Psychopharmacology

Question 1

Define drugs, therapeutic effect and side effects

Answer 1

Drugs: specific for certain receptors causing molecular changes in cell

Therapeutic effect: desirable change of drug-receptor

Side effects: other effects following main effect

Question 2

What does pharmacokinetics and pharmacodynamics mean?

Answer 2

Pharmacokinetics: process by which drugs are absorbed, distributed, metabolised and excreted (what body does to drug)

Pharmacodynamics: study of effects of drug within target tissue (what drug does to body)

Question 3

What is ED50 and TD50 and therapeutic index?

Answer 3

ED50: dose at which 50% of subjects experience beneficial effect

TD50: dose at which 50% of subjects suffer toxic effect

Therapeutic index: TI = TD50/ED50

The closer together the index is the less safe drug

Question 4

Describe the blood-brain barrier

Answer 4

Brain capillaries have tight junctions and covered in astrocyte feet –> small uncharged molekules pass through membrane, some bigger are carried by active transport, large charged molecules cannot pass –> sometimes drugs must be manipulated to pass (ie dopamine -> L-dopa)

Question 5

Describe the ‘lock and key’ methods for drugs

Answer 5

Structurally similar compounds can bind to receptor sites (usually proteins) - Agonist

Affinity: degree of attraction between molecule and receptor

Efficacy: the degree to which compound may bind to receptor site and initiate

Antagonist: No cellular effect after binding (that way they can block receptor sites and prevent other agonists from binding)

Question 6

Describe drug tolerance

Answer 6

Pharmocodynamic tolerance: decreased response to drug over time

behavioural tolerance: People learn to cope with being intoxicated (ie alcohol)

Metabolic tolerance: increase levels of enzymes that breakdown a drug

Question 7

How does a PET scanner work and what does it do?

Answer 7

Detects a decaying positron (via gamma ray emission)

can measure the extent to which a drug binds to specific receptor site

Question 8

What are the 3 phases of bringing drugs to the market?

Answer 8

Preclinical (in animals)

1) In healthy people (<100); proof of mechanism; safety at high doses
2) In specific patients (100s), check efficacy and side effects
3) efficacy and safety in many patients (1000s)