PHAR232 - pharmacokinetics wk 5 Flashcards
What is pharmacokinetics?
Pharmacokinetics is the study of how the body absorbs, distributes, metabolizes, and eliminates drugs.
What are the 4 key areas of pharmacokinetics?
The four main processes of pharmacokinetics are:
Absorption: This is the process by which drugs enter the bloodstream from the digestive tract, skin, or other tissues.
Distribution: This is the process by which drugs are transported throughout the body.
Metabolism: This is the process by which drugs are broken down by the liver and other organs.
Excretion: This is the process by which drugs are excreted from the body, typically through the kidneys or liver.
What are tissue reservoirs?
A place where a drug can hide e.g. fat cells
Where is the major site for metabolic biotransformation?
The liver
What is the primary organ for excretion?
Kidney function
CV intergrity
When you age do you lose plasma protein?
Yes
What’s the role of pharmacokinetics in research?
- Invsestigate implications for developing foetus
- Designing safe and effective doses
- Amelioration of disease
- Inter-species variability (animals vary massively)
What is the accronym for the basis of Pharmacokinetics?
L=Liberation= release of drug from formulation
A = Absorption - update of drug into circulation
D = Distribution - Movement of drug between body compartments
M = Metabolism - effect of ENZYMES on drug
E = Excretion - Removal of unchanged drug or metabolite from body
What is the addition term for ‘metabolism + excretion’?
Elimination
What is the additional term for ‘Distribution + elimination’?
Disposition
The are the key family of liver metabolic enzymes?
CYP450 family
What phase of detoxification does CYP450 enzymes convert drugs/metabolites to?
Phase I
Is the metabolite (offspring) the same as the drug (parent)?
No e.g. if 100% of the drug was metabolised, there is no more DRUG. The drug no longer exists.
How do you evaluate systemic drug exposure?
- Circulation: Plasma, serum, whole blood
- Products: milk, urine, saliva, exhaled air
UNDERSTAND MORE ABOUT PLASMA DRUG CONCENTRATIONS
WHAT MATTERS IS THE FREE-UNBOUND DRUG IN PLASMA
Bound to plasma protein = CANNOT EXERT AN EFFECT
Measurement of plasma concentration = bound & unbound
MUST KNOW KINETICS and how much is bound and effective concentration
What are disadvantages of plasma drug concentration evaluation?
- Measurement of plasma concentration = bound & unbound drug
- Assumes good integrity of circulation (atherosclerosis etc)
- Assumes homogenous distribution of drug e.g equilibrium of drug between plasma & tissues (intereference)
UNDERSTAND MORE ABOUT COMPARISON OF PLASMA & WHOLE BLOOD CONCENTRATIONS FOR DRUG EVALUATIONS
What is the exposure-time profile determined by?
- Rate of drug administration
- Dose administered at this rate
- Distribution
- Rate of elemination
What does Cmax stand for?
Maximum concentration of drug
What does tMax stand for?
Time of maximum concentration