Introduction to pharmacology Flashcards
define pharmacology
Pharmacology = science of drug action
Many drugs have a mixture of positive and negative effects.
Through pharmacology we can begin to understand how a small pill can do many things…give examples
Euphoric (morphine)
on top of the world (antidepressants)
Ulcerate your stomach? (NSAIDS)
Gain weight
totally chilled (diazepam)
get hench (anabolic steroids)
what does botox do?
Pharmacology exploits muscle paralysis effect of Botox medicinally for:
– muscle paralysis in spasmodic conditions
– Cosmetic
– However, Botox is very toxic!
How is botox toxicity regulated?
• Government has set up regulations to protect the public through the European Medicines Agency and MHRA
• These agencies make decisions on whether the benefits outweigh the risks of drug use
• Stipulate the legal status of drugs:
– POM prescription only medication
– P pharmacy medication
– GSL general sales list medication (i.e. not as regulated)
what does pharmacology open the door to?
• Therapeutic research, development • Application in medical practice • Understanding drug mechanism = explain therapeutic and adverse effects of agents • Understand interactions - Compete, negate drug action - Synergy, work better together - have no effects
what are the 2 branches of pharmacology?
- Relationship between body and drug
- How the body affects the drug (pharmacokinetics)
- How the drug affects the body (pharmacodynamics)
what is a drug?
• A substance used in the – diagnosis, treatment, or prevention of a disease – or as a component of a medication. - Molecules - Smaller than proteins - Smaller than polypeptides …
why is it advantageous for a drug to be “SMALL”?
- Quicker access into body
- Reach target (chemically sensitive site) sooner
- Longer to excrete (IVUFH vs LMWH)
A drug can be an agonist or an antagonist. Define these terms
• AGONIST: activate receptors and elicit a response
- Drug
- Hormone
- Neurotransmitter
- Signalling molecule
• ANTAGONIST
- Prevent (block) effect of agonist.
- Competitive
- Non-competitive
what do we mean by “chemical receptor sites”?
- If we consider drugs to be ‘keys
- Chemical receptor sites are the ‘locks’
• Receptors = proteins located on cell membrane ….Respond to endogenous compounds (hormones etc)
• Transport systems: Ion channels:
– Voltage gated (Ca++ / K+ / Na+)
– Ligand gated
• G coupled proteins
define affinity
• AFFINITY: how well does the drug bind to receptor
– Depends on concentration of drug
– Removal depends on how well it bound in the 1st place
– Relationship between drug concentration and receptor binding (how many receptors occupied) is calculated as
why is affinity important?
• If we know how much drug we need to occupy our receptor sites we begin to understand how much drug we need for therapeutic response = dose
Botox vs paracetamol
what do we expect to see when a drug binds to its receptor?
Hopefully a chemical response … but this depends on:
EFFICACY
– 2 drugs
– Same concentration
– Same receptor binding ability (affinity)
– Different efficacy!
– Different chemical effects
Example: Benzodiazepines, lorazepam and temazepam, have a 10-fold difference in dose
Do not assume drugs in the same class and receptor site will have similar doses!
what are the 4 stages of pharmacokinetics?
- Absorption
- Distribution
- Metabolism
- Excretion
describe absorption
- Getting the drug into the body – so that it can work!
- Everything given via mouth will go through a dissolution (break it down and dissolve it) phase
- Absorption = Pass through the gut wall into the blood stream even distribution around the body
