was to compare the efficacy of 3 commonly used topical agents by collating loss of sensitivity over time. MATERIALS AND METHODS: Three topical anesthetic creams, a topical anti-inflammatory cream, and a moisturizing cream were applied on the left volar forearm of each of the 48 healthy Caucasian participants. Sensitivity was assessed with the dynamic 2-point discrimination and the Semmes-Weinstein test at 0, 60, 90, 120, 150, and 180 minutes after cream application. RESULTS: After 180 minutes, benzocaine showed a significantly lower 2-point discrimination reduction than lidocaine alone and a lidocaine and prilocaine mixture. Sensory threshold measurements by the Semmes-Weinstein test after 60 minutes revealed a significantly higher effect with lidocaine alone and with the lidocaine and prilocaine mixture than with benzocaine. CONCLUSION: The authors found a stronger skin sensitivity reduction by the eutectic lidocaine and prilocaine mixture and lidocaine alone compared with benzocaine. We suggest increased discomfort reduction in topical anesthetic supported dermatologic surgery by the eutectic mixture and lidocaine alone.

Efficacy of Topical Benzocaine in Maxilla: A Randomized Controlled Trial.

This study aims to compare the effect of topical anesthesia against the use of no topical agent on pain of needle penetration and local anesthesia deposition during buccal infiltration in anterior maxilla. In a randomized controlled trial, 100 adult participants were randomly allocated to the benzocaine group (received 20% benzocaine gel) and no benzocaine group (received no topical agent) prior to buccal infiltration in maxillary anterior teeth. A 27-gauge needle was used to deposit 2% lidocaine with 1:100,000 epinephrine. Pain of needle penetration and local anesthesia deposition was recorded separately using an 11-point Numeric Pain Rating Scale. Results showed that although 20% benzocaine significantly reduced pain on needle penetration during buccal infiltration in maxillary anterior teeth, the difference was small and the clinical significance is not clear. Topical anesthetic did not affect pain of local anesthetic deposition.

Liposomal butamben gel formulations: toxicity assays and topical anesthesia in an animal model.

The aim of this study was to evaluate the in vitro cytotoxicity and the in vivo analgesic effect and local toxicity of the local anesthetic butamben (BTB) encapsulated in conventional or elastic liposomes incorporated in gel formulations. The results showed that both gel formulations of liposomal BTB reduced the cytotoxicity (p < 0.001; one-way ANOVA/Tukey's test) and increased the topical analgesic effect (p < 0.05; one-way ANOVA/Tukey's test) of butamben, compared to plain BTB gel. The gel formulations presented good rheological properties, and stability assays detected no differences in physicochemical stability up to 30 d after preparation. Moreover, histological assessment revealed no morphological changes in rat skin after application of any of the gel formulations tested.

Effect of Topical Anesthesia with Lidocaine-prilocaine (EMLA) Cream and Local Pressure on Pain during Infiltration Injection for Maxillary Canines: A Randomized Double-blind clinical trial.

OBJECTIVES: This study compared the effect of local pressure and topical lidocaine-prilocaine (EMLA) cream on pain during infiltration injection for maxillary canine teeth. MATERIALS AND METHODS: A total of 140 volunteer students participated in this split-mouth design randomized clinical trial. The subjects were randomly divided into four groups (n = 35). Before administration of anesthesia, in each group, one side was randomly selected as the experimental and the opposite side as the control. In group 1, finger pressure was applied on the alveolar mucosa on the experimental side and on the tooth crown on the control side. In group 2, 5% EMLA cream and placebo; in group 3, finger pressure and 5% EMLA cream; and in group 4, 5% EMLA cream and 20% benzocaine gel were applied. In all the groups, a buccal infiltration procedure was carried out. Pain during injection was recorded with visual analog scale (VAS). Wilcoxon and McNemar tests were used for statistical analysis of the results. Statistical significance was set at p < 0.05. RESULTS: The results showed that EMLA reduced the injection pain significantly more than benzocaine (p = 0.02). Also, injection pain was significantly lower with the use of EMLA in comparison to placebo (p = 0.00). Application of local pressure reduced the injection pain, but the difference from the control side was not significant (p = 0.05). Furthermore, the difference between application of local pressure and EMLA was not statistically significant (p = 0.08). CONCLUSION: Topical anesthesia of 5% EMLA was more effective than 20% benzocaine in reducing pain severity during infiltration injection. However, it was not significantly different in comparison to the application of local pressure.

Behavioral response and pain perception to computer controlled local anesthetic delivery system and cartridge syringe.

