Drug Absorption Flashcards
(31 cards)
What is a pharmaceutical process?
the process of getting the drug into the patient
What is the pharmacokitenic process - and define ADME.
The process of getting the drug to the site of action/ what the body does to the medicine. Absorption Distribution Metabolism Elimination
What is the pharmacodynamic process?
A process to produce the correct pharmacological effect.
What is the therapeutic process?
A process to produce the correct therapeutic effect.
What must occur for biological action to occur?
The drug must enter the blood stream and be distributed to the site of action.
What is the definition of absortion?
‘The process of movement of the unchanged drug from the sight of administration to the systematic circulation.
What is the therapeutic range?
The range that the drug is active across.
What happens above the therapeutic range?
The drug becomes toxic - harms the patient.
Name three physiochemical factors that affect the transfer of drugs across cell membrane.
Ionisation, Lipid solubility, Structure
Most drugs are weak acids and bases, so do not completely ionise. The degree of disossiation depends on the pH of the environment, so a small change in pH dramatically effects the whole drug absorption by the body. But which type of drug crosses the membrane easily, ionised or de-ionised?
De-ionised.
Do drugs need to be lipid soluble or insoluble to cross the membrane?
Soluble.
What must the structure of the drug resemble in order to cross the membrane?
A naturally occuring substance - to pass through the pumps in active transport.
What three factors affect the absorption of drug from the GI tract?
1) Motility (speed of gastric activity)
2) Food
3) illness
Does food impair or enhance drug absorption from the GI tract?
Could do both.
What is first pass metabolism?
Metabolism of drug PRIOR to it reaching the site of activity.
How can you avoid first pass metabolism?
Using other drug delivery methods.
Where does first pass metabolism happen?
gut lumen, gut wall, liver.
What are the benefits of IV?
100% bioavailability, bypasses First pass metabolism.
What are the benefits of Topical medicine?
Can have local/systematic effects, controlled dose, bypasses first pass metabolism.
What are the benefits of inhalating medication?
Drug delivered straight to sight of action, only need a small dose, rapid. Little systematic effects, so less adverse reactions.
What is bioavailability?
The amount of drug that reaches circulation and is available for action.
What affects bioavailability?
Ability to pass through membrane, GI effects, first pass mechanisms.
What is the ultimate aim of drug delivery ?
To deliver drug therapy without toxicity.
Does rectal administration bypass first pass metabolism?
Yes.
