Table 4 Product Testing
Product attributes by dermatosensory panel Claim substantiation Instrumentation Pharmaceutical testing formulation (Table 4). Even untrained individuals may be able to distinguish overall acceptability but use of trained panelists allows much greater refinement of the overall and individual aspects of the product. Commercial testing is available (entitled the DermatoSensory Profile), which describes and grades or compares products for their characteristics of appearance and feel on the skin. Testing includes evaluation of the rate of absorption of the product into the skin, including spreadability and stickiness, immediate afterfeel, including shininess, greasy or oily feeling, drag (the sensation of resistance to motion over the skin), and residue (the sensation or perception of something remaining on the skin). Perception of residue after set periods of time such as 5, 15, and 30 min is called delayed afterfeel. Various descriptions of the product itself, aside from its characteristics on the skin such as color, odor, thickness, substantivity, consistency, grittiness, or smoothness can also be described. Many of these product characteristics are important in consumer acceptance of the cosmeceutical as well as in their perception of benefit.
No matter if cosmetic or pharmaceutical endpoints are sought, adequate trial design is critical for accurate, precise, consistent, reproducible, and valid observations in photoaging. The optimum trial for pharmaceutical, and to some extent cosmeceutical, purposes is double-blind, placebo (vehicle)-controlled, multicenter, and frequently, for the chronic process of photoaging, of at least several months' duration. Study of a relatively large, genetically homogeneous population of a narrow range of similar skin type (usually skin types I—III) is often required to observe statistically significant differences. Cosmetic testing may be of much shorter duration in fewer subjects but should optimally follow the same basic logic. Study of the parameter that is most important to the product is essen- -g tial; a facial moisturizer designed for older females living in the north should not |
be artificially tested in male and female college students in the south. Similarly, establishment of change of transepidermal water loss (TEWL) is irrelevant if the -a product is claiming to affect wrinkles.
Overall severity rating for study entry and follow-up of global appearance 4
has been accomplished with a photographically derived rating scale, with 0 = |
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