Injectable and topical local anesthetics for acute dental pain: 2 systematic reviews.

BACKGROUND: Local anesthesia is essential for pain control in dentistry. The authors assessed the comparative effect of local anesthetics on acute dental pain after tooth extraction and in patients with symptomatic irreversible pulpitis. TYPES OF STUDIES REVIEWED: The authors searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and the US Clinical Trials registry through November 21, 2020. The authors included randomized controlled trials (RCTs) comparing long- vs short-acting injectable anesthetics to reduce pain after tooth extraction (systematic review 1) and evaluated the effect of topical anesthetics in patients with symptomatic pulpitis (systematic review 2). Pairs of reviewers screened articles, abstracted data, and assessed risk of bias using a modified version of the Cochrane risk of bias 2.0 tool. The authors assessed the certainty of the evidence using the Grading of Recommendations Assessment, Development and Evaluation approach. RESULTS: Fourteen RCTs comparing long- vs short-acting local anesthetics suggest that bupivacaine may decrease the use of rescue analgesia and may not result in additional adverse effects (low certainty evidence). Bupivacaine probably reduces the amount of analgesic consumption compared with lidocaine with epinephrine (mean difference, -1.91 doses; 95% CI, -3.35 to -0.46; moderate certainty) and mepivacaine (mean difference, -1.58 doses; 95% CI, -2.21 to -0.95; moderate certainty). Five RCTs suggest that both benzocaine 10% and 20% may increase the number of people experiencing pain reduction compared with placebo when managing acute irreversible pulpitis (low certainty). PRACTICAL IMPLICATIONS: Bupivacaine may be superior to lidocaine with epinephrine and mepivacaine with regard to time to and amount of analgesic consumption. Benzocaine may be superior to placebo in reducing pain for 20 through 30 minutes after application.

Asymptomatic benzocaine spray-induced methaemoglobinaemia in preoperative sedation for oesophagogastroduodenoscopy.

Methaemoglobinaemia is defined as elevated methaemoglobin in the blood which is characterised by conversion of some of the reduced ferrous iron elements [Fe2+] to the oxidised ferric [Fe3+] form which does not have capacity to bind and transport oxygen resulting in functional anaemia. Causes can be genetic mutations or acquired by medications such as dapsone, nitrates or benzocaine. Benzocaine is currently being used as a topical anaesthetic agent before certain procedures. We report a case of benzocaine spray-induced methaemoglobinaemia in a patient who underwent oesophagogastroduodenoscopy for evaluation of upper gastrointestinal bleeding.

Evaluating the Preemptive Analgesic Effect of Photo-biomodulation Therapy on Pain Perception During Local Anesthesia Injection in Children: A Split-mouth Triple-blind Randomized Controlled Clinical Trial.

To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of 6 to 9 years-old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J cm-2 ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and postoperation pain at two timestamps, 1 h and 24 h after treatment. Patients' heart rate was also evaluated. Paired t, Wilcoxon signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P = 0.000). However, no significant differences were documented between the two methods concerning the 1-h (P = 0.26) and 24-h (P = 1.00) postoperation pain. PBMT can be an effective nonpharmacological technique for controlling injection pain.

Effect of pre-cooling agent on intensity of pricking pain at intraoral injection site in adults: An experimental study.

OBJECTIVE: To determine the effect of pre-cooling agent on the intensity of pricking pain at the intraoral injection site in adult patients. METHODS: The in-vivo interventional study was conducted at the Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, from September 2018 to August 2019, and comprised adult patients of either gender. The pricking pain perception during needle administration was assessed using split-mouth technique. Topical anaesthesia benzocaine gel was applied on the left side, which was treated as controls, for 1 min, while on the right side, which was treated as the experimental side, refrigerated cartridge was placed for 2 min. Infiltration anaesthesia was then administered on both sides. Pain perception ratings were measured through visual analogue scale. After profound anaesthesia was achieved, restorative treatment was performed under rubber dam isolation. Data was analysed using SPSS 24. RESULTS: Of the 152 subjects, 77(50.65%) were females and 75(49.34%) were males. The overall mean age was 35.97±8.669 years (range: 21-50 years). The effect of refrigerated cartridge was significant on the intensity of pricking pain at the intraoral injection site in patients aged 41-50 years, and in female patients aged 21-30 years (p<0.05), whereas its effect was non-significant in males aged 21-30 years and patients aged 31-40 years (p>0.05). CONCLUSIONS: Pre-cooling agent was found to be effective in decreasing pricking pain felt by patients.

