Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Clearance-limited drugs

High-clearance drugs are those for which there is no saturation of the reaction that converts the drug, and therefore, the clearance rate approaches the blood-flow rate. For capacity-limited drugs, flow rate is irrelevant, and clearance is a simple product of the unbound fraction and the intrinsic clearance. [Pg.350]

Since UFR cannot exceed blood flow through the hemofilter/ that establishes the theoretical upper limit for CLuf- The major determinants of SC are molecular size and the unbound fraction of a compound in plasma water. Values of SC may range from 0/ for macromolecules that do not pass through the pores of the hemofilter membrane/ to 1, for small-molecule drugs that are not protein bound. Although less information has been accumulated about the ultrafiltration clearance of drugs than about their dialysis clearance/ in many cases the unbound fraction of drug in plasma water can be used to approximate SC. [Pg.65]

Capacity-Limited Metabolism For some drugs clearance changes with the drug concentration. Increases in maintenance doses will result in a disproportionate increase in the steady-state drug concentration. Phenytoin is the classic capacity-limited drug. [Pg.2]

Metabolite clearance rate -limited by clearance of Drug... [Pg.202]

Figure 20.1 Schematic diagram illustrating how antidepressants increase the concentration of extraneuronal neurotransmitter (noradrenaline and/or 5-HT). In the absence of drug (b), monoamine oxidase on the outer membrane of mitochondria metabolises cytoplasmic neurotransmitter and limits its concentration. Also, transmitter released by exocytosis is sequestered from the extracellular space by the membrane-bound transporters which limit the concentration of extraneuronal transmitter. In the presence of a MAO inhibitor (a), the concentration of cytoplasmic transmitter increases, causing a secondary increase in the vesicular pool of transmitter (illustrated by the increase in the size of the vesicle core). As a consequence, exocytotic release of transmitter is increased. Blocking the inhibitory presynaptic autoreceptors would also increase transmitter release, as shown by the absence of this receptor in the figure. In the presence of a neuronal reuptake inhibitor (c), the membrane-bound transporter is inactivated and the clearance of transmitter from the synapse is diminished... Figure 20.1 Schematic diagram illustrating how antidepressants increase the concentration of extraneuronal neurotransmitter (noradrenaline and/or 5-HT). In the absence of drug (b), monoamine oxidase on the outer membrane of mitochondria metabolises cytoplasmic neurotransmitter and limits its concentration. Also, transmitter released by exocytosis is sequestered from the extracellular space by the membrane-bound transporters which limit the concentration of extraneuronal transmitter. In the presence of a MAO inhibitor (a), the concentration of cytoplasmic transmitter increases, causing a secondary increase in the vesicular pool of transmitter (illustrated by the increase in the size of the vesicle core). As a consequence, exocytotic release of transmitter is increased. Blocking the inhibitory presynaptic autoreceptors would also increase transmitter release, as shown by the absence of this receptor in the figure. In the presence of a neuronal reuptake inhibitor (c), the membrane-bound transporter is inactivated and the clearance of transmitter from the synapse is diminished...
Drug delivery to the respiratory tract has been characterized in the past decade by an increase in knowledge of drug droplet or particle manufacture, behavior, aerosol dispersion, lung deposition and clearance. The number of diseases for which aerosol therapy may be applicable has increased dramatically. The pharmaceutical scientist is no longer limited to pulmonary diseases as therapeutic targets. Substantial progress has been made in every area of pharmaceutical aerosol science, and it is anticipated that this will ultimately lead to many new therapies. [Pg.499]


See other pages where Clearance-limited drugs is mentioned: [Pg.14]    [Pg.117]    [Pg.42]    [Pg.266]    [Pg.301]    [Pg.304]    [Pg.35]    [Pg.60]    [Pg.73]    [Pg.618]    [Pg.243]    [Pg.598]    [Pg.253]    [Pg.2429]    [Pg.92]    [Pg.185]    [Pg.153]    [Pg.329]    [Pg.46]    [Pg.101]    [Pg.97]    [Pg.102]    [Pg.289]    [Pg.218]    [Pg.700]    [Pg.450]    [Pg.518]    [Pg.89]    [Pg.726]    [Pg.250]    [Pg.1457]    [Pg.71]    [Pg.141]    [Pg.233]    [Pg.629]    [Pg.208]    [Pg.76]    [Pg.326]    [Pg.314]    [Pg.174]    [Pg.422]    [Pg.420]    [Pg.480]   
See also in sourсe #XX -- [ Pg.212 ]




SEARCH



Drugs Limitations

© 2024 chempedia.info