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The «renal clearance» rate will be determined by factors such as the degree of plasma protein binding as the drug will only be filtered out if it is in the unbound free form, the degree of saturation of the transporters (active secretion depends on transporter proteins that can become saturated) or the number of functioning nephrons (hence ...
Distribution is defined as the reversible transfer of a drug between one compartment to another. Some factors affecting drug distribution include regional blood flow rates, molecular size, polarity and binding to serum proteins, forming a complex. Distribution can be a serious problem at some natural barriers like the blood–brain barrier.
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 ...
Substances in the body can be cleared by various organs, including the kidneys, liver, lungs, etc. Thus, total body clearance is equal to the sum clearance of the substance by each organ (e.g., renal clearance + hepatic clearance + pulmonary clearance = total body clearance). For many drugs, however, clearance is solely a function of renal ...
A drug's removal rate will be determined by the proportion of the drug that is removed from circulation by each organ once the drug has been delivered to the organ by the circulating blood supply. [1] This new concept builds on earlier ideas and it depends on a number of distinct factors: The drugs characteristics, including its pKa.
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.
Time course of drug plasma concentrations over 96 hours following oral administrations every 24 hours (τ). Absorption half-life 1 h, elimination half-life 12 h. Biological half-life ( elimination half-life , pharmacological half-life ) is the time taken for concentration of a biological substance (such as a medication ) to decrease from its ...
A reaction's factors of non-linearity include the following: Multiphasic absorption: Drugs injected intravenously are removed from the plasma through two primary mechanisms: (1) Distribution to body tissues and (2) metabolism + excretion of the drugs. The resulting decrease of the drug's plasma concentration follows a biphasic pattern (see figure).