Two Randomized, Double-Blind, Placebo-Controlled Studies Evaluating the S-Caine Peel for Induction of Local Anesthesia Before Long-Pulsed Nd:YAG Laser Therapy for Leg Veins JOHN Z. S. CHEN, MD, n MACRENE R. ALEXIADES-ARMENAKAS, MD,PHD, n LEONARD J. BERNSTEIN, MD, n LAURIE G. JACOBSON, MD, n PAUL M. FRIEDMAN, MD, w AND ROY G. GERONEMUS, MD n n Laser and Skin Surgery Center of New York, New York, and w Dermatologic Surgery Associates, Houston, Texas BACKGROUND. Topical anesthetics are valuable tools for many dermatologic procedures. OBJECTIVE. To evaluate the efficacy and safety of S-Caine Peel composed of 1:1 (wt:wt) mixture of 7% lidocaine and 7% tetracaine in the induction of local anesthesia before longpulsed Nd:YAG laser therapy for leg veins. METHODS. Two randomized, double-blinded, placebo-controlled trials were performed. In study 1, 60 adults received S- Caine Peel and placebo cream for 30 or 60 minutes. Efficacy was evaluated by a patient visual analog scale and impression. The pain scale and impression were evaluated by the investigator and an independent observer. In study 2, 40 adults received 60- and 90-minute applications. RESULTS. In study 1, the 30- and 60-minute application times were grouped: Patients had adequate pain relief in 48% of S- Caine sites versus 23% of placebo sites (Po0.001). Investigators reported none-to-mild pain in 50% of active sites versus 33% of placebo sites (P 5 0.007), with adequate anesthesia in 65% of active sites versus 43% of placebo sites (P 5 0.002). The independent witness assessed none-to-mild pain in 52% of active sites versus 37% of placebo sites (P 5 0.067). In study 2, investigators rated none-to-mild pain in 75% of 60-minute and 85% of 90-minute S-Caine sites versus 30% and 50% of placebo sites (P 5 0.012 and P 5 0.002, respectively), with adequate anesthesia in 70% and 85% of 60- and 90-minute of active sites versus 25% and 20% of placebo sites (P 5 0.029 and P 5 0.001, respectively). The independent witness rated none to mild pain in 80% and 85% of 60 and 90 minute of S- Caine sites versus 35% and 50% of placebo sites (P 5 0.008 and P 5 0.004). CONCLUSION. The S-Caine Peel provides safe and highly effective local anesthesia when applied for at least 60 minutes for laser therapy of leg veins. Facile removal of the peel provides a unique advantage and ease in administration. ZARS INC. SPONSORED THIS STUDY AND SUPPLIED MATERIALS USED IN THE STUDY. TOPICAL ANESTHETICS have become a necessity for many dermatologic procedures. Several topical anesthetics exist. EMLA cream (Astra Pharmaceuticals, Wayne, PA) is an emulsion in which the oil phase is an eutectic mixture of 2.5% lidocaine and 2.5% prilocaine. ELA-Max (Ferndale Laboratories, Ferndale, MI) is a topical anesthetic cream with 4% liposomal lidocaine. Others include amethocaine gel, a 4% lidocaine that has been approved for use in Europe, and Velvachol, a 30% to 40% lidocaine compounded with acid mantle. Ethyl chloride is a vapocoolant that causes transient anesthesia. Lidocaine can also be introduced into the skin through iontophoresis, a process of introducing ionic drugs Address correspondence and reprint requests to: Roy G. Geronemus, MD, PhD, Laser and Skin Surgery Center of New York, 317 East 34th Street, New York, NY, 10016, or e-mail: mail@laserskinsurgery.com into the body for therapeutic purposes. TAC solution (tetracaine epinephrine cocaine) has a formulation of 0.5% tetracaine, 0.05% epinephrine 1:2000, and 11.8% cocaine in normal saline. Several preparations of topical anesthetics are available for oral and mucosal anesthesia. These include Xylocaine, which contains lidocaine as 2% viscous solution, 5% liquid, or 5% ointment formulations; Hurricaine, which contains 20% benzocaine in liquid, gel, or spray formulations; and Cocaine of 4% or 10% solutions. 1 The disadvantages to EMLA and other such topical anesthetics include the lengthy application period, their need to be applied under occlusion, the inability to provide adequate anesthesia at the periphery, and the often messy application and removal. 2 4 The ideal topical anesthetic agent would be the one that provides effective anesthesia in a short period of time, works on intact skin without local or systemic r 2003 by the American Society for Dermatologic Surgery, Inc. Published by Blackwell Publishing, Inc. ISSN: 1076-0512/03/$15.00/0 Dermatol Surg 2003;29:1012 1018
