Atopic dermatitis (AD) is the most common non-infectious chronic inflammatory skin disease. In addition to suitable and regular care of atopic skin, local therapy with anti-inflammatory drugs is of crucial importance. Due to their similarity to the intercellular lipids of the stratum corneum, delivery systems with lamellar structure could provide a favourable supportive therapy for patients with AD in addition to prolonged release of anti-inflammatory drugs such as betamethasone dipropionate (BDP).
Within the scope of this Master's thesis, eight lamellar liquid crystal (LC) systems with different qualitative and quantitative composition based on hemp or flaxseed oil with incorporated BDP was studied, namely a stability study, in vitro release study and microstructure evaluation were performed.
As observed within the 10-week accelerated stability study the stability of incorporated BDP depends mainly on the water content in individual formulations. BDP stability was the highest in samples with 30 % aqueous phase and the lowest in formulations with 80% aqueous phase. The choice of emulsifier has a minor effect on the stability of BDP, which was slightly lower in the samples with Montanov 68 compared to the samples with Tween 80. The BDP degradation in lamellar LC systems follows the 1st order kinetics.
The microstructure of the samples was evaluated by the small angle X-ray scattering analysis with confirmed lamellar mesophases in all samples in addition to micellar structures in systems with higher water content and Montanov 68. The microstructure was evaluated at different temperatures relevant for dermal delivery, i.e. 25 ° C (room temperature), 32 ° C (skin temperature) and 37 ° C (body temperature). The temperature did not have a significant effect on the microstructure of the samples being preserved following skin application. Also, the incorporation of BDP did not affect the LC systems’ microstructure.
Prolonged BDP release from all eight systems tested was observed within in vitro release study using Franz diffusion cells and Strat-M® membranes. The BDP release was significantly influenced by the microstructure of individual samples. From formulations with lamellar mesophases and micelles, the release of BDP was faster and higher ((L / M) Lo80, (L / M) Ko80) after 24h compared to other systems. BDP release from LC systems was compared to Beloderm® cream (with same BDP content, i.e. 0,64 mg/g of formulation) and higher release was observed for the LC systems.