Adsorption of methotrexate and calcium leucovorin onto cholestyramine in vitro

The Bile Sequestrant Cholestyramine Increases Survival in a Rabbit Model of Brodifacoum Poisoning

Patients exposed to long acting anticoagulant rodenticides (LAARs) are typically administered large amounts of oral vitamin K1 (VK1) to counteract life-threatening anticoagulant effects. Although VK1 treatment effectively prevents mortality, additional methods are needed to reduce the long duration of VK1 treatment which can last for months at high expense. We developed a model of brodifacoum (BDF) poisoning, one of the most potent LAARs, in adult male New Zealand White (NZW) rabbits. The LD50 for oral BDF was determined to be 192 μg/kg, similar to that calculated for adult rats. However, in contrast to rats, NZW rabbits exhibited severe internal hemorrhage including in the brain, symptoms which mimic what occurs in cases of human poisoning. Similar to warfarin, BDF and other LAARs undergo enterohepatic recirculation which contributes to their long half-lives. We therefore tested effects of cholestyramine (CSA), an FDA-approved bile sequestrant, on BDF-induced mortality. When given daily (0.67 g/kg, oral) starting the day of BDF administration, CSA reduced mortality from 67% to 11%. At the same CSA prevented the increase in clotting time, and reduced the decrease in core body temperature due to BDF. Given its excellent safety record and that it is approved for children older than 6 years, these findings suggest CSA could be considered as an adjunct to VK1 for treatment of LAAR poisoning.

Fabrication and evaluation of cationic exchange nanofibers for controlled drug delivery systems

The number of ion exchange fibers in development has increased over the last several years. However, few studies have reported the use ion-exchange fibers in drug delivery system. In this study polystyrene nanofiber ion exchangers (PSNIE) were fabricated by electrospinning techniques, crosslinking and sulfonation. The degree of crosslinking and the ion exchange capacity (IEC) were determined. The morphology and diameter of the nanofiber mats were analyzed using scanning electron microscopy (SEM). Five cationic model drugs (dextromethorphan, chlorpheniramine, diphenhydramine, propranolol and salbutamol) were loaded into PSNIE. The loading capacity, release and release kinetics of the exchangers were investigated. PSNIE were successfully prepared by electrospinning and were allowed to crosslink for 10 min, resulting in a maximum IEC of 2.86±0.1 meq/g dry PSNIE. The diameter of the fibers after sulfonation was 464±35 nm. Dextromethorphan provided the highest loading in PSNIE while diphenhydramine gave the highest percentage release in both simulated gastric and intestinal fluid (SGF and SIF). The release kinetics of all drugs in SGF and SIF provided the best fit with the particle diffusion model. Our results showed that the development of a PSNIE-based drug delivery system was successful, and PSNIE were able to control drug release.