AIM: The present study evaluated and compared the pain perception, behavioral response, physiological parameters, and the role of topical anesthetic administration during local anesthetic administration with cartridge syringe and computer controlled local anesthetic delivery system (CCLAD). DESIGN: A randomized controlled crossover study was carried out with 120 children aged 7-11 years. They were randomly divided into Group A: Receiving injection with CCLAD during first visit; Group B: Receiving injection with cartridge syringe during first visit. They were further subdivided into three subgroups based on the topical application used: (a) 20% benzocaine; (b) pressure with cotton applicator; (c) no topical application. Pulse rate and blood pressure were recorded before and during injection procedure. Objective evaluation of disruptive behavior and subjective evaluation of pain were done using face legs activity cry consolability scale and modified facial image scale, respectively. The washout period between the two visits was 1-week. RESULTS: Injections with CCLAD produced significantly lesser pain response, disruptive behavior (P < 0.001), and pulse rate (P < 0.05) when compared to cartridge syringe injections. Application of benzocaine produced lesser pain response and disruptive behavior when compared to the other two subgroups, although the result was not significant. CONCLUSION: Usage of techniques which enhance behavioral response in children like injections with CCLAD can be considered as a possible step toward achieving a pain-free pediatric dental practice.

Airway anesthesia: theory and practice.

Topical anesthesia of the airway is a necessary for awake intubation and is usually achieved using lidocaine delivered by various means. Although some experts favor the use of airway blocks, a more common approach is to use pure topical methods in combination with "spray as you go" techniques. Once the topicalization is complete, the patient should be able to easily tolerate the use of an oral airway used to facilitate awake oral intubation. Nasal intubation requires additional topicalization of the nasal passages in conjunction with a vasoconstrictor. Finally, judicious sedation is frequently used when awake intubation is carried out.

Low intensity laser for reducing pain from anesthetic palatal injection.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of pain reduction techniques for palatal injection, namely, low intensity laser therapy (LILT), topical anesthesia, pressure, and light touch. BACKGROUND DATA: Previous evidence indicates that LILT may prevent pain from palatal injection. However, no clinical trials evaluating this clinical question have been performed. METHODS: A double-blind clinical trial was conducted using 80 healthy volunteers, 18-25 years of age. The subjects were randomly allocated into four groups with 10 females and 10 males each group. Pain reduction techniques were administered at an injection point that was 10 mm from the margin of the palatal gingiva of the upper left first molar according to the following groups: (1) a 790 nm 30 mW continuous wave with a 0.13 cm2 focal spot at an applied energy of 3.6 J and fluence of 27.69 J/cm2, (2) 20% benzocaine, (3) pressure, and (4) light touch as the control. Then, 2% lidocaine with 1:100,000 epinephrine was injected using a 27-gauge needle with a pressure and volume control intraligamentary syringe. All subjects recorded pain on a 10 cm visual analog scale (VAS). RESULTS: The pain score in the LILT group was <50 mm. The median of pain scores of the LILT, 20% benzocaine, pressure, and light touch groups were 11, 23, 27, and 31 mm, respectively. There was no statistically significant difference in VAS among the groups, using Kruskal-Wallis test (p=0.385). CONCLUSIONS: No statistically significant differences in pain scores were noted among low intensity laser, 20% benzocaine, pressure, and light touch.

Microemulsion for simultaneous transdermal delivery of benzocaine and indomethacin: in vitro and in vivo evaluation.

This study investigated simultaneous transdermal delivery of indomethacin and benzocaine from microemulsion. Eucalyptus oil based microemulsion was used with Tween 80 and ethanol being employed as surfactant and cosurfactant, respectively. A microemulsion formulation comprising eucalyptus oil, polyoxyethylene sorbitan momooleate (Tween 80), ethanol and water (20:30:30:20) was selected. Indomethacin (1% w/w) and benzocaine (20% w/w) were incorporated separately or combined into this formulation before in vitro and in vivo evaluation. Application of indomethacin microemulsion enhanced the transdermal flux and reduced the lag time compared to saturated aqueous control. The same trend was evident for benzocaine microemulsion. Simultaneous application of the two drugs in microemulsion provided similar enhancement pattern. The in vivo evaluation employed the pinprick method and revealed rapid anesthesia after application of benzocaine microemulsion with the onset being 10 min and the action lasting for 50 min. For indomethacin microemulsion, the analgesic effect was recorded after 34.5 min and lasted for 70.5 min. Simultaneous application of benzocaine and indomethacin provided synergistic effect. The onset of action was achieved after 10 min and lasted for 95 min. The study highlighted the potential of microemulsion formulation in simultaneous transdermal delivery of two drugs.