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.

Ear drops for the removal of ear wax.

BACKGROUND: Ear wax (cerumen) is a normal bodily secretion that can become a problem when it obstructs the ear canal. Symptoms attributed to wax (such as deafness and pain) are among the commonest reasons for patients to present to primary care with ear trouble.Wax is part of the ear's self-cleaning mechanism and is usually naturally expelled from the ear canal without causing problems. When this mechanism fails, wax is retained in the canal and may become impacted; interventions to encourage its removal may then be needed. Application of ear drops is one of these methods. Liquids used to remove and soften wax are of several kinds: oil-based compounds (e.g. olive or almond oil); water-based compounds (e.g. sodium bicarbonate or water itself); a combination of the above or non-water, non-oil-based solutions, such as carbamide peroxide (a hydrogen peroxide-urea compound) and glycerol. OBJECTIVES: To assess the effects of ear drops (or sprays) to remove or aid the removal of ear wax in adults and children. SEARCH METHODS: We searched the Cochrane ENT Trials Register; Cochrane Register of Studies; PubMed; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 23 March 2018. SELECTION CRITERIA: Randomised controlled trials (RCTs) in which a 'cerumenolytic' was compared with no treatment, water or saline, an alternative liquid treatment (oil or almond oil) or another 'cerumenolytic' in adults or children with obstructing or impacted ear wax. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by Cochrane. The primary outcomes were 1) the proportion of patients (or ears) with complete clearance of ear wax and 2) adverse effects (discomfort, irritation or pain). Secondary outcomes were: extent of wax clearance; proportion of people (or ears) with relief of symptoms due to wax; proportion of people (or ears) requiring further intervention to remove wax; success of mechanical removal of residual wax following treatment; any other adverse effects recorded and cost. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. MAIN RESULTS: We included 10 studies, with 623 participants (900 ears). Interventions included: oil-based treatments (triethanolamine polypeptide, almond oil, benzocaine, chlorobutanol), water-based treatments (docusate sodium, carbamide peroxide, phenazone, choline salicylate, urea peroxide, potassium carbonate), other active comparators (e.g. saline or water alone) and no treatment. Nine of the studies were more than 15 years old.The overall risk of bias across the 10 included studies was low or unclear. PRIMARY OUTCOME: proportion of patients (or ears) with complete clearance of ear waxSix studies (360 participants; 491 ears) contributed quantitative data and were included in our meta-analyses.Active treatment versus no treatmentOnly one study addressed this comparison. The proportion of ears with complete clearance of ear wax was higher in the active treatment group (22%) compared with the no treatment group (5%) after five days of treatment (risk ratio (RR) 4.09, 95% confidence interval (CI) 1.00 to 16.80); one study; 117 ears; NNTB = 8) (low-quality evidence).Active treatment versus water or salineWe found no evidence of a difference in the proportion of patients (or ears) with complete clearance of ear wax when the active treatment group was compared to the water or saline group (RR 1.47, 95% CI 0.79 to 2.75; three studies; 213 participants; 257 ears) (low-quality evidence). Two studies applied drops for five days, but one study only applied the drops for 15 minutes. When we excluded this study in a sensitivity analysis it did not change the result.Water or saline versus no treatmentThis comparison was only addressed in the single study cited above (active versus no treatment) and there was no evidence of a difference in the proportion of ears with complete wax clearance when comparing water or saline with no treatment after five days of treatment (RR 4.00, 95% CI 0.91 to 17.62; one study; 76 ears) (low-quality evidence).Active treatment A versus active treatment BSeveral single studies evaluated 'head-to-head' comparisons between two active treatments. We found no evidence to show that one was superior to any other.Subgroup analysis of oil-based active treatments versus non-oil based active treatmentsWe found no evidence of a difference in this outcome when oil-based treatments were compared with non-oil-based active treatments. PRIMARY OUTCOME: adverse effects: discomfort, irritation or painOnly seven studies planned to measure and did report this outcome. Only two (141 participants;176 ears) provided useable data. There was no evidence of a significant difference in the number of adverse effects between the types of ear drops in these two studies. We summarised the remaining five studies narratively. All events were mild and reported in fewer than 30 participants across the seven studies (low-quality evidence).Secondary outcomesThree studies reported 'other' adverse effects (how many studies planned to report these is unclear). The available information was limited and included occasional reports of dizziness, unpleasant smell, tinnitus and hearing loss. No significant differences between groups were reported. There were no emergencies or serious adverse effects reported in any of the 10 studies.There was very limited or no information available on our remaining secondary outcomes. AUTHORS' CONCLUSIONS: Although a number of studies aimed to evaluate whether or not one type of cerumenolytic is more effective than another, there is no high-quality evidence to allow a firm conclusion to be drawn and the answer remains uncertain.A single study suggests that applying ear drops for five days may result in a greater likelihood of complete wax clearance than no treatment at all. However, we cannot conclude whether one type of active treatment is more effective than another and there was no evidence of a difference in efficacy between oil-based and water-based active treatments.There is no evidence to show that using saline or water alone is better or worse than commercially produced cerumenolytics. Equally, there is also no evidence to show that using saline or water alone is better than no treatment.

