Evaluation of topical anesthetics by laser-induced sensation: comparison of EMLA 5% cream and 40% lidocaine in an acid mantle ointment

Topical anaesthetic effects on skin vasculature with potential implications for laser treatment

Laser treatment of vascular lesions is affected by parameters including the diameter and depth of the vessels and flow within the vessels. Topical anaesthetics are in common use prior to laser treatment but may have effects on vessel parameters and, subsequently, the efficacy of laser treatment. Eleven patients with capillary vascular malformations were investigated for vessel diameter before and after elective application of a topical anaesthetic, Eutectic Mixture of Local Anaesthetics (EMLA) (AstraZeneca) or Ametop (S&N Health), prior to pulsed dye laser treatment. EMLA contains 2.5% lidocaine ad 2.5% prilocaine, and Ametop gel contains 4% tetracaine. Patients' capillary malformations were assessed using confocal laser scanning microscopy (CLSM) (Vivascope 1500 Mavig GmbH, Munich). Six of the 11 patients recruited had EMLA topical anaesthetic, and five had Ametop. Four hundred twenty-one diameters were measured. The mean vessel diameter was 50.87 μm. Previous laser treatments undergone by each patient were noted to exclude this as a confounding variable, and no significant difference was found between topical anaesthetic groups. Statistical calculations were made using GenStat and Minitab. There is no evidence that Ametop affects mean diameter (p value is 0.361). EMLA reduces the mean diameter of vessels (p = 0.002), with a 27% reduction in post-EMLA diameter. This study demonstrates that the use of EMLA cream has a statistically significant reduction vessel diameter. As it is known that vessel diameter is important for the response of laser treatment, the use of EMLA may affect outcome.

Providing pain relief for laser resurfacing: Effectiveness of the CoolAnalgesia© device

Laser resurfacing is a painful procedure, and is therefore usually carried out under general anaesthetic or local anaesthetic with sedation. However, the small but significant risk of adverse events from either of these methods has resulted in an effort to develop other methods of controlling the pain associated with the use of lasers. This trial describes of the use of a cooling device (the CoolAnalgesia device) with a carbon dioxide laser. The only anaesthetic used was a eutectic mixture of lidocaine anaesthetic (EMLA) applied as a cream to the face at least 60 min prior to the procedure. Twenty consecutive patients attending two laser centres for facial resurfacing were recruited. Each patient was asked to assess the level of pain on a visual analogue scale from 1-10 every 2 min during lasering. Only one of the patients had a mean pain score for the duration of the treatment of above five, four patients recorded a pain score of above five at some stage during their treatment, but none requested that the treatment be stopped. It would appear that the CoolAnalgesia device in combination with EMLA cream provides a level of anaesthesia sufficient to allow laser resurfacing without the use of local anaesthetic injections or intra-venous agents.

Evaluation of the S-Caine Peel for Induction of Local Anesthesia for Laser-Assisted Tattoo Removal: Randomized, Double-Blind, Placebo-Controlled, Multicenter Study

BACKGROUND

Topical anesthetics are important tools for many dermatologic procedures. The S-Caine Peel is composed of a 1:1 (w:w) eutectic mixture composed of lidocaine base 7%, USP, and tetracaine base 7%, USP. It is applied as a cream, dries on exposure to air, and forms a flexible membrane, which can be easily peeled off.

OBJECTIVE

To evaluate the effectiveness of the S-Caine Peel in providing clinically useful local dermal anesthesia for laser-assisted tattoo removal and to monitor the nature and frequency of adverse events associated with the safety of the S-Caine Peel.

METHODS

Thirty adult patients undergoing laser-assisted tattoo removal were enrolled in this multicentered, randomized, double-blind, placebo-controlled study. Each subject received both the S-Caine Peel and placebo simultaneously for 60 minutes. The primary efficacy parameter was a 100 mm visual analog scale (VAS) for patient self-assessment of pain. Secondary efficacy parameters included both the investigator's and an independent observer's evaluation of subject pain (4-point categorical scale: no pain through severe pain) and the patient's and the investigator's overall impression of the local anesthetic.

