Gabard B, Ademola J
Department of Biopharmacy, Spirig Pharma Ltd., Egerkingen, Switzerland.
Dermatology. 2001;203(3):244-7. doi: 10.1159/000051758.
There is a well-documented need for effective human UVA and UVB photoprotection. Since there are important anatomical variations, the sun protection factor (SPF) of a lipstick sunscreen was measured on the anatomical site intended for use.
The SPF tests were performed according to Federal US and European COLIPA guidelines. Prior to performing a test on the lip, the minimal erythemal dose (MED) of the unprotected back skin was determined. Subsequently, the sunscreen SPF was measured on the anatomical target site (lip). The evaluator was blinded with respect to scoring the SPF of each sunscreen treatment. Individual test sites were assigned to one of the following treatment conditions: (1) no treatment (MED of unprotected skin); (2) test formulation; (3) reference standard.
The MED on unprotected back skin was found to be 25% lower than on unprotected lip skin. The SPF of the lipstick sunscreen was measured 2 units lower than the SPF determined in the classical way on the back skin.
It was hypothesized that the higher MED of the lower lip compared with back skin was due to the adaptation of this tissue to the continuous exposure to UV radiation.
有充分文献记载表明需要有效的人体UVA和UVB光防护。由于存在重要的解剖学差异，口红防晒霜的防晒系数（SPF）在预期使用的解剖部位进行测量。
SPF测试按照美国联邦和欧洲COLIPA指南进行。在对唇部进行测试之前，先确定未防护背部皮肤的最小红斑剂量（MED）。随后，在解剖学目标部位（唇部）测量防晒霜的SPF。评估者在对每种防晒霜处理的SPF评分时保持盲态。各个测试部位被分配到以下治疗条件之一：（1）不治疗（未防护皮肤的MED）；（2）测试配方；（3）参考标准。
发现未防护背部皮肤的MED比未防护唇部皮肤的MED低25%。口红防晒霜的SPF比在背部皮肤以传统方式测定的SPF低2个单位。
据推测，下唇的MED高于背部皮肤是由于该组织适应了持续的紫外线辐射暴露。
