Biocompatibility of polymethyl methacrylate heat-polymerizing denture base resin copolymerized with antimicrobial monomers.

STATEMENT OF PROBLEM: Quaternary ammonium (QA)-based monomers such as dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI) and 2-dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) have been investigated as copolymerizable monomers to impart antimicrobial activity to dental restorative and prosthetic materials. However, the biocompatibility of these antimicrobial monomers needs to be investigated in vivo before their clinical use. PURPOSE: The purpose of this study was to assess the in vivo biocompatibility of polymethyl methacrylate (PMMA) heat-polymerizing denture base resin copolymerized with varying concentrations of DHMAI and DDMAI. MATERIAL AND METHODS: The toxicity and genotoxicity of the antimicrobial monomers (DHMAI 5 µg/mL and DDMAI 20 µg/mL) at 1 to 100 µg/mL concentrations were investigated against zebrafish embryos (Danio rerio, n=10) using a zebrafish embryotoxicity test (ZET) or fish embryotoxicity test (FET) and comet assay, respectively. Further, DHMAI 5 µg/mL and DDMAI 20 µg/mL were incorporated into a conventional PMMA denture base system and a similar test was done on specimens of modified PMMA resin. For the evaluation of in vivo biocompatibility, modified PMMA specimens were subcutaneously implanted into Wistar rats (n=6) and biochemical, hematological, and histopathological parameters were investigated. Results were analyzed and compared using ANOVA and the Tukey post hoc test (α=.05). RESULTS: Toxicity and genotoxicity studies using zebrafish embryos revealed that the incorporation of monomer to PMMA did not increase the toxicity, as confirmed by post-hour fertilization. Modified PMMA did not affect the hematological parameters, such as red blood cell (RBC) and white blood cell (WBC) except for the platelet count, which was significantly increased (P<.001), and the biochemical parameter, such as total protein (TP), blood urea nitrogen (BUN), serum glutamic-oxaloacetic transaminase (SGOT), triglyceride (TG), creatinine (Crea), total cholesterol, and serum glutamic pyruvic transaminase (SGPT), except for high-density lipoprotein (HDL) cholesterol, which was significantly decreased (P<.01). Histopathologically, no changes were observed in the sections of the liver, kidney, spleen, and subcutaneous tissues in the modified PMMA implanted rats. Additionally, no significant variation was found in the expression of immunohistochemical marker tumor necrosis factor alpha (TNF-α), confirming the noninflammatory response exerted by the modified PMMA on experimental rats. CONCLUSIONS: Zebrafish embryos treated with modified PMMA specimens demonstrated favorable biological properties and did not exhibit significant cytotoxicity and genotoxicity. Subcutaneously implanted modified PMMA did not cause any major hematological, biochemical, and histopathological alterations in Wistar albino rats, thus confirming the biocompatibility of PMMA heat-polymerizing denture base resin incorporated with DHMAI and DDMAI for dental applications.

Biomedicine and pharmacotherapeutic effectiveness of combinatorial atorvastatin and quercetin on diabetic nephropathy: An in vitro study.

INTRODUCTION: Diabetic nephropathy is a type of kidney disorder that develops as a complication of multifactorial diabetes. Diabetic nephropathy is characterized by microangiopathy, resulting from glucose metabolism, oxidative stress, and changes in renal hemodynamics. This study strived to evaluate the in vitro cytoprotective activity of atorvastatin (ATR), and quercetin (QCT) alone and in combination against diabetic nephropathy. METHODS: The MTT assay was utilized to analyze the effects of the test compounds on NRK-52E rat kidney epithelial cells. The detection of apoptosis and ability to scavenge free radicals was assessed via acridine orange-ethidium bromide (AO-EB) dual fluorescence staining, and 2,2-diphenyl-1-picrylhydrazyfree assay (DPPH), respectively. The ability of anti-inflammatory effect of the test compounds and western blot analysis against TGF-ß, TNF-α, and IL-6 further assessed to determine the combinatorial efficacy. RESULTS: Atorvastatin and quercetin treatment significantly lowered the expression of TGF-ß, TNF-α, and IL-6 indicating the protective role in Streptozotocin-induced nephrotoxicity. The kidney cells treated with a combination of atorvastatin and quercetin showed green fluorescing nuclei in the AO-EB staining assay, indicating that the combination treatment restored cell viability. Quercetin, both alone and in combination with atorvastatin, demonstrated strong DPPH free radical scavenging activity and further encountered an anti-oxidant and anti-inflammatory effect on the combination of these drugs. CONCLUSION: Nevertheless, there is currently no existing literature that reports on the role of QCT as a combination renoprotective drug with statins in the context of diabetic nephropathy. Hence, these findings suggest that atorvastatin and quercetin may have clinical potential in treating diabetic nephropathy.

Stability indicating ion chromatography method for the simultaneous determination of ibandronate sodium drug substance and its impurities.

A simple and sensitive ion chromatography method has been developed for the simultaneous assay of ibandronate sodium drug substance and the determination of its impurities. The separation was achieved on Allsep™ anion column 150 mm × 4.6 mm, 7 µm particle diameter. The mobile phase consisted of 1% (v/v) aqueous formic acid and acetone 98:2% (v/v); flow rate 1.0 ml min(-1) at ambient temperature. The analytes were monitored by conductometric detector. The drug substance was subjected to stress conditions of hydrolysis, oxidation, photolytic, thermal and humidity degradation. Considerable degradation was achieved only under oxidative conditions. Mass balance was demonstrated in all stress conditions. The method was validated for specificity, precision, linearity, solution stability and accuracy. The limits of detection (LOD) and limits of quantification (LOQ) for impurities were in the range of 0.36-0.80 µg ml(-1) and 1.00-2.40 µg ml(-1), respectively. For ibandronate LOD was 38 µg ml(-1) and LOQ was 113 µg ml(-1). The average recoveries for impurities and ibandronate were in the range of 99.0-103.1% and the method can be successfully applied for the routine analysis of ibandronate sodium drug substance.

Identification, isolation and characterization of a new degradation product in sultamicillin drug substance.

A new degradant of sultamicillin drug substance was found during the gradient reverse phase HPLC analysis of stability storage samples. The level of this degradant impurity was observed up to 1.0%. The impurity (formaldehyde adduct with 5-oxo-4-phenylimidazolidin-1-yl moiety) was identified by LC/MS and was characterized by ((1)H NMR, (13)C NMR, 2D-NMR ((1)H-(1)H COSY, NOESY, HSQC and HMBC), LC/MS/MS, MS/TOF, elemental analysis and IR. This impurity was prepared by isolation and co-injected into HPLC system to confirm the retention time.