RESULTS

Mean VAS scores were 42 mm for the S-Caine Peel and 66 mm for placebo treatment sites (p=.001). Patients received adequate pain relief in 50% of S-Caine Peel sites versus 7% of placebo sites (p=.002). The percentage of those who would like to use the S-Caine Peel again were 43% for the S-Caine Peel compared with 7% for placebo (p=.005). Investigators' evaluations revealed that 70% of patients had less pain at S-Caine Peel treatment sites compared with 10% with less pain at placebo sites (p<.001), and 70% of the S-Caine Peel-treated sites achieved adequate anesthesia versus 10% of placebo sites (p<.001). The independent witness assessed less pain in 67% of S-Caine Peel-treated sites versus 10% of the placebo sites (p=.002). One occurrence of moderate to severe erythema was noted at both an S-Caine Peel and a placebo treatment site on removal of the S-Caine Peel after 60 minutes, which self-resolved quickly. There was no statistical difference between the two groups. Other side effects were limited to local mild, transient erythema at the application sites.

CONCLUSION

Administration of the S-Caine Peel for 60 minutes prior to laser-assisted tattoo removal was effective in significantly reducing pain levels associated with the procedure.

Lasers in pediatric dentistry

Pediatric dentistry's mission in delivering care to our young patients is simple: provide optimal preventive, interceptive, and restorative dental care in a stress-free environment. Lasers such as argon, diode, Nd:YAG, CO2, and now the erbium family enable minimally invasive dentistry for hard- and soft-tissue procedures. This article offers an understanding of treatment planning in the pediatric practice and demonstrates the procedures that dental lasers can perform on younger patients.

Transdermal microconduits by microscission for drug delivery and sample acquisition

BACKGROUND

Painless, rapid, controlled, minimally invasive molecular transport across human skin for drug delivery and analyte acquisition is of widespread interest. Creation of microconduits through the stratum corneum and epidermis is achieved by stochastic scissioning events localized to typically 250 microm diameter areas of human skin in vivo.

METHODS

Microscissioning is achieved by a limited flux of accelerated gas: 25 microm inert particles passing through the aperture in a mask held against the stratum corneum. The particles scize (cut) tissue, which is removed by the gas flow with the sensation of a gentle stream of air against the skin. The resulting microconduit is fully open and may be between 50 and 200 microm deep.

RESULTS

In vivo adult human tests show that microconduits reduce the electrical impedance between two ECG electrodes from approximately 4,000 Omega to 500 Omega. Drug delivery has been demonstrated in vivo by applying lidocaine to a microconduit from a cotton swab. Sharp point probing demonstrated full anaesthesia around the site within three minutes. Topical application without the microconduit required approximately 1.5 hours. Approximately 180 microm deep microconduits in vivo yielded blood sample volumes of several microl, with a faint pricking sensation as blood enters tissue. Blood glucose measurements were taken with two commercial monitoring systems. Microconduits are invisible to the unaided eye, developing a slight erythematous macule that disappears over days.

CONCLUSION

Microscissioned microconduits may provide a minimally invasive basis for delivery of any size molecule, and for extraction of interstitial fluid and blood samples. Such microconduits reduce through-skin electrical impedance, have controllable diameter and depth, are fully open and, after healing, no foreign bodies were visible using through-skin confocal microscopy. In subjects to date, microscissioning is painless and rapid.

60-minute application of S-Caine Peel prior to 1,064 nm long-pulsed Nd:YAG laser treatment of leg veins

BACKGROUND AND OBJECTIVES

Advancements in laser treatment of leg veins necessitate concurrent investigations in topical anesthesia to minimize treatment-related pain. To evaluate the efficacy of the S-Caine Peel for providing topical anesthesia after a 60-minute application.

STUDY DESIGN/PATIENTS AND METHODS

A randomized, double-blinded, placebo-controlled trial was performed in two centers. Sixty patients received S-Caine Peel and placebo vehicle on different treatment sites for 60 minutes prior to laser treatment of leg veins using a 1,064 nm long-pulsed Nd:YAG laser. Patients rated their level of pain using a visual analog scale. Adequacy of anesthesia and expressed pain at each site were rated by the investigator.

RESULTS

The mean visual analog scale (VAS) was 27 mm for active sites compared to 43 mm for placebo (P < 0.001). Improved pain relief was noted for 67% of active versus 30% of placebo sites (P < 0.001). Anesthesia was judged adequate by the investigator for 55% of active compared with 12% of placebo sites (P < 0.001).

CONCLUSIONS

The S-Caine Peel is safe and effective when applied for 60 minutes prior to laser therapy of leg veins.

Thirty-minute application of the S-Caine peel prior to nonablative laser treatment

BACKGROUND

Advancements in nonablative laser technology necessitate concurrent developments in topical anesthesia, as patients have reported varying degrees of discomfort during these procedures. Although topical anesthetics have proven efficacious, they possess inherent limitations related to ease of use.