A new method of topical anesthesia by using anesthetic solution in a patch.

INTRODUCTION: We investigated the effects of topical anesthesia of the oral mucosa by using an adhesive patch instilled with 2% lidocaine hydrochloride solution. METHODS: The subjects were 20 healthy adult volunteers who gave written informed consent. Each patient was treated in a randomized crossover fashion with a hemostatic adhesive patch instilled with one of the following agents: 2% lidocaine hydrochloride with 12.5 µg/mL epinephrine, 2% lidocaine hydrochloride, 20% ethyl aminobenzoate, or physiological saline solution. A cotton ball containing 20% ethyl aminobenzoate was also tested. The adhesive patch or cotton ball was placed on the gingivobuccal fold of the maxillary right canine for 2 or 5 minutes. Then, a 33-gauge or 30-gauge needle was inserted to a depth of 2 mm. Insertion pain was evaluated with a visual analog scale (VAS) and a 4-level verbal rating scale immediately after needle removal. Efficacy of analgesia was calculated from the verbal rating scale. RESULTS: The VAS was lower and the efficacy of analgesia was higher on 33-gauge needle insertion than on 30-gauge needle insertion in all treatments. The VAS was also significantly lower and the efficacy of analgesia was higher in the lidocaine groups than in the other groups. Adding epinephrine did not enhance the anesthetic effect of lidocaine hydrochloride. CONCLUSIONS: Topical mucosal anesthesia with an adhesive patch containing 2% lidocaine hydrochloride solution is simple and may be more effective than conventional methods.

Topical lidocaine enhanced by laser pretreatment: a safe and effective method of analgesia for facial rejuvenation.

BACKGROUND: Injectable forms of anesthesia for nonsurgical facial rejuvenation, although efficacious, are uncomfortable for the patient. Preclinical studies have demonstrated that laser pretreatment at low energies enhances absorption of topical lidocaine. OBJECTIVES: The authors assess the safety and efficacy of laser-assisted transdermal delivery of topical anesthetic. METHOD: Ten patients were split into 2 groups (A and B). All patients received 15 g of BLT (20% benzocaine, 6% lidocaine, and 4% tetracaine triple anesthetic cream) for 20 minutes with no occlusion. Then the cream was removed and the first blood draw taken. Group A patients were pretreated with the full ablative laser and group B patients with a fractional ablative laser to the full face. A further 15 g BLT was applied for another 20 minutes. Group A patients then underwent full ablative laser treatment, and group B received fractionated ablative laser treatment. Blood draws were taken at 60, 90, 120, 180, and 240 minutes after the initial topical anesthetic application, and the serum was analyzed for lidocaine and monoethylglycinexylidide (MEGX) levels. Patients were asked to rate the pain felt at intervals during the procedure. RESULTS: No patient required supplemental nerve blocks. Pain scores were equivalent at the end of the first pass for both groups (P = .436). Group A patients had significantly lower pain scores at the start of the second laser treatment (P = .045), but pain scores became equivalent by the end (P = .323). Combined serum lidocaine and MEGX levels were significantly higher in group A patients up to 90 minutes (peak average of 0.61 µg/mL for group A and 0.533 µg/mL for group B; P = .0253), which corresponded to greater initial analgesic effect. CONCLUSIONS: Data from this study demonstrate that topical anesthetic for facial rejuvenation can be enhanced with laser pretreatment while maintaining safe blood serum levels. Further studies should examine optimal application amount and time to allow safe multipass facial rejuvenation without the need for invasive nerve blocks.

Risk of topical anesthetic-induced methemoglobinemia: a 10-year retrospective case-control study.

