PHAR1101 Lecture Notes - Lecture 2: Coronary Circulation, Paracetamol, Angina Pectoris
How Do Drugs Work?
Most drugs are used to treat disease
Eg. – Angina: blockage of arteries that lead to the heart depriving of oxygen.
- Treatment – metoprolol: has nitroglycerin to relieve intensity of angina episodes
: has other drugs to thin blood and lower cholesterol, and reduce
chance of heart attack.
Ways of administering drugs:
- Oral: most common and convenient.
: NOT suitable for all drugs – some drugs inactivated (i.e. penicillin by acid in stomach.
adrenaline by enzymes in gut and
liver).
- some toxic to gut (e.g. some anti-cancer drugs)
- do’t work iediately, not ideal for emergencies.
- Injection: into skin, muscle or bloodstream
: bypasses gut and liver.
: quicker than oral.
- Topically: i.e. directly to – lungs by inhalation
- skin by creams/patches
- eye drops, etc.
How do drugs produce their effects?
Bind to specific targets
- membrane receptors and transporters
- 60% to receptors i.e. metropolol
- 5% to transporters, i.e. antidepressants.
- Ion channels
- 5% i.e. local anesthetics
- enzymes
- 30% i.e. paracetamol.
How does metropolol reduce angina??
- Adrenaline contributes to angina:
- by increasing heart rate and contraction. When coronary
arteries blocked, O2 to heart is less than necessary.
- on surface of heart cells are receptors that specifically
recognize adrenaline.
- adrenaline binds to and activates them, because the
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Document Summary
Angina: blockage of arteries that lead to the heart depriving of oxygen. Treatment metoprolol: has nitroglycerin to relieve intensity of angina episodes. : has other drugs to thin blood and lower cholesterol, and reduce chance of heart attack. : not suitable for all drugs some drugs inactivated (i. e. penicillin by acid in stomach. adrenaline by enzymes in gut and liver). Some toxic to gut (e. g. some anti-cancer drugs) Do(cid:374)"t work i(cid:373)(cid:373)ediately, not ideal for emergencies. Topically: i. e. directly to lungs by inhalation. When coronary arteries blocked, o2 to heart is less than necessary. On surface of heart cells are receptors that specifically recognize adrenaline. Adrenaline binds to and activates them, because the protein binding sites have complementary structures, and by forces of attraction (weak chemical forces). If binding occurs, drug has affinity for target. (adrenaline has high affinity for b-ar) Causes them to change shape so they can activate intracellular pathways that cause heart cells to contract.
