Concomitant components

Excipients bring properties to formulations that facilitate the conversion of the API to a medicine. These functional properties will depend on the particular formulation. For parenteral products, open wound treatments, and ocular treatments, there are specific additional requirements concerning impurities, microbiological load, and endotoxins. However, excipients intended for nonsterile applications very often function, because they are not single chemical compounds. There are other functional or concomitant components frequently present, which are necessary to achieve the required performance (functionality) of the excipient in use. These should be considered separately from any impurities, process residues, or foreign substances that may be present. (In some applications, certain components that have traditionally been considered to be impurities or residues, may actually be concomitant components.) It is important to understand that these other components, whatever their source, may also interact with the API or other excipients. 

Concomitant components Bulk pharmaceutical chemicals (frequently referred to as API in the pharmaceutical industry) may have concomitant... 

The USP defines five types of impurities foreign substances, toxic impurities, concomitant components, signal impurities, and ordinary impurities. 

Impurities are typically resolved from the drug by a chromatographic procedure and quantified by comparison to an external standard, often the drug itself, rather than by comparison to standards of the individual impurities. Pharmacopoeial methods must be suitable for pharmaceuticals produced by different manufacturers that may contain different types and amounts of impurities. Pharmacopoeias typically view 1.0-2.0% as the general limit for total ordinary impurities, unless there is documentation to support a higher or lower level. Concomitant components, toxic or signal impurities are not included in the estimate of ordinary impurities and separate limits may be set for these, as necessary. 

Conjugated Estrogens, USP Identification assay, content of 17a-dihydroequilin, 17j8-dihydroequilin, and 17 alpha-estradiol (concomitant components)— C 0.25... 

The double-stranded structure of DNA can be separated into two component strands (melted) in solution by increasing the temperature or decreasing the salt concentration. Not only do the two stacks of bases puU apart but the bases themselves unstack while still connected in the polymer by the phosphodiester backbone. Concomitant with this denaturation of the DNA molecule is an increase in the optical absorbance of the purine and pyrimidine bases—a phenomenon referred to as hyperchromicity of denaturation. Because of the... 

The differentiation of cells occurs concomitantly to modifications of wall components. The nature of the pectins of the walls changes under the action of enzymes, among which esterases, secreted between the apical meristematic cells and the more basal differentiated cells. The apposition of new layers of pectins with different compositions at the inner surface of the walls is another mechanism by which the cells adapt their immediate environment. Using the 2F4 antibody, we have observed, in plant suspensions as well as in tissues, a third mechanism involved in wall modification. Numerous invaginations of the... 

A two-component 2-halobenzoate 1,2-dioxygenase has been purified from Pseudomonas cepacia strain 2CBS that is able to metabolize 2-fluorobenzoate, 2-chlorobenzoate, 2-bromobenzoate, and 2-iodobenzoate to catechol by concomitant decarboxylation and loss of halide (Fetzner et al. 1992). The inducible 2-halobenzoate 1,2-dioxygenase consisted of... 

Intermolecular hydroalkoxylation of 1,1- and 1,3-di-substituted, tri-substituted and tetra-substituted allenes with a range of primary and secondary alcohols, methanol, phenol and propionic acid was catalysed by the system [AuCl(IPr)]/ AgOTf (1 1, 5 mol% each component) at room temperature in toluene, giving excellent conversions to the allylic ethers. Hydroalkoxylation of monosubstituted or trisubstituted allenes led to the selective addition of the alcohol to the less hindered allene terminus and the formation of allylic ethers. A plausible mechanism involves the reaction of the in situ formed cationic (IPr)Au" with the substituted allene to form the tt-allenyl complex 105, which after nucleophilic attack of the alcohol gives the o-alkenyl complex 106, which, in turn, is converted to the product by protonolysis and concomitant regeneration of the cationic active species (IPr)-Au" (Scheme 2.18) [86]. 

Matrix Components The term matrix component refers to the constituents in the material aside from those being determined, which are denoted as analyte. Clearly, what is a matrix component to one analyst may be an analyte to another. Thus, in one hand for the case of analyses for elemental content, components such as dietary fibre, ash, protein, fat, and carbohydrate are classified as matrix components and are used to define the nature of the material. On the other hand, reference values are required to monitor the quality of determinations of these nutritionally significant matrix components. Hence, there is a challenging immediate need for certified values for dietary fibre, ash, protein, fat, and carbohydrate. Concomitantly, these values must be accompanied by scientifically sound definitions (e.g. total soluble dietary fibre, total sulpha-ted ash, total unsaturated fat, polyunsaturated fat, individual lipids, simple sugars, and complex carbohydrates). 

Syn-sedimentary chemical deposits form by chemical and biochemical precipitation of valuable metal components carried in solution, concomitant with the formation of the enclosing sedimentary rock. The manner of such deposition depends on the concentration of the metal in the solvent, the solubility of the precipitating product, the solution chemistry, and the deposition environment. Iron, manganese, phosphorus, lead, zinc, sulfur and uranium are some of the elements that have formed economically valuable deposits by chemical precipitation during sedimentation. 

Fig. 4. Substrate first binds to the complete system containing all three protein components. Addition of NADH next effects two-electron reduction of the hydroxylase from the oxidized Fe(III)Fe(III) to the fully reduced Fe(II)Fe(II) form, bypassing the inactive Fe(II)Fe(III) state. The fully reduced hydroxylase then reacts with dioxygen in a two-electron step to form the first known intermediate, a diiron(III) peroxo complex. The possibility that this species itself is sufficiently activated to carry out the hydroxylation reaction for some substrates cannot be ruled out. The peroxo intermediate is then converted to Q as shown in Fig. 3. Substrate reacts with Q, and product is released with concomitant formation of the diiron(III) form of the hydroxylase, which enters another cycle in the catalysis.

Electrolytes Daily doses based on daily maintenance requirements, renal function, gastrointestinal losses, acid-base status, concomitant drug therapy, nutritional and anabolic status Pa lion I has hyponatremia, hypokalemia, hypomagnesemia, and hypophosphatemia, also has low serum bicarbonate concentration, could be component of metabolic acidosis due to sepsis... 

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