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If we compare the two different dosage forms having same active ingredients and compare the two drug bioavailability is called comparative bioavailability. [18] Although knowing the true extent of systemic absorption (referred to as absolute bioavailability) is clearly useful, in practice it is not determined as frequently as one may think.
First-pass metabolism may occur in the liver (for propranolol, lidocaine, clomethiazole, and nitroglycerin) or in the gut (for benzylpenicillin and insulin). [4] The four primary systems that affect the first pass effect of a drug are the enzymes of the gastrointestinal lumen, [5] gastrointestinal wall enzymes, [6] [7] [8] bacterial enzymes [5] and hepatic enzymes.
Primary cell culture is the ex vivo culture of cells freshly obtained from a multicellular organism, as opposed to the culture of immortalized cell lines.In general, primary cell cultures are considered more representative of in vivo tissues than cell lines, and this is recognized legally in some countries such as the UK (Human Tissue Act 2004). [1]
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug ...
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism.
Cell membranes may act as barriers to some drugs. They are essentially lipid bilayers which form semipermeable membranes. Pure lipid bilayers are generally permeable only to small, uncharged solutes. Hence, whether or not a molecule is ionized will affect its absorption, since ionic molecules are charged. Solubility favors charged species, and ...
The relationship between the biological and plasma half-lives of a substance can be complex depending on the substance in question, due to factors including accumulation in tissues, protein binding, active metabolites, and receptor interactions. [7]
Because of the difficulty for drugs to pass through the blood–brain barrier, a study was conducted to determine the factors that influence a compound’s ability to transverse the blood–brain barrier. In this study, they examined several different factors to investigate diffusion across the blood–brain barrier.