What data compares LET gel and EMLA cream as topical anesthetic of choice for lacerations? Is there any data in pediatrics?

Comment by InpharmD Researcher

Available data in pediatrics, while limited, have demonstrated LET gel to have potentially superior anesthetic properties for lacerations compared to EMLA cream. This is primarily based on a prospective observational study that found LET to have significantly better pain control compared to EMLA during skin repair in children. Additionally, a meta-analysis of pooled data found that LET gel significantly reduces pain compared to control, while no benefit was observed with EMLA cream. In general, LET appears to be the preferred topical anesthetic for lacerations due to improved dermal penetration.

Background

A 2022 meta-analysis aimed to evaluate the efficacy of topical anesthetics in pediatric wound management. A comprehensive literature search across five databases identified eight eligible studies for review that utilized lidocaine-prilocaine (EMLA) and lidocaine-epinephrine-tetracaine (LET) for pain reduction. The meta-analysis revealed that LET significantly reduced pain compared to control interventions (standardized mean difference [SMD] -0.46; 95% confidence interval [CI] -0.69 to -0.23; p<0.0001; 3 studies), while a eutectic mixture of local anesthetics (EMLA) did not show a statistically significant difference in pain reduction (SMD -0.79; 95% CI -1.82 to -0.24; p= 0.13; 3 studies). The incidence of adverse events (AEs) was minimal and was not significantly different between the groups for both LET (odds ratio [OR] 0.99; 95% CI 0.15 to 6.50; p= 0.99) and EMLA (OR 2.31; 95% CI 0.67 to 7.93; p= 0.18). These findings suggest that LET may be effective in reducing pain during pediatric wound management, with minimal AEs, while EMLA’s efficacy is less conclusive. [1]

A 1998 randomized, double-blind trial compared the efficacy of 5% LET and 5% EMLA in producing local anesthesia on intact skin. Forty healthy volunteers received 1 mL of LET or EMLA on separate forearms under an occlusive dressing for one hour. Superficial anesthesia was assessed by nine 1-mm pinpricks, while deeper anesthesia was evaluated using a 22-gauge needle penetrating to 3 mm, contingent on the perception of fewer than four pinpricks. Pain intensity was recorded using a visual analogue scale (VAS). Subjects also ranked the overall anesthetic effect and expressed a preference between the two formulations. Compared with EMLA, LET demonstrated superior superficial anesthesia, with a significantly lower median number of pinpricks perceived (1.0 vs. 1.5, p<0.01), with fewer volunteers experiencing greater than four pinpricks (6 vs. 12, p<0.01). Although LET exhibited a trend toward lower mean VAS scores for deeper anesthesia (1.5 vs. 2.4), this difference did not reach statistical significance (p= 0.065). Overall anesthetic effect was rated significantly better for LET (p= 0.024), with 62.5% of volunteers preferring LET, compared to 20% preferring EMLA. Mild erythema was observed in 80% of LET-treated subjects, while 58% of EMLA-treated subjects exhibited blanching. The findings suggest that LET provides enhanced superficial anesthesia relative to EMLA, likely due to improved dermal penetration via liposomal encapsulation. [2]

Literature Review

A search of the published medical literature revealed 2 studies investigating the researchable question:

Comparison of LET gel and Emla cream as the topical anesthetic of choice for lacerations. We would also need to include any data specifically on use in pediatrics.

Level of evidence

C - Multiple studies with limitations or conflicting results Read more→

Please see Tables 1-2 for your response.

Lidocaine-Epinephrine-Tetracaine Gel Is More Efficient than Eutectic Mixture of Local Anesthetics and Mepivacaine Injection for Pain Control during Skin Repair in Children: A Prospective, Propensity Score Matched Two-Center Study
Design	Prospective, propensity score-matched multicenter study N= 73
Objective	To compare local eutectic mixture of local anesthetics (EMLA; lidocaine-prilocaine) plus mepivacaine infiltration with topical anesthetics lidocaine-epinephrine-tetracaine (LET gel) for pain control during skin repair in children
Study Groups	LET (n= 37) EMLA + mepivacaine infiltration (n= 22)
Inclusion Criteria	Age 3 to 16 years; dermal laceration with the need for suturing
Exclusion Criteria	Laceration older than 24 hours, laceration involving digits, nose, ears, and penis, bite wounds, children suffering from chronic diseases, pregnancy, and known allergy to any provided medication
Methods	Children received either LET gel or EMLA cream applied at the site of the laceration. LET gel or EMLA cream was applied for 20-30 minutes, followed by wound coverage using sterile gauze; EMLA was followed by a mepivacaine 1% infiltration around the wound edges (after 20-30 minutes). Pain was assessed using the faces pain rating scale or visual analogue scale. Follow-up assessed wound infection rates and overall satisfaction. A maximum of 5 mL of LET or EMLA was applied at the laceration site to avoid lidocaine toxicity.
Duration	Not specified
Outcome Measures	Primary: Pain during skin repair Secondary: Procedure time, need for secondary infiltration, infection rate, overall satisfaction
Baseline Characteristics		LET (n= 37)	EMLA (n= 22)
	Age, years	8.78 ± 3.13	9.57 ± 4.22
	Male	24 (64.9%)	16 (72.7%)
	Wound length, cm	3.31 ± 1.97	3.79 ± 2.41
	Wound shape, location, contamination level, and presence of foreign bodies were not significantly different between groups.
Results		LET (n= 37)	EMLA (n= 22)	p-value
	Pain during pretreatment	Significantly less	---	<0.05
	Pain during skin repair	Similar	Similar	NS
	Need for additional infiltration	5 (13.5%)	1 (4.5%)	0.28
	Application time, minutes	29.49 ± 11.16	28.72 ± 10.92	0.80
	The longest application time was 60 minutes in both groups. A longer application time (more than 30 minutes) did not improve procedural pain in either group. The pain VAS scores were not reported, and neither were any significant levels. Wound closure, including debridement, was equally painful in both groups.
Adverse Events	Three patients in the LET group and one in the EMLA group had at least one indirect sign of infection, such as swelling, redness, or color. Only one patient required antibiotic treatment for a wound infection in the LET group.
Study Author Conclusions	LET is superior to conventional anesthesia including mepivacaine infiltration in the pediatric emergency departments. Pretreatment with LET is significantly less painful but equally effective. Hence, LET is recommended as a topical anesthetic in the pediatric emergency department.
Critique	The study's prospective design and use of propensity score matching are strengths, but it is not a randomized controlled trial, which may introduce biases (e.g., selection bias). The EMLA application time was shorter than typically recommended, potentially biasing results against EMLA. Reliance on parental assessment for follow-up may underestimate infection rates. The study did not include nonpharmacologic interventions, which could have influenced pain perception. No VAS pain scores or p-values were reported, making detailed or further comparisons difficult.

