Dermal patch anaesthesia: comparison of 10% lignocaine gel with absorption promoter and EMLA cream

Comparison of the onset, depth, and duration of cutaneous anesthesia between topical 10% lidocaine and EMLA creams: A randomized, intraindividual, comparative trial

BACKGROUND

The eutectic mixture of local anesthetics (EMLA) is an effective cutaneous anesthetic, although its application is time consuming and poses a risk of methemoglobinemia. Currently, the efficacy of topical 10% lidocaine cream is unclear.

OBJECTIVE

To compare the onset, anesthesia depth, and duration of topical 10% lidocaine and EMLA cream.

METHODS

The randomized, split-body, comparative trial performed on 40 participants who received a topical 10% lidocaine cream or EMLA on forearms for 15-150 min. Pain was stimulated using a 21-gauge needle insertion and evaluated with the Verbal Pain Score. Adverse effects were recorded.

RESULTS

EMLA conferred significantly better efficacy than 10% lidocaine (p < 0.001). For acceptable pain at 4-mm depth, the minimal application times were 40.88 and 45.38 min of EMLA and 10% lidocaine creams, respectively. With 60/120-min application, the maximal needle-insertion depths with acceptable pain were 6.61/9.47 mm (EMLA) and 6.01/8.94 mm (10% lidocaine). EMLA's anesthetic effect showed an early increase after removal which was sustained for 60-90 min. Both creams caused adverse effects, with EMLA showing higher proportions, although the differences were statistically insignificant.

CONCLUSION

The efficacy of EMLA was superior to 10% lidocaine cream, especially regarding anesthesia onset and duration.

Effective permeation of 2.5 and 5% lidocaine hydrochloride in human skin using iontophoresis technique

BACKGROUND

Lidocaine Hydrochloride (HCL) is one of the commonest topical local anesthetic drugs. The permeation of the lidocaine can be enhanced by iontophoresis (IOP). The purpose of this study was to evaluate the permeability of 2.5 and 5% lidocaine permeation in ex vivo human skin using different IOP waveform.

METHODS

Continuous and modulated IOP at the current density of 0.5 mA/cm² were applied across human skin (n = 3) in donor chamber of vertical diffusion cell at 2.5 and 5% lidocaine concentration. High Performance Liquid Chromatography was used to determine lidocaine concentration.

RESULTS

Findings revealed that lidocaine concentration increased effectively in a time-dependent manner in both modulated and continuous IOP at 2.5 and 5% lidocaine concentration. Compared to the passive group, the flux of lidocaine with modulated and continuous IOP were higher of about six and ten-fold, respectively. However, no significant difference was observed between continuous and modulated IOP groups at both lidocaine concentrations. At 2.5% lidocaine concentration, the permeation time taken by modulated and continuous IOP to attain therapeutic levels of 142 and 164 μg/cm₂ , respectively, was approximately 10 minutes. At 5% lidocaine, the therapeutic permeation of 129 and 147 μg/cm₂ , respectively, was achieved at approximately 5 minutes after applying iontophoresis waveform.

CONCLUSION

Study shows that modulated IOP can be a promising alternative method in clinical settings aside from continuous IOP. Based on the clinical requirements, IOP can be used at 2.5 and 5% lidocaine concentration depending on need of relatively short or very short onset action.

From Physical Pharmacy to Clinical Pharmacology

Research works on molecular interactions in solutions were carried out at School of Pharmacy, the University of Wisconsin under the direction of Prof. T. Higuchi and at Faculty of Pharmaceutical Sciences, Kyoto University under the direction of Prof. H. Sezaki. Studies on permeation of drugs through polymer membranes were carried out at Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada and at Pharmaceutical Chemistry Research Laboratories at Food and Drug Directorate, Department of Health and Welfare, Canada. Studies on modification of delivery patterns by means of pharmaceutical approaches were carried out at Faculty of Pharmaceutical Sciences, Hokkaido University. Topics related to modification of drug delivery patterns include employment of amorphous forms such as ground mixture with micro-crystalline cellulose and coprecipitate with polyvinylpyrrolidone, use of biodegradable polymers such as polylactic acid and polycarbonates, gel-forming materials such as konjac, agar and hydroxypropylcellulose, and physicochemical systems such as complexation. Works related to drug delivery and disposition of drugs in humans were carried out at Department of Pharmacy, Kumamoto University Hospital. Topics related to drug delivery in humans include injections containing anticancer drugs for intra-arterial administration, lidocaine gels for dermal anesthesia, glucagon solution for nasal administration. Topics related to disposition of drugs in humans include clinical pharmacokinetic studies in infants and elderly and medical uses of adsorbents.

