Week 2 - Basics Of Drugs Flashcards
1
Q
What is metoprolol used to treat?
A
A drug used to treat chest pain (angina). A symptom produced when the heart is not getting enough oxygen.
2
Q
What are the common forms of drug administration?
A
- Orally via tablet
- Topically (cream/inhalation)
- Intravenous Injection
3
Q
How does metoprolol treat angina?
A
- Body produces adrenaline in response to exercise.
- Adrenaline binds Beta - adrenoreceptors (High affinity).
- Metoprolol also binds to Beta - adrenoreceptors blocking adrenaline from binding.
- This reduces heart rate and so chest pain.
- “beta-blocker”
- Note: Metoprolol does not treat the underlying cause but only masks the symptoms.
4
Q
What is drug affinity?
A
- the tendency for a drug to bind to its target.
- this tendency is based on chemical attractions between the drug and receptor.
5
Q
What is drug efficacy?
A
- its tendency to be effective once it binds to the receptor site.
6
Q
Agonists vs Antagonists
A
- Agonists have high affinity and efficacy. Binds to and effects the receptor. e.g. adrenaline
- Antagonists have high affinity and low efficacy. primarily used to block receptors and receptor activation. e.g. metoprolol.
7
Q
Is drug binding reversible? Why? Why not?
A
- The chemical forces found in drug binding are typically very weak. So yes drugs like metoprolol and Adrenaline are reversible.
8
Q
What are some examples of inhibiting drugs and some activating drugs?
A
- Hydrocodone -> Opioid receptors -> Activator -> Pain
- Paracetamol ->Cycloaxygenase -> Inhibitor -> Pain
- Levothyroxine ->Thyroid hormone receptor ->Activator -> Hypothyroidism
9
Q
What is the common relationship between Dose/Therapeutic Effect and Toxicity?
A
- Each drug has a therapeutic window in which it works with the most efficiency, this results from the “optimal dose”. If you go in excess of this dose the drug may become toxic.
- An example is paracetamol used in the recommended dose it is effective at relieving pain but can be very toxic to the liver at high doses.
10
Q
Pharmacokinetics vs Pharmacodynamics
A
- Pharmacokinetics is the effects the body has on the drug as it moves around the body. Kinetics meaning “rate” at which drug levels rise and fall.
- Pharmacodynamics is the effects the drug has on the body.
11
Q
Absorption and Bioavailability
A
- Drug Absorption is a process whereby ingested drug molecules relocate from interior of GI‐tract into the portal blood. - Bioavailability is the fraction of the drug dose reaching the systemic circulation. this is effected by large size, low greasiness and carried charge.
12
Q
Types of Distribution
A
- Some drugs remain in the blood and bind to proteins.
- Some drugs penetrate into body tissues to effect muscles,fat etc. These are influenced by blood flow to target tissue.
- Hard to get to the brain due to blood brain barrier.
13
Q
Hydrophilic and Hydrophobic Drugs
A
- Hydrophilic not likely to bind to plasma protein in blood (10% bound). Mostly circulates as unbound drug
- Hydrophobic very likely to bind to proteins in blood (90% bound). Circulates while bound.
14
Q
Metabolism
A
- Lipophilic drugs enter the body tissue, they can become toxic to body if they accumulate in body tissues. The bodies solution to this is to convert them to water-soluble metabolites so they may be removed via the kidneys.
- The drug is converted using 100’s of different drug metabolising enzymes found in the gut, liver, kidneys etc.
15
Q
Effects of metabolism on drug
A
- Drug goes through 2 stages of metabolism first through oxidate metabolism the parent drug becomes metabolite 1, next conjugative metabolism creates metabolism 2 which can be passed through urine.
- As the drug is further metabolized it becomes less effective and less active, the alteration of the drugs structure cause reduced affinity with the binding site.
