Basic Pharmacokinetics Flashcards
What does PK data allow?
To calculate correct dose
What is DL?
Initial dose
What is Cmax?
Max plasma conc
What is Tmax?
Time to reach Cmax
What is VD?
Distribution vol
What is C?
Plasma conc
How do you calculate DL?
V X C
What does PK give us?
Which dose to give
Which administration route
How often to give dose
Which administration formulation
What are the different administration routes?
Oral Parental Nasal Topical Rectal Vaginal
Describe systemic
Uses circulatory system to distribute drug
Whole body exposed
Greater risk of side effects
Describe topical
Drug applied to specific part of body
Only small areas of body exposed to drug
Adverse effects are local
Describe channel protein
Forms pores in membrane
Small molecules can pass through adjacent cells connected at tight junctions
Describe carrier protein
Bind specific drugs
As consequence undergo conformational change = molecules pass through
What is therapeutic range?
Range of plasma conc of drug, which therapeutic effect is achieved, which is safe + doesn’t cause major side effects
What is narrow therapeutic range?
Very short range of drug serum conc at which drug has therapeutic effect = drug can be easily over/under dosed
Describe ionic drug binding
Association of ions of opposite charge by transfer of e-
What does it mean in ionic drug binding that they are weak?
Easily broken through induction of different ion with greater affinity
Describe hydrogen drug binding
Strongest bound
What does hydrogen bound determine?
The way the drug interacts with target molecule
Degree of binding to plasma protein
What is different about hydrogen bound drugs?
Binding is reversible, conc dependent + subject to competition with other drugs
Describe continuous capillary bed
In almost all vascularised tissues
Complete endothelial lining with tight junctions
NOT associated with brain
Describe fenestrated capillary bed
Has pores
Permeable to larger molecules
Where is fenestrated capillary bed common?
Small intestine + kidney
Describe sinusoid capillary bed
Intracellular gaps + incomplete basement membrane
Intracellular clefts + fenestrations
Passage of large molecules
Which is the least common capillary bed?
Sinusoid
Describe blood flow in sinusoid capillary bed
Very slow = more time for drug exchange
Where is sinusoid capillary bed?
Liver, spleen, bone marrow, lymph nodes + endocrine glands
Describe blood brain barrier structure
Continuous non-fenestrated vessels
Specialised layer of tightly packed capillary endothelial + glia cells
What is function of BBB?
Protect CNS from toxins
Provides obstacle for drug delivery
What is problem with BBB?
Inflammation can make BBB more permeable
= bacterial meningitis, penicillin can penetrate through inflammation
