Impact of streptozotocin on altering normal glucose homeostasis during insulin testing in diabetic rats compared to normoglycemic rats

Nidal A Qinna,1 Adnan A Badwan2 1Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra, 2Research and Innovation Centre, The Jordanian Pharmaceutical Manufacturing Co. Plc. (JPM), Amman, Jordan Abstract: Streptozotocin (STZ) is currently the most used diabetogenic agent in testing insulin and new antidiabetic drugs in animals. Due to the toxic and disruptive nature of STZ on organs, apart from pancreas, involved in preserving the body’s normal glucose homeostasis, this study aims to reassess the action of STZ in inducing different glucose response states in diabetic rats while testing insulin. Diabetic Sprague-Dawley rats induced with STZ were classified according to their initial blood glucose levels into stages. The effect of randomizing rats in such a manner was investigated for the severity of interrupting normal liver, pancreas, and kidney functions. Pharmacokinetic and pharmacodynamic actions of subcutaneously injected insulin in diabetic and nondiabetic rats were compared. Interruption of glucose homeostasis by STZ was challenged by single and repeated administrations of injected insulin and oral glucose to diabetic rats. In diabetic rats with high glucose (451–750 mg/dL), noticeable changes were seen in the liver and kidney functions compared to rats with lower basal glucose levels. Increased serum levels of recombinant human insulin were clearly indicated by a significant increase in the calculated maximum serum concentration and area under the concentration–time curve. Reversion of serum glucose levels to normal levels pre- and postinsulin and oral glucose administrations to STZ diabetic rats were found to be variable. In conclusion, diabetic animals were more responsive to insulin than nondiabetic animals. STZ was capable of inducing different levels of normal glucose homeostasis disruption in rats. Both pharmacokinetic and pharmacodynamic actions of insulin were altered when different initial blood glucose levels of STZ diabetic rats were selected for testing. Such findings emphasize the importance of selecting predefined and unified glucose levels when using STZ as a diabetogenic agent in experimental protocols evaluating new antidiabetic agents and insulin delivery systems. Keywords: protein delivery, animal model, diabetes mellitus, experimental, antidiabetic agents, streptozotocin&nbsp

Influence of glucosamine on the bioactivity of insulin delivered subcutaneously and in an oral nanodelivery system

Zakieh I Al-Kurdi,1,2 Babur Z Chowdhry,2 Stephen A Leharne,2 Nidal A Qinna,3 Mahmoud MH Al Omari,1 Adnan A Badwan1 1The Jordanian Pharmaceutical Manufacturing Company (PLC), Naor, Jordan; 2Faculty of Engineering and Science, University of Greenwich, Medway Campus, Kent, UK; 3Department of Pharmacology and Biomedical Sciences, Faculty of Pharmacy and Medical Sciences, University of Petra, Amman, Jordan Abstract: The aim of the work reported herein was to study the effect of glucosamine HCl (GlcN·HCl) on the bioactivity (BA) of insulin, administered via subcutaneous (SC) and oral routes, in adult male Sprague Dawley rats. The oral insulin delivery system (insulin–chitosan reverse micelle [IC-RM]) was prepared by solubilizing insulin–chitosan (13 kDa) polyelectrolyte complex in a RM system consisting of oleic acid, PEG-8 caprylic/capric glycerides, and polyglycerol-6-dioleate. The BA of insulin in vivo was evaluated by measuring blood glucose level using a blood glucose meter; the results revealed that the extent of hypoglycemic activity of SC insulin was GlcN·HCl dose dependent when they were administered simultaneously. A significant reduction in blood glucose levels (P<0.05) was found for the insulin:GlcN·HCl at mass ratios of 1:10 and 1:20, whereas lower ratios (eg, 1:1 and 1:4) showed no significant reduction. Furthermore, enhancement of the action of SC insulin was achieved by oral administration of GlcN·HCl for 5 consecutive days prior to insulin injection (P<0.05). For oral insulin administration via the IC-RM system, the presence of GlcN·HCl increased the hypoglycemic activity of insulin (P<0.05). The relative BA were 6.7% and 5.4% in the presence and absence of GlcN·HCl (ie, the increase in the relative BA was approximately 23% due to incorporating GlcN·HCl in the IC-RM system), respectively. The aforementioned findings offer an opportunity to incorporate GlcN·HCl in oral insulin delivery systems in order to enhance a reduction in blood glucose levels. Keywords: oral insulin, bioactivity, glucosamine, low molecular weight chitosan, nanoparticle