Warm Steaming Enhances the Topical Anesthetic Effect of Lidocaine

Warm steaming has been used for hydrating the skin, thereby increasing its permeability. We studied whether skin pretreatment with a steamed towel (at 45 degrees C) for 5 min could enhance the anesthetic effect of a topical lidocaine tape in 14 female volunteers. After each volunteer received the skin pretreatment on one of the forearms, lidocaine tape was applied for 30 min on both the treated and the untreated forearms. Superficial anesthesia was scored by recording the number of painful experience during 5 pinpricks delivered with a 27-gauge needle. To assess anesthesia of the deeper layer, single insertion of a 27-gauge needle to a depth of 3 mm was made and pain was scored by a visual analog scale (VAS). There were significant reductions in the scores of superficial anesthesia (median [range]: treated arm, 2 [0-5], versus untreated arm, 4 [1-5]; P < 0.01) and the VAS scores of deeper insertion (median [range]: treated arm, 4.5 [0-8], versus untreated arm, 8 [2-10]; P < 0.01). In conclusion, the application of a warm steamed towel enhanced the anesthetic effect of a topical lidocaine tape.

IMPLICATIONS

We showed that the skin pretreatment with a steamed towel (at 45 degrees C) enhanced the anesthetic effect of a topical lidocaine tape in female volunteers.

Rapid onset of cutaneous anesthesia with EMLA cream after pretreatment with a new ultrasound-emitting device

In this randomized, double-blinded, placebo-controlled, crossover trial of 42 human subjects, we examined the speed of onset of cutaneous anesthesia by eutectic mixture of local anesthetics (EMLA) cream after brief (approximately 10-s) pretreatment of the underlying skin with low-frequency (55 kHz) ultrasound. Four treatments were compared: ultrasound pretreatment followed by application of 1 g EMLA or placebo cream for 5 min, 10 min, 15 min, and 60 min without ultrasound pretreatment as positive control. Pain was tested by pricks with a 20 g needle. Pain scores and patient preference for EMLA or placebo cream were measured at each time point. Based on both pain scores and patient preference, cutaneous anesthesia was achieved in the EMLA groups as compared with placebo at all time points. After ultrasound pretreatment and then 5, 10, or 15 min after EMLA cream application, pain scores and overall preference were statistically indistinguishable from EMLA cream application for 60 min (without ultrasound pretreatment). There were no significant adverse effects. Low-frequency ultrasound pretreatment appears to be safe and effective in producing rapid onset of EMLA cream in this model, with results as early as 5 min.

IMPLICATIONS

A prospective, randomized, double-blinded, placebo-controlled clinical trial demonstrated rapid onset of cutaneous anesthesia by pretreatment of the skin with ultrasound before application of EMLA cream.

Intra-oral topical anaesthetics: a review

OBJECTIVE

This review considers the use of topical anaesthetics in the mouth to reduce the discomfort of local anaesthetic injections and intra-oral operative procedures.

DATA SOURCES

Electronic literature search using Pub Med, manual search of references within papers found by the primary search and manual searching of abstracts from scientific meetings.

STUDY SELECTION

The articles selected for this review investigate or used topical anaesthesia in dental procedures.

CONCLUSIONS

The use of topical anaesthetics does not guarantee pain-free dental local anaesthesia. Efficacy is dependent upon the duration of application and the gauge of needle used. Evidence is available that the use of topical anaesthesia alone is sufficient to perform some intra-oral procedures including periodontal manipulations, operative dentistry and oral surgery.

