Standardization of type 1 and type 2 diabetic nephropathy models in rats: Assessment and characterization of metabolic features and renal injury.

BACKGROUND: Diabetes mellitus and its complications, such as nephropathy, represent a global burden. Recent research focuses on developing drugs that specifically target the pathogenesis of diabetic nephropathy rather than merely treating hyperglycemia. Rodent models of animal disease are integral in drug discovery and represent an obligatory regulatory requirement. AIM: The aim of this study was to develop and standardize rat models of type 1 and type 2 diabetic nephropathy, resembling characteristics of human clinical condition. MATERIALS AND METHODS: Rats were administered streptozotocin (STZ) 50 mg/kg intraperitoneally (i.p.), and STZ 50 mg/kg i.p. + nicotinamide (NA) 110 mg/kg i.p., for induction of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), respectively. Metabolic parameters (body weight, feed and water intake, blood glucose, serum insulin, oral glucose tolerance test, intraperitoneal insulin tolerance test, and indices of insulin sensitivity) were evaluated to characterize the symptoms of T1DM and T2DM. Renal damage was confirmed by the estimation of renal function biomarkers, kidney antioxidant status, kidney hypertrophy index, and histopathology. RESULTS: STZ and STZ + NA administration increased blood glucose levels significantly. Metabolic parameters indicated that administration of STZ resulted in clinical features of human T1DM, whereas STZ + NA rats resembled human T2DM. STZ- and STZ + NA-treated rats developed diabetic nephropathy in 4 weeks, indicated by altered levels of renal function markers, increased kidney hypertrophy index, increased renal oxidative stress, and altered tissue architecture. The study proposes reproducible and cost-effective rat models for both T1DM- and T2DM-induced diabetic nephropathy characterized by stable metabolic features and typical renal lesions.

Enhanced skin permeation of Methotrexate from penetration enhancer containing vesicles: In vitro optimization and in vivo evaluation.

Low dose Methotrexate (MTX) therapy is considered a gold standard for Rheumatoid Arthritis (RA). Transdermal drug delivery is hypothesized as an alternative to conventional therapies to alleviate its adverse effects. In our study, MTX was entrapped in deformable liposomes and loaded in a hydroxyethyl cellulose gel. This system was evaluated by the Box Behnken statistical design for optimization. The effect of formulation variables on particle size, entrapment and ex vivo skin permeation was studied. The MTX nanogel was evaluated for its dermal toxicity (acute and repeat dose safety), in vivo biodistribution (using 125I radio-labelled MTX) and therapeutic efficacy (collagen induced arthritis [CIA] model). The optimized formulation demonstrated appreciable nanosize (110 ± 20 nm), drug entrapment (42 ± 1.9%) and high ex vivo transdermal flux (17.37 ± 1.5 µg/cm2/hr). In the dermal toxicity studies, nanogel formulation did not show any signs of irritation or toxicity, whereas in the biodistribution study, the MTX nanogel formulation depicted sustained systemic delivery up to 48 h with low accumulation in its organs of toxicity such as the liver, kidneys and gut. In the CIA model, the MTX nanogel significantly ameliorated hind paw swelling, reduced arthritic score, joint damage (histological, radiological examination) and attenuated the rise in serum cytokines such as TNF-ɑ and IL-6. In conclusion, the optimized MTX nanogel formulation displayed skin biocompatibility, sustained systemic delivery, safety as well as therapeutic efficacy.

Synthesis and biodistribution studies of 99m Tc labeled fatty acid derivatives prepared via "Click approach" for potential use in cardiac imaging.

