Catarina Florindo

Evaluation of solubility and partition properties of ampicillin-based ionic liquids

In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing L-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of L-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25 °C and 37 °C (body temperature) as well as octanol-water partition coefficients (Kows) and HDPC micelles partition at 25 °C were measured. Critical micelle concentrations (CMCs) in water at 25 °C and 37 °C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements.

Cholinium-based ionic liquids with pharmaceutically active anions

Novel ionic liquids (ILs) containing cholinium as a benign cation combined with anions based on five active pharmaceutical ingredients (APIs), namely, nalidixic acid, niflumic acid, 4-amino-salicylic acid, pyrazinoic acid and picolinic acid, were prepared via a simple and sustainable two-step anion exchange reaction. The solubility of the prepared pharmaceutically active ILs (API-ILs) in both water and simulated biological fluids at 25 °C and 37 °C, as well as the solubility of the parent APIs, were measured. Further, in vitro cytotoxicity levels for both cholinium-based API-ILs and parent APIs were established using two different human cells lines, namely Caco-2 colon carcinoma cells and HepG2 hepatocellular carcinoma cells. Herein, the dual nature of ILs is exploited by combining the cheap, available and essential nutrient cholinium cation with pharmaceutically active anions, upgrading the chemical, physical and biopharmaceutical properties, particularly melting point, aqueous solubility and the potential to penetrate cell membranes of the parent APIs, without impair their cytotoxicity response which prompt opportunities for creating further advances in pharmaceutical challenges.

Novel organic salts based on fluoroquinolone drugs: synthesis, bioavailability and toxicological profiles.

In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), novel organic salts containing fluoroquinolones (e.g. ciprofloxacin and norfloxacin) were prepared, using an optimized synthetic procedure based on direct protonation, with different biocompatible counter ions such as mesylate, gluconate and glycolate. All the prepared organic salts were characterized by spectroscopic techniques, mass spectrometry and thermal analysis. Solubility studies in water and simulated biological fluids at 25°C and 37°C were also performed. Additionally, octanol-water and phospholipid-water partition coefficients were measured at 25°C. The cytotoxicity and anti-inflammatory efficacy using an human cell model of intestinal epithelia (Caco-2 cells) were also evaluated and compared to those of the parent APIs. The adequate selection of the biocompatible anions allows the tuning of important physical, thermal and toxicological properties.