References:

Königs I, Wenskus J, Boettcher J, Reinshagen K, Boettcher M. Lidocaine-Epinephrine-Tetracaine Gel Is More Efficient than Eutectic Mixture of Local Anesthetics and Mepivacaine Injection for Pain Control during Skin Repair in Children: A Prospective, Propensity Score Matched Two-Center Study. Eur J Pediatr Surg. 2020;30(6):512-516. doi:10.1055/s-0039-3400283

LET versus EMLA for Pretreating Lacerations: A Randomized Trial
Design	Randomized, double-blind clinical trial N= 60
Objective	To compare the anesthetic efficacy of EMLA cream with that of LET solution for pretreating lacerations prior to lidocaine injection
Study Groups	LET (n= 29) EMLA (n= 31)
Inclusion Criteria	Patients at least 1-year-old; uncomplicated lacerations less than 6 hours old thought to require closure
Exclusion Criteria	Patient age < 1 year; multiple trauma; peripheral vascular disease; diabetes mellitus; bleeding diathesis; history of keloids or hypertrophic scars; allergy to any study medication; bites, puncture wounds, or crush injuries; presence of devitalized tissue; infected or heavily contaminated lacerations; lacerations more than 6 hours old; lacerations on the digits, nose, ears, penis
Methods	Patients were randomized to LET gel (lidocaine 2%, epinephrine 1:1,000, tetracaine 2%) or EMLA cream (eutectic mixture of lidocaine 2.5% and prilocaine 2.5%); maximum 5 mL of either to keep the total dose of lidocaine below the toxic range. A nurse applied the topical anesthetic to the laceration with a 5-mL syringe. A physician assessed the laceration edges for blanching and anesthesia to a 27-gauge needlestick. Supplemental lidocaine 1% was infiltrated through the wound edges. Pain of infiltration was recorded on a 100-mm visual analog scale.
Duration	Four-month study period
Outcome Measures	Primary: Pain of lidocaine infiltration, proportion of adequately anesthetized wounds Secondary: Pain of topical application, presence of wound infection
Baseline Characteristics		LET (n= 29)	EMLA (n= 31)
	Children less than age 18, no. (%)	22 (76%)	20 (65%)
	Female	7 (24%)	7 (23%)
	Facial lacerations	22 (76%)	22 (71%)
	Median laceration length, cm (IQR)	2 (1.6–3.0)	2 (1–3.0)
	Median duration of application, minutes (IQR)	34 (26–45)	40 (34–50)
	Type of wound closure Suture Staples Tissue adhesive	15 (52%) 6 (21%) 4 (14%)	24 (77%) 4 (10%) 2 (6%)
Results		LET (n= 29)	EMLA (n= 31)	p-value
	Median pain of application, mm (IQR)	5 (0–13)	0 (0–1)	0.003
	Completely anesthetized wounds	19 (73%)	12 (40%)	0.01
	Supplemental lidocaine injection in closed wound	23 (79%)	28 (97%)	0.29
	Median pain of injection for entire group, mm (IQR)	12 (4–36)	13 (6–32)	0.89
Adverse Events	No wound infections reported in either group
Study Author Conclusions	Pretreatment of simple lacerations with LET or EMLA results in similar amounts of pain during subsequent lidocaine infiltration. LET is preferred due to lower cost and no contraindication for open wounds.
Critique	The study was well-designed with a randomized, double-blind approach, but the small sample size and convenience sampling may limit generalizability. The study did not standardize wound preparation, which could affect pain outcomes. The short duration of EMLA application may have biased results against it. The study's focus on facial wounds may not apply to other wound types.

References:

Singer AJ, Stark MJ. LET versus EMLA for pretreating lacerations: a randomized trial. Acad Emerg Med. 2001;8(3):223-230. doi:10.1111/j.1553-2712.2001.tb01297.x