Dermatol Surg 29:10:October 2003 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA 1013 side effects, is clean and easy to use, and invokes neither pain nor discomfort. The S-Caine Peel is a novel 1:1 eutectic mixture of lidocaine base, USP 7% (wt:wt), and tetracaine base, USP 7% (wt:wt). This formulation applies as a cream, and when exposed to air, it dries and forms a flexible membrane that can be easily peeled off. The S-Caine Peel is not occluded during application. Different perceptible pain inducers for evaluating anesthetic efficacy have been used, including a pinprick test and thermal stimuli. 5,6 Using nonscarring laser pulses as thermal stimuli has been proven to be reliable and reproductive pain inducers for assessing topical anesthetics showing a low intraindividual variation. 7,8 Laser pulses seem to offer some advantages over the traditional methods because (1) laser stimuli are well controlled, measurable, and reproducible; (2) they can be applied to different skin area; and (3) they can elicit a specific afferent activity without contamination from mechanosensitive receptors. 9,10 The aims of these two studies were to evaluate the effectiveness of the S-Caine Peel when applied topically in providing clinically useful local anesthesia before laser therapy and to monitor the nature and frequency of adverse events associated with the S- Caine Peel. Painful sensation associated with the Altus CoolGlide laser treatment for leg veins has been described as moderate to severe and was therefore chosen to test adequate pain control. Methods Formulations The S-Caine Peel is manufactured by ZARS, Inc. (Salt Lake City, UT). It is a 1:1 eutectic mixture of lidocaine base, USP 7% (wt:wt), and tetracaine base, USP 7% (wt:wt). The excipients in the formulation are polyvinyl alcohol, lecithin, corn starch, and water. The placebo formulation is manufactured by ZARS, Inc., and it contains olive oil, national formulary instead of the active formulation. All other excipients are identical to those in the active formulation. The placebo and active formulation are identical in appearance. Study Design and Patient Selection Two consecutive, randomized, double-blinded, placebo-controlled studies were conducted to evaluate the effectiveness of the S-Caine Peel in providing clinically useful local anesthesia during laser therapy for leg veins. The inclusion criteria for the studies were as follows: (1) 18 years of age or older; (2) Fitzpatrick s skin type of I, II, or III and of either gender; (3) patients electing for a laser therapy procedure for the treatment of lower extremity telangiectasias (0.5 to 3 mm in diameter) with two similar treatment sites; (4) no known allergies or sensitivities to lidocaine, tetracaine, or other local anesthetics of the amide or ester type. The exclusion criteria included the following: (1) known sensitivity to any components (i.e., sulfites, adhesives) of the test materials; (2) the patient taking concomitant analgesic medication during the past 24 hours; (3) damaged, denuded, or broken skin at the designated treatment site; and (4) pregnant or breast feeding. In study 1, 60 subjects who met all of the inclusion and exclusion criteria were enrolled. Each patient was originally randomly assigned to one of two treatment groups (30- or 60-minute application group) and served as his or her own control, receiving both active and placebo drugs. The application of each drug was also randomized to cover one of two leg vein treatment sites, which were designated as the top/right and bottom/ left treatment sites. It was later discovered that the 30-minute application was inadequate, and all subsequent 48 patients received the 60-minute application. In study 2, 40 subjects with same parameters were enrolled comparing 60 and 90 minutes of application. Informed consent was obtained from each patient. The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki, as reflected in approval by the institution s human research review committee. Before dispensing the drug, the tube was weighed, and the weight was recorded on the case report forms. The drug was dispensed to cover the treatment area with a uniform thickness of 2 