Pharmacokinetics Flashcards
Charged drugs cross freely across membrane in SI true or false?
False - charged drugs are not absorbed and are defecated
What can the Hendelsohn Hasselbach equation be used for? Give equation…
Estimating % ionisation of a drug - therefore % charged/not absorbed at given pH
pH = pKa + log([A-]/[HA])
Why should drugs by lipophilic UP TO A POINT?
Lipophilia increases permeability in SI for absorption
However, it also decreases solubility and reduces how much the drug spreads away from site of injection
Which is the fastest route of drug administration? Slowest?
Fastest = IV Slowest = topical/transcutaneous
Which is faster - inhalation or intramuscular/subcutaneous?
Inhalation
Which is faster, oral/rectal or sublingual?
Sublingual
What’s faster, oral/rectal or intramuscular/subcutaneous?
Oral/rectal
Which absorb faster - liquids or capsules?
Liquids
How might you control drug release of tablet in the body?
Modifying particle size
Modifying solubility of coating
What does coating a tablet do to absorption and peak concentration?
Lowers both of them
Distribution of drugs bound to plasma proteins?
They don’t get distributed as much as it reduces free drug concentration
Also keeps drug in system for longer as it reduces renal clearance
ADME - match each to different points on concentration curve:
Increase towards peak conc.
Peak conc.
Decreasing conc. after peak
Absorption occurs as drug conc. increases
At peak conc. drug is distributed
As durg conc. decreases, it is being metabolised and excreted
