SAN FRANCISCO A cream containing an onion extract and UVA and UVB sun protection significantly improves the appearance and feel of postsurgical scars, a small randomized trial found.
Nonprescription Mederma cream plus SPF 30 performed in the study comparably to Mederma onion extract gel without SPF for reduction of postsurgical scarring. Additionally, patients rated the cream as significantly more soothing than Mederma gel, Dr. Zoe D. Draelos reported at the annual meeting of the American Academy of Dermatology.
No placebo arm was included in the comparative trial because the study aim was to establish whether parity exists between the two onion extract formulations, both marketed OTC by Merz Pharmaceuticals, which sponsored the study. The gel formulation, which doesn't include sun protection, had already demonstrated superiority to placebo in an earlier randomized trial conducted by Dr. Draelos (J. Cosmet. Dermatol. 2008;7:101-4).
The new trial involved 20 patients with symmetric seborrheic keratoses at least 8 mm in diameter located on their right and left upper chest. The lesions were removed with a scalpel shave under local anesthesia. After the wound sites were permitted to heal for 2 weeks, patients returned for randomization. Three times daily for 8 weeks, they put a thin layer of the onion extract cream on the right chest scar and a layer of gel on the left chest scar, or vice versa, explained Dr. Draelos, who practices in High Point, N.C.
Blinded investigator assessment of the scars documented by photography showed significant improvement over time on 4-point scales assessing scar redness, texture, softness, and global appearance. The degree of improvement was similar for onion extract cream- and gel-treated scars.
There was also significantly less transepidermal water loss at the onion extract cream-treated excision sites than the gel-treated sites after treatment, probably because of the moisturizing base in the cream vehicle.
The therapeutic basis for the onion extract product's efficacy is believed to lie in its anti-inflammatory effects and its inhibition of fibroblast proliferation. The SPF 30 sun protection was incorporated into the cream formulation because scars are sunlight sensitive, and once they sunburn they often darken and become cosmetically unacceptable, she explained.
Dr. Draelos disclosed that she is a consultant to Merz and has been paid to conduct research for numerous pharmaceutical companies.