What are pharmacists recommending for infant teething treatment?

OBJECTIVES: In 2011, the Food and Drug Administration issued a warning to avoid the use of any benzocaine-containing products for infant teething treatment owing to a risk of methemoglobinemia. Several benzocaine-containing products targeted for infant teething are currently available over the counter. Pharmacists are commonly asked for medical advice in the community, and there is no current literature evaluating what pharmacists are recommending for infant teething. The objectives of this study were to evaluate what pharmacists are currently recommending for infant teething treatment and assess what percentage would inappropriately recommend a benzocaine-containing product. METHODS: From March to June 2016, a 16-item in-person paper-and-pen questionnaire was administered to 200 pharmacists in the San Francisco Bay area at 115 outpatient over-the-counter pharmacies. Questions included demographic information, work and educational background, infant teething recommendations, and preferred educational resources. RESULTS: The overall response rate was 94.3%. One-half (50.5%) of the pharmacists' approaches to infant teething treatment was to recommend a nondrug option first and then, if needed, an over-the-counter medication. A majority (63.0%) of the pharmacists surveyed would inappropriately select a benzocaine-containing product. CONCLUSION: Despite warnings, the majority of pharmacists would still inappropriately recommend a benzocaine-containing product for treatment of infant teething. Further education is warranted to ensure that all pharmacists, health care providers, and consumers are aware of the potential harm of benzocaine use in infants.

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.

Recent advances in topical anesthesia

Topical anesthetics act on the peripheral nerves and reduce the sensation of pain at the site of application. In dentistry, they are used to control local pain caused by needling, placement of orthodontic bands, the vomiting reflex, oral mucositis, and rubber-dam clamp placement. Traditional topical anesthetics contain lidocaine or benzocaine as active ingredients and are used in the form of solutions, creams, gels, and sprays. Eutectic mixtures of local anesthesia cream, a mixture of various topical anesthetics, has been reported to be more potent than other anesthetics. Recently, new products with modified ingredients and application methods have been introduced into the market. These products may be used for mild pain during periodontal treatment, such as scaling. Dentists should be aware that topical anesthetics, although rare, might induce allergic reactions or side effects as a result of an overdose. Topical anesthetics are useful aids during dental treatment, as they reduce dental phobia, especially in children, by mitigating discomfort and pain.

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.

Topical intrapocket anesthesia during scaling and root planing: a randomized clinical trial.

