Pharmacokinetics Flashcards
What are the 4 types of processes?
- Absorption
- Distribution
- Metabolism
- Elimination
What is the purpose of absorption?
- The absorption stage starts when the drug is administered
- The rate of absorption is directly affected by the route administration
- The better the blood supple, the quicker the rate of absorption and the higher the bioavailability
What is bioavailability?
- the amount of drugs that reaches the circulation tract (unaltered)
What are the types of route administrations?
- Intravenous (IV)
- Intramuscular (IM)
- Subcutaneous (S/C)
- Per rectum (P/R)
- Oral (PO)
What is the quickest to the slowest administration route?
Highest:
IV
IM
S/C
PO
Lowest:
What is the first-pass effect?
- The drug molecules are identified by the liver as toxins and some of them are metabolised
What is the purpose of distribution?
- Drug enters systemic circulation
- Then, it’s let free or binded to albumin
- if it binded with albumin its inactive
- if it is let free it diffuses into tissue and equilibrium is processed between tissues
Purpose of distribution continued…
- Prevention of distribution can occur using natural barriers that act to protect themselves against toxicity
- The blood brain barrier acts to protect the brain against toxicity
It is a lipid barrier so only lipophilic drug molecules can cross - Redistribution occurs when the tissues redistribute back into the circulation to move to other area where tissues are les perfused
What is the purpose of metabolism phase 1?
- The metabolism is split into 3 different parts called oxidation, reduction or hydrolysis
- Then this is metabolised
What is the purpose of metabolism. phase 2?
- When it metabolised this added up. with endogenous substrate
- Then its makes up hydrophilic inactive conjugate
What are the types of elimination ways?
- Milk
- Sebrum
- Saliva
- Urine
- Bile/faeces
- Exhalation
What is the process of elimination in urine one way?
- Once way is hydrophilic drugs metabolite OR hydrophilic low MV drug
- Then it moves though the kidneys to produce urine
What is the process of elimination in urine second way?
- Second way os non-hydrophilic
- Then it moves though the kidney then it is reabsorbed and produces urine
What is the process of elimination in faeces?
- Large molecules weight drugs/ metabolites in liver
- Then goes through the biliary tract
- Then its moves though the small intestine to make faeces
What is a half-life?
- The amount of time required for the concentration of drug in the blood to decrease by 50%
What will happen with therapeutic drugs with too wide range?
- Large overdose to cause toxicity
What will happen with therapeutic drugs with too narrow range?
- Small dose to cause toxicity
What is pharmacokinetics?
- Drug movement or what the body does to the drug
What is pharmacodynamics?
- Drug action or what the drug dose to the body
What does protein binding do?
A drug molecule binds to albumin which renders it inactive in the circulation
What does three-way equilibrium do?
Between the drug molecules in the target tissues, the protein bound drug molecules in the systemic circulation and the unbound or free molecule in the systemic
What does the blood brain barrier do?
A lipid barrier that prevent toxins from entering the brain. Drug molecules must be lipophilic to cross into the brain
