Pro-vitamin B5

• Measured on: barrier recovery after experimentally induced irritation, TEWL and erythema versus placebo.
• Proksch & Nissen induced irritation with SLS in patch test chambers, then applied a 5% dexpanthenol cream or its vehicle twice daily and followed barrier repair, stratum corneum hydration, roughness and redness by serial biophysical readings: barrier repair was significantly faster than both vehicle and untreated skin, hydration higher, and redness reduced where the vehicle did nothing.
• Barrier recovery after acute SLS damage is a days-long curve read repeatedly, which is why this is the fastest well-supported endpoint for the ingredient and why the answer is days rather than weeks.
• Two limits on reading it as consumer reality: the population is healthy volunteers in an induced-irritation model, not patients with dermatitis, and 5% dexpanthenol is well above the 0.5-2% panthenol in most serums.
• In undamaged skin the hydration effect is slower and less well dated.
• The Biro study often quoted alongside this does not support a days-scale figure and is not used here.

Proksch & Nissen, J Dermatolog Treat 2002;13(4):173-8, 'Dexpanthenol enhances skin barrier repair and reduces inflammation after sodium lauryl sulphate-induced irritation', PMID:19753737 (abstract read). Biro et al., Contact Dermatitis 2003;49(2):80-4, PMID:14641355, read and rejected as support for this row: 26-day pre-treatment protection design, SLS on days 15-22, endpoints sebumetry/corneometry/pH, only corneometry significant, no TEWL.