LHD - Pharmacodynamics

Question 1

Who introduced the concept of receptors?

Answer 1

Paul Ehrlich

Question 2

What 3 tests did J.N Langley conduct with the NMS?

Answer 2

1. Stimulated nerve (contraction)
2. Applied nicotine (contraction)
3. Stimulated muscle (contraction)

Question 3

What did testing with curare show?

Answer 3

Curare blocked stimulation of the nerve and application of nicotine

During stimulation of the muscle, a response was still elicited

• Showed a receptive substance was present (ACh)

Question 4

What is a receptor?

Answer 4

A macromolecular component of a cell with which a drug interacts to produce its characterisitic biological effect

Question 5

What are 7 properties of receptors?

Answer 5

1. Present in low concentrations and show saturable binding
2. Many drugs have high affinities for their receptors
3. Receptors show selectivity
4. Drug-receptor interactions are usually fully reversible
5. Drugs are usually small molecules
6. Receptors have a binding site with a complementary structure to the drug
7. Agonists induce conformational changes in their receptors

Question 6

What is bigger a drug or its receptor?

Answer 6

Receptor (1000x bigger)

Question 7

What are some exceptions of drugs that are reversible? (2)

Answer 7

1. Toxins
2. Phenoxybenzamine

Question 8

Whay is a close fit required for drug-receptor interactions?

Answer 8

Only held together by weak forces

Question 9

What are 3 quantitative drug-receptor assumptions?

Answer 9

1. Assume the law of Mass Action
2. Assume that only a negligible amount of the total drug is bound
   - free drug = total drug
3. At equilibrium
   - k1[D][R] = k-1[DR]