ABSTRACT
Introduction: topical rapamycin has been established as an
effective and safe therapy for facial angiofibromas in tuberous
sclerosis. Different formulations have been tested for this skin
disease, most using an ointment as a vehicle.
Purpose : to improve the classical formulation of topical
rapamycin and to determine the validity period of the proposed options
based on chemical, physical and microbiological stability studies.
Methods : four different 0.4% rapamycin formulations were
prepared (ointment, emulsion, gel and liposomes). The stability studies
for each formulation were: chemical (extraction with lipophilic solvents
and high-performance liquid chromatography assay), physical (pH,
uniformity, extensibility, absence of crystals, absence of phase
separation and only for liposomal formulation was determined particle
size, zeta potential and encapsulation efficiency) and microbiological
(culture samples in blood-agar media) during 56 days.
Results : only liposomes were chemically, physically and
microbiologically stable after 8 weeks. Ointment, emulsion and gel
formulations lost their chemical and physical stability before 56 days.
Conclusions : this study describes a new four formulations to
improve the previously treatment for facial angiofibromas in tuberous
sclerosis. It also provides favorable stability data only for liposomes.
However, more dermokinetic and clinical studies are needed to confirm
that liposomes are most appropriate to ensure effectiveness, safety and
high patient satisfaction.