mm. After dispensing the drug, the tube was weighed again, and the value was recorded on the case report forms. Immediately after peel removal, the treatment sites were examined closely for any evidence of adverse reactions, such as erythema/eschar formation (0 to 5), edema (0 to 5), and blanching (0 to 5) scales. The cream dried to form flexible membrane and peeled off before laser irradiation (Figure 1). Laser Treatment and Efficacy Assessments The top/right area was treated first, followed by the lower/left area by the investigator. Ten to 50 pulses of LP Nd:YAG (1064 nm, 140 to 400 J/cm 2, 30 to 100 ms, 1.5- to 5-mm spot size, contact cooling) were delivered. Both treatment sites (active and placebo) received the same number of pulses. After completion of these pulses at each treatment site (active or placebo), efficacy was evaluated by patient s visual analog scale (VAS), in which patient rates the amount of pain that he or she experienced during the
1014 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA Dermatol Surg 29:10:October 2003 Figure 1. S-Caine Peel is applied as a cream. It dries upon exposure to the air and forms a flexible membrane, which can be easily peeled off. procedures on both areas using a 100-mm scale from 0 (no pain) to 100 (the most pain imaginable). The efficacy was also evaluated by an investigator pain scale (1 to 4) and impression and an independent observer pain scale (1 to 4). After the completion of the pain scores, the investigator resumed the laser treatment. The location and size of the lesion, drug application time, drug removal time, duration of the laser procedure, and total number of pulses given were recorded on the case report form. Statistical Analysis VAS results were analyzed using repeated-measures analysis of variance with the grouping factor of administration time as well as using Wilcoxon signed rank tests. Investigator and witness pain scales were compared between drug types using Wilcoxon signed rank tests. To evaluate the consistency of drug differences between administration times, the paired changes between S-Caine Peel and placebo were compared using Mann-Whitney tests. The patient s and investigator s assessments of adequate anesthesia and whether the patient would use the treatment again were compared among treatments using McNemar chi-square tests for each administration time separately and combined. Results In study 1, each patient was originally randomly assigned to one of the two treatment groups of 30- or 60-minute drug application time. During the course of the study, it was evident that the 30-minute application was inadequate, and all subsequent (48) patients received a 60-minute application. The results for the 30- and 60- minute applications were grouped. Patients had VAS scores lower for active sites (P 5 0.046) with no-mild pain in 33% of active versus Figure 2. Assessment of pain elimination from study 1: percentage of patients with no mild pain. 18% of placebo sites (Po0.001) (Figure 2) and reported to have adequate pain relief in 48% of active versus 23% of placebo sites (Po0.001) (Figure 3). Investigators reported no mild pain in 50% of active sites versus 33% of placebo sites (P 5 0.007) (Figure 2), and adequate anesthesia was achieved in 65% of active sites versus 43% of placebo sites (P 5 0.002) (Figure 3). Independent observer assessed no mild pain in 52% of active versus 37% of placebo sites (P 5 0.067) (Figure 2). Safety evaluation showed one case of erythema developing after 60 minutes, which resolved completely in 20 minutes. The results of study 2 comparing 60- and 90- minutes application are shown in Table 1. Patients had mean VAS scores 23 points better for S-Caine Peel than placebo for the 60-minute administration and 27 points better for the 90-minute administration. These results were statistically significant (P 5 0.01 and Po0.001, respectively), with no significant difference between administration times found. For the 60- minute administration, 75% of patients had lower scores with S-Caine Peel, and for 90 minutes, this proportion was 90% (Table 1). Overall, the median VAS pain score with S-Caine Peel was 16.5 compared
