The influence of the viscosity of the ointment vehicles magisterial topical preparations, on the speed transfer of biologically active substances

The aim of this study was to analyze the morphological parameters (viscosity, viscous elasticity and the rate of volatile component loss) of salicylic and boric acid-containing magisterial formulae (ointments). Moreover, the effects of these parameters on the diffusion rate of a therapeutic agent (salicylic acid) to an in vitro external compartment were analyzed. Finally, the applicatory properties of the ointments prepared by way of a conventional technique (in a mortar) and with the aid of an unguator, were compared. The rheological parameters of the analyzed ointments suggest that the preparations made with an aid of an unguator, irrespective of the physicochemical characteristics of their vehicles, are characterized by higher values of diffusion coefficient (D). In addition, conventionally-prepared formulae containing salicylic were shown to be characterized by better viscous elasticity. Surprisingly, irrespective of the preparation technique, the ointments based on an absorptive vehicle (containing lanolin) were characterized by similar viscous elasticity. The rate of volatile (water) component loss from ointments containing a 3% solution of boric acid suggests that such formulae lose no more than 2.3% of their mass when exposed at 37℃. Therefore, the viscosity of such ointments applied onto a patient’s skin should remain relatively stable.