A Comparison of Laser-Assisted Drug Delivery at Two Output Energies for Enhancing the Delivery of Topically Applied LMX-4® Cream Prior to Venipuncture

Evidence-Based Clinical Practice Guidelines for Laser-Assisted Drug Delivery

Importance

Laser-assisted drug delivery (LADD) is used for various medical and cosmetic applications. However, there is insufficient evidence-based guidance to assist clinicians performing LADD.

Objective

To develop recommendations for the safe and effective use of LADD.

Evidence Review

A systematic literature review of Cochrane Central Register of Controlled Trials, Embase, and MEDLINE was conducted in December 2019 to identify publications reporting research on LADD. A multidisciplinary panel was convened to draft recommendations informed by the systematic review; they were refined through 2 rounds of Delphi survey, 2 consensus meetings, and iterative review by all panelists until unanimous consensus was achieved.

Findings

Of the 48 published studies of ablative fractional LADD that met inclusion criteria, 4 were cosmetic studies; 21, oncologic; and 23, medical (not cosmetic/oncologic), and 6 publications of nonablative fractional LADD were included at the request of the expert panel, producing a total of 54 studies. Thirty-four studies (63.0%) were deemed to have low risk of bias, 17 studies (31.5%) had moderate risk, and 3 (5.5%) had serious risk. The key findings that informed the guidelines developed by the expert panel were as follows: LADD is safe in adults and adolescents (≥12 years) with all Fitzpatrick skin types and in patients with immunosuppression; it is an effective treatment for actinic keratosis, cutaneous squamous cell carcinoma in situ, actinic cheilitis, hypertrophic scars, and keloids; it is useful for epidermal and dermal analgesia; drug delivery may be increased through the application of heat, pressure, or occlusion, or by using an aqueous drug solution; laser settings should be selected to ensure that channel diameter is greater than the delivered molecule; antibiotic prophylaxis is not recommended, except with impaired wound healing; antiviral prophylaxis is recommended when treating the face and genitalia; and antifungal prophylaxis is not recommended. The guideline's 15 recommendations address 5 areas of LADD use: (I) indications and contraindications; (II) parameters to report; (III) optimization of drug delivery; (IV) safety considerations; and (V) prophylaxis for bacterial, viral, and fungal infections.

Conclusions and Relevance

This systematic review and Delphi consensus approach culminated in an evidence-based clinical practice guideline for safe and effective use of LADD in a variety of applications. Future research will further improve our understanding of this novel treatment technique.

Efficacy of Er,Cr:YSGG laser-assisted delivery of topical anesthesia in the oral mucosa

OBJECTIVE

Lasers which can reduce epithelium thickness will enhance the penetration of topical drugs. To date, no study has assessed the efficacy of this technique in the oral mucosa. The aim of this study was the evaluation of efficacy of this technique in increasing the effect of topical anesthesia in the oral mucosa.

MATERIALS AND METHODS

On 20 volunteers, half of the lower lip mucosa was irradiated with Er,Cr:YSGG laser with 2780 nm wavelength and 1.3 J/cm² energy for 1 min; then, topical lidocaine was applied on the entire lower lip mucosa. After 5 min, a 27-gauge needle was inserted to each half of the lip mucosa, and the length of the needle inserted into the mucosa without feeling pain was considered the depth of insertion. This measurement was repeated every 15 min for 1 h.

RESULTS

The mean depth of anesthesia at the control side was 6.95 ± 2.43, 8.45 ± 4.05, 6.5 ± 3.00, and 3.85 ± 2.08 mm at 5, 20, 35, and 60 min, respectively. These values at the test side were 12.25 ± 5.42, 13.25 ± 5.02, 11.4 ± 5.03, and 9.10 ± 5.84 mm, respectively. According to repeated-measures ANOVA, the effect of the type of the treatment on the depth of insertion was significant (P < 0.001).

CONCLUSIONS

The results showed that irradiation of Er,Cr:YSGG laser before the topical application of the anesthetic agents on the oral mucosa increases their efficacy.

CLINICAL RELEVANCE

Topical anesthesia is used to enhance dental procedures painlessly, but there is controversy in their efficacy. Laser-assisted drug delivery to the oral mucosa can enhance their efficacy.

Laser assisted drug delivery: a review of an evolving technology

BACKGROUND

Topically applied drugs have a relatively low cutaneous bioavailability.

OBJECTIVE

This article reviews the existing applications of laser assisted drug delivery, a means by which the permeation of topically applied agents can be enhanced into the skin.

RESULTS

The existing literature suggests that lasers are a safe and effective means of enhancing the delivery of topically applied agents through the skin. The types of lasers most commonly studied in regards to drug delivery are the carbon dioxide (CO2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) lasers. Both conventional ablative and fractional ablative modalities have been utilized and are summarized herein.

