Phases Of A Drug Action Flashcards
What occurs during the Pharmaceutical phase of drug action
This is the administration of a drug, disintegration and dissolution
What occurs during the pharmacodynamic phase of drug action?
ADME
What occurs during the Pharmacodynamics phase of drug action
The interaction between the drug and target in order to produce a pharmacological response
What properties must a drug have to pass a membrane?
Lipophillic & unionised
Properties of a drug in order to be excreted in the urine?
• must suitable size to pass glomerular membrane
• soluble in water at the urine PH
Where are lipophillic compounds e created
In bile
What are the physiochemical properties of a drug?
• ionisation
• lipophlicity 
• shape and size
Partition coefficient is used to measure what?
Hydrophobicity of a drug
High P value - hydrophobic compounds
Low P value - hydrophilic comppunds
What does log P express ?
Hydrophobicity
Relationship between log P and biological activity
• drugs may become so hydrophobic that it is poorly soluble in aqueous phase
• can be trapped in fat deposits and never each it’s indented site
• hydrophobic drugs are more prone to metabolisms and then elimination
Does biological acitivity increase and log p increases ?
Yes
The value of log p at the max biological activity (log p0) - represent maximum partition coeffiencent
After this if log p increases biological activity decreases
Drugs targeted for the CNS, should have a log P of….
What does dissociation constant measure?
Extent of ionisation at a certain extent
Where so weak acids exist in the body
Stomach (ph 1-2)
Where so weak bases exist
Small intestine (ph - 6-8)
