Concentration and response Flashcards
What is pharmacokinetics?
How the body affects a drug.
Also known, as the study of the movement of a drug into, within and out of an organism.
What are the 4 phases of pharmacokinetics?
- Absorption
- Distribution
- Metabolism
- Excretion
known as ADME
What does pharmacological effect depends on?
- Active molecule reaching the site of action.
- Adequate concentration at the site of action.
What does the drug Clopidogrel require?
This requires oxidation and hydrolysis. (The hydrolysis is mediated by the liver enzyme.
What do pro - drugs require before they become active?
They require a metabolic step before they become ‘active’.
What does the drug Sulfasalazine require?
They require intestinal bacteria in order to activate metabolites sulfapyridine and 5 - aminosalicyclic acid.
What is the law of mass action?
Chemical principle which proposes the rat of reaction is proportional to the product of the concentrations of the reactants.
What is kb/kf known as?
This is known as the apparent dissociation curve.
What does a hyperbolic line represent?
A non - linear relationship is expressed.
What is the threshold model?
Points at which the effects are going to be seen.
List the pharmacokinetic factors which determine the concentration of a drug at its target (ADSORPTION).
Drug Factors - Dissolution characteristics // solubility // permeability.
Patient Factors - When the meal is taken : gastric pH elevates and thus the drug precipitates in its un - ionised form. This means LESS is absorbed.
List the pharmokinetic factors which determine the concentration of a drug at its target (DISTRIBUTION).
Drug Factors - Chemical characteristics (lipid / water solubility) // molecule size // protein binding.
Patient Factors - Blood flows to the organs.
List the pharmokinetic factors which determine the concentration of a drug at its target (METABOLISM).
Drug Factors - Mentioned in A and D.
Patient Factors - Enzyme activity // organ function // age.
List the pharmokinetic factors which determine the concentration of a drug at its target (EXCRETION).
This is interlinked to the METABOLISM one
Drug Factors - Mentioned in A and D.
Patient Factors - Enzyme activity // organ function // age.
Explain the law of mass action.
Free drug D and free receptor R reaches equilibrium with drug receptor compound DR: achieved via rate constants kf (forward) and kb (backward).
