Drug Metabolism And Kinetics Flashcards
What are the three phases of drug action?
Pharmaceutical phase (release of the drug)
Pharmacokinetics phase (what the body does to the drug)
Pharmacodynamic phase (what the drug does to the body)
What are the pharmacokinetics factors that make a good drug?
Absorbed well by the body
Reaches target easily
Not modified, inactivated or removed by the body too quickly
What are the pharmacodynamic factors that make a good drug?
Effective at targeting the disease process
Not toxic
What is potency?
The dose required to achieve the effect
What is efficacy?
The maximal effect
What does ADME stand for?
Absorption
Distribution
Metabolism
Elimaination
What does absorption mean in ADME?
Process of drug entering the body
What does distribution mean in ADME?
Drug leaving the bloodstream and distributing into the interstitial and intracellular fluids of various compartments of the body
What does metabolism mean in ADME?
Bio transformation of drug molecules
What does elimination mean in ADME?
Clearance of drugs
What are the factors affecting drug absorption?
Solubility = needs to be water-soluble
Ionisation= needs to be close to neutral
Stability= needs to be chemically stable
What are the factors affecting distribution of drug?
Plasma-solubility= including binding to plasma proteins
Lipophilicity= balance between water and fat solubility
Perfusion= level of blood flow to a tissue/ other areas of the body
What are the major routes of drug elimination?
Urine, faeces
What are the minor routes of dog elimination?
Exhalation
Sweat
How many phases of metabolism is there?
2
Phase I
Phase II
What is phase I metabolism?
Chemically diverse small molecules transformed to more polar compounds
What are CYP-P450 enzymes?
Haemoproteins
In liver cells
Belong to monoxygenoses
What type of reactions are present in CYP-P450 reactions.
Hydroxylation
Epoxidation
Dealcylation
Deamination
Oxidation
Dehalogenation
What type of reactions are present in non-CYP reactions?
Oxidation
Hydrolysis
Reduction
Deamination
What is phase II metabolism?
Conjunction reactions generally result in more polar compounds. These are rapidly eliminated via urine and/or bile.
What reactions are present in phase II metabolism?
Glucuronidation
Sulfation
Methylation
Amino acids
Acetylation
What is the first pass effect?
Drugs that are taken orally pass directly to the liver once they enter the blood supply. They are therefore exposed to metabolism before they are distributed around the rest of the body
