Enhanced Intestinal Absorption of Insulin by Capryol 90, a Novel Absorption Enhancer in Rats: Implications in Oral Insulin Delivery

Labrasol® is a self-emulsifying excipient that contains saturated polyglycolysed C6–C14 glycerides and this additive is known to improve the intestinal absorption of poorly absorbed drugs after oral administration. However, the effects of formulations similar to Labrasol® on the intestinal absorption of poorly absorbed drugs have not been characterized. In this study, we used insulin as a model peptide drug and examined the absorption-enhancing effects of Labrasol® and its related formulations for insulin absorption in rats. The co-administration of Labrasol-related formulations with insulin reduced the blood glucose levels. Among these formulations, Capryol 90 was the most effective additive. Notably, the effect of Capryol 90 was greater at pH 3.0 than at pH 7.0. Additionally, almost no mucosal damage was observed in the presence of these formulations, as these formulations did not affect the activity of lactate dehydrogenase (LDH) and the amount of protein released from the small intestine. In mechanistic studies, Capryol 90 improved the stability of insulin and suppressed the association with insulin under acidic conditions. The loosening of the tight junctions (TJs) could be the underlying mechanism by which Capryol 90 improved intestinal insulin absorption via a paracellular route. These findings suggest that Capryol 90 is an effective absorption enhancer for improving the intestinal absorption of insulin, without inducing serious damage to the intestinal epithelium.

Quality by Design for the Development and Analysis of Enhanced In-Situ Forming Vesicles for the Improvement of the Bioavailability of Fexofenadine HCl In Vitro and In Vivo

Drug absorption from the gastrointestinal tract (GIT) is one of the major problems affecting the bioavailability of orally absorbed drugs. This work aims to enhance Fexofenadine HCl oral bioavailability in vivo, the drug used for allergic rhinitis. In this study, novel spray-dried lactose-based enhanced in situ forming vesicles were prepared using different absorption enhancer by the slurry method. Full factorial design was used to obtain an optimized formulation, while central composite design was used to develop economic, environment-friendly analysis method of Fexofenadine HCl in plasma of rabbits. The optimized formulation containing Capryol 90 as absorption enhancer has a mean particle size 202.6 ± 3.9 nm and zeta potential −31.6 ± 0.9 mV. It achieved high entrapment efficiency of the drug 73.7 ± 1.7% and rapid Q3h release reaches 71.5 ± 2.7%. The design-optimized HPLC assay method in rabbit plasma could separate Fexofenadine HCl from endogenous plasma compounds in less than 3.7 min. The pharmacokinetic study and the pharmacological effect of the fexofenadine-loaded optimized formulation showed a significant increase in blood concentration and significantly higher activity against compound 48/80 induced systemic anaphylaxis-like reactions in mice. Therefore, enhanced in situ forming vesicles were effective nanocarriers for the entrapment and delivery of Fexofenadine HCl.

Development and In Vitro and In Vivo Evaluation of Microspheres Containing Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate for the Oral Delivery of Berberine Hydrochloride

Microspheres containing absorption enhancer (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate, SNAC) were developed to enhance the oral bioavailability of berberine hydrochloride (BER) with poor intestinal membrane permeability. Microspheres were prepared and characterized by particle size measurements, scanning electron microscopy, differential scanning calorimetry, BER payload and release, Caco-2 cell monolayer transport, and rat pharmacokinetics. The microspheres were spherical and had uniform size, high encapsulation efficiency and high loading capacity. In vitro release studies showed that BER-loaded microspheres had good sustained release characteristics. The Caco-2 cell monolayer transport study proved that SNAC could significantly enhance permeability of BER 2–3-fold. Pharmacokinetic studies demonstrated a 9.87-fold increase in area under the curve (AUC) of BER mixed with SNAC and a 14.14-fold increase in AUC of microspheres compared with BER alone. These findings indicate that SNAC is a promising absorption enhancer for oral delivery of BER in the form of both solution and microspheres.