In-vitro Evaluation of p-Sulfonatocalix[n] arenes (SCnA) as Novel Excipients Using a Vectorized BCS Approach

Abstract

This study introduced a novel vectorized Biopharmaceutics Classification System (BCS) model designed to evaluate the biopharmaceutical properties of active pharmaceutical ingredients (APIs) and their variations under different influencing factors. The model was validated using water-soluble supramolecular p-Sulfonatocalix[n]arenes (SCnA, n = 6, 8), promising pharmaceutical adjuvants, to enhance the solubility and bioavailability of a series of APIs in vitro.

The binding interactions of SCnA with 22 alkaloids were assessed for their impact on solubility and permeability using the classical shake-flask method and the parallel artificial membrane permeability assay (PAMPA). To quantify the effects, the change in directional cosine (θ) for each API was calculated by measuring the ratio of the differences in x- and y-coordinates before and after binding. The linear distance and modulus length (r) changes for each API were determined using the Pythagorean theorem, enabling a quantitative assessment of the modifications in solubility and permeability.

The potential changes in oral bioavailability pre- and post-binding were visualized using heat maps based on θ and r, highlighting significant improvements in the solubility of compounds such as allicin, tetrandrine, lycorisine, and others. These changes corresponded with shifts in BCS classification, indicating a positive relationship between SCnA concentration, cavity size, and enhanced solubility. The study also evaluated the influence of pH, and concentrations of host and guest, to assess the tolerance of SCnA for further pharmaceutical applications.

Based on prior safety assessments, SCnA (n = 6, 8) demonstrated significant potential as solubilizing excipients. The vectorized BCS model enabled precise, quantitative analysis of biopharmaceutical property variations without added experimental complexity, offering a tool for high-throughput screening of excipients in pharmaceutical formulation and processing.