Study Set Content:
90% used by drugs
Passive diffusion
Concentration gradient
Passive diffusion
a passive process
governed by Fick’s Law
Convective transport
No energy required, non-saturable process
Passive Diffusion
Drug molecules dissolved in aqueous medium at
the absorption site move along with the solvent
through the pore
Convective transport
Water filled pore
Convective transport
Move against concentration gradient
Requires a carrier – carrier mediated
Requires the expenditure of ATP
Active transport
Pathway for small molecules, hydrophilic drugs,
ionic drugs
Convective transport
Follows saturation kinetics:
Active transport
Follows saturation kinetics: when active
transport become saturated the rate becomes
saturated the rate process will be
zero-order
(Michaelis Menten Equation)
not governed by Fick’s
law and is capacity-limited
Facilitated Diffusion
The rate of transport is dependent on
concentration
Convective transport
Permeability is not affected by pH and the
surface area (Ex. Urea, Ionic drugs, Mannitol)
Convective transport
Follows concentration gradient
Competitive inhibition
Poisoning of Carrier
Saturation of Carrier
Facilitated diffusion
large cations, highly
ionized compounds.
Ion-pair transport
Ions of ()
charges come together and passes through
the membrane like an unionized moiety
Opposite
Follows a concentration gradient (passive
diffusion)
No energy expenditure
First order kinetics
Ion-pair Transport
phagocytosis and
pinocytosis
Endocytosis
Conformational change
Endocytosis
Membrane vesicles move another
membrane vesicles
Endocytosis
