BACKGROUND

Aqueous Cream BP is frequently prescribed for patients with eczema and is known to induce sensitivity in certain patients and also to decrease the thickness of the stratum corneum (SC). We have previously reported methodology to quantify corneocyte maturity and size, protease activity and protein content within different levels of the SC.

OBJECTIVES

The aim of the present study was to investigate changes in corneocyte size, corneocyte maturity, selected protease activities, protein content and transepidermal water loss (TEWL) in normal skin after a 28-day application of Aqueous Cream BP.

METHODS

The left and right mid volar forearms of six healthy female volunteers were selected as the study sites. Aqueous Cream BP was applied twice daily to treated sites for 28 days. At the end of this period, the site was tape-stripped and corneocyte maturity, corneocyte size and protease activity of the desquamatory kallikrein proteases, KLK5 and KLK7, and the inflammatory proteases tryptase and plasmin were measured. Protein content and TEWL measurements were also recorded.

RESULTS

Corneocyte maturity and size decreased with increasing number of tape strips, and were significantly lower in treated sites compared with untreated sites. Protease activity and TEWL values were higher (P < 0·05) for the treated sites compared with untreated sites. The amount of protein removed from deeper layers of treated sites was significantly lower than from untreated sites.

CONCLUSIONS

We report rapid minimally invasive measures of the effects of Aqueous Cream BP at the cellular and molecular level of the skin. Treatment with this formulation is associated with increased desquamatory and inflammatory protease activity. Changes in corneocyte maturity and size are also indicative of accelerated skin turnover induced by chronic application of this emollient. These findings question firmly the routine prescription of this preparation as a moisturizer in patients with atopic dermatitis.