Pharmacokinetics Flashcards
What is pharmacokinetics?
The movement of drugs in and the alteration of the drug by the body
List the pharmacokinetic processes?
Absorption
Distribution
Metabolism
Elimination
List the pharmacokinetic variables?
Bioavailability
Volume of distribution
Half life
Clearance
Absorption is to?
Bioavailability
Distribution is to?
Volume of distribution.
Metabolism is to?
Half life
Excretion is to?
Clearance.
What is absorption??
Movement of drugs from site if administration to systemic circulation.
What are the factors that affect absorption?
- Biological membranes
- Lipid-water solubility
- Physical/dosage forms
- Molecular and particle sizes
- Concentration
- Degree of ionisation and pH
- Chemical nature and route of admin
- Area of absorptive surface
- Vascularity of absorbing surface.
- Gi motility
- Diseases
- Presence of other substances.
What is bioavailability?
The percentage or fraction or portion of administered dose that reaches systemic circulation in an unchanged form irrespective of the route of drug administration.
What is distribution??
The passage of drugs from systemic circulation to other tissues that initially had no drug.
What are the factors that influence distribution?
Lipid solubility.
Ionisation at Physiological pH.
Extent of binding to plasma and tissue protein.
Presence of tissue specific transporters.
Difference in regional blood flow.
What is volume of distribution?
It is the apparent volume of drug that is distributed to provide the same conc as is in the blood plasma.
What is drug metabolism?
It’s the chemical alteration of drugs in the body.
What are the sites of metabolism?
Liver
Kidney
Lungs
Plasma
Placenta
Testis
List examples of hydrophilic drugs
Streptomycin
Neostigmine
Pancuronium
What are the phases of metab?
Phase 1
Phase 2
What is phase one reaction?
Addition of a small polar group to a drug molecule
What is the most important phase 1 reaction?
Oxidation.
List the oxidation reaction enzymes?
Monoxygenases
Cytochrome p450 heme protein
Cytochrome p450 reductase
Nadph