Determinants of Drug Action

Question 1

Variable Effects of Drugs:

Answer 1

• Same drug can have multiple actions and effects due to multiple target sites
  
  • Can have therapeutic effects or side effects

Diagram + Explanation

Question 2

Site of Drug Action:

Answer 2

• Not always site of drug effect

Beta blockers are used as anti anxiety drugs, can’t cross BBB, reduces physical effects of anxiety in periphery

Question 3

Similar Drug Effects:

Answer 3

Similar drug effects can be initiated by different drugs
• Atropine is a muscarinic antagonist that dilates pupil
Can effect pupil contraction/dilation like morphine, can also cause respiratory depression (side effect)

** Diagram + Explanation*

Question 4

Determinants of Drug Action:

Answer 4

• Chemical structure of drug determines whether it can bind to receptors
• Where the drug acts- may be multiple receptors and locations where receptors are found
• Dos- related to speed of action and effects of drug
Bioavailability- how much drug is free to bind to target sites

Question 5

Pharmacokinetics:

Answer 5

• How quickly drug reaches target sites
  
  • How long drug is available at target sites
  • Influenced by bioavailability

Question 6

Factors Influencing Pharmacokinetics:

Answer 6

• Drug administration

* Absorption and distribution
* Binding

• Excretion
• Inactivation All factors work simultaneously, ultimate drug effect depends on interactions between these factors and nonspecific factors