Although the use of injectable anesthesia prior to subgingival scaling and root planing (SRP) reduces pain, many patients report fear and prolonged numbness of adjacent tissues. The aim of the present study was to compare the effects of a eutectic mixture containing 25 mg/g of lidocaine and 25 mg/g of prilocaine, injectable 2% lidocaine, topical 2% benzocaine and a placebo substance on reducing pain during SRP. In this randomized, split-mouth, masked clinical trial, thirty-two patients presenting more than two teeth with probing depth and clinical attachment level ≥ 5 mm in at least 4 sextants were randomly allocated to four groups: EMLA(r); injectable 2% lidocaine; topical 2% benzocaine and placebo. Pain and discomfort were measured using a visual analogue scale (VAS) and verbal scale (VS). Repeated-measures analysis of variance and Poisson regression were used for analysis. Patient satisfaction with the anesthesia was determined at the end of each treatment session. VAS and VS scores did not differ between injectable 2% lidocaine and EMLA (p > 0.05) and both substances showed significantly better pain control compared to 2% benzocaine and placebo (p < 0.05). 93.7% and 81.2% of the individuals were satisfied with the injectable anesthetic and EMLA, respectively (p = 0.158). Dissatisfaction with benzocaine and placebo was approximately 10 times greater than injectable anesthesia (p = 0.001). In conclusion, EMLA showed an equivalent effect on pain control when compared to the injectable anesthesia and performed better than 2% benzocaine in SRP. Thus, EMLA is a viable anesthetic option during scaling and root planning, despite the frequent need for second application.

Topical Intrapocket Anesthesia During Scaling and Root Planing: a Randomized Clinical Trial

Although the use of injectable anesthesia prior to subgingival scaling and root planing (SRP) reduces pain, many patients report fear and prolonged numbness of adjacent tissues. The aim of the present study was to compare the effects of a eutectic mixture containing 25 mg/g of lidocaine and 25 mg/g of prilocaine, injectable 2% lidocaine, topical 2% benzocaine and a placebo substance on reducing pain during SRP. In this randomized, split-mouth, masked clinical trial, thirty-two patients presenting more than two teeth with probing depth and clinical attachment level ≥5 mm in at least 4 sextants were randomly allocated to four groups: EMLA(r); injectable 2% lidocaine; topical 2% benzocaine and placebo. Pain and discomfort were measured using a visual analogue scale (VAS) and verbal scale (VS). Repeated-measures analysis of variance and Poisson regression were used for analysis. Patient satisfaction with the anesthesia was determined at the end of each treatment session. VAS and VS scores did not differ between injectable 2% lidocaine and EMLA (p>0.05) and both substances showed significantly better pain control compared to 2% benzocaine and placebo (p<0.05). 93.7% and 81.2% of the individuals were satisfied with the injectable anesthetic and EMLA, respectively (p=0.158). Dissatisfaction with benzocaine and placebo was approximately 10 times greater than injectable anesthesia (p=0.001). In conclusion, EMLA showed an equivalent effect on pain control when compared to the injectable anesthesia and performed better than 2% benzocaine in SRP. Thus, EMLA is a viable anesthetic option during scaling and root planning, despite the frequent need for second application.

Embora a anestesia injetável previamente a raspagem e alisamento subgengival (RASUB) reduza a dor, muitos pacientes relatam medo e amortecimento prolongado dos tecidos adjacentes. O objetivo deste estudo foi comparar o efeito de uma mistura eutética contendo 25mg/g de lidocaína e 25 mg/g de prilocaína, lidocaína 2% injetável, benzocaína 2% tópica e um placebo na redução da dor durante a RASUB. Neste ensaio clínico randomizado, cego de boca dividida, trinta e dois pacientes que apresentavam mais que dois dentes com profundidade de sondagem e nível de inserção clínica ≥ 5 mm, em no mínimo 4 sextantes, foram randomicamente alocados em 4 grupos: EMLA(r), lidocaína 2% injetável, benzocaína 2% tópica ou placebo. Dor e desconforto foram mensurados usando uma Escala Visual Analógica (EVA) e Escala Verbal (EV). A satisfação dos pacientes com a anestesia foi determinada ao final de cada consulta. Análise de variância de medidas repetidas e regressão de Poisson foram usadas para análise. Os escores da EVA e EV não demonstraram diferenças estatisticamente significantes entre lidocaína injetável e EMLA(r) (p > 0,05) e ambas as substâncias demonstraram significativamente melhor controle da dor comparadas a benzocaína 2% e placebo (p<0,05). 93,7% e 81,2% dos indivíduos ficaram satisfeitos com o anestésico injetável e EMLA(r), respectivamente (p=0,158). A insatisfação com a benzocaína e placebo foi aproximadamente 10 vezes maior do que com a anestesia injetável (p=0,001). Em conclusão, o EMLA(r) demonstrou um efeito equivalente no controle da dor quando comparado com a anestesia injetável e melhor do que a benzocaína 2% em RASUB. Assim, o EMLA(r) é uma opção anestésica viável durante a raspagem e alisamento radicular, apesar da necessidade frequente de segunda aplicação.

