Cytotoxicity of ß-Cyclodextrins in Retinal Explants for Intravitreal Drug Formulations.

Cyclodextrins (CDs) have been widely used as pharmaceutical excipients for formulation purposes for different delivery systems. Recent studies have shown that CDs are able to form complexes with a variety of biomolecules, such as cholesterol. This has subsequently paved the way for the possibility of using CDs as drugs in certain retinal diseases, such as Stargardt disease and retinal artery occlusion, where CDs could absorb cholesterol lumps. However, studies on the retinal toxicity of CDs are limited. The purpose of this study was to examine the retinal toxicity of different beta-(ß)CD derivatives and their localization within retinal tissues. To this end, we performed cytotoxicity studies with two different CDs-2-hydroxypropyl-ßCD (HPßCD) and randomly methylated ß-cyclodextrin (RMßCD)-using wild-type mouse retinal explants, the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and fluorescence microscopy. RMßCD was found to be more toxic to retinal explants when compared to HPßCD, which the retina can safely tolerate at levels as high as 10 mM. Additionally, studies conducted with fluorescent forms of the same CDs showed that both CDs can penetrate deep into the inner nuclear layer of the retina, with some uptake by Müller cells. These results suggest that HPßCD is a safer option than RMßCD for retinal drug delivery and may advance the use of CDs in the development of drugs designed for intravitreal administration.

Biotin and arginine modified hydroxypropyl-ß-cyclodextrin nanoparticles as novel drug delivery systems for paclitaxel.

A novel biotin and arginine modified hydroxypropyl-ß-cyclodextrin (biotin-Arg(pbf)-HP-ß-CD) was successfully synthesized. The hydroxyl groups of HP-ß-CD on the primary faces were coupled with carboxyl groups of biotin using arginine as the functional spacer. Using biotin-Arg(pbf)-HP-ß-CD as the carrier, paclitaxel (PTX)-loaded nanoparticles were developed by modified emulsion solvent evaporation method. The optimized PTX-loaded biotin-Arg(pbf)-HP-ß-CD nanoparticles had a mean diameter of 121.9 nm and zeta potential of -57.7 mV. Transmission electron microscopy (TEM) observation revealed that the nanoparticles were spherical in shape. XRD spectra confirmed the successful encapsulation of PTX. Moreover, in vitro and in vivo evaluations were performed to demonstrate the superior antitumor activity of the PTX-loaded nanoparticles. The cellular uptake study demonstrated the biotin receptor-mediated endocytosis of biotin-Arg(pbf)-HP-ß-CD nanoparticles and the increase of cellular uptake by introduction of biotin and arginine. It can be concluded that the biotin-Arg(pbf)-HP-ß-CD nanoparticles are efficient tumor-targeting drug delivery systems for PTX.

Development and pharmaceutical evaluation of the anticancer Anthrafuran/Cavitron complex, a prototypic parenteral drug formulation.

To improve the water solubility of the anticancer drug candidate LCTA-2034 (A1), we investigated the formation of complexes of this anthrax[2,3-b]furan congener with the solubilizing 2-hydroxypropyl derivative of ß-cyclodextrin HP-ßCD (Cavitron®). The interaction of A1 with HP-ßCD resulted in the inclusion complex A1/HP-ßCD in 1:1 stoichiometry. The A1/HP-ßCD complex was used to develop a prototype of a lyophilised drug formulation with enhanced (>10-fold) aqueous solubility than A1 and a long-term stability. The use of HP-ßCD decreased the acute toxicity of A1 by >30%. The A1/HP-ßCD drug formulation as well as A1 in equal doses (5×30mg/kg) to increase the lifespan by up to 140% for mice with i.p. transplanted P388 leukaemia. Furthermore, the A1/HP-ßCD formulation demonstrated a significant and reliable antitumor efficacy in a Р388/ADR drug resistant leukaemia and B16/F10 melanoma, proving a perspective of investigations of toxicology, biodistribution and pharmacokinetics.