Topical anesthetic agents in dermatologic surgery. A review

BACKGROUND

The ideal topical anesthetic agent is one that provides 100% anesthesia in a short period of time, work on intact skin without systemic side effects, and invokes neither pain nor discomfort. The quest to find such an agent continues today. Because a topical anesthetic agent will induce anesthesia painlessly, the need for an effective agent is clear. This will serve to eliminate painful injections with lidocaine prior to many dermatologic procedures.

OBJECTIVE

To provide a review of topical agents used in the past, to present products that are being used today, and to look to the future of topical anesthesia. CONCLUSIVE: During the last three decades a variety of methods have been employed to administer topical anesthesia. Presently, EMLA (eutectic mixture of local anesthetics) is the most often used method among practicing dermatologists. However, iontophoresis and the anesthetic patch are equally effective with a few notable advantages over EMLA. Liposomal agents show promise as we enter into a new millennium.

Lidocaine tape relieves pain due to needle insertion during stellate ganglion block

PURPOSE

To investigate the efficacy of lidocaine tape, a new preparation of lidocaine for cutaneous topical anaesthesia in the form of a self-adhesive tape, in alleviating the pain of needle insertion during stellate ganglion block.

METHODS

In a double-blind, placebo controlled study, 30 adult outpatients undergoing stellate ganglion block were allocated to receive all of the following five treatments in random order: placebo tape applied to the intended site of the block (control), or lidocaine tape applied for 7, 15, 30, and 60 min. After the block was performed using a 24-gauge needle, the pain associated with needle insertion was assessed using a visual analogue scale (10 cm VAS) and the four-point verbal rating score (VRS 0-3).

RESULTS

With placebo tape, the VAS and VRS scores were 2.4 +/- 1.27 (0.5-4.8) (mean +/- SD (range)) and 1.5 (1-2) (mean (range)), respectively. The pain scores were reduced (P < 0.01) by lidocaine tape after application for 7 min (1.6 +/- 1.06 and 1.0 (0-2) for VAS (mean +/- SD) and VRS (mean (range)), respectively), 15 min (1.5 +/- 1.00 and 1.0 (1-2)), 30 min (1.5 +/- 1.08 and 1.0 (1)), and 60 min (0.6 +/- 0.70 and 0.6 (0-1)). Skin erythema was more frequent with lidocaine tape than with placebo tape (seven minutes of lidocaine tape vs placebo tape, P < 0.05; 15, 30, and 60 min of lidocaine tape vs placebo, P < 0.0005).

CONCLUSION

Stellate ganglion block without analgesia is fairly painful in some patients, even when using a 24-gauge needle, and needle pain is reduced by lidocaine tape after an application time of seven minutes or more.

A double-blinded evaluation of intraperitoneal bupivacaine vs saline for the reduction of postoperative pain and nausea after laparoscopic cholecystectomy

BACKGROUND

Intraperitoneal local anesthesia has been reported to reduce postoperative pain after laparoscopy for gynecologic procedures that do not require a great deal of dissection or manipulation of viscera. This study was performed to determine the efficacy of intraperitoneal bupivacaine in laparoscopic cholecystectomy (LC).

METHODS

Fifty-five patients were evaluable in this randomized, double-blind, placebo-controlled study. Twenty-six patients received bupivacaine (0.1%) and 29 patients received placebo (saline). Prior to any dissection of the gallbladder, the surgeon irrigated 100 ml of experimental solution under the right hemidiaphragm, over Glisson's capsule, over the gallbladder serosa, and into the subhepatic space. The operation was then performed as usual. Postoperatively, analgesic medication usage, nausea, vomiting, and pain scores were determined during hospitalization. A questionnaire was given to each patient upon discharge from the hospital in order to continue monitoring medications and pain for the first 48 h at home.

RESULTS

Postoperative pain was reduced significantly (P < 0.05) in the patients who received bupivacaine, but the effect was modest and observable only during the first 6 h after surgery. Despite this difference, there was no significant reduction in the amount of analgesic medication used by the patients who received bupivacaine, nor was there any reduction in nausea, vomiting, or shoulder pain when queried specifically.

CONCLUSIONS

Intraperitoneal bupivacaine offered a detectable, albeit subtle benefit to patients undergoing LC. However, the effect was transient and had little impact upon the patient's convalescence.