Admixture Studies

Therefore, admixture studies are performed on parenteral drugs with commonly used intravenous diluents. Studies are performed by preparing admixtures of the drug product with various diluents in an appropriate type of flexible intravenous bag. Initial samples are taken for analysis before the bags are stored in temperature-controlled stability chambers. Subsequent samples may be pulled at 6-, 12-, 24-, 48-, and 72-h time points. The analytical tests commonly performed include visual appearance, pH, and HPLC assay. Degradation products are not commonly tested unless the method has been previously evaluated for specificity and stability-indicating ability with a particular intravenous diluent. This is necessary because there may be differences in the stability profile of the product in its original formulation compared to the admixture solution. Formation of any particulate matter is detected by visual 

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Nicotine may be detected by the colourless, crystalline mercurichloride obtained when an aqueous solution is added to a solution of mercuric chloride, by the black precipitate formed under similar conditions with potassium platinic iodide and the characteristic crystalline periodide, BI2. HI, m.p. 123°, produced on admixture, under specified conditions, 2 of ethereal solutions of nicotine and iodine (cf Anabasine, p. 43). A polarographic study of nicotine has been made by Kirkpatrick. ... 

Estimation of Other Alkaloids in Opium. Of the other alkaloids the most important is codeine, and processes for its estimation in opium have been described by Cespari, Andrews,and Annett and co-workers methods for its assay in admixture with other drugs in tablets and other products are also available. The estimation of papaverine has been described by Issekutz,i and of narcotine by Snesarov. As to methods for the separation and estimation of two or more of these subsidiary alkaloids, codeine and narcotine have been dealt with by van der Widen,narcotine and papaverine by Annett and Bose, ( and the bromination of codeine and narceine has been studied by Vaisberg et al. with a view to estimation by this means. 

The phenomena accompanying the admixture of gases were first accurately studied experimentally by John Dalton (1801), who arrived at the following conclusions ... 

The decomposition of MgC03 (magnesite) is an interface process [734] between 813—873 K and E = 150 kJ mole-1. In the presence of C02, E was increased to 234 kJ mole-1 but was reduced slightly on the addition of ZnO or NiO. Admixture with CaO reduced the value of E to 54 kJ mole-1. This is a surprising result since the value of E for decomposition [734,753] of the mixed carbonate (Ca, Mg)C03, dolomite, is 220 kJ mole-1, larger than the value for each constituent. The influence of PCOz and of alkali metals on MgC03 decomposition has been the subject of a DTA study [404]. 

Studies conducted by Barenghi eta.1. (1990) and Lodge etal. (1993) independently have demonstrated the facile, multicomponent analysis of a wide range of PUFA-derived peroxidation products (e.g. conjugated dienes, epoxides and oxysterols) in samples of oxidized LDL by high-field H-NMR spectroscopy. Figure 1.9 shows the applications of this technique to the detection of cholesterol oxidation products (7-ketocholesterol and the 5a, 6a and 5/3,60-epoxides) in isolated samples of plasma LDL pretreated with added coppcr(Il) or an admixture of this metal ion with H2O2, an experiment conducted in the authors laboratories. 

Derivation of simple and unambiguous quantitative relations between the signal amplitude of a sensor, i.e., the value of the change of electric conductivity, work function, etc. and concentration of detected traces of admixture in the medium under study is also important for successful development of the sensor measuring technique. Theoretical considerations given in this book show that such relations exist in most simple form. The purpose of experiment consists in statistical substantiation that these dependencies rigorously hold at proper conditions. 

Quantitative studies of such processes are of great interest for understanding the mechanism of chemisorption and a number of heterogeneous catalytic reactions, because it is superstechiometric (admixture) atoms (ions) of metals become active centers of adsorption of different particles (radicals, molecules) on metal oxides, or centers of catalysis. Such... 

The possibility of container-closure interactions should be considered, taking into account any admixture and dilution of products. Sorption of active ingredients and excipients should be considered as should leaching of container-closure components over the shelf life. Studies should extend to simulation of use. Pack components, administration devices (e.g., giving sets), and label adhesives should be considered. 

Water, methanol, and n-hexane do not influence the photooxidation of PVC (43), but the photodegradation is accelerated by ferric chloride (70,71) and certain other compounds containing iron (70,71,72). Purification of the polymer might be expected to enhance its photostability by removing deleterious impurities such as iron compounds that are derived from metal equipment. This type of result was obtained in one recent study (58) but not in others (30,59). In contrast, the photo-oxidative degradation of PVC should be enhanced by admixture of the polymer with materials that are unusually susceptible to photooxidation themselves. Such behavior has been observed for impact-modified PVC containing polybutadiene-based polyblends (69,73). 

In a review of the course and mechanism of the catalytic decomposition of ammonium perchlorate, the considerable effects of metal oxides in reducing the explosion temperature of the salt are described [1], Solymosi s previous work had shown reductions from 440° to about 270° by dichromium trioxide, to 260° by 10 mol% of cadmium oxide and to 200°C by 0.2% of zinc oxide. The effect of various concentrations of copper chromite , copper oxide, iron oxide and potassium permanganate on the catalysed combustion of the propellant salt was studied [2], Similar studies on the effects of compounds of 11 metals and potassium dichromate in particular, have been reported [3], Presence of calcium carbonate or calcium oxide has a stabilising effect on the salt, either alone or in admixture with polystyrene [4],... 

The explosive oxidation of nitrogen in admixture with ozone in metallic vessels has been studied. 

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