Ultra‑high resolution X‑ray structures of two forms of human recombinant insulin at 100 K

The crystal structure of a commercially available form of human recombinant (HR) insulin, Insugen (I), used in the treatment of diabetes has been determined to 0.92 Å resolution using low temperature, 100 K, synchrotron X-ray data collected at 16,000 keV (λ = 0.77 Å). Refinement carried out with anisotropic displacement parameters, removal of main-chain stereochemical restraints, inclusion of H atoms in calculated positions, and 220 water molecules, converged to a final value of R = 0.1112 and Rfree = 0.1466. The structure includes what is thought to be an ordered propanol molecule (POL) only in chain D(4) and a solvated acetate molecule (ACT) coordinated to the Zn atom only in chain B(2). Possible origins and consequences of the propanol and acetate molecules are discussed. Three types of amino acid representation in the electron density are examined in detail: (i) sharp with very clearly resolved features; (ii) well resolved but clearly divided into two conformations which are well behaved in the refinement, both having high quality geometry; (iii) poor density and difficult or impossible to model. An example of type (ii) is observed for the intra-chain disulphide bridge in chain C(3) between Sγ6–Sγ11 which has two clear conformations with relative refined occupancies of 0.8 and 0.2, respectively. In contrast the corresponding S–S bridge in chain A(1) shows one clearly defined conformation. A molecular dynamics study has provided a rational explanation of this difference between chains A and C. More generally, differences in the electron density features between corresponding residues in chains A and C and chains B and D is a common observation in the Insugen (I) structure and these effects are discussed in detail. The crystal structure, also at 0.92 Å and 100 K, of a second commercially available form of human recombinant insulin, Intergen (II), deposited in the Protein Data Bank as 3W7Y which remains otherwise unpublished is compared here with the Insugen (I) structure. In the Intergen (II) structure there is no solvated propanol or acetate molecule. The electron density of Intergen (II), however, does also exhibit the three types of amino acid representations as in Insugen (I). These effects do not necessarily correspond between chains A and C or chains B and D in Intergen (II), or between corresponding residues in Insugen (I). The results of this comparison are reported

The suitability of disintegrating force kinetics for studying the effect of manufacturing parameters on spironolactone tablet properties

The aim of this paper was to study the effect of the granulate properties and tablet compression force on disintegrating force behavior in order to investigate the capability of the disintegrating force to characterize tablets that have the same composition but were manufactured in different conditions. Several tablets containing spironolactone in the external or internal granulated mixture of calcium carbonate and maize starch differing in particle size distribution, were prepared at 3 compression levels. The force developed by tablets during water uptake and disintegration was measured and plotted versus time. The curves obtained were analyzed by the Weibull equation in order to calculate the parameters characterizing the tablet disintegration kinetics. The disintegrating force time parameter, the maximum force developed, and the area under the curve were determined. In general, the reduction of time parameter value and/or the increase in maximum force developed corresponded to an acceleration in tablet disintegration. In addition, the area under the force curve increased in stronger tablets, monitoring in a sensitive way the tablet structural changes introduced by compression force. The results showed that the disintegrating force measurement can detect small changes in the structure of the tablet that cannot be discriminated by pharmacopoeia tests. The effect of manufacturing, in particular compression force, on tablet properties was quantified by the parameters of disintegrating force kinetics

Evaluation of alginate compressed matrices as prolonged drug delivery systems

This research investigated the use of sodium alginate for the preparation of hydrophylic matrix tablets intended for prolonged drug release using ketoprofen as a model drug. The matrix tablets were prepared by direct compression using sodium alginate, calcium gluconate, and hydroxypropylmethylcellulose (HPMC) in different combinations and ratios. In vitro release tests and erosion studies of the matrix tablets were carried out in USP phosphate buffer (pH 7.4). Matrices consisting of sodium alginate alone or in combination with 10% and 20% of HPMC give a prolonged drug release at a fairly constant rate. Incorporation of different ratios of calcium gluconate leads to an enhancement of the release rate from the matrices and to the loss of the constant release rate of the drug. Only the matrices containing the highest quantity of HPMC (20%) maintained their capacity to release ketoprofen for a prolonged time