Principles of pharmacology

Question 1

Give examples of drugs which produces their effects due to their physiochemical properties

Answer 1

1. Antacids- i.e. sodium bicarbonate, base- increases pH, counters indigestion
2. Bulk laxatives- i.e. methylcellulose, not absorbed, streches gut wall, relieves constipation
3. Osmotic laxatives- i.e. magnesium sulfate, increases the aount of water in faeces
4. Osmotive diuretics- i.e. mannitol, give by IV, fltered in kidneys, ot reabsorbed into bloodstream leading to more urine
5. General anesthetic- i.e. halothane, lipid soluble thus interats with lipids in the cell membrane, renders individual unconcious
6. Alcohol- acts as a general anaesthetic

Question 2

What is meant by the potency of a drug?

Answer 2

• Potency is the measure of drug activity in a biological system
• high potency means effective at very low concentrations

Question 3

What is meant by specificity of a drug?

Answer 3

• Chemical specificity- drug wise
  
  • drugs are specific and complimetary to their receptor
• Biological specificity- receptor wise
  
  • receptors are located on different tissues
  • lead to different effects

Question 4

What is an agonist?

Answer 4

Bind to a receptor and produce a response

possess affinity and efficacy

• i.e.acetylcholine, histamine

Question 5

What is an antagonist?

Answer 5

• binds to a rece[tpr but do not produce a response
• prevent agonist binding and so block the response to an agonist
• possess affinity but not efficacy
• i.e. atropine, mepyramine

Question 6

What are the three types of antagonists?

Answer 6

1. Competitive
2. Irreversible
3. Other

Question 7

What is meant by quantitative pharmacology?

Answer 7

based on the assuption that drugs act by entering int a simple chemical relation with certain receptors in cells and that there is a simple relation between the amount of drug fixed by these receptors and the action produced

Question 8

What is the relationship between drug concentration and response?

Answer 8

• Graded- the level of increase in response chages as concentration changes
• Saturating- the maimum response cannot be exceeded
• exhibits threshold- minimum concentration required for effect

Assumption- ‘response’ = concentration of drug recepor complexes