IMPORTANCE: Methemoglobinemia is a rare but serious disorder, defined as an increase in oxidized hemoglobin resulting in a reduction of oxygen-carrying capacity. Although methemoglobinemia is a known complication of topical anesthetic use, few data exist on the incidence of and risk factors for this potentially life-threatening disorder. OBJECTIVE: To examine the incidence of and risk factors for procedure-related methemoglobinemia to identify patient populations at high risk for this complication. DESIGN AND SETTING: Retrospective study in an academic research setting. PARTICIPANTS: Medical records for all patients diagnosed as having methemoglobinemia during a 10-year period were reviewed. EXPOSURES: All cases of methemoglobinemia that occurred after the following procedures were included in the analysis: bronchoscopy, nasogastric tube placement, esophagogastroduodenoscopy, transesophageal echocardiography, and endoscopic retrograde cholangiopancreatography. MAIN OUTCOMES AND MEASURES: Comorbidities, demographics, concurrent laboratory values, and specific topical anesthetic used were recorded for all cases. Each case was compared with matched inpatient and outpatient cases. RESULTS: In total, 33 cases of methemoglobinemia were identified during the 10-year period among 94,694 total procedures. The mean (SD) methemoglobin concentration was 32.0% (12.4%). The methemoglobinemia prevalence rates were 0.160% for bronchoscopy, 0.005% for esophagogastroduodenoscopy, 0.250% for transesophageal echocardiogram, and 0.030% for endoscopic retrograde cholangiopancreatography. Hospitalization at the time of the procedure was a major risk factor for the development of methemoglobinemia (0.14 cases per 10,000 outpatient procedures vs 13.7 cases per 10,000 inpatient procedures, P < .001). CONCLUSIONS AND RELEVANCE: The overall prevalence of methemoglobinemia is low at 0.035%; however, an increased risk was seen in hospitalized patients and with benzocaine-based anesthetics. Given the potential severity of methemoglobinemia, the risks and benefits of the use of topical anesthetics should be carefully considered in inpatient populations.

Liposomal-benzocaine gel formulation: correlation between in vitro assays and in vivo topical anesthesia in volunteers.

The aim of the present study was to characterize a liposome-based benzocaine (BZC) formulation designed for topical use on the oral mucosa and to evaluate its in vitro retention and permeation using the Franz-type diffusion cells through pig esophagus mucosa. To predict the effectiveness of new designed formulations during preclinical studies, a correlation between in vitro assays and in vivo efficacy was performed. Liposomal BZC was characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and morphology. Liposomal BZC (BL10) was incorporated into gel formulation and its performances were compared to plain BZC gel (B10) and the commercially available BZC gel (B20). BL10 and B10 presented higher flux and retention on pig esophagus mucosa with a shorter lag time, when compared to B20. BZC flux was strongly correlated with in vivo anesthetic efficacy, but not with topical anesthesia duration. The retention studies did not correlate with any of the in vivo efficacy parameters. Thus, in vitro permeation study can be useful to predict anesthetic efficacy during preclinical tests, because a correlation between flux and anesthetic efficacy was observed. Therefore, in vitro assays, followed by in vivo efficacy, are necessary to confirm anesthetic performance.

Effect of topical anesthesia on pain during infiltration injection and success of anesthesia for maxillary central incisors.

INTRODUCTION: This study was performed to investigate the effect of topical anesthesia on pain during needle penetration and infiltration injection as well as the effect of pain during injection on success rate of anesthesia in maxillary central incisors. METHODS: In a crossover double-blind study, 25 volunteers randomly received either topical anesthesia or placebo before infiltration injection with prilocaine for their maxillary central incisors in 2 separate appointments. The pain after needle penetration and during injection was separately recorded. An electric pulp tester was used to evaluate the success of the anesthetic injection. Data were analyzed by McNemar, Wilcoxon, and χ(2) tests. RESULTS: Overall for 50 injections, 72% of the teeth had successful anesthesia. No significant difference was found between placebo and topical anesthetic groups for the pain of needle penetration as well as pain during injection (P > .05). The volunteers who reported moderate-to-severe pain during injection showed no significant difference in the success rate of anesthesia compared with those with no or mild pain during injections (P > .05). CONCLUSIONS: Use of topical anesthesia had no significant effect on pain during either needle penetration or injection. Pain during injection had no significant effect on the success of anesthesia.

Clinical efficacy of tetracaine anesthetic paste.

Benzocaine, the most commonly used topical anesthetic in dentistry, often fails to eliminate the pain associated with injections. One type of anesthetic used frequently in medicine with success is tetracaine, but minimal research has been done regarding the application of tetracaine in dentistry. This study sought to evaluate the effectiveness and safety of tetracaine anesthetic paste (TAP), a newly formulated topical anesthetic. For this study, TAP was applied to the maxillary mucobuccal fold of one side of the arch and benzocaine paste was applied to the opposite side prior to injection of anesthetic. Patients then reported the level of pain experienced on each side and were evaluated for any adverse reactions. The results showed no difference in effectiveness between TAP and benzocaine paste, and no adverse reactions were reported. Because of the safety and effectiveness of tetracaine extraorally, further research is warranted on its intraoral use.