LIMITATIONS

The majority of the existing studies on laser assisted drug delivery have been performed on animal models and additional human studies are needed.

CONCLUSIONS

Laser assisted drug delivery is an evolving technology with potentially broad clinical applications. Multiple studies demonstrate that laser pretreatment of the skin can increase the permeability and depth of penetration of topically applied drug molecules for both local cutaneous and systemic applications.

Topical lidocaine enhanced by laser pretreatment: a safe and effective method of analgesia for facial rejuvenation

BACKGROUND

Injectable forms of anesthesia for nonsurgical facial rejuvenation, although efficacious, are uncomfortable for the patient. Preclinical studies have demonstrated that laser pretreatment at low energies enhances absorption of topical lidocaine.

OBJECTIVES

The authors assess the safety and efficacy of laser-assisted transdermal delivery of topical anesthetic.

METHOD

Ten patients were split into 2 groups (A and B). All patients received 15 g of BLT (20% benzocaine, 6% lidocaine, and 4% tetracaine triple anesthetic cream) for 20 minutes with no occlusion. Then the cream was removed and the first blood draw taken. Group A patients were pretreated with the full ablative laser and group B patients with a fractional ablative laser to the full face. A further 15 g BLT was applied for another 20 minutes. Group A patients then underwent full ablative laser treatment, and group B received fractionated ablative laser treatment. Blood draws were taken at 60, 90, 120, 180, and 240 minutes after the initial topical anesthetic application, and the serum was analyzed for lidocaine and monoethylglycinexylidide (MEGX) levels. Patients were asked to rate the pain felt at intervals during the procedure.

RESULTS

No patient required supplemental nerve blocks. Pain scores were equivalent at the end of the first pass for both groups (P = .436). Group A patients had significantly lower pain scores at the start of the second laser treatment (P = .045), but pain scores became equivalent by the end (P = .323). Combined serum lidocaine and MEGX levels were significantly higher in group A patients up to 90 minutes (peak average of 0.61 µg/mL for group A and 0.533 µg/mL for group B; P = .0253), which corresponded to greater initial analgesic effect.

CONCLUSIONS

Data from this study demonstrate that topical anesthetic for facial rejuvenation can be enhanced with laser pretreatment while maintaining safe blood serum levels. Further studies should examine optimal application amount and time to allow safe multipass facial rejuvenation without the need for invasive nerve blocks.

Next generation intra- and transdermal therapeutic systems: using non- and minimally-invasive technologies to increase drug delivery into and across the skin

The number of drug molecules approved by the regulatory authorities for transdermal administration is relatively modest - less than two dozen. Many other therapies might benefit from the advantages offered by the transdermal route. That they have not already done so is due to the exceptional efficacy of the stratum corneum as a diffusional barrier and its remarkable ability to restrict molecular transport. As a result only extremely potent therapeutics possessing the necessary physicochemical properties can be delivered by passive diffusion across intact skin at pharmacologically relevent rates. This has led to the development of several delivery technologies that might be used to expand the range of medicinal agents that can be administered transdermally with the requisite delivery kinetics. There are essentially two approaches: (i) provide an improved driving force to increase the rate of transport (i.e., act on the molecule) or (ii) modify the properties of the microenvironment through which diffusion must occur (i.e., act on the stratum corneum). The challenge for the latter approach is to compromise the barrier in a reversible and relatively painless manner that minimises irritation, is practical for chronic conditions and has minimal risk of infection. Here, we review some of the physical methods that have been used to either transiently perturb the skin barrier or to provide additional driving forces to facilitate molecular transport with a particular focus on technologies that have either led to marketed products or have at least reached the clinical development stage.

Novel methods and devices to enhance transdermal drug delivery: the importance of laser radiation in transdermal drug delivery

Skin permeation-enhancement technology is a rapidly developing field, which could significantly increase the number of drugs suitable for transdermal delivery. In this review, we highlight recent advances in both ‘passive’ and ‘active’ transdermal drug-delivery technologies, as well as in the laser ablation method. This paper concludes with a brief forward-looking perspective discussing what can be expected as laser technology continues to develop in the coming years.

Can fractional lasers enhance transdermal absorption of topical lidocaine in an in vivo animal model?

BACKGROUND AND OBJECTIVE

It has been shown in vitro that pretreatment of skin with fractional lasers enhances transdermal delivery of drugs. The aim of this study is to demonstrate in vivo firstly that laser enhances transdermal drug absorption and secondly that this can be manipulated by altering laser settings.

