Browsing by Author "Aucamp, M"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Application of fundamental techniques for physicochemical characterizations to understand post-formulation performance of pharmaceutical nanocrystalline materials
    (MPDI, 2021) Aucamp, M; Witika, B.A; Mweetwa, L.L
    Nanocrystalline materials (NCM, i.e., crystalline nanoparticles) have become an important class of materials with great potential for applications ranging from drug delivery and electronics to optics. Drug nanocrystals (NC) and nano co-crystals (NCC) are examples of NCM with fascinating physicochemical properties and have attracted significant attention in drug delivery. NCM are categorized by advantageous properties, such as high drug-loading efficiency, good long-term physical stability, steady and predictable drug release, and long systemic circulation time. These properties make them excellent formulations for the efficient delivery of a variety of active pharmaceutical ingredients (API). In this review, we summarize the recent advances in drug NCM-based therapy options. Currently, there are three main methods to synthesize drug NCM, including top-down, bottom-up, and combination methods. The fundamental characterization methods of drug NCM are elaborated. Furthermore, the applications of these characterizations and their implications on the post-formulation performance of NCM are introduced.
  • Thumbnail Image
    Item
    Assessment of thermal and hydrolytic stabilities and aqueous solubility of artesunate for formulation studies
    (AAPS PharmSciTech, 2023) Aucamp, M; Bezuidenhout, J. W.; Stieger, N; Liebenberg, W; Haynes, R. K
    For the purpose of establishing the optimum processing parameters and storage conditions associated with nanolipid formulations of the artemisinin derivative artesunate, it was necessary to evaluate the thermal stability and solubility profiles of artesunate in aqueous solutions at various temperatures and pH. The effect of increased temperature and humidity on artesunate was determined by storing samples of the raw material in a climate chamber for 3 months and analyzing these by an established HPLC method
  • Thumbnail Image
    Item
    Physicochemical stability of enriched phenolic fractions of cyclopia genistoides and ex vivo bi-directional permeability of major xanthones and benzophenones
    (Georg Thieme Verlag, 2021) Aucamp, M; Miller, N; Malherbe, C.J
    Fractions of an ultrafiltered Cyclopia genistoides extract, respectively enriched in xanthones and benzophenones, were previously shown to inhibit mammalian α -glucosidase in vitro. The present study investigated ex vivo intestinal transport of these fractions, using excised porcine jejunal tissue, to determine whether the gut could be a predominant in vivo site of action. The major bioactive compounds, the xanthones (mangiferin, isomangiferin) and benzophenones (3- β -D-glucopyranosyliriflophenone, 3- β -D-glucopyranosyl-4- O - β -D-glucopyranosyliriflophenone) exhibited poor permeation in the absorptive direction with a relatively high efflux ratio (efflux ratio > 1). The efflux ratio of 3- β -D-glucopyranosyl-4- O - β -D-glucopyranosyliriflophenone (3.05) was similar to rhodamine 123 (2.99), a known substrate of intestinal P-glycoprotein 1 efflux transporters. Low epithelial membrane transport rates, coupled with efflux mechanisms, would effectively concentrate these bioactive compounds at the target site (gut lumen). Storage stability testing and moisture sorption assays of the xanthone-enriched fraction, benzophenone-enriched fraction, and ultrafiltered Cyclopia genistoides extract were performed to determine their susceptibility to physical and chemical degradation during storage. Hygroscopicity of the powders, indicated by moisture uptake, decreased in the order: benzophenone-enriched fraction (22.7%) > ultrafiltered Cyclopia genistoides extract (14.0%) > xanthone-enriched fraction (10.7%). 3- β -D-Glucopyranosylmaclurin, a minor benzophenone, was the least stable of the compounds, degrading faster in the benzophenone-enriched fraction than in ultrafiltered Cyclopia genistoides extract, suggesting that the ultrafiltered extract matrix may provide a degree of protection against chemical degradation. Compound degradation during 12 wk of storage at 40°C in moisture-impermeable containers was best explained by first order reaction kinetics.