pharmacokinateics Flashcards
Dfine abosrption:
Transfer of drug from its site of administration to the blood stream.
define bioavailabilty:
Percentage of the administered dose of the drug that is
present in the systemic circulation in unchanged form.
passive diffusion is ;
-Driving force is
the concentration
gradient
passive diffusion features :
-No carrier
-Not saturable
-Low structural
specificity
-Lipid or aqueous
diffusion
Facilitated
diffusion
-Need specific carrier
-Saturable
-Not Energy dependent
-Drugs move from regions of high conc. To
regions of lower
conc.
Filtration
-Water soluble drugs and small sized ions
-Pass across water filled pores
-No energy
-According to osmotic or hydrostatic pressure
Active transport features
-Need specific
carrier
-Saturable
-Energy
dependent
-Drugs move
against
concentration
gradient
define endocytosis :
-Cell membrane folds in on itself engulfing substance in a vesicle
endocytosis is used mainly for
absorption of drug with high molecular weight
Ion-pair transport
-Highly lipophobic drugs combine reversibly with endogenous compound
to form neutral ion pair
complex that penetrate lipid membrane passive diffusion
Most substances, lipid or water soluble, cross……..
rates rapid in
comparison with their rates of passage across other body membrane.
capillary wall
major mechanism of passage
of drugs across most capillary endothelial Membrane,
Bulk flow of liquid occurs through intercellular pores in most capillary endothelial Membrane,
except:
CNS
through tight junction
(ionization constant) defined as
the ability or tendency of the drug to
ionise.