Dermatol Surg 29:10:October 2003 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA 1015 Figure 3. Assessment of adequate anesthesia from study 1: percentage of patients with adequate anesthesia. Figure 4. Assessment of pain elimination from study 2: percentage of patients with no-mild pain. Table 1. Patient Evaluation Number of patients 60 Minutes 90 Minutes S-Caine Placebo Change S-Caine Placebo Change Number of patients 20 20 20 20 20 20 VAS Result Mean 25.2 48.0 22.8 15.2 42.5 27.3 Median 16.5 54.5 29.5 6.5 47.5 26.5 SD 20.6 28.1 32.7 17.7 20.2 22.1 Range 0 61 4 84 43 72 0 62 14 82 14 63 % S-Caine with lower scores 75% 90% % Placebo with lower scores 25% 10% Wilcoxon Test P-Value 0.010 o0.001 VASr25 m 60% 30% 75% 30% F-Statistic (1,38 d.f.) 5 32.174, Po0.001 Drug difference by time comparison F-Statistic (1,38 d.f.) 5 0.266, P 5 0.609 Eliminate pain (adequate anesthesia) No 5 13 3 16 Yes 15 7 17 4 % Adequate 75% 35% 85% 20% MCNemar Test P-value 0.033 o0.001 % Preferring active 55% 65% % Preferring placebo 15% 0% MCNemar test P-Value 0.033 o0.001 MCNemar chi-square 5 16.333, Po0.001 Would use again No 5 12 2 14 Yes 15 8 18 6 % Preferring active 45% 60% % Preferring placebo 10% 0% MCNemar Test P-Value 0.035 0.001 Overall drug Comparison MCNemar chi-square 5 15.696, Po0.001
1016 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA Dermatol Surg 29:10:October 2003 Figure 5. Assessment of adequate anesthesia from study 2: percentage of patients with adequate anesthesia. with 54.5 for placebo (Table 1). For the patient s assessment of pain elimination, 60% of patients reported no mild pain with S-Caine Peel versus 30% with placebo for the 60-minute administration, whereas among the 90-minute applications, 75% was rated to have no or slight pain versus 30% with placebo (P 5 0.02 and Po0.001; Figure 4). For the patient s assessment of adequate anesthesia, 75% of patients had adequate anesthesia with S-Caine Peel versus 35% with placebo for the 60-minute administration, whereas 85% of patients had adequate anesthesia with S-Caine Peel versus 20% with placebo for the 90- minute administration (P 5 0.033 and Po0.001, respectively; Figure 5). Overall, adequate anesthesia was Table 2. Investigator/Witness Evaluation Number of Patients 60 Minutes 90 Minutes S-Caine Placebo S-Caine Placebo Number of Patients 20 20 20 20 Investigator pain evaluation No pain 5 1 12 1 Slight pain 10 5 5 9 Moderate pain 5 13 3 10 Severe pain 0 1 0 0 % S-Caine effective 75% 85% % Placebo effective 30% 50% Wilcoxon test P-value 0.012 0.002 Wilcoxon Z-statistic 5 3.988, Po0.001 Drug difference by time comparison Mann-Whitney statistic 5 182.0, P 5 0.605 Investigator assessment of adequate anesthesia No 6 15 3 16 Yes 14 5 17 4 % Adequate 70% 25% 85% 20% MCNemar test P-value 0.029 0.001 % S-Caine better 65% 70% % Placebo better 20% 5% MCNemar test P-value 0.029 0.001 MCNemar chi-square 5 15.125, Po0.001 Witness pain evaluation No pain 6 1 11 2 Slight pain 10 6 6 8 Moderate pain 3 10 4 13 Severe pain 0 0 0 0 % S-Caine effective 80% 85% % Placebo effective 35% 50% Wilcoxon test P-Value 0.008 0.004 Wilcoxon Z-statistic 5 3.915, Po0.001 Drug difference by time comparison Mann-Whitney Statistic 5 190.0, P 5 0.775
Dermatol Surg 29:10:October 2003 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA 1017 achieved in 80% of all S-Caine Peel administrations and 28% of placebo administrations. For the 60-minute administration, 45% of the patients said they would use S-Caine Peel again but only 10% for placebo, whereas for the 90-minute administration, this proportion was 60% (P 5 0.035 and P 5 0.001; Table 1). Table 2 shows the investigator and independent witness assessments. For the investigator s assessment of pain elimination, 75% of 60-minute S-Caine Peel applications were rated to have no or slight pain versus 30% with placebo, whereas among all the 90-minute applications, 85% were rated to have no or slight pain versus 50% with placebo (Figure 4). No significant differences between administration times were found (Table 2). For the investigator s assessment of adequate anesthesia, 70% of 60-minute S-Caine Peel applications were noted to be adequate versus 25% with placebo, and 85% of 90-minute applications were rated to be adequate versus 20% with placebo (Figure 5). Overall, 78% of all S-Caine Peel applications had adequate anesthesia compared with 23% of all placebo applications, as assessed by