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.

Lidocaine contact allergy is becoming more prevalent.

BACKGROUND: Allergic contact dermatitis (ACD) to lidocaine is rising in prevalence. This is due to a growing number of over-the-counter (OTC) products containing topical amide and ester anesthetics. The phenomenon poses a real threat to the authors' surgical anesthetic options. OBJECTIVE: To investigate the epidemiology of topical anesthetic ACD in British Columbia, Canada and provide an approach for clinicians to deal with this problem. MATERIALS AND METHODS: A retrospective chart review of 1,819 patients who underwent patch testing at the University of British Columbia Contact Dermatitis Clinic between January 2009 and June 2013 was completed. The authors also performed a detailed review of Canadian OTC preparations containing lidocaine in 2013. RESULTS: The prevalence of ACD to local anesthetics is significant at 2.4%. The most common allergen is benzocaine (45%) followed by lidocaine (32%) and dibucaine (23%). CONCLUSION: The proportion of ACD caused by lidocaine is higher than expected. This is likely secondary to an increase in OTC medicaments containing lidocaine. Patients who are patch test-positive to a local anesthetic should be challenged intradermally to confirm clinical relevance. Because ACD is a delayed Type IV hypersensitivity reaction (localized dermatitis), the risk of anaphylaxis is not a concern.

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.

Benzocaine and clove oil as anesthetics for pejerrey (Odontesthes bonariensis) fingerlings / Benzocaina e óleo de cravo como anestésicos para alevinos de peixe-rei (Odontesthes bonariensis)

Pejerrey (Odontesthes bonariensis) is a native species from Rio Grande do Sul, Uruguay and Argentina where it is of great economic importance for artisanal fishing. One difficulty in laboratory research with pejerrey is related to its sensitivity, as it presents higher basal cortisol levels than other freshwater species. For this reason, the aim of this work was to evaluate the efficiency of benzocaine and clove oil as anesthetics for pejerrey fingerlings. Two experiments were done where fingerlings (57±7.8mm and 1.1±0.44g) were exposed to benzocaine with concentrations between 40mgL-1 and 120mgL-1 and to clove oil with concentrations between 12mgL-1 and 75mgL-1. Survival, anesthesia induction time and recovery time for each pharmaceutics were evaluated. Both benzocaine and clove oil pharmaceutics showed efficiency as anesthetics for pejerrey fingerlings, with negative correlation between the dose of anesthetics and the anesthesia induction time. For benzocaine, the concentrations between 80mgL-1 and 100mgL-1 showed better results, as for clove oil the optimal concentrations were between 25mgL-1 and 50mgL-1. On the other hand, the anesthesia recovery time did not present significant variation on the different concentrations of the tested products. The tested products are highly metabolizable by pejerrey.

O peixe-rei (Odontesthes bonariensis) é uma espécie nativa do Rio Grande do Sul, Uruguai e Argentina, onde tem grande importância econômica para a pesca artesanal. Uma dificuldade da pesquisa em laboratório com peixe-rei está relacionada à sua sensibilidade, pois apresenta níveis basais de cortisol mais elevados que outras espécies de água doce. Este trabalho avaliou a eficiência da benzocaína e do óleo de cravo como anestésicos para alevinos de peixe-rei. Foram realizados dois experimentos em que alevinos (57±7,08mm e 1,1±0,44g) foram expostos à concentração entre 40mg-1 e 120mgL-1 de benzocaína e entre 12mgL-1 e 75mgL-1 de óleo de cravo. Avaliaram-se a sobrevivência, o tempo de anestesia e o tempo de recuperação para cada um dos fármacos. Ambos os fármacos, benzocaína e óleo de cravo, mostraram eficiência para anestesiar peixe-rei, com correlação negativa entre a dose e o tempo de indução de anestesia. Para benzocaína, concentrações entre 80mgL-1 e 100mgL-1 mostraram melhor resultado, enquanto para óleo de cravo as melhores concentrações ficaram entre 25mgL-1 e 50mgL-1. Por outro lado, o tempo de recuperação do estado de anestesia não apresentou variação significativa nas diferentes concentrações testadas. O peixe-rei tem elevada capacidade de metabolização dos produtos testados.