Sustained Release Formulation of Hydroxypropyl-ß-cyclodextrin Eye Drops Using Xanthan Gum.

Bietti's crystalline dystrophy (BCD) is an autosomal recessive chorioretinal degeneration caused by mutations in the CYP4V2 gene. It is characterized by cholesterol accumulation and crystal-like deposits in the retinas. Hydroxypropyl-ß-cyclodextrin (HP-ß-CyD) exerts therapeutic effects against BCD by reducing lysosomal dysfunction and inhibiting cytotoxicity in induced pluripotent stem cell (iPSC)-RPE cells established from patient-derived iPS cells. However, the ocular retention of HP-ß-CyD is low and needs to be improved. Therefore, this study used a viscous agent to develop a sustained-release ophthalmic formulation containing HP-ß-CyD. Our results suggest that HP-ß-CyD-containing xanthan gum has a considerably higher sustained release capacity than other viscous agents, such as methylcellulose and sodium alginate. In addition, the HP-ß-CyD-containing xanthan gum exhibited pseudoplastic behavior. It was less cytotoxic to human retinal pigment epithelial cells compared with HP-ß-CyD alone. Furthermore, the slow release of HP-ß-CyD from xanthan gum caused a sustained decrease in free intracellular cholesterol. These results suggest that xanthan gum is a useful substrate for the sustained release formulation of HP-ß-CyD, and that HP-ß-CyD-containing xanthan gum has potential as an eye drop for BCD treatment.

Conversion of raltegravir carrying a 1,3,4-oxadiazole ring to a hydrolysis product upon pH changes decreases its antiviral activity.

Raltegravir (RAL), a human immunodeficiency virus (HIV)-1 integrase inhibitor, has been administered as part of antiretroviral therapy. Studies in patients with HIV-1 have shown high variability in the pharmacokinetics of RAL, and in healthy volunteers, coadministration of proton-pump inhibitors has been shown to increase the plasma RAL concentrations. Here, we found that RAL containing a 1,3,4-oxadiazole ring is converted to a hydrolysis product (H-RAL) with a cleaved 1,3,4-oxadiazole ring at pH 1.0 and 13.0 conditions in vitro, thereby reducing the anti-HIV activity of the drug. The inclusion of cyclodextrins (beta-cyclodextrin [ßCD], random methyl-ßCD [RAM-ßCD], and hydroxypropyl-ßCD [HP-ßCD]) can protect RAL from pH-induced changes. The conversion of RAL to H-RAL was detected by using various mass spectrometry analyses. The chromatogram of H-RAL increased in a time-dependent manner similar to another 1,3,4-oxadiazole-containing drug, zibotentan, using high-performance liquid chromatography. Oral bioavailability and target protein interactions of H-RAL were predicted to be lower than those of RAL. Moreover, H-RAL exhibited significantly reduced anti-HIV-1 activity, whereas combinations with ßCD, RAM-ßCD, and HP-ßCD attenuated this effect in cell-based assays. These findings suggest that ßCDs can potentially protect against the conversion of RAL to H-RAL under acidic conditions in the stomach, thereby preserving the anti-HIV-1 effect of RAL. Although clinical trials are needed for evaluation, we anticipate that protective devices such as ßCDs may improve the pharmacokinetics of RAL, leading to better treatment outcomes, including reduced dosing, long-term anti-HIV-1 activity, and deeper HIV-1 suppression.

Efficient Anticancer Drug Delivery for Pancreatic Cancer Treatment Utilizing Supramolecular Polyethylene-Glycosylated Bromelain.

Pancreatic cancer is one of the most difficult cancers to treat largely because of the inability of anticancer drugs to penetrate into the cancer tissue as the result of the dense extracellular matrix (ECM). On the other hand, bromelain is known to degrade the ECM in cancerous tissue. However, the half-life of bromelain in blood is short, leading to its low accumulation in tissues. Recently, we developed a reversible poly(ethylene glycol) (PEG) modification technology that is able to improve blood retention of proteins without loss of activity and termed it "Self-assembly PEGylation Retaining Activity (SPRA)" technology. Here, we prepared reversible PEGylated bromelain using SPRA technology (SPRA-bromelain) possessing high activity, long blood retention, and high tumor accumulation and evaluated its potential as a drug delivery system for pancreatic cancer. SPRA-bromelain was prepared by mixing adamantane-modified bromelain and multisubstituted-PEGylated ß-cyclodextrins (ß-CyDs) containing 2 or 20 kDa PEG chains in water. SPRA-bromelain was formed by a host-guest interaction between adamantane and ß-CyD (Kc > 104 M-1). SPRA-bromelain showed high in vitro gelatin-degrading activity and enhanced not only the accumulation of fluorescein isothiocyanate (FITC)-dextran (2 MDa) in the tumor but also the in vivo antitumor activities of doxorubicin and doxorubicin encapsulated in PEGylated liposomes (DOXIL) after intravenous administration in tumor-bearing mice. These findings suggest that SPRA-bromelain could be a powerful tool for drug delivery in pancreatic cancer.

