Pharmacology Flashcards
define “Ke”
it is the elimination rate constant i.e:
the amount of drug eliminated by the body per unit time
calculate Ke if the amount of drug in the body is 100% and 10% is eliminated per unit time
0.1
define first order kinetics
rate of elimination is DIRECTLY proportional to the drug conc
what happens to the Ke and t1/2 of 1sr order drugs when the dose is changed
THEY DONT CHANGE
what is clearance?
the volume of PLASMA cleared of drug per unit time
clearance only applies to drugs that exhibit __ order kinetics
first
what parameter determines the maintenance dose rate of a drug
clearance
for drugs that exhibit first order kinetics, the steady state plasma conc is __ related to the infusion rate
linearly
steady state plasma conc is reached after approx __ half lives
5
Vd is…
the volume into which a drug appears to be distributed with a conc equal to that of plasma
t/12 = /
VD/Cl
give an example of a zero order drug
ethanol
phenytoin
what does zero order kinetics mean?
drug is eliminated at a constant rate
phase 1 of drug metabolism?
oxidation reduction and hydrolysis
phase 2 of drug metabolism?
conjugation
main aim of drug metabolism?
increase polarity
how does phase 1 increase polarity?
adds a chemically reactive group
how does phase 2 increase polarity?
adds an endogenous compound
where does drug metabolism occur?
liver
only bound/unbound drug molecules can enter the glomerular filtrate
unbound
which of these drugs doesnt have to be monitored in renal impairment and why: ACEi PPI B blocker diuretic statin allopurinol
PPI
almost completely metabolised by the liver so avoids the kidneys
diuretics must be given after an MI T or F
F
what kind of diuresis do loop diuretics provide
strong
which of these drugs is most likely to cause hyperkalaemia: ACEi PPI B blocker diuretic statin allopurinol
ACEi
furosemide causes hypo/hyperkalaemia
hypo
ACEi ___ the reabsorption of sodium
decreases (get more K)
does simvastatin cause hypertension? explain your answer
no
has no effect on vascular smooth muscle or CO
why do nitrates cause hypotension
cause venodilatation and reduce preload
diuretics have what effect on blood vessels?
dilate them
which PPI can not be used with clopidogrel to treat gastric ulcers?
omeprazole
steady state plasma conc is achieved when…
rate of administration = rate of elimination
describe the relationship between time to steady state and dose rate
independent of each other
rate of elimination of the drug is independent of plasma conc T or F
F
Cp drives elimination
a large Vd is associated with a __ rate if elimination
slow
what value do you need to calculate the loading dose of a drug
Vd
penile erection depends on release of what chemical?
NO
what drug must NOT be used with viagra
nitrates
how do nitrates cause vasodilatation?
produces NO which increases intracellular cGMP in smooth muscle
what does viagra (sildenafil) do?
inhibits phosphodiesterase
is it safe to take b blockers with viagra?
yes
what common medication can exacerbate gout?
thiazide and loop diuretics
what drug should NOT be taken with grapefruit juice and why?
simvastatin
inceases oral bioavailability and toxicity of a statin
what common drug may be decreased in efficacy by impaired renal function
furosemide
secretion will be reduced in the PCT due to reduced GFR
Tx acute gout (include 1st 2nd and 3rd line)
- NSAID eg naproxen
- colchicine
- steroid
colchicine main side effects?
N+V
diarrhoea
how many days before surgery should warfarin be stopped?
5
what does warfarin block?
vitamin K reductase
how many half lives does it take for a drug to be excreted completely from the body
5
counteracting drug for paracetamol overdose?
IV N-acetylcysteine
MoA clonidine
a2 agonist eg antihypertensive
how does spinal anaesthesia cause hypotension?
blocks sympathetic transmission to blood vessels causing vasodilatation
