PHARMACOKINETICS (diffusion, transport) Flashcards
Mechanisms of drug absorption:
- Simple Diffusion
- Facilitated Diffusion
- Active Transport
- Filtration
- Pinocytosis
– most common, passive process in which of the drugs are absorbed.
Simple Diffusion
Characteristics of Simple Diffusion:
a. pass lipid soluble drugs
b. movement is from higher to lower concentration
c. (-) energy requirement
d. (-) carrier mediated mechanism
Factors that affect movement of drugs molecules:
a. Molecular Size - main factor
b. Molecular Shape
C. Molecular Charge
Characteristics of Facilitated Diffusion:
a. pass lipid insoluble drugs
b. movement is from higher to lower concentration
c. (-) energy requirement
d. carrier mediated mechanism
– responsible for maintaining low intracellular Na+ levels & high intracellular K+ levels characterized by non-depolarized neural tissue
Active Transport
a type of membrane transport that does not require energy to move substances across cell membranes.
Passive Transport
Characteristics of Active Transport:
a. pass electrolytes
b. movement is from lower to higher concentration
c. (+) energy requirement
d. carrier mediated mechanism
movement of drug molecules thru structures of coarse porosity in the presence of pressure gradient e.g. hydrostatic or osmotic pressure
Filtration
dissolved substances (liquid form) are transported by endocytosis & excreted by exocytosis
Pinocytosis
Higher to Lower drug concentration:
- Simple Diffusion
- Facilitated Diffusion
Lower to Higher drug concentration
Active Transport
Lipid soluble drug
Simple Diffusion
Lipid insoluble drugs:
- Facilitated diffusion
- Active Transport
( - ) negative energy requirement
- Simple diffusion
- Facilitated Diffusion
