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Pharmacokinetics is based on mathematical modeling that places great emphasis on the relationship between drug plasma concentration and the time elapsed since the drug's administration. Pharmacokinetics is the study of how an organism affects the drug, whereas pharmacodynamics (PD) is the study of
Acid dissociation constants are also essential in aquatic chemistry and chemical oceanography, where the acidity of water plays a fundamental role. In living organisms, acid–base homeostasis and enzyme kinetics are dependent on the pK a values of the many acids and bases present in
The absorption rate constant K a is a value used in pharmacokinetics to describe the rate at which a drug enters into the system. It is expressed in units of time −1. [1] The K a is related to the absorption half-life (t 1/2a) per the following equation: K a = ln(2) / t 1/2a. [1] K a values can typically only be found in research articles. [2]
In cell biology, ion trapping is the build-up of a higher concentration of a chemical across a cell membrane due to the pKa value of the chemical and difference of pH across the cell membrane. [1] [2] This results in basic chemicals accumulating in acidic bodily fluids such as the cytosol, and acidic chemicals accumulating in basic fluids.
The stomach's acidic pH and the subsequent alkalization in the intestine modifies the degree of ionization of acids and weak bases depending on a substance's pKa. [1] The pKa is the pH at which a substance is present at an equilibrium between ionized and non-ionized molecules. The Henderson–Hasselbalch equation is used to calculate pKa.
In chemistry, biochemistry, and pharmacology, a dissociation constant (K D) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions.
Processes in pharmacokinetics. ADME is the four-letter abbreviation (acronym) for absorption, distribution, metabolism, and excretion, and is mainly used in fields such as pharmacokinetics and pharmacology. The four letter stands for descriptors quantifying how a given drug interacts within body over time.
There is no regulatory requirement to define the intravenous pharmacokinetics or absolute bioavailability however regulatory authorities do sometimes ask for absolute bioavailability information of the extravascular route in cases in which the bioavailability is apparently low or variable and there is a proven relationship between the ...