Biocompatible Cationic Lipoamino Acids as Counterions for Oral Administration of API-Ionic Liquids

Rilpivirine Ionic Liquid Nanoemulsion Augments the Oral Bioavailability of Rilpivirine and Its Delivery to the HIV Sanctuary Sites

Rilpivirine (RPV) is a potent antiretroviral drug used for the long-term management of HIV infection. The high crystallinity and very low aqueous solubility of RPV are responsible for the highly variable pharmacokinetics of RPV seen in HIV-infected patients. While fatty meals can increase the absorption of RPV, the low lipid solubility of RPV precludes the development of oral lipid-based formulations such as self-nanoemulsifying systems (SNES). To improve the oral delivery of RPV, we evaluated the potential of six biocompatible bulky anions to transform RPV into amphiphilic RPV ionic liquids with high lipid solubility and only sodium docusate successfully yielded an amphiphilic RPV ionic liquid (IL), RPV docusate (RPV-Doc). Spectroscopic, chromatographic, and thermal characterization techniques confirmed the formation of RPV-Doc as an IL. RPV-Doc showed remarkably higher (∼100-200-fold) solubility in lipids compared to pure RPV. RPV-Doc was incorporated into two SNES formulations that, depending upon the composition of the SNES formulation, yielded a <100 or <250 nm nanoemulsion irrespective of the pH of the dilution medium. Oral pharmacokinetics and biodistribution studies in mice showed that both SNES formulations containing RPV-Doc yielded rapid and significantly higher oral bioavailability (∼6-fold higher Cmax and AUC) of RPV compared to the RPV suspension. Furthermore, compared to the RPV suspension, both SNES formulations containing RPV-Doc resulted in significantly higher and sustained RPV levels in the HIV sanctuary sites such as mesenteric lymph nodes and the brain. Taken together, our innovative approach can be used to improve the oral bioavailability and tissue penetration of RPV, which can eventually result in a reduction in the pharmacokinetic variability and therapeutic dose of RPV leading to optimal drug utilization.

Enabling superior drug loading in lipid-based formulations with lipophilic salts for a brick dust molecule: Exploration of lipophilic counterions and in vitro-in vivo evaluation

Lipid-based formulations (LbFs) are an extensively used approach for oral delivery of poorly soluble drug compounds in the form of lipid suspension and lipid solution. However, the high target dose and inadequate lipid solubility limit the potential of brick dust molecules to be formulated as LbFs. Thus, the complexation of such molecules with a lipophilic counterion can be a plausible approach to improve the solubility in lipid-based solutions via reducing drug crystallinity and polar surface area. The study aimed to enhance drug loading in lipid solution for Nilotinib (Nil) through complexation or salt formation with different lipophilic counterions. We synthesized different lipophilic salts/ complexes via metathesis reactions and confirmed their formation by 1H NMR and FTIR. Docusate-based lipophilic salt showed improved solubility in medium-chain triglycerides (∼7 to 7.5-fold) and long-chain triglycerides (∼30 to 35-fold) based lipids compared to unformulated crystalline Nil. The increased lipid solubility could be attributed to the reduction in drug crystallinity which was further confirmed by the PXRD and DSC. Prototype LbFs were prepared to evaluate drug loading and their physicochemical characteristics. The findings suggested that structural features of counterion including chain length and lipophilicity affect the drug loading in LbF. In addition, physical stability testing of formulations was performed, inferring that aliphatic sulfate-based LbFs were stable with no sign of drug precipitation or salt disproportionation. An in vitro lipolysis-permeation study revealed that the primary driver of absorptive flux is the solubilization of the drug and reduced amount of lipid. Further, the in vivo characterization was conducted to measure the influence of increased drug load on oral bioavailability. Overall, the results revealed enhanced absorption of lipophilic salt-based LbF over unformulated crystalline Nil and conventional LbF (drug load equivalent to equilibrium solubility) which supports the idea that lipophilic salt-based LbF enhances drug loading, and supersaturation-mediated drug solubilization, unlocking the full potential of LbF.

Biodegradable Cationic and Ionizable Cationic Lipids: A Roadmap for Safer Pharmaceutical Excipients

Cationic and ionizable cationic lipids are broadly applied as auxiliary agents, but their use is associated with adverse effects. If these excipients are rapidly degraded to endogenously occurring metabolites such as amino acids and fatty acids, their toxic potential can be minimized. So far, synthesized and evaluated biodegradable cationic and ionizable cationic lipids already showed promising results in terms of functionality and safety. Within this review, an overview about the different types of such biodegradable lipids, the available building blocks, their synthesis and cleavage by endogenous enzymes is provided. Moreover, the relationship between the structure of the lipids and their toxicity is described. Their application in drug delivery systems is critically discussed and placed in context with the lead compounds used in mRNA vaccines. Moreover, their use as preservatives is reviewed, guidance for their design is provided, and an outlook on future developments is given.

New Betulin Derivatives with Nitrogen Heterocyclic Moiety-Synthesis and Anticancer Activity In Vitro

As part of the search for new medicinal substances with potential application in oncology, the synthesis of new compounds combining the betulin molecule and the indole system was carried out. The structure of the ester derivatives obtained in the Steglich reaction was confirmed by spectroscopic methods (¹H and ¹³C NMR, HR-MS). The obtained new 3-indolyl betulin derivatives were evaluated for anticancer activity against several human cancer cell lines (melanomas, breast cancers, colorectal adenocarcinomas, lung cancer) as well as normal human fibroblasts. The significant reduction in MCF-7 cells viability for 28-hydroxy-(lup-20(29)-ene)-3-yl 2-(1H-indol-3-yl)acetate was observed at a concentration of 10 µg/mL (17 µM). In addition, cytometric analysis showed that this compound strongly reduces the proliferation rate of breast cancer cells. For this, the derivative showing the promising cytotoxic effect on MCF-7 breast cancer cells, the pharmacokinetic profile prediction was performed using in silico methods. Based on the results obtained in the study, it can be concluded that indole-functionalized triterpene EB367 is a promising starting point for further research in the field of breast cancer therapy or the synthesis of new derivatives.