1.3 Drug Action

Question 1

Drug targets

Answer 1

• Drugs are designed to interact with one selected target in the body.
  The majority these targets for drugs are called receptors
• few classes of drugs bind to other targets in the body

Question 2

Receptor

Answer 2

• molecule or a complex of molecules located on the outside or inside of a cell that has a regulatory role in the homeostasis or the organism
• normally bound to and activated by ligands (hormones and neurotransmitters)
• many exists, location determined where a drug will act and whether the response is beneficial or detrimental
• most drugs can mimic the action of, or block the effect of the ligand at the receptor

Question 3

Agonists

Answer 3

Drugs that bind to and stimulate a receptor

Question 4

Antagonists

Answer 4

Drugs that fine too but block the response at a receptor

Question 5

Lock and key analogy

Answer 5

• Easy way to think of a drug acting on its receptor
• The receptor is the lock the drug is the key that turns the lock and sets events in motion
• antagonist binds to receptor but does not activate it

Question 6

Other drug targets

Answer 6

• some drugs activate with the biological system
  -Commonly used antacids neutralize stomach acid through a simple acid base neutralization reaction
  Cholestyramine works by chemically binding to bile acids is the gastrointestinal tract, preventing their reabsorption
• this is why increasing the elimination of bile salts that are used to make cholesterol

Question 7

Drug response

Answer 7

• Intensity of the pharmacological effects produced by a drug increases in proportion to the dose
• Dose response relationship

Question 8

Dose response relationship

Answer 8

• For a drug to receive its desired response many receptors need to be activated at once
• at low doses of drug very little response is observed as not many receptors are being activated
• as dose of drug increases more receptors activated until desired response is seen
• Threshold exists where a certain number of receptors need to be activated before and effect will be seen
• after this little dose result in large increase in response
• once reach maximal effect increasing effect will have no increase in response

Question 9

Efficacy

Answer 9

The maximum pharmacological response that could be produced by specific drug in that biological system

Question 10

Potency

Answer 10

• Dose of a drug that is required to produce a response of a certain magnitude 50% of the maximal response for that drug
• refers only to the amount of drug that must be given to obtain a particular response
• Drug is more Porten than drug be this means that one needs to take less of drug A to achieve the same effect that is obtained from drug B

Question 11

Efficacy in depth

Answer 11

• The amount of drug needed does not matter what matters is the maximum effect that the drug can produce
• Morphine has greater efficiency than aspirin in the relief of pain this is because aspirin is only effective in relieving mild to moderate pain while morphine is able to relieve pain of nearly all intensities
• More important than potency

Question 12

Therapeutic range

Answer 12

• Drugs are administered to achieve a therapeutic effect
• Aim of therapy is to give a dose that keeps the blood concentration of the drug above the minimum concentration that produces the desirable response but below the concentration that produces a toxic response