Principles of pharmacology 1/2

Question 1

Drugs which work through physiochemical properties

Problems?

Answer 1

Antacids, Bulk laxatives, Osmotic laxatives, Osmotic diuretics, General aneasthetics, alcohol.

Non-specific, high concentration needed to work

Question 2

Biological specificity

Answer 2

(tissue specific) E.g:- Acetylcholine can cause contraction in skeletal muscle when given in drug form but relaxation in smooth muscle when given at the same dose.

Question 3

Chemical specificity

Answer 3

(optical isomers) stereoselectivity, 100,000 fold difference between specificity of isomer
Shape of drug complements shape of receptor (chemical specificity); lock and key model

Question 4

How does the isolated ileum preparation work?

Answer 4

Small piece of ileum from Guinea Pig, if contraction occurs pulls down lever and pen recorder records this. Supply drug at bottom to see response on sample.
Adding ACh, hist caused contraction of the muscle, Atropine didn’t induce response but inhibited response of ACh, hist effect on tissue was not prevented by presence of atropine, adding more ACh than previously you could produce a contraction (out-competed atropine)

Question 5

The receptor concept?

Answer 5

Drugs produce their effects by combing with specific receptor sites in cells.
The response is a function of the number of occupied receptors

Question 6

EC50

Answer 6

EC50:- effective concentration which produces 50% of maximum response
Relationship is:- Graded, Saturating, Exhibits threshold

Question 7

Emax

Answer 7

Emax:- maximum response produced by a drug (Threshold)

Question 8

What is the Aspirin receptor?

Answer 8

Cyclooxygenase (COX)

Question 9

How could you block Ca2+ channels?

Answer 9

Nifedipine

Question 10

What are the NA transporters/pumps blocked by?

Answer 10

Cocaine

Question 11

What are physiological receptors?

Answer 11

Receptors for hormones/neurotransmitters

Question 12

How can we regulate a cells function?

Answer 12

Altered Em, enzyme activity, gene expression

Question 13

Blocker of Ach receptors?

Answer 13

Tetrodoxin

Question 14

How are receptors classified/named?

Answer 14

1) Classified on the basis of selective action of the drugs
2) Named according to the hormone/neurotransmitter with which they interact e.g nicotinic,mucarinic Ach receptors
3) Most hormones/neurotransmitter interact with more than one type of receptor

Question 15

What are the receptor superfamilies?

Answer 15

Integral ion channels (nicotinic) Ionotropic:- Ligand gated
G- protein coupled receptor (muscarinic) Metatrobic
Integral tyrosine kinases (insulin)
Cytokine receptors (growth hormone)
Steroid receptors (Oestrogen)

Question 16

Spare receptors?

Answer 16

Highly efficacious agonists can produce a maximal response without binding to all available receptors

Question 17

Partial agonists

Answer 17

Cannot produce maximal response even when bound to all available receptors