Search results for "Drug Stability"

Mutational analysis of disulfide bonds in the trypsin-reactive subdomain of a Bowman-Birk-type inhibitor of trypsin and chymotrypsin--cooperative ver…

1998

It is widely believed that protein folding is a hierarchical process proceeding from secondary structure via subdomains and domains towards the complete tertiary structure. Accordingly, protein subdomains should behave as independent folding units. However, this prediction would underestimate the well-established structural significance of tertiary context and domain interfaces in proteins. The principal objective of this work was to distinguish between autonomous and cooperative refolding of protein subdomains by means of mutational analysis. The double-headed Bowman-Birk inhibitor of trypsin and chymotrypsin of known crystal structure was selected for study. The relative orientation of th…

Investigation of the phase transitions occurring during and after the dehydration of xylazine hydrochloride monohydrate.

2014

This paper reports an investigation of a complex solid state phase transition where two inter-converting polymorphs (X and A) of the pharmaceutical molecule xylazine hydrochloride formed and transformed during and after the dehydration of its monohydrate (H). The crystal structures of all three forms were compared. During the investigation of this solid state phase transition it was determined that the dehydration of H produced either a pure X form, or a mixture of the X and A forms. The phase composition depended on the sample preparation procedure and the experimental conditions. It was found that grinding of the hydrate enhanced the formation of polymorph X as a product of dehydration, w…

Stability of Morphine, Morphine-3-Glucuronide, and Morphine-6-Glucuronide in Fresh Blood and Plasma and Postmortem Blood Samples

2001

The present study was designed to determine the stability of morphine and its glucuronides in spiked fresh blood and plasma from live individuals as well as in four authentic postmortem blood specimens for a time interval of up to six months. The samples were stored in glass vials at -20 degrees C, 4 degrees C, and 20 degrees C. Additionally, spiked samples were exposed to light through window glass and subjected to a forced-degradation study at 40 degrees C. Data were established using solid-phase extraction and high-performance liquid chromatography coupled to atmospheric pressure ionization mass spectrometry for isolation and quantitation, providing a sensitive and specific detection met…

Drug delivery devices based on mesoporous silicate.

2004

A mesoporous material based on aluminosilicate mixture was studied to investigate its ability to include drugs and then release them. Nonsteroidal anti-inflammatory agents such as diflunisal, naproxen, ibuprofen and its sodium salt have been used in this study. The preparation of the mesoporous material and its characterization by X-ray, N2 absorption-desorption isotherm, and thermogravimetry analysis have been described. Drug loading was performed by a soaking procedure. Drug-loaded matrices were characterized for entrapped drug amount, water absorption ability, and thermogravimetric behavior. Drug release studies also were performed at pH 1.1 and 6.8 mimicking gastrointestinal fluids. Exp…

Stability of opiates in hair fibers after exposure to cosmetic treatment.

1996

Abstract The stability of opiates in clipped natural human hair was investigated. Hair fibers were incubated with defined solutions of morphine, codeine and dihydrocodeine (pH 7.4) until saturated. Original opiate-positive hair samples collected from drug addicts also were examined. Commercially available bleaching as well as perming formulas (Poly Blonde Ultra®, Poly Lock®; Henkel, Dusseldorf, Germany) were applied in vitro to the hair strands of both groups under investigation. After these treatments, the drug concentration had decreased for both bleaching and permanent waving. In the spiked hair, only 2–18% of the starting solution could be found after bleaching. About 20–30% of the drug…

Compatibility of epirubicin-loaded DC bead™ with different non-ionic contrast media

2016

Purpose The aim of this study was to determine the compatibility of epirubicin-loaded DC bead™ with different non-ionic contrast media over a period of seven days when stored light protected under refrigerated conditions. Methods DC bead™ (2 ml) (Biocompatibles UK Ltd) of the bead size 70–150 µm ( = DC bead M1) or bead size 100–300 µm were loaded with 75 mg epirubicin powder formulation (Farmorubicin® dissolved in 3 ml water for injection to a concentration of 25 mg/ml) or 76 mg epirubicin injection solution (Epimedac® 2 mg/ml) within 2 h or 6 h, respectively. After removal of the excess solution, the epirubicin-loaded beads were mixed in polypropylene syringes with an equal volume (∼1.5 ml…

Partition coefficient, blood to plasma ratio, protein binding and short-term stability of 11-nor-Delta(9)-carboxy tetrahydrocannabinol glucuronide.

2002

11-Nor-Delta(9)-carboxy tetrahydrocannabinol glucuronide (THCCOOglu) is a major metabolite of tetrahydrocannabinol in blood. Despite its mass spectrometric identification already in 1980, further physicochemical data of THCCOOglu have not been established. Therefore, the octanol/buffer partition coefficient P and the blood to plasma ratio b/p for THCCOOglu concentrations of 100 and 500ng/ml were investigated. Protein binding of the glucuronide was established from spiked albumin solutions at a level of 250ng/ml as well as from authentic samples. The data were compared to those of 11-nor-Delta(9)-carboxy tetrahydrocannabinol (THCCOOH). In addition, the short-term stability of THCCOOglu in pl…

A New Type of Artificial Oxygen Carrier: Soluble Hyperpolymeric Haemoglobin with Negligible Oncotic Pressure—Production of Thermally Stable Hyperpoly…

1992

Nitroblue-tetrazolium test for the functional evaluation of phagocytic cells: a critical analysis of the methodology.

1981

The reduction of NBT to formazan has been suggested as an indicator of the reduction potential of biological systems. An increase in the amount of reduced formazan reflects the activation of the hexose monophosphate shunt of phagocytes cultivated in vitro, as a result of cellular stimulation by chemical or biological factors, or during phagocytosis. This phenomenon has been widely used for the determination of activated phagocytes by different methods. However, the technical limitations of these methods have not been evaluated carefully. In the investigations presented here three solvents for formazan, pyridine, dioxane and dimethyl-formamide, have been tested for their suitability as extra…

Influence of poloxamers on the dissolution performance and stability of controlled-release formulations containing Precirol® ATO 5

2005

Abstract Lipid excipients are usually used for the development of sustained-release formulations. When used in relatively high quantities, Precirol ® ATO 5 imparts sustained-release properties to solid oral dosage forms, by forming a lipid matrix. To control or adjust the drug release kinetics from such lipid matrix however, one must often resort to complementary ingredients or techniques. This study investigates the influence of poloxamers (Lutrol ® ) included in lipid matrices composed of glyceryl palmitostearate (Precirol ® ATO 5) on their dissolution performance and their stability. The addition of these hydrophilic polymers in the lipid matrix increased the amount of theophylline relea…