12 Questions
What is the effect of plasma protein binding on drugs?
Drugs are effectively inactive and stored in the bloodstream
What is a result of a drug being lipid-soluble and unionised?
The drug can more easily traverse biological membranes
What is a limitation of water-soluble drugs?
They are unable to access tissues with tight junctions between cells
What is a factor that affects the rate of drug distribution to organs?
The perfusion of the organ
How can liver disease affect drug distribution?
It alters blood protein production
What is a consequence of inflammation and damage on drug distribution?
It reduces the integrity of diffusion barriers
What happens to drugs when they bind to plasma proteins?
They are effectively inactivated and stored
Which type of drug is more likely to traverse biological membranes?
Unionised and lipid-soluble
What determines the rate at which drugs are distributed to organs?
The perfusion of the organ
How can shock or heart failure affect drug distribution?
By decreasing organ perfusion
What is a consequence of liver disease on drug distribution?
Altered blood protein production
What happens to the duration of action of some drugs due to tissue protein binding?
It is prolonged
Study Notes
Factors Affecting Drug Distribution
Protein Binding
- Bound to plasma proteins, drugs are effectively inactive and stored in the bloodstream
- Only free drug can enter tissues
- Binding to tissue proteins creates a store, contributing to a longer duration of action and delayed metabolism and elimination
Lipid Solubility and Ionisation State
- Lipid-soluble and unionised drugs can easily traverse biological membranes
- Leads to 'ion-trapping' in tissues
Barriers to Diffusion
- Water-soluble drugs cannot access tissues with tight junctions between cells, unless by specific transport mechanism
- Lipid-soluble drugs can transverse cell membranes, easily accessing tissues across diffusion barriers
Compartment or Organ Size and Perfusion
- Well-perfused and larger organs receive drugs faster than poorly perfused organs
Disease Presence and Type
- Conditions like shock or heart failure reduce organ perfusion
- Liver disease or malnutrition alter blood protein production
- Abnormal metabolic states like uraemia change protein binding
- Inflammation and damage affect integrity of diffusion barriers
Factors Affecting Drug Distribution
Protein Binding
- Bound to plasma proteins, drugs are effectively inactive and stored in the bloodstream
- Only free drug can enter tissues
- Binding to tissue proteins creates a store, contributing to a longer duration of action and delayed metabolism and elimination
Lipid Solubility and Ionisation State
- Lipid-soluble and unionised drugs can easily traverse biological membranes
- Leads to 'ion-trapping' in tissues
Barriers to Diffusion
- Water-soluble drugs cannot access tissues with tight junctions between cells, unless by specific transport mechanism
- Lipid-soluble drugs can transverse cell membranes, easily accessing tissues across diffusion barriers
Compartment or Organ Size and Perfusion
- Well-perfused and larger organs receive drugs faster than poorly perfused organs
Disease Presence and Type
- Conditions like shock or heart failure reduce organ perfusion
- Liver disease or malnutrition alter blood protein production
- Abnormal metabolic states like uraemia change protein binding
- Inflammation and damage affect integrity of diffusion barriers
This quiz covers the factors affecting drug interactions, including protein binding and lipid solubility. Understand how drugs interact with plasma and tissue proteins, and how lipid solubility and ionization state impact their activity.
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