STUDY DESIGN/MATERIALS AND METHODS

Four pigs were used in the IACUC approved animal study. On day 0, 5 g of 4% topical lidocaine was applied under occlusion for 60 minutes to a 400 cm(2) area on the abdomen. Blood was drawn at 0, 60, 90, 120, 180, and 240 minutes. On day 7, the Er:YAG laser was used at 500, 250, 50, and 25 µm ablative depth, respectively, over a 400 cm(2) area on the abdomen. Five grams of 4% topical lidocaine was applied immediately with occlusion for 60 minutes, and then removed. Blood was drawn at 0, 60, 90, 120, 180, and 240 minutes. The serum was extracted and analyzed for lidocaine and its metabolite monoethylglycinexylidide (MEGX).

RESULTS

Serum levels of lidocaine and MEGX were undetectable in untreated skin. Following laser treatment both lidocaine and MEGX were detectable. Peak levels of lidocaine were significantly higher (P = 0.0002) at 250 µm (0.62 mg/L), compared to 500 µm (0.45 mg/L), 50 µm (0.48 mg/L), and 25 µm (0.3 mg/L). Peak levels of MEGX were significantly higher (P ≤ 0.0001) at 250 µm (0.048 mg/L), compared to 500 µm (0.018 mg/L), 50 µm (0.036 mg/L), and 25 µm (0.0144 mg/L).

CONCLUSIONS

This study demonstrates that laser pretreatment significantly increases absorption of topical lidocaine so that it is detectable in the blood and that manipulating laser settings can affect drug absorption. Future work will look at translating this effect into clinical benefit.

Transdermal delivery of proteins

Transdermal delivery of peptides and proteins avoids the disadvantages associated with the invasive parenteral route of administration and other alternative routes such as the pulmonary and nasal routes. Since proteins have a large size and are hydrophilic in nature, they cannot permeate passively across the skin due to the stratum corneum which allows the transport of only small lipophilic drug molecules. Enhancement techniques such as chemical enhancers, iontophoresis, microneedles, electroporation, sonophoresis, thermal ablation, laser ablation, radiofrequency ablation and noninvasive jet injectors aid in the delivery of proteins by overcoming the skin barrier in different ways. In this review, these enhancement techniques that can enable the transdermal delivery of proteins are discussed, including a discussion of mechanisms, sterility requirements, and commercial development of products. Combination of enhancement techniques may result in a synergistic effect allowing increased protein delivery and these are also discussed.

Pharmacologic approaches for reducing venous access pain in children

A variety of pharmacologic options are available to clinicians who want to provide effective and safe topical local anesthesia to children undergoing venous access procedures. These options can be distinguished on the basis of how they deliver active drug through the impermeable outer layer of skin, the stratum corneum, to pain receptors located in the dermis and epidermis. Three general methodologies are typically used to bypass the stratum corneum: direct injection of local anesthetics, usually via a small-gauge hypodermic syringe; passive diffusion from topical creams or gels; and active needle-free drug strategies that enhance the rate of drug passage into the dermis and epidermis. Examples of the latter mechanisms include heat-enhanced diffusion, iontophoresis, sonophoresis, laser-assisted transdermal passage, and pressurized gas delivery of powdered drug particles. Pharmacologic options in this setting can also be distinguished on the basis of the time to onset of full anesthetic effect. Several available agents induce significant local anesthesia within 1 to 3 minutes of administration, or faster, allowing easy integration into the skin preparation and subsequent venous access procedure. In combination with nonpharmacologic approaches, these agents can be used to dramatically lessen this significant source of pediatric pain.

Ultrasound-enabled topical anesthesia for pain reduction of phlebotomy for whole blood donation

BACKGROUND

Ultrasound-facilitated delivery of topical anesthetics has been used to achieve effective anesthesia within 5 minutes for venipuncture and the insertion of intravenous access devices, but has never been studied for blood donation.

STUDY DESIGN AND METHODS

This study was a single-center, prospective, randomized, sham treatment-controlled, single-blinded clinical evaluation. Repeat donors were randomly assigned to undergo treatment with ultrasound and topical anesthetic or sham ultrasound and placebo anesthetic before phlebotomy for whole blood donation. The primary outcome measures were pain assessments using the Verbal Categorical Scale (VCS) and the Visual Analogue Scale and the assessment of skin irritation at the target site.

RESULTS

One-hundred subjects were enrolled and all completed the study. Compared to the sham/placebo control group, donors receiving ultrasound/anesthetic had lower pain scores on the VCS (1.81 +/- 0.67 vs. 2.17 +/- 0.68; p = 0.01) and Visual Analog Scale (17.2 +/- 15.5 vs. 27.6 +/- 19.5; p = 0.006). The proportion of subjects in the treatment group who experienced skin irritation (8%) was similar to that in the control group (2%; p = 0.20).

CONCLUSION

Ultrasound-enhanced delivery of topical anesthetic was demonstrated to be a safe means of quickly achieving clinically meaningful reduction in the pain of phlebotomy for whole blood donation compared to sham/placebo treatment.