Drug distribution Flashcards Preview

Principles of disease (Ross Lilley) > Drug distribution > Flashcards

Flashcards in Drug distribution Deck (18)
Loading flashcards...
1

drug distribution

the Reversible Transfer of a Drug between the Blood and the Extra Vascular Fluids and Tissues of the body

2

factors that affects the amount of bound drug to plasma proteins

-renal failure (less binding therefore increased distribution)
-hypoalbuminaemia (less binding increases distribution)
-pregnancy (decreased binding increased distribution)
-other drugs
-saturability of binding

3

Apparent Volume Of Distribution (Vd)

Fluid volume that would be required to contain the amount of drug present in the body at the same concentration as in the plasma

4

the greater the Vd the...

greater the ability of the drug to diffuse into and through membranes

5

Vd of highly protein bound drug

3L

6

clearance

the theoretical volume from which a drug is completely removed over a period of time. it is a measure of elimination

7

what is clearance dependent on?

-conc.
-urine flow rate
-metabolism
-biliary excretion

8

biliary excretion

Irreversible transfer of drug or drug metabolites from the plasma to the bile through the hepatocytes

9

half life ( t1/2)

time taken for the drug concentration to drop by a half of the current value

10

effect of prolongation of half life

increase in toxicity, due to reduction in clearance and large volume distribution.

11

chronic administration

used to reach a therapeutic range, this may take 4 or 5 doses/ half-lifes

12

how does half life affect time to stabalisation

the longer the half life the longer the time to stabalisation and the therapeutic range

13

2 parts of drug elimination

drug metabolism
drug excretion

14

three principal mechanisms for excretion form kidneys

-glomerular filtration
-passive tubular absorption
-active tubular absorption

15

glomerular filtration

filters out unbound drug

16

active tubular filtration

acidic and basic compounds are actively secreted into the proximal tubule, eliminates protein bound cationic and anionic drugs

17

passive tubular reabsorption

passive diffusion of down concentration gradient allows drug to move back into tubule to circulation

18

biliary secretion

drugs are excreted in bile through liver