Anionic liposome formulation for oral delivery of thuricin CD, a potential antimicrobial peptide therapeutic.

Thuricin CD is a two-peptide antimicrobial produced by Bacillus thuringiensis. Unlike previous antibiotics, it has shown narrow spectrum activity against Clostridioides difficile, a bacterium capable of causing infectious disease in the colon. However, peptide antibiotics have stability, solubility, and permeability problems that can affect their performance in vivo. This work focuses on the bioactivity and bioavailability of thuricin CD with a view to developing a formulation for delivery of active thuricin CD peptides through the gastrointestinal tract (GIT) for local delivery in the colon. The results indicate that thuricin CD is active at low concentrations only when both peptides are present. While thuricin CD was degraded by proteases and was unstable and poorly soluble in gastric fluid, it showed increased solubility in intestinal fluid, probably due to micelle encapsulation. Based on this, thuricin CD was encapsulated in anionic liposomes, which showed increased activity compared to the free peptide, maintained activity after exposure to pepsin in gastric fluid and intestinal fluid, was stable in suspension for over 21 days at room temperature and for 60 days at 4 °C, and exhibited no toxicity to epithelial intestinal cells. These findings suggest that an anionic lipid-based nano formulation may be a promising approach for local oral delivery of thuricin CD.

Microcrystalline Cellulose Extracted from Native Plants as an Excipient for Solid Dosage Formulations in Drug Delivery.

Excipients represent the complement of the active principle in any pharmaceutical form. Their function is to provide stability, protection, and to ensure absorption of the drug and acceptability in patients. Cellulose is a conventional excipient in many pharmaceutical solid dosage products. Most of the sources used to extract microcrystalline cellulose come from cotton or wood, which are expensive and in high demand from other industries. As plants are considered the main source of excipient production, we have taken advantage of the biodiversity of Ecuador to evaluate microcrystalline cellulose extracted from borojó (Alibertia patinoi), a native plant, as an excipient for solid dosage formulations. The method of choice for tablet manufacturing was direct compression since it is a conventional fabrication method in the pharmaceutical industry. First, we performed scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) in order to compare the structure and characteristics of the extracted cellulose with two reference commercial cellulose materials. Second, we performed quality tests to evaluate the use of the isolate as an excipient including fluidity, hardness, friability, and disintegration. Compared with commercial and microcrystalline cellulose, the extracted cellulose from the native plant showed comparable characteristics and is consequently a potential excipient that could be used in the pharmaceutical industry. Last, we performed a dissolution test in which we concluded that all tablets have a short release time of active principle.