Cyclodextrin-based sustained and controllable release system of insulin utilizing the combination system of self-assembly PEGylation and polypseudorotaxane formation.

Sustained and controllable release of insulin is strongly required to achieve the ideal treatment of diabetes. We previously developed "self-assembly PEGylation retaining activity (SPRA) technology" via a host-guest interaction between PEGylated ß-cyclodextrin and adamantane-appended insulin, and resulting PEGylated insulin was termed SPRA-insulin. So far, we also demonstrated that covalently PEGylated insulin forms polypseudorotaxanes (PPRXs) with cyclodextrins (PPRX technology). In the present study, we designed and evaluated the combination system of SPRA technology and PPRX technology to achieve a sustained and controllable release system of insulin. SPRA-insulin formed PPRXs with α-cyclodextrin and γ-cyclodextrin. In addition, SPRA-insulin/cyclodextrin PPRXs provided sustained and controllable release of insulin beyond the each single technology both in vitro and in vivo. These results suggest that the combination system of SPRA technology and PPRX technology is useful for design of a sustained and controllable release system of insulin.

Stabilizing Effects for Antibody Formulations and Safety Profiles of Cyclodextrin Polypseudorotaxane Hydrogels.

Antibodies often have poor physicochemical stability during storage and transport, which is a serious drawback for the development of antibody-based drugs. In this study, we prepared polypseudorotaxane (PPRX) hydrogels consisting of cyclodextrins (CyDs) and polyethylene glycol, and evaluated them as stabilizers for commercially available antibody-based drugs. α-CyD and γ-CyD formed PPRX hydrogels with polyethylene glycol (molecular weight 20,000 Da) in the presence of antibody-based drugs such as omalizumab, palivizumab, panitumumab, and ranibizumab. Importantly, both α- and γ-CyD PPRX hydrogel formulations provided high stabilizing effects (ca. 100%) to the all antibody-based drugs used in this study. Furthermore, approximately 100% of the binding activity of omalizumab to the immunoglobulin E receptor was retained after the release from the hydrogels. Plasma levels of omalizumab after subcutaneous injection of the γ-CyD PPRX hydrogel to rats were equivalent to those of omalizumab alone. According to the results of blood chemistry tests, the weights of organs and histological observations α- and γ-CyD PPRX hydrogels induced no serious adverse effects. These results suggest that CyD PPRX hydrogels are useful as safe and promising stabilizing formulations for antibody-based drugs.

Self-Assembly PEGylation Retaining Activity (SPRA) Technology via a Host-Guest Interaction Surpassing Conventional PEGylation Methods of Proteins.

Polyethylene glycol (PEG) modification (PEGylation) is one of the best approaches to improve the stabilities and blood half-lives of protein drugs; however, PEGylation dramatically reduces the bioactivities of protein drugs. Here, we present "self-assembly PEGylation retaining activity" (SPRA) technology via a host-guest interaction between PEGylated ß-cyclodextrin (PEG-ß-CyD) and adamantane-appended (Ad) proteins. PEG-ß-CyD formed stable complexes with Ad-insulin and Ad-lysozyme to yield SPRA-insulin and SPRA-lysozyme, respectively. Both SPRA-proteins showed high stability against heat and trypsin digest, comparable with that of covalently PEGylated protein equivalents. Importantly, the SPRA-lysozyme possessed ca. 100% lytic activity, whereas the activity of the covalently PEGylated lysozyme was ca. 23%. Additionally, SPRA-insulin provided a prolonged and peakless blood glucose profile when compared with insulin glargine. It also showed no loss of activity. In contrast, the covalently PEGylated insulin showed a negligible hypoglycemic effect. These findings indicate that SPRA technology has potential as a generic method, surpassing conventional PEGylation methods for proteins.

Design and Evaluation of the Highly Concentrated Human IgG Formulation Using Cyclodextrin Polypseudorotaxane Hydrogels.

To achieve the potent therapeutic effects of human immunoglobulin G (IgG), highly concentrated formulations are required. However, the stabilization for highly concentrated human IgG is laborious work. In the present study, to investigate the potentials of polypseudorotaxane (PPRX) hydrogels consisting of polyethylene glycol (PEG) and α- or γ-cyclodextrin (α- or γ-CyD) as pharmaceutical materials for highly concentrated human IgG, we designed the PPRX hydrogels including human IgG and evaluated their pharmaceutical properties. The α- and γ-CyDs formed PPRX hydrogels with PEG (M.W. 20,000) even in the presence of highly concentrated human IgG (>100 mg/mL). According to the results of (1)H-NMR, powder X-ray diffraction, and Raman microscopy, the formation of human IgG/CyD PPRX hydrogels was based on physical cross-linking arising from their columnar structures. The release profiles of human IgG from the hydrogels were in accordance with the non-Fickian diffusion model. Importantly, the stabilities of human IgG included into the hydrogels against thermal and shaking stresses were markedly improved. These findings suggest that PEG/CyD PPRX hydrogels are useful to prepare the formulation for highly concentrated human IgG.