12 Quantitative Pharmacodynamics

Question 1

Levodopa (L-DOPA)

Answer 1

Immediate precursors to dopamine in the biosynthetic pathway (endogenous)

Carbidopa is an inhibitor of of DOPA decarbocylase, carbidopa blocks dopamine crossing blood brain barrier and increases the amount of dopamine in the brain and reduces the effects of Parkinson’s

Question 2

Pro-drug definition

Answer 2

precursor of a drug, prodrug must undergo a chemical conversion within the body before becoming an active pharmacological agent

Question 3

General concepts of pharmacodynamics

Answer 3

Relationship between drug concentration and drug effects

Develop bioassays and biomarkers

Creating dose and response curves which allow pharmacologists to quantitatively measure and compare drug efficacy and potency

Question 4

Pharmacodynamics (PD) definition

Answer 4

Study of biochemical and physiological effects of drugs on the body, the mechanisms of drug action and the relationship between drug concentration and effect (what a drug does to the body)

Question 5

Dose-Response Curves (DR)

Answer 5

Size of a response to an agonist depends on how much of the drug is administered

Question 6

2 types of DR curves

Answer 6

1. Hyperbolic
2. Sigmoidal

Question 7

Advantages of log(conc) ploys

Answer 7

Small change in concentration produces a relatively larhe change in response (easier to measure in log plot) / easy to compare relative potency of agonists (eg. Measuring EC50 - conc giving 50% response)

Question 8

Full agonists

Answer 8

drugs whose max response is the largest a tissue or cell is capable of giving (high efficacy)

Question 9

Partial agonists

Answer 9

drugs whose max repsonse is lower than this (even when the occupy all available repertors

(Graph on onenote)

Question 10

Reversible drug binding

Answer 10

Weak chemical bond between drug and receptor, agonists dissociates readily from the receptor (almost all agonists bind reversibly and many antagonist)

Question 11

Competitive antagonists (affinity and efficacy)

Answer 11

High affinity but no efficacy

In the presence of increasing antagonist concentrations the log(conc) response curves for an agonist will be shifted to the right, for competitive antagonists, the shift will be parallel

Question 12

Competitive antagonists (effect on DR curve)

Answer 12

In the presence of increasing antagonist concentrations the log(conc) response curves for an agonist will be shifted to the right, for competitive antagonists, the shift will be parallel

Question 13

Competitive antagonists (displacement)

Answer 13

A competitive antagonist can be displaced from the receptor by increasing the concentration of the agonist

Question 14

Competitive antagonists (example)

Answer 14

Atripone - blocks the binding of acetylcholine to muscarinic Ach receptors

Question 15

All agonists shift the DR curve to the…

Answer 15

Right

Question 16

Competitive vs Non-competitive antagonists

Answer 16

Competitive - max repsonse stays the same, response curves are shifted in parallel manner (can be displaced by agonist)

Non-competitive - max response is reduced, curve isnt parallel to that of the agonist alone (bind at another site - not that at which the agonist binds)