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The elimination rate constant K or K e is a value used in pharmacokinetics to describe the rate at which a drug is removed from the human system. [1]It is often abbreviated K or K e.
Each curve corresponds to a different Hill coefficient, labeled to the curve's right. The vertical axis displays the proportion of the total number of receptors that have been bound by a ligand. The horizontal axis is the concentration of the ligand. As the Hill coefficient is increased, the saturation curve becomes steeper.
Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms , or combinations of organisms (for example, infection ).
The Hill equation is the following formula, where is the magnitude of the response, [] is the drug concentration (or equivalently, stimulus intensity) and is the drug concentration that produces a 50% maximal response and is the Hill coefficient.
In biochemistry, control coefficients [1] are used to describe how much influence a given reaction step has on the flux or concentration of the species at steady state. This can be accomplished experimentally by changing the expression level of a given enzyme and measuring the resulting changes in flux and metabolite levels.
The term "pharmacometrics" first appeared in literature in the preface of the 1964 book "Evaluation of Drug Activities: Pharmacometrics" [3]: The sub-title of the book is, as far as we are aware, a neologism, coined by one of us (A.L.B.), and the word is defined by the main title of the book, which could have been even more explicitly, if more verbosely, expressed as "The Identification and ...
The dissociation constant is commonly used to describe the affinity between a ligand (such as a drug) and a protein; i.e., how tightly a ligand binds to a particular protein. Ligand–protein affinities are influenced by non-covalent intermolecular interactions between the two molecules such as hydrogen bonding , electrostatic interactions ...
However, if a delay is observed between the drug administration and the drug effect, a temporal dissociation needs to be taken into account and more complex models exist: [6] [7] Direct vs Indirect link PK/PD models; Direct vs Indirect response PK/PD models [8] Time variant vs time invariant; Cell lifespan models; Complex response models