Masterclass Flashcards
Overall revision of suggested questions from UOB.
What is pharmakokinetics?
The way in which the body affects the drug.
What are the processes involved in pharmakokinetics?
ADME
Absorption
Distribution
Metabolism
Excretion
What is absorption?
The process by which a drug gets absorbed into the systemic circulation.
What factors can affect absorption?
- Blood flow to site of absorption.
- Route of administration.
- Drug solubility.
- PO: Food/stomach pH/GI motility.
What is distribution?
The process by which drugs move from the bloodstream into different tissues/organs in the body to act at receptor sites.
What can affect distribution?
- Blood flow.
- Plasma protein binding.
- Drug solubility.
2) Only unbound drugs can move into tissues/organs.
3) Lipid-soluble drugs can distribute into fat-rich tissue however water-soluble prefers to stay in watery areas like blood.
What is metabolism?
The process by which the body breaks down the drug to form metabolites. They can be:
1) Inactive
2) Equally or more active
What are the 2 phases of metabolism?
1) Oxidation/Hydrolysis: Usually involves CYP450 enzymes.
2) Conjugation of phase 1 metabolite: To help elimination.
Explain the first pass effect?
The metabolism of a drug and its passage from the liver into the circulation.
Orally: Drugs given orally may be extensively metabolised by the liver before reaching the systemic circulation.
IV: Drugs given IV bypass this process therefore more drug reaches circulation.
Explains why doses are changed for PO vs. IV.
What factors can affect metabolism?
- Blood flow to the liver.
- Hepatic impairment.
- Genetic variations affecting enzyme systems.
What is excretion?
The process by which the body clears the drug usually by the kidneys via urine.
Can also be excreted by sweat, the bilary system and faeces.
