Rheological properties of three different vitamin D ointments and their clinical perception by patients with mild to...

Ointments, classically used for the treatment of dermatological diseases, are monophasic viscous semisolid formulations. According to the proportion of their compounds, they have physicochemical and organoleptic properties and when applied on skin show a specific behaviour allowing to be spread more or less easily.

To measure in vitro rheological characteristics of three vitamin D derivative ointments prescribed for the treatment of psoriasis, and to compare their viscosity and clinical acceptability when applied on the diseased skin.

Rheological characteristics of tacalcitol 4 microg/g, calcipotriol 50 microg/g and calcitriol 3 microg/g ointments were assessed by measuring the oscillatory viscoelastic parameters and the permanent flow analysis. Clinical acceptability was studied in 20 psoriatic male or female subjects, aged 18 years or older. A survey evaluated the acceptability of calcitriol vs. tacalcitol and calcipotriol. Questions included information about fluidity, spreading capacity and stickiness after application.

We demonstrated that viscoelastic parameters were four times higher for ointment tacalcitol than for calcipotriol and calcitriol, corresponding to a higher consistency of ointment tacalcitol compared to calcipotriol and calcitriol showing both similar results; better fluidity was demonstrated by calcitriol than by tacalcitol and calcipotriol. Comparable results were obtained for the quality to be spread. The sensation of stickiness, significantly different between tacalcitol and calcitriol, was not different between calcipotriol and calcitriol.

The above results confirm the relationship between rheological in vitro and sensorial in vivo results: variations between different formulations may have an important influence on non-adherence and treatment failure.