Effectiveness of two flavored topical anesthetic agents in reducing injection pain in children: a comparative study.

UNLABELLED: Topical anesthesia is widely advocated in pediatric dentistry practice to reduce pain and anxiety produced by administration of local anesthesia. There are different combinations of topical anesthetic agents that are marketed worldwide. However, sparse literature reports exist regarding clinical efficacy of these agents. AIM: To compare the clinical effectiveness of two strawberry flavored topical anesthetics viz. Precaine (8% Lidocaine + 0.8% Dibucaine) and Precaine B (20% Benzocaine) in children before intra oral local anesthetic injections and for extraction of mobile primary teeth. STUDY DESIGN: This triple blind clinical study included sixty children divided equally under three techniques--palatal injections, inferior alveolar nerve block and extraction of mobile primary teeth. Both the products were used alternately using split mouth design in two visits and the child's pain response was assessed using VAS and SEM pain scale. The scores obtained were subjected to statistical analysis. RESULTS: Precaine has shown lower mean scores in all the techniques under both the pain scales, but were statistically insignificant. Gender wise comparison has also shown lower mean scores for Precaine for both males and females, however these were statistically insignificant. On visit wise comparison, Precaine B reported significant lower scores (p < 0.05) in visit 2 compared to visit 1 for inferior alveolar nerve block and extraction of mobile primary teeth under SEM pain scale. CONCLUSION: Precaine (8% Lidocaine + 0.8% Dibucaine) can be used as effectively as Precaine B (20% Benzocaine).

Cerumen removal: comparison of cerumenolytic agents and effect on cognition among the elderly.

Cerumen impaction may affect hearing and decrease hearing acuity, thus decreasing cognitive functions among the elderly. The objective of this study was to compare the safety and the efficacy of three cerumenolytic agents and to assess the effect of cerumen removal on cognition. Thirty eight elderly subjects (mean age: 78 years, total 76 ears) were treated with either Auro®, Cerumol® or the newer CleanEars®, and the change in the degree of ear canal occlusion was examined after a week. In addition, a change in cognition following cerumen removal was evaluated using Raven's standard progressive matrices (RSPM) test. There was no difference regarding the eventual degree of occlusion between the three treatment groups. Only in the CleanEars® group a complete resolution of obstruction in both ears was achieved. A statistically significant difference between the RSPM score before and after the removal of cerumen was found. Using CleanEars® is as effective and safe as other agents and may be advantageous due to its spray application. Removal of cerumen significantly improves the well-being of elderly patients.

The use of local anesthetic agents in medicine.

Local anesthetics are commonly used in both dentistry and medicine. These drugs are also used in some office-based medical practices. Except for minor procedures, most physicians who require complicated nerve blocks rely on anesthesiologists to administer the local anesthesia. Both ester and amide local anesthetics are routinely used in medical practice. This article reviews the types and uses of local anesthesia in anesthesiology.

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.

[Comparison of two forms of nasal and pharyngeal topical anestesia for performing esophageal manometry]. / Comparación de dos formas de anestesia tópica nasal y faríngea para la realización de manometría esofágica.

BACKGROUND: The esophageal manometry (EM) is an invasive procedure that causes nasal pain, pharyngeal pain, and nausea. A topical anesthetic may improve tolerance of the examination. OBJECTIVE: To compare the effectiveness of 10% lidocaine with 20% benzocaine as topical anesthetics in order to reduce discomfort during an EM. MATERIALS AND METHODS: 251 patients who had been prescribed an EM received either lidocaine or benzocaine in the nose and pharynx before inserting the catheter An EM was carried out using the usual pull-trough technique and an observer registered the insertion time of the catheter. Patients assessed the intensity of nasal pain and nausea by means of a visual analog scale. Finally, patients were asked whether, if necessary, they would repeat the study. RESULTS: 127 patients were studied in the lidocaine group and 124 in the benzocaine group. The EM was carried out on all patients without complications. Although benzocaine tended to be the preferred anesthetic, no significant differences were found between the groups in relation to nasal pain, nausea, and insertion time. The percentage of patients with moderate or intense discomfort was significantly less in the benzocaine group (nasal pain 10 vs. 33%, p < 0.001; and nausea 24 vs. 36%, p = 0.05). A similar percentage of patients said they would not agree to having another EM (p = NS). CONCLUSIONS: Both lidocaine and benzocaine are topical anesthetics that can reduce discomfort during an EM. Benzocaine seems to achieve a better effect among more patients submitted to this procedure.