OBJECTIVE

To evaluate the efficacy of the S-Caine Peel (ZARS Inc., Salt Lake City, UT), a novel topical anesthetic that dries to form a flexible membrane, for induction of anesthesia after only a 30-minute application period.

METHOD

Twenty patients received concurrent 30-minute applications of both the S-Caine Peel and a placebo cream randomized to the right and left cheeks in a double-blinded manner. After one pass of the 1450-nm diode laser (Smoothbeam, Candela Corp., Wayland, MA), patients' pain levels were recorded on a visual analog scale (VAS). Both the investigator and an independent observer rated perceived discomfort and immediate skin reaction based on a numerical scale.

RESULTS

Differences in VAS scores between active sites (average rating of 15 mm) and placebo sites (average rating of 47 mm) were statistically significant (P<0.001). A painless procedure was noted at 50% and 65% of active sites by the independent observer and investigator, respectively. This was statistically different (P<0.001) from the independent observer and investigator perception of pain-free procedure at the placebo site, 0% and 5%, respectively.

CONCLUSION

The S-Caine Peel provided effective and safe dermal anesthesia after only a 30-minute application period for nonablative laser treatment with the 1450-nm diode laser. The unique vehicle readily delivers anesthetic to contoured regions of the body and eliminates the need for occlusion.

The S-Caine peel: a novel topical anesthetic for cutaneous laser surgery

BACKGROUND

The S-Caine peel (Zars, Inc., Salt Lake City, UT) is a novel eutectic lidocaine/tetracaine mixture that is applied as a cream, drying upon exposure to air to form a flexible film that can be peeled off easily. The patented formulation can be used to anesthetize the skin prior to a variety of cutaneous procedures.

OBJECTIVE

To examine the clinical efficacy of the S-Caine peel as a topical anesthetic for pulsed dye laser (PDL) treatment and to determine the optimal application time for adequate cutaneous anesthesia.

METHODS

Sixty patients were enrolled in one of three separate double-blind, placebo-controlled protocols in which the active product or a placebo was applied to the skin and left intact for 20, 30, or 60 minutes prior to laser treatment. A 585 nm or 595 nm PDL was used to treat facial telangiectases or port-wine stains in each protocol. Patients rated the level of pain experienced during laser treatment on a visual analog scale (VAS). Independent assessments of observed discomfort and side effects were recorded.

RESULTS

All patients experienced significant pain reduction with the S-Caine peel as their sole topical anesthetic. An application time of 20 or 30 minutes was as effective as 60 minutes in achieving anesthesia. Side effects of the peel application were limited to transient mild erythema.

CONCLUSION

The S-Caine peel is a rapid, safe, and effective method of topical anesthesia for cutaneous PDL treatment.

Efficacy of erbium:yttrium-aluminum-garnet laser-assisted delivery of topical anesthetic

BACKGROUND

Penetration through the stratum corneum limits effectiveness of topical anesthetics.

OBJECTIVE

Our aim was to evaluate the effectiveness of 5% lidocaine (ELA-Max) cream applied after erbium:yttrium-aluminum-garnet (Er:YAG) laser ablation of the stratum corneum.

METHODS

Randomized, controlled, split-face comparison of anesthesia was performed on 12 volunteers. The stratum corneum was painlessly ablated with a low-fluence Er:YAG laser on half of the face, then the whole face was covered with ELA-Max cream for 60 minutes. Full-face laser resurfacing was performed, and visual analog pain scores (0 to 10) were recorded during each of 2 passes.

RESULTS

Laser-assisted topical anesthesia demonstrated significantly lower mean pain scores than topical anesthesia alone. This was more pronounced during the more painful second pass. Resurfacing after laser-assisted topical anesthesia was well tolerated by 72% of subjects in pass 1 and 58% in pass 2.

CONCLUSION

Laser-assisted topical anesthesia is fast, painless, and substantially more effective than conventional topical anesthesia but does not provide adequate anesthesia for full-face resurfacing in all subjects.

Topical anesthetics update: EMLA and beyond

BACKGROUND

Topical anesthetics remain a powerful, new advance for pain relief prior to cutaneous procedures. They are frequently used by dermatologists to decrease the pain associated with laser pulses, surgical procedures, or soft tissue augmentation. EMLA is the most commonly used agent, however, several new topical anesthetic agents have been released recently that claim increased efficacy and a faster onset of action.

OBJECTIVE

We review and compare the efficacy of several commonly used topical anesthetics and provide a look into the future.

