Flashcards in Medicines Deck (15)
Describe the term pharmacokinetics?
Pharmoacokinetics literally means drug movement and describes what the body does to the drug.
List the four processes of pharmacokinetics?
Absorption, distribution, metabolism and elimination.
What is meant by the term ‘bioavailability? Give an example of a route of administration that would have 100% bioavailability (or a bioavailability of 1)?
The term ‘bioavailability describes the amount of intact drug that reaches the circulation. An administration of an intravenous drug is considered to have 100% bioavailability.
Describe what happens to a tablet given to a patient from ingestion to the first pass?
The tablet will travel from the mouth to the GI tract. The tablet will be dissolved before being absorbed. The drug will be absorbed across the intestinal wall to enter the hepatic portal circulation to travel to the liver. The drug may be broken down partially or completely in the liver.
Would this oral drug need to be lipophilic or hydrophilic to reach the circulation more efficiently?
The drug formulation should be lipophilic to diffuse through the cell membranes of the GI wall to reach the circulation.
Define the term therapeutic effect?
Therapeutic effect is the desired effect of the drug on its target organ.
How does the drug travel to the target site?
The drug molecules attach themselves to plasma proteins ( known as protein binding).
How does a drug become active at the target site?
The drug molecule must detach itself from the plasma protein to become unbound/free to become active.
Define the term ‘elimination rate’?
The rate at which a drug is eliminated from the body is known as the elimination rate and it is measured in mg/h.
Why is it important to know the elimination half life of a drug?
It is important to know the elimination half life of a drug as it determines the frequency of repeat doses.
If the therapeutic index is low, is it more or less safe for a patient?
If the therapeutic index is low it is deemed less safe for the patient.
Describe the term ‘pharmacodynamics’?
The term pharmacodynamics explains the movement of a drug through the body and how it exerts its effect on target organs.
Describe what is meant by therapeutic range?
For drug therapy to work, drug concentrations must be maintained within the therapeutic range. This range is between the minimum effective concentration and the maximum safe concentration.
Describe the effect an agonist drug may have on a cell?
The change may be to stimulate the cell in a similar way to the endogenous ligand which is known as the agonist effect.