METHODS

• Human donor skin tissue samples of 500-µm thickness were pretreated with a 1440-nm or 
1927-nm laser (Clear + Brilliant® laser system; Solta Medical, Bothell, WA), or received no 
pretreatment (Table 1) 

Table 1. Experimental Parameters for Uptake Analysis 

• Following laser pretreatment, an in-house 4% hydroquinone serum (hydrophilic formulation) 
was applied, and permeation was measured up to 24 hours after application (Figure 1)

• Laser-treated skin and untreated controls were analyzed using high-performance liquid 
chromatography at various time points up to 24 hours after application to measure cumulative 
permeation and retention and to quantify uptake of 4% hydroquinone serum

• Total uptake was calculated as the sum of the normalized cumulative permeation and 
retention in each sample

Figure 1. Study design for testing uptake of topicals on skin tissue. 

PBS, phosphate-buffered saline.

RESULTS

• Pretreatment with the 1927-nm wavelength resulted in greater cumulative uptake of 4% 
hydroquinone serum compared to the 1440-nm wavelength and untreated control (Figure 2)

Figure 2. Cumulative permeation of 4% hydroquinone serum at 24 hours after 1440-nm and  
1927-nm pretreatment.  

Values are mean ± standard deviation.

• Compared to untreated controls, topical uptake was 
 – 1.8 times greater with 1440-nm (1.2-W) pretreatment
 – 2.7 times greater with 1927-nm (0.6-W) pretreatment
 – 4.6 times greater with 1927-nm (1.0-W) pretreatment

• The lower-power 1927-nm settings (0.6 and 1.0 W) were associated with 1.5- and 2.6-times 
greater uptake, respectively, compared to 1440-nm (1.2-W) pretreatment (Table 2)

Table 2. Uptake Ratios of 4% Hydroquinone With Various Laser Wavelengths and Power Settings

SYNOPSIS

• Non-ablative fractional diode laser pretreatment can enhance transdermal delivery and uptake of topicals and minimize thermal side effects that are more typical of ablative laser therapy1,2

• Fractionation can create microscopic treatment zones that spare surrounding tissue and further minimize postprocedural downtime1,2

• Clinical practice may be improved by understanding the relationship between topical uptake and energy-device settings, such as wavelength, peak power, and spot density

Quantifying Uptake 
of Topical 4% 
Hydroquinone After 
1440-nm and 1927-nm  
Non-ablative Fractional 
Diode Laser Treatment 

Jordan V. Wang, MD, MBE, MBA1; Paul M. Friedman, MD1,2; Adarsh Konda, PharmD3; Catherine Parker, NP, MSN4; Roy G. Geronemus, MD1
1Laser & Skin Surgery Center of New York, New York, NY; 2Dermatology and Laser Surgery Center, Houston, TX; 3Bausch Health US, LLC, Bridgewater, NJ; 4Solta Medical, Bothell, WA 

OBJECTIVE
• To quantify uptake of 4% hydroquinone serum 

using skin tissue pretreated with either a  
1440-nm or 1927-nm non-ablative fractional 
diode laser

CONCLUSIONS
• Non-ablative fractional diode laser 

pretreatment with the 1927-nm wavelength 
resulted in greater uptake of hydrophilic  
4% hydroquinone serum compared to the  
1440-nm wavelength, despite lower peak  
power and pulse energy settings

• For the 1927-nm wavelength, higher power 
settings can cause greater superficial disruption 
to the stratum corneum and epidermis with 
subsequent uptake enhancement1 

 – The current analysis demonstrates the ability 
of the 1927-nm wavelength to produce more 
favorable uptake, especially at the higher  
power setting

• Taken together, these results suggest that the 
1927-nm wavelength may be used as laser 
pretreatment to enhance topical delivery,  
even for relatively hydrophilic topicals 

Presented at the 2021 Fall Clinical Dermatology Conference • October 21-24, 2021 • Las Vegas, NV, and Virtual

Funding information: This study was sponsored by Solta Medical. Medical writing support was provided by MedThink 
SciCom and funded by Solta Medical. 

Disclosures: JVW is an investigator for Solta Medical. PMF serves on the advisory board and speaker bureau for Solta Medical. 
AK and CP are employees of and may hold stock or stock options in Solta Medical. RGG is an investigator and advisory board 
member for Solta Medical.

References: 1. Friedman et al. J Drugs Dermatol. 2020;19:s3-s11. 2. Ganti and Banga. J Pharm Sci. 2016;105:3324-3332.

Parameter Setting

Device wavelength, nm 1440 1927 1927

Spot density, MTZ/cm2 80 80 80

Peak power, W 1.2 0.6 1.0

Spot size, µm 130 130 130

Pulse energy, mJ 9.0 4.5 7.5

MTZ, microscopic treatment zones.

Sample & refill

500-µm skin graft

Topical formulation

PBS solution w/ 0.2% sodium azide

Donor chamber

Permeation/Diffusion chamber
Stir bar
Stir rotation

1440 nm (1.2 W) 1927 nm (0.6 W) 1927 nm (1.0 W)
Control 1.77 ± 0.41 2.65 ± 0.24 4.60 ± 0.80
1440 nm (1.2 W) — 1.50 ± 0.26 2.60 ± 0.61
1927 nm (0.6 W) — — 1.74 ± 0.63

2.63
4.45

7.46

14.48

0
2
4
6
8

10
12
14
16
18

0 5 10 15 20 25 30
Time, hours

Control

1435nm-1.2W-9mJ

1927nm-0.6W-4.5mJ

1927nm-1.0W-7.5mJ

Control

1440 nm/1.2 W

1927 nm/0.6 W

1927 nm/1.0 W

C
um

ul
at

iv
e 

pe
rm

ea
ti
o
n,

 m
g/

cm
2