PHARMACOKINETICS

Question 1

protein binding
Main plasma protein for binding alkaline drugs?
Main for acidic drugs?

Answer 1

1. Alkaline- a-1 acid glycoprotein
2. Albumin- acidic

Question 2

what is transported easily across BBB

higher the lipid-water partition coefficient,,,

Answer 2

unionised molecules that are freely available and less protein bound

,,, greater the ability to cross the barrier

Question 3

what are circumventricular organs that lack BBB

Answer 3

• subfornical organ
• area postrema of medulla
• median eminance

Question 4

For a drug to reach steady state it typically takes

Answer 4

5-6 half lives.

Question 5

CYp enzymes act in endoplasmic reticulum of..

Answer 5

hepatocytes and cells in intestine (why if hepatitis or cirrhosis then affects metabolism)

Question 6

CYP and …
1. SSRIS -
2 Carbamazepine
3. TCA + haloperidol
- inducers
- inhibiters

Answer 6

1. SSRIS - inhibit CYP. fluoxetine increases plasma TCA, fluvoxammine increases plasma clozapine 10X
   2 Carbamazepine - decreases plasma conc of drugs eg contraceoptive pills
2. TCA + haloperidol - compete with each other
   - inducers - alcohol, smoking
   - inhibiters grapefruit juice, caffeine

Question 7

what enzymes does smoking and caffeine affect

Answer 7

CYP1A2 + UGT enzyme (glucuronidation reaction)
e.g. clozapine and olanzapine affected

Question 8

Which enzyme is involved in the aetiology of alcoholic brain damage?

Answer 8

Transketolase - it requires thiamine (vitamin B1) as a co-factor. Chronic alcohol misuse can lead to thiamine deficiency

Question 9

the least cardiotoxic TCA

Answer 9

Lofeprmaine

Question 10

BEST antipsychotic in .iver disease

Answer 10

amisulphride

Question 11

volume of distribution

Answer 11

Vd = amount of drug in the body/concentration in the plasma

Question 12

antidepressants is associated with a relatively lower incidence of sexual dysfunction?

Answer 12

Reboxetine

Question 13

weight gain caused by antipsychotic drugs is thought to be mediated, in part, via what mechanism?

Answer 13

Histamine receptor antagonism.