Split-Face Study of Topical 23.8% L-Ascorbic Acid Serum in Treating Photo-Aged Skin

January 2012 | Volume 11 | Issue 1 | Original Article | 51 | Copyright © January 2012

Tian-Hua Xu MD,a John ZS Chen MD,b Yuan-Hong Li MD,a Yan Wu MD,a Yao-Jia Luo MD,a Xing-Hua Gao MD,a Hong-Duo Chen MDa

aDepartment of Dermatology, No. 1 Hospital of China Medical University, Shenyang, China bSheftel Associates Dermatology, Tucson, AZ


Background: L−ascorbic acid has been widely used to treat photo-aged skin. However, its aqueous formula is prone to oxidation. Therefore, a new formula that contains 23.8% L−ascorbic acid and a chemical penetration enhancer was developed.
Objective: Observe the efficacy and safety of topical 23.8% L−ascorbic acid serum on photo-aged skin.
Methods: Twenty Chinese women with photo-aged skin were enrolled in this split-face study. They were treated with topical L−ascorbic acid serum with iontophoresis on one side of the face once a day for 2 weeks; the other side of the face was spared treatment through participants´ self-control. Changes in photo-aged skin were evaluated using a global evaluation, an overall self-assessment, a spectrophotometer, the phase-shift rapid in vivo measurement of skin (PRIMOS) 3D, and a corneometer.
Results: Sixteen of 20 patients (80%) experienced a score decrease of 2 or 3 grades, according to the dermatologist. Fifteen patients (75%) rated their overall satisfaction as excellent or good. Dyspigmentation, surface roughness, and fine lines on the treated side improved significantly.
Conclusion: Topical 23.8% L−ascorbic acid serum is effective for the treatment of photo-aged skin and does not cause any obvious side effects.

J Drugs Dermatol.2012;11(1):51-56.


Cumulative exposure to sun is the main reason for skin aging. Fine and coarse wrinkles, dyspigmentation, telangiectasia, sallow color, dehydration, rough texture, skin laxity, increased pore size, and a leathery appearance in habitually sun-exposed skin all characterize photo-aging of the skin.1
The body protects itself naturally from reactive oxygen species (ROS) by using antioxidants to neutralize them before they cause damage to the skin and its components. Vitamin C, or L−ascorbic acid, is the most abundant natural antioxidant in the skin.2 However, taking vitamin C derivatives orally does not guarantee an increase in vitamin C levels in the skin. Furthermore, ascorbic acid is water soluble, quickly oxidized in aqueous solutions. Only L-ascorbic acid can be absorbed into the skin before being oxidized. L−ascorbic acid inhibits tyrosinase and neutralizes ROS and is successfully used to treat photo-damage.3-6
To maximize the protective effects of topical L−ascorbic acid for skin, we present a clinical study of a new treatment system that contains 23.8% L-ascorbic acid and a chemical penetration enhancer consisting of N-methyl-2-pyrrolidone and dimethyl isosorbide with iontophoresis so that maximal amounts of L−ascorbic acid can be delivered into the skin.

Materials and Patients

The serum containing 23.8% L−ascorbic acid and a chemical penetration enhancer (N-methyl-2-pyrrolidone and dimethyl isosorbide) is labeled and sold as C′max (Sage, Pharmaceuticals Inc., Shreveport, LA).
Twenty photo-aging patients with an average age of 35.5 years (range: 28−63 years) and Fitzpatrick skin type III or IV were enrolled in this study. The patients were enrolled from the outpatient clinic of the Department of Dermatology, No. 1 Hospital of China Medical University, Shenyang, China. Each patient signed an informed consent. The Medical Ethics and Human Research Committee of China Medical University approved the study, which was conducted from December 2008 through March 2009. Exclusion criteria were any sign of infection or inflammation on the skin, pregnancy, use of oral retinoids in the previous 12 months, current use of nonsteroidal anti-inflammatory drugs, and exposure to ultraviolet irradiation within four weeks of treatment.
Before treatment, patients were required to rinse their face thoroughly with a neutral lotion and rest in a temperature- (20 °C) and humidity-controlled (40%) room for at least 30 minutes.