Active substance physicochemical characteristics

Comprehensive physicochemical characterization of any raw material is a crucial and multi-phased requirement for the selection and validation of that matter as a constituent of a product or part of the product development process (Morris et al., 1998). Such demand is especially important in the pharmaceutical industry because of the presence of several compounds assembled in a formulation, such as active substances and excipients, which highlights the importance of compatibility among them. Besides, variations in raw materials due to different sources, periods of extraction and various environmental factors may lead to failures in production and/or in the dosage form performance (Morris et al., 1998). Additionally, economic issues are also related to the need for investigating the physicochemical characteristics of raw materials since those features may determine the most adequate and low-cost material for specific procedures and dosage forms. 

Reverse pharmacology has great possibilities in drug discovery. Classical pharmacology starts with an active molecule and then looks for its effects and the receptor or enzyme through which these effects are exerted. For example, acetylcholine (ACh) was known from Loewy s experiments and from other studies in the periphery as an active substance. The target must be, by definition, an acetylcholine receptor. You knew it must exist you already had a name for it when you found it and all you had to do was find it, localize it, and discover its physicochemical, biochemical, and pharmacological characteristics. 

In summary, biopharmaceutics relates the physicochemical characteristics of an active substance, the functionalities and a medicinal product and the route of administration to the performance in the living organism and to the efficacy and safety of the medicinal product The biopharmaceutical... 

A risk assessment for explosivity, oxidising properties and flammability is required unless none of the product s constituents possess such properties, and, in addition, that on the basis of information available the product is unlikely to present dangers of this kind. Due to the type and nature of the studies conducted under the physicochemical data requirements section (see Tables 1 and 2 for a list of the required studies on the active substance and 23 product types to fulfill the BPD), a physico-chemical risk assessment on a particular product is usually qualitative and is based solely on the intrinsic hazards of the constituents. Therefore, the outcome of a physicochemical risk assessment usually relies on the eventual classification of the product for physical and chemical characteristics and this then leads directly to risk management proposals. 

Although energy-requiring transport mechanisms ensure that valuable materials such as sugars and amino adds are actively absorbed into the bloodstream, useless and even harmful substances may pass across the intestinal barrier if their physicochemical characteristics are such as to allow them to traverse it by passive means. Once water and other materials have been absorbed they are distributed among the various fluid compartments. 

Physicochemical properties are required in their own right as part of the description of the characteristics of a chemical (e.g., for regulatory submission), or as one of the three components of quantitative structure-activity relationships (QSARs) (see Chapter 1, Figure 1.1 and Figure 1.2 for more details). While the properties of a pure chemical substance may be measured, the computation of physicochemical properties has many advantages. These include the speed and low cost of calculation and, more importantly, the fact that calculation may be performed for chemicals that are not available. 

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