CONCLUSION

EMLA remains the most widely used topical anesthetic given its proven efficacy and safety by several clinical trials. There has been a recent release of several new topical anesthetic agents with some demonstrating efficacy after a 30-minute application time. A reservoir of anesthetic is located and stored in the upper skin layers during application, providing additional anesthetic benefit 30 minutes after removal. As the options for the practitioner continue to grow, the demand for faster onset, comparative efficacy, and safety trials will continue to be of paramount importance.

Topical anesthetics in dermatology

Topical anesthetics are valuable tools for the dermatologists. The purpose of this study is to educate dermatologists about the pharmacology and clinical applications of topical anesthetics. A review of the current topical anesthetics was conducted. Several topical anesthetics are available to provide safe and effective cutaneous analgesia. Patient care can be improved by reducing the discomfort of local procedures and by minimizing the side effects of the anesthetics.

Topical anesthesia for laser hair removal: comparison of spot sizes and 755 nm versus 800 nm wavelengths

BACKGROUND

The Candela alexandrite and the Coherent diode laser systems come equipped with built-in skin cooling systems that are designed to both protect the epidermis, allowing higher fluences, and to alleviate discomfort. Nevertheless, pain can be a significant problem especially with treatment of larger areas. Scatter of the laser beam is reportedly affected by the spot size. It is claimed that larger spot sizes are more effective at identical fluences.

OBJECTIVE

This study evaluated the effectiveness of a topical 5% lidocaine cream (ELA-Max) to control pain and compared pain levels at identical fluences between the 8 mm and 12 mm spot size of the alexandrite laser and between the alexandrite and diode laser with its 9 mm spot size.

METHODS

The study was conducted in the axillae of 12 patients. Each axilla was divided in half for side-by-side comparison. Half of the right axilla was treated with the alexandrite 8 mm and the other half with the 12 mm spot size at identical fluences. The left axilla was treated at the maximum tolerated fluences with the alexandrite 12 mm spot size and the diode 9 mm spot size.

RESULTS

At identical fluences and other parameters, there was significantly more pain with the alexandrite 12 mm spot size than with the alexandrite 8 mm spot size, both with or without topical anesthesia. The alexandrite laser was significantly less painful than the diode laser both with and without topical anesthetic. The difference was most noticeable between the alexandrite 8 mm spot size and the diode 9 mm spot size. Topical 5% lidocaine anesthesia was effective in reducing pain, though not completely, for both the alexandrite and the diode lasers.

CONCLUSION

Topical 5% lidocaine cream is a simple and effective method for reducing patient discomfort during laser hair removal procedures, even when a skin cooling device is being used. A larger spot size causes more pain than a smaller spot size at identical fluences. The 800 nm diode laser causes greater discomfort than the 755 nm alexandrite laser.

Comparative study of the efficacy of four topical anesthetics

BACKGROUND

With the emergence of new laser and dermatologic procedures, the need for more effective topical anesthesia continues to grow. There are now several topical anesthetics that are being used prior to laser and surgical procedures.

OBJECTIVE

To compare the degree and duration of anesthesia produced by four commonly used topical anesthetics, we performed a prospective study investigating the efficacy of EMLA (eutectic mixture of local anesthetics), ELA-Max, 4% tetracaine gel, and betacaine-LA ointment (formerly eutectic-LA).

METHODS

Equal amounts of the above topical anesthetics plus a control (eucerin cream) were applied to 10 test sites under occlusion on the volar forearms of 12 adult volunteers. After a 60-minute application time, the degree of anesthesia was assessed immediately by a Q-switched Nd:YAG laser at 1064 nm. Pain testing was also performed 30 minutes after the 60-minute application period. Volunteer responses to pain stimuli were recorded using an ordinal scale of 0 (no pain) to 4 (maximal pain). The mean scores for the time intervals were obtained. Analysis of the data was performed using analysis of variance (ANOVA), Newman-Keuls test, Friedman rank order test, and paired t-tests.

RESULTS

ELA-Max, EMLA, and tetracaine were statistically superior to control after the 60-minute application period. Thirty minutes later, ELA-Max, EMLA, tetracaine, and betacaine-LA were all statistically superior to the control. Comparing individual anesthetics, ELA-Max and EMLA were the superior anesthetics at both time intervals. Although the mean pain scores for each anesthetic were lower 30 minutes after their removal, the differences did not reach statistical significance.

CONCLUSION

This is the first prospective study comparing the efficacy of several new topical anesthetic agents. Using the methodology of this study, in which the anesthetics were applied under occlusion, ELA-Max and EMLA were the superior anesthetics after a 60-minute application time and 30 minutes later. In addition, there was a clinical increase in efficacy suggested with all of the anesthetics 30 minutes after their removal.