Conclusions
An improved potency classification system with the necessary clinical
relevance to facilitate the choice of an appropriate potency for a
specific indication is proposed. The TCP containing CP
(Dermovate®) was found to be more potent than that
containing MF (Elocon®) where the rank order was in
line with existing classification systems. However, the inherent potency
assessments of the TCs, CP and MF, showed opposite results. The
potencies of the TCPs under investigation were then compared to the
inherent potencies of their corresponding TCs. It was observed that the
potency of the TCP containing 0.05% CP (Dermovate®)
was higher than its corresponding TC, even though the concentration of
the drug in the TCP was 50% lower than the TC solution (0.1%).
Furthermore, Elocon®, despite containing the same
strength of MF (0.1%) exhibited a reduced potency compared to the TC
API itself. Although the inherent potency of MF was shown to be higher
than that of CP, when the TCs are formulated into products, the
potencies were altered. Hence, potency of a TC may be increased or
decreased based on the type of formulation and vehicle components. These
data clearly indicate the effects and importance of formulation on TCs.
Furthermore, inconsistencies seen in the existing TCP classification
systems, stresses the need for the development of an improved potency
classification system that consistently ranks the potencies of TCPs by
using standardised and validated methods.