Is hyaluronic acid the perfect excipient for the pharmaceutical need?

Hyaluronic acid has become an interesting and important polymer as an excipient for pharmaceutical products due to its beneficial properties, like solubility, biocompatibility and biodegradation. To improve the properties of hyaluronic acid, different possibilities for chemical modifications are presented, and the opportunities as novel systems for drug delivery are discussed. This review gives an overview over the production of hyaluronic acid, the possibilities of its chemical modification and the current state of in vitro and in vivo research. Furthermore, market approved and commercially available products are reviewed and derivatives undergoing clinical trials and applying for market approval are shown. In particular, hyaluronic acid has been studied for different administrations in rheumatology, ophthalmology, local anesthetics, cancer treatment and bioengineering of tissues. The present work concludes with perspectives for future administration of pharmaceuticals based on hyaluronic acid.

Storage stability of proteins in a liquid-based formulation: Liquid vs. solid self-emulsifying drug delivery.

The objective of the present study was the development of self-emulsifying drug delivery systems (SEDDS) for oral delivery of therapeutic proteins providing storage stability. Horseradish peroxidase (HRP) serving as model protein was ion paired with docusate and incorporated into three liquid and three solid SEDDS formulations. Storage stability of HRP was determined over three weeks by quantifying its enzymatic activity. Generally, HRP maintained 78% of its initial enzymatic activity after complexation and loading into SEDDS. Having been incorporated in liquid SEDDS the protein showed limited stability and precipitated within a few hours. In contrast, in all solid SEDDS comprising of hard fats such as Witepsol W45 and solid surfactants such as Gelucire 44/14 and 48/16 as solidifying agents HRP was successfully stabilized. No decrease in HRP activity could be observed over the entire observation period. Solid SEDDS based on high-melting components can provide storage stability of incorporated proteins, whereas liquid SEDDS cannot.

Oral delivery of non-viral nucleic acid-based therapeutics - do we have the guts for this?

Gene therapy with RNA and pDNA-based drugs is limited by poor enzymatic stability and poor cellular permeation. The delivery of nucleic acids, in particular by the oral route, remains a major hurdle. This review will focus on the barriers to the oral delivery of nucleic acids and the strategies, in particular formulation strategies, which have been developed to overcome these barriers. Due to their very low oral bioavailability, the most obvious and most investigated biomedical applications for their oral delivery are related to the local treatment of inflammatory bowel diseases and colorectal cancers. Preclinical data but not yet clinical studies support the potential use of the oral route for the local delivery of formulated nucleic acid-based drugs.