We have designed a pseudopolyrotaxane (PPRX), known as a molecular necklace, consisting of phenylboronic acid-modified γ-cyclodextrin (PBA-γ-CyD) and naphthalene-modified polyethylene glycol (Naph-PEG) for developing sugar-responsive insulin delivery systems. Interestingly, structural analyses show that the Naph-PEG/PBA-γ-CyD PPRX obtained by our method was single stranded, whereas ordinary PPRXs using parent γ-CyD were double stranded. The Naph-PEG/PBA-γ-CyD PPRX was poorly water soluble at pH 7.4; however, sugar addition induced disintegration of the PPRX, and the components were dissolved, suggesting that the PBA moiety acts as a sugar sensor. We also have developed a PPRX consisting of Naph-PEG-appended insulin (Naph-PEG-Ins) and PBA-γ-CyD and have confirmed that the release rate of Naph-PEG-Ins was accelerated following sugar addition.

Supramolecular structures were developed from phenylboronic acid-modified cyclodextrins (PBA-CyDs). The intermolecular interaction between the PBA moiety and the CyD cavity was proved using two dimensional (2D)-NMR and powder X-ray diffraction techniques. PBA-α-CyD formed a head-to-tail supramolecular polymer, whereas PBA-β-CyD formed a head-to-head dimer. The supramolecular structures were disintegrated in the presence of sugars owing to the resulting boronate sugar interactions.

Guidelines for cardiovascular drug therapy recommend monitoring serum digoxin concentration (SDC) in patients receiving digoxin treatment, especially those with renal dysfunction and hypokalemia. However, only a few studies have reported the prevalence of SDC monitoring and laboratory testing in clinical practice. Therefore, the aim of this study was to describe the frequency of SDC monitoring and laboratory testing in digoxin users and to assess the association between SDC monitoring and patient characteristics. We used the Japanese insurance claims data covering approximately 1.7 million patients aged 20−74 years between January 1, 2005 and March 31, 2014. All patients who had at least one prescription for digoxin were included. The frequency of SDC and laboratory tests was calculated and the association between patient characteristics and SDC monitoring was assessed using logistic regression analysis. A total of 98,867 prescriptions of digoxin were issued to 3,458 patients between 2005 and 2014. The annual mean frequencies of monitoring SDC, serum potassium level and serum creatinine level and of recording electrocardiograms was 16.8%, 34.8%, and 38.7% and 24.1%, respectively. Atrial fibrillation, chronic heart failure, renal diseases, and use of oral anticoagulants were associated with SDC monitoring. We found the frequency of SDC monitoring to be relatively low in Japanese clinical practice.