the investigator. The independent witness rated 80% and 85% of 60- and 90-minute S-Caine Peel applications to have no or slight pain compared with 35% and 50% of placebo applications (P 5 0.008 and P 5 0.004; Figure 4). Again, no significant differences between administration times were found (Table 2). Overall, 80% of all S- Caine Peel administrations had no or slight pain compared with 40% of all placebo administrations for the investigator evaluation. For the independent witness evaluation, these proportions were 83% for all S-Caine Peel administrations and 43% for all placebo administrations. Safety evaluation showed no occurrence of erythema/eschar, edema or blanching, or any other types of local or systemic adverse reactions. Discussion The ideal local anesthetic should have minimal or no side effects, should exert its effect in the shortest time possible, and should not produce irreversible damage to nerve fibers while providing a lasting effect to complete any planned procedures. EMLA application under occlusion has been the most commonly used method for achieving topical anesthesia. 1 Although it has been proven to be an effective analgesic agent useful in a variety of clinical situations, there have been reports of adverse reactions. The most typical of these reactions is blanching or redness at the site of application, which can be particularly bothersome when performing laser treatment for vascular lesion, such as leg veins or port wine stains. It has been postulated that this is the result of peripheral vasoconstriction or vascular shunts, respectively. 11 Other side effects, such as local irritation or swelling, have also been reported. EMLA cream is difficult to be applied evenly, rubbed off easily, is messy and difficult to be occluded, and requires a lengthy application time (1 to 2 hours). In contrast, S-Caine Peel has been proven to be effective in relatively short period of time for laser therapy of leg veins (60 minutes) and very safe to use in the sense that it does not cause local blanching, swelling, or irritation. The application of S-Caine Peel is even and facile; once it hardens into membrane form, it is not easily rubbed off and is very convenient to remove. The purpose of these studies was to evaluate the effectiveness of the S-Caine Peel when applied topically in providing clinically useful local anesthesia before laser therapy for leg veins. The sensation of pain is a subjective phenomenon, and although sensory thresholds for pain vary little between individuals, the tolerance level varies considerably between cultures and individuals and even in the same person at different times. 12 This occurs because the subjective intensity of pain depends not only on the extent of the stimulus but also on the degree to which it occupies the subject. Redirection of attention can weaken the sensation and, in extreme conditions such as stress of an accident or hypnosis, can abolish it. 13 Therefore, the quantification of levels of analgesia has always been a major problem in experimental studies. The use of VAS has been proven to be a reliable and useful indicator of the direction and magnitude of change of pain. 14 Because of the subjective nature of pain, it is common practice in any study involving pain to supplement the patient s assessment by separate objective measures by one or more observers. This approach can enhance the reliability of the experimental data. Therefore, in our studies, we chose to use several different types of pain measurement, including VAS, and pain evaluation by the patient, investigator, and independent observer. The end points employed in these two studies have indicated that S-Caine Peel treatment reduced or abolished the pain associated with laser treatment of leg veins. This was evinced by a significant decrease in the VAS graded by patient after the laser treatment of areas of S-Caine Peel treated skin compared with placebo areas, as well as by the improvement of different pain measurements assessed by patient, investigator, and independent observer. As shown in study 2, the overall median VAS pain score with S- Caine Peel was 16.5 compared with 54.5 for placebo. Pain was eliminated for 80% of all S-Caine Peel applications and 28% of placebo applications by patient s pain assessment and 80% of all S-Caine Peel applications and 40% of placebo applications by
