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We are exploiting the use of a versatile catalyst taken from heterogeneous catalysis, i.e., ZrOCl2.8H2O to efficiently catalyze the reaction of dextran-succinate conjugate (Dex-SAn) with salicylic acid (SA) under homogeneous reaction conditions. Dextran was first linked with succinic anhydride using triethylamine as a base in DMAc to provide active functionalities (succinate moieties) situated away from the polymer chains. The resultant Dex-SAn conjugate was further esterified with SA using zirconium (IV) oxychloride octahydrate (ZrOCl2.8H2O) as a catalyst at 80 °C under N2. Reaction conditions and amount of catalyst ZrOCl2.8H2O and chiral support MCM-41 were optimized. This reaction methodology resulted in macromolecular prodrugs of SA as Dex-SAn-SA conjugates in good yield. The structures of Dex-SAn and newly synthesized Dex-SAn-SA conjugates were characterized using various spectroscopic techniques, i.e., FT-IR, 1H, and APT-13C NMR spectroscopy. The degree of substitution of SA on to Dex-SAn-SA was determined by UV/Vis spectroscopic methods. This reaction methodology can be modeled as a new protocol for facile attachment of several drug molecules onto the highly potential and biodegradable drug carrier dextran.

Macromolecular prodrugs (MPDs) of aspirin and salicylic acid were synthesized by covalent attachment to hydroxypropylcellulose (HPC) using p-toluenesulfonyl chloride in N,N-dimethylacetamide. The present synthesis strategy resulted in organo-soluble MPDs with 78–86 % yield and degree of drug substitution 0.53–1.96 and 0.68–2.10 for aspirin and salicylic acid, respectively. The size exclusion chromatography showed DP 192 and 214 for HPC–aspirin and HPC–salicylic acid conjugates, respectively. HPC–aspirin and HPC–salicylic acid conjugates were found thermally more stable than native drugs. The activation energy (Ea) of thermal degradation of drugs, polymer and prodrugs was calculated with the help of Broido and Chang kinetic models. Order of reaction (n) was calculated from thermal data using Chang model. Various thermodynamic parameters, i.e., enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) were also calculated. Doyle’s method was employed on thermal data of MPDs to calculate integral procedural decomposition temperature and comprehensive index of intrinsic thermal stability. Amphiphilic HPC–aspirin conjugates showed formation of nanoparticles at water/DMSO interface with size distribution from ~500 to 750 nm by transmission electron microscopy.

Introduction Excessive fluid intake can lead to water intoxication, electrolyte abnormalities, exacerbation of heart failure and anatomical changes in the urinary tract that may present diagnostic and therapeutic challenges for patients and physicians. Although the development of nonobstructive hydronephrosis is recognized in patients with central and nephrogenic diabetes insipidus, pregnancy or psychiatric polydipsia, it is rarely a diagnostic consideration in healthy individuals with excessive fluid ingestion. We now present what we believe to be the first report of nonobstructive hydronephrosis associated with social polydipsia. Case presentation A 53-year-old African-American woman with moderate back pain was found to have bilateral moderate hydronephrosis and hydroureter by abdominal computed tomography. She underwent ureteral stent placement followed by exploratory laparoscopy with lysis of adhesions and a right oophorectomy, without resolution of the nonobstructive hydronephrosis. A careful assessment revealed a social habit of consuming approximately 5.5L of fluid daily in an effort to remain hydrated in accordance with public health service announcements. It was recommended that the patient reduce her fluid intake. A repeat ultrasound after six weeks revealed complete resolution of the bilateral hydronephrosis and hydroureter. Conclusion Recognition of the nonobstructive nature of hydronephrosis caused by polydipsia in healthy individuals is important to prevent unnecessary interventions.