L1 Pharmacodynamics 1 Flashcards
Define pharmacology
Pharmacology is the study of chemical agents (drugs) that interact with living systems through chemical processes
Define pharmacodynamics
Pharmacodynamics is the study of the effects of drugs on the body, or ‘drug action’
What is the effect of metoprolol?
Metoprolol reduces the frequency of angina
Do drugs treat the cause of a disease? Give examples.
Most drugs treat the symptoms rather than the cause e.g. metoprolol treats angina (the symptom) but does not treat the blocked coronary artery (the cause).
Exceptions include antimicrobial drugs e.g. antibiotics such as penicillin.
What are the different approaches used in combination to treat disease? Use angina as an example.
Treatment of most diseases involves drug and non-drug therapy. For angina -
(1) Lifestyle - stop smoking, healthy weight, diet
(2) Medication - relieve intensity of angina (nitroglycerin), decrease frequency of angina (metoprolol), reduce chances of heart attack (blood thinners, lower cholesterol)
(3) Surgery - clear blocked coronary artery
When should metoprolol be taken and why is this important for its effect? Give an example of another drug taken in a different pattern.
Drugs treating chronic diseases, such as angina, are typically taken prophylactically -meaning it must be taken regularly, every day. Metoprolol is taken prophylactically, and with regular use it reduces the frequency of angina attacks.
Nitroglycerin is taken as needed to relieve (during) or prevent (before) symptoms.
Define potency.
Potency = the dose required to produce a desired therapeutic effect
Describe the term “effective” as a measure of drug action.
The effectiveness of a drug is determined by its maximum level of effect where greater max level of effect = more effective
Are potency and/or effectiveness determining factors in selecting the best drug to use?
Potency is rarely a determining factor, but is important when there is limited capacity to administer large amounts of a drug (e.g. transdermal patches; elephant anaesthetic darts).
Effectiveness is a determining factor (e.g. morphine vs. paracetamol).
How do drugs produce effects?
Drugs work by binding to molecular targets.
List the molecular targets for drugs and state which target is the most common.
(1) Membrane receptors* and transporters
(2) Ion channels
(3) DNA
(4) Nuclear receptors
(5) Enzymes
*Membrane receptors are the most common target for drugs.
What are the 2 requirements for drug binding?
(1) Complementary 3D fit
2) Forces of attraction (weak chemical bonds such as H bonds, ionic bonds and van der Waals forces
What is affinity?
Affinity is the tendency of the drug to bind to a target.
What are the factors that determine drug affinity?
(1) TYPE of bond (covalent > ionic > H > van der Waals)
(2) DISTANCE between drug and binding site (better 3D fit = drug and binding site in close proximity)
(3) NUMBER of bonds
What are the 2 functions of receptors?
Recognition and transduction