1018 CHEN ET AL.: S-CAINE PEEL FOR LOCAL ANESTHESIA Dermatol Surg 29:10:October 2003 investigator s pain assessment. For the independent witness evaluation, these proportions were 83% for all S-Caine Peel applications and 43% for all placebo applications. Overall, 78% of all S-Caine Peel applications had adequate anesthesia compared with 23% of all placebo applications by the investigator s assessment of adequate anesthesia. Although there was a greater decrease in the mean VAS scores for the 90- minute application compared with the 60-minute application and a higher percentage of pain elimination by both the investigator s and independent witnesses evaluation for the 90-minute application compared with the 60-minute application, these differences were not statistically significant, indicating that the 60-minute application of S-Cain Peel would provide adequate and effective anesthesia. Of particular interest is the association of the analgesia achieved with the specific trauma produced by the laser beam. Most other studies on topical analgesia have involved procedures in which trauma and thereby the presumed concomitant stimulation of pain fibers are at variable and unknown depths. It has been demonstrated that the 1064-nm laser beam alters the dermal blood vessels as far as the mid to lower reticular dermis, and the depth at 50% penetration by the laser beam is appropriately 1.6 mm. 15 Thefactthata marked reduction in pain was achieved in the laser treated areas with S-Caine Peel suggests that sufficient quantities of the anesthetics must have penetrated into the mid to lower reticular dermis to block the pain fibers. More recently, Bryan and Alster 16 and Alster and Lupton 17 published two separate studies on the S-Cain Peel. Their first study examined the efficacy of S-Cain peel for induction of local anesthesia before pulsed dye laser treatment for facial telangiectasia or port-wine stains and determined the optimal application time for adequate anesthesia by comparing 20-, 30-, or 60- minute applications. In their second study, S-Caine Peel was applied for 30 minutes before full-face singlepass CO 2 laser resurfacing. Both studies concluded that an application time of 30 minutes was adequate in achieving anesthesia. This was in contrast to our current study, in which 60-minute application was found to be the minimal length of application, and 30 minutes was ineffective. This may be due to the different anatomic locations that S-Caine Peel was applied to during the two studies. In our study, the S- Caine Peel was applied to leg area, where there are much thickened epidermis and subcutaneous tissues, which potentially can prolong the absorption time for any topical agent. Whether 45-minute application was adequate for laser leg vein therapy needs to be determined. In summary, the S-Caine Peel provides safe and highly effective local anesthesia when applied for at least 60 minutes before laser treatment for leg veins. Facile removal of the peel provides a unique advantage and ease in administration. The S-Caine Peel can potentially provide a noninvasive method of anesthetizing the skin before painful medical procedures such as injections, cannulations, biopsies, minor superficial surgeries, and laser procedures. It gives a clean and convenient alternative to anesthetic creams that must be applied under occlusion and wiped off from the treatment area before surgical procedures. Acknowledgments The authors thank Marisol Edward, RN, Alexis Moreno, and Michelle Turnbull at research department oflaserandskinsurgerycenterofnewyorkfortheirhard work and endless support. References 1. Huang W, Vidimos A. Topical anesthetics in dermatology. 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Acute Pain. Boston: Butterworth, 1985:104 32. 15. Anderson RR. Laser Tissue Interactions: Cutaneous Laser Surgery: The Art and Science of Selective Photothermolysis. St. Louis: Mosby, 1999:1 18. 16. Bryan HA, Alster T. The S-Caine Peel: a novel topical anesthetic for cutaneous laser surgery. J Dermatol Surg 2002;28:999 1003. 17. Alster T, Lupton J. Evaluation of a novel topical anesthetic agent for cutaneous laser resurfacing: a randomized comparison study. J Dermatol Surg 2002;28:1004 6.