Administration, Distribution, and Metabolism of Drug Classes

In contrast, the therapeutic use of AMDs generally involves treating animals individually with AMDs formulated for parenteral (usually intramuscular or subcutaneous) or oral dosing, with animals dosed on a mg/kg body weight basis. Here, dosing can be more accurate even if body weight is normally assessed rather than measured under clinical conditions. 

As drug residue science is concerned with metabolites, as well as parent molecules, it should be noted that most (especially phase II) metabolites are more polar, less lipid-soluble, and less biologically active than parent drugs. Hence, most metabolites follow the general rules on disposition (poor penetration of cell membranes) and elimination (high concentrations in urine and/or bile) applicable to poorly lipid-soluble drugs. 

6 Influence of Antimicrobial Drug (AMD) Physicochemical Properties on Residues and WhT 

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Furthermore, pharmacokinetic administration, distribution, metabolism and excretion (ADME) factors affect drug bioavailability, efficacy and safety, and, thus, are a vital consideration in the selection process of oral drug candidates in development pipelines. Since solubility, permeability, and the fraction of dose absorbed are fundamental BCS parameters that affect ADME, these BCS parameters should prove useful in drug discovery and development. In particular, the classification can used to make the development process more efficient.For example, in the case of a drug placed in BCS Class II where dissolution is the rate-limiting step to absorption, formulation principles such as polymorph selection, salt selection, complex formation, and particle size reduction (i.e., nanoparticles) could be applied earlier in development to improve bioavailability. 

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