Drug absorption Flashcards
What does ADME stand for
Absorption
Distribution
Metabolism
Excretion
What is absorption
The process by which unchanged drug enter the circulation
What is distribution
Diversion of a drug among fluids and tissues of the body
What is metabolism
Transformation of a drug into daughter compound(s)
What is excretion
Removal of drugs/metabolites from the body
What happens when the route of administration for a drug changes
Different barriers to absorption
Different bioavailability and onset
Oral administration
- many barriers
- Digestive enzymes
- All drugs funnelled through the hepatic portal vein and therefore into the liver
Intravenous injection
- No barrier
- No drug is lost
Tropical cream
-Direct administration
Inhalers
- Direct delivery to the lungs
- Helps with the safety profile as it doesn’t need to reach the level of concentration in the systemic circulation which might have toxic effects
Why is the choice of delivery a compromise
- Speed of onset
- Convenience
- Bioavailability; proportion of administered drug reaching the systemic circulation
- Side effects
- Specificity of action
What is transcellular absorption
Drug travels through cells
What is paracellular absorption
Drug travels in-between cells
How can absorption occur from the most common to the least common
- Passive diffusion
- Facilitated diffusion
- Active transport
What is Fick’s law
Rate of diffusion = Surface area * concentration difference * permeability
