Consideration of the efficacy of non-ionic vesicles in the targeted delivery of oral vaccines

Advances in formulation and manufacturing strategies for the delivery of therapeutic proteins and peptides in orally disintegrating dosage forms

Therapeutic proteins and peptides (TPPs) are increasingly favoured above small drug molecules due to their high specificity to the site of action and reduced adverse effects resulting in increased use of these agents for medical treatments and therapies. Consequently, there is a need to formulate TPPs in dosage forms that are accessible and suitable for a wide range of patient groups as the use of TPPs becomes increasingly prevalent in healthcare settings worldwide. Orally disintegrating dosage forms (ODDF) are formulations that can ensure easy-to-administer medication to a wider patient population including paediatrics, geriatrics and people in low-resource countries. There are many challenges involved in developing suitable pharmaceutical strategies to protect TPPs during formulation and manufacturing, as well as storage, and maintenance of a cold-chain during transportation. This review will discuss advances being made in the research and development of pharmaceutical and manufacturing strategies used to incorporate various TPPs into ODDF systems.

Development of a solid dosage platform for the oral delivery of bilayer vesicles

Within this work, we develop vesicles incorporating sub-unit antigens as solid dosage forms suitable for the oral delivery of vaccines. Using a combination of trehalose, dextran and mannitol, freeze-dried oral disintegrating tablets were formed which upon rehydration release bilayer vesicles incorporating antigen. Initial studies focused on the optimisation of the freeze-dry cycle and subsequently excipient content was optimised by testing tablet hardness, disintegration time and moisture content. The use of 10% mannitol and 10% dextran produced durable tablets which offered strong resistance to mechanical damage yet appropriate disintegration times and dispersed to release niosomes-entrapping antigen. From these studies, we have formulated a bilayer vesicle vaccine delivery system as rapid disintegrating tablets and capsules.

Niosomes Consisting of Tween-60 and Cholesterol Improve the Chemical Stability and Antioxidant Activity of (-)-Epigallocatechin Gallate under Intestinal Tract Conditions

In order to improve the chemical stability and antioxidant activity of (-)-epigallocatechin gallate (EGCG) in the gastrointestinal tract, niosomes composed of Tween-60 and cholesterol were developed to encapsulate EGCG in this investigation. EGCG loaded niosomes with encapsulation efficiency around 76% exhibited a small Z-average diameter about 60 nm. Compared to free EGCG, the EGCG remaining in dialysis tubes was significantly improved for niosomes at pH 2 and 7.4. Meanwhile, the residual EGCG for niosomes increased from 3% to 49% after 2 h incubation in simulated intestinal fluid (SIF). Pancreatin was found to impact the stability of niosomes in SIF mainly. Furthermore, the results from ferric reducing antioxidant power and cellular antioxidant activity tests indicated that EGCG loaded niosomes exhibited stronger antioxidant ability than free EGCG during intestinal digestion. Thus, we can infer that niosomal encapsulation might be a promising approach to improve the oral bioavailability of EGCG in the body.

Readily restoring freeze-dried probilosomes as potential nanocarriers for enhancing oral delivery of cyclosporine A

Formulating vesicular nanocarriers into dried precursors so as to overcome the drawbacks associated with liquid formulations is challengeable due to low efficiency of restoration. In this study, bilosomes interiorly thickened with gelatin (G-BLs) was evaluated for the ability to withstand freeze-drying stress and enhanced oral bioavailability of a model drug, cyclosporine A (CyA). The restoration efficiency of freeze-dried pro-G-BLs is investigated by comparing the particle size distribution, entrapment efficiency and morphology of the bilosomes before and after freeze-drying. Particle size and polydispersity index (PI) of pro-G-BLs after restoration was similar to that before freeze-drying, whereas freeze-dried bilosomes without gelatin thickening (pro-BLs) show irreversible damage and aggregation along with significantly increased particle size and PI after restoration. Entrapment efficiency of pro-G-BLs remains as high as 83.7%, in sharp contrast with 66.7% for pro-BLs. Pharmacokinetics in beagle dogs show improved absorption of CyA in pro-G-BLs as compared to pro-BLs, G-BLs and microemulsion-based Sandimmun Neoral(®). The relative oral bioavailability of CyA-loaded pro-G-BLs, pro-BLs and G-BLs was 165.2%, 123.5% and 130.1%, respectively, with Neoral(®) as the reference. It is concluded that interior thickening with gelatin significantly enhanced the stability against freeze-drying stress, which as a result improves the restoring efficiency and oral bioavailability.