123 I-Iodophenylpentadecanoic acid (IPPA) is a metabolic agent used in nuclear medicine for diagnosis of myocardial defects. Efforts are underway worldwide to develop a 99m Tc substitute of the above radiopharmaceutical for the aforementioned application. Herein, we report synthesis and biodistribution studies of 99m Tc labeled fatty acids (8, 11, and 15 carbons) obtained via "click chemistry" for its potential use in myocardial imaging. ω-Bromo fatty acids (8C/11C/15C) were synthetically modified at bromo terminal to introduce a heterocyclic triazole with glycine sidearm in a five step procedure. Modified fatty acids were subsequently radiolabeled with preformed [99m Tc(CO)3 ]+ synthon to yield the desired fatty acid complexes which were evaluated in Swiss mice. All the radiolabeled complexes were obtained with radiochemical purities >80%, as characterized by HPLC. Biodistribution studies of all three complexes in Swiss mice showed myocardial uptake of ~6-9% ID/g at 2 minutes post-injection, close to* I-IPPA (~9% ID/g). Complexes exhibited significant retention in the myocardium up to 30 minutes (~1% ID/g) but were lower to the standard agent (~7% ID/g). Similar uptake of activity in myocardium for the newly synthesized complexes in comparison to 125 I-IPPA along with favorable in vivo pharmacokinetics merits potential for the present "click" design of complexes for myocardial imaging.

Bulk Scale Formulation of Therapeutic Doses of Clinical Grade Ready-to-Use 177Lu-DOTA-TATE: The Intricate Radiochemistry Aspects.

INTRODUCTION: 177Lu-DOTA-TATE is a clinically useful and promising therapeutic radiopharmaceutical for peptide receptor radionuclide therapy of neuroendocrine tumors (NETs) overexpressing somatostatin receptors. Currently, the radiopharmaceutical is prepared in-house at nuclear medicine centers, thereby restricting its use to limited centers only. In this article, the authors describe systematic studies toward bulk scale formulation of "ready-to-use" 177Lu-DOTA-TATE using medium specific activity 177Lu (740-1110 GBq/mg) at a centralized radiopharmacy facility. METHODS: In an optimized protocol, 177Lu-DOTA-TATE synthesis was carried out by direct heating of 177LuCl3 (Sp. act. 740-1110 GBq/mg) with DOTA-TATE peptide (1.5-3.0 equivalents) in ammonium acetate buffer (0.2 M) containing 2,5-dihydroxy benzoic acid (gentisic acid). Thereafter, the crude labeled product was purified using a Sep-Pak® C18 column and diluted with acetate buffer-gentisic acid (1.5% w/v) solution to final radioactive concentration of 740 MBq/mL. This was further sterilized and dispensed as 7.4 GBq patient dose/vial with 2 days postformulation calibration. RESULTS: A peptide/metal ratio of 1.5-3.0 is essential for complexation wherein radiolabeling yields >90% are obtained minimizing free 177Lu waste. For formulation of 7.4 GBq patient dose (2 days postproduction), even specific activity of about 555 GBq/mg was found to be adequate for the radiometal. The ready-to-use 740 MBq/mL 177Lu-DOTA-TATE formulation with gentisic acid (1.5% w/v) is observed to be safe for human use for more than 1 week (radiochemical purity >98%) from the day of production when stored at -70°C. However, the target specificity may get affected beyond 2 days as the total peptide content for 7.4 GBq dose may exceed the critical peptide limit of 300 µg. Patient treatment carried with several batches of present formulation in diseased NET patients exhibited desired distribution at the tumor and its metastatic site. CONCLUSIONS: A ready-to-use formulation of 177Lu-DOTA-TATE was successfully prepared and optimized for regular bulk scale production and supply to distant nuclear medicine centers.

Development of samarium [32P] phosphate colloid for radiosynoviorthesis applications: preparation, biological and preliminary clinical studies experience.

A new therapeutic radio colloid for radiosynoviorthesis (RS) applications is reported. The method of preparation involves the reaction of SmCl3 carrier with carrier added [32P]H3PO4 in the presence of gelatin. The pure colloid was recovered by dialysis purification leading to radiochemical yield of around 90%. The radiochemical purity of the pure colloid formulated in isotonic saline was over 98%, for the usage period of 14 days, as assessed by paper chromatography. Ninety percent of colloid particles were in the size of 1-10 microm as evident from the laser diffraction particle size analysis, ideally suitable for the intended end use. Animal studies revealed complete retention of the radio colloid in the rabbit knee joint. The results of clinical trials in humans are satisfactory and encouraging, satisfactory retention of the colloid in the knee joint and negligible leakage into the systemic circulation.