Pharmacology- Drugs and Therapeutics Flashcards
What is a drug?
A chemical with a selective therapeutic action
What is pharmacology?
Science that deals with the study of drugs and their actions on living systems
What are the TWO integral branches of pharmacology?
Pharmocodynamics- What the drug does to the body- Drug action and mechanisms
Pharmocokinetics- What the body does to the drug- ADME
What does the Adrenergic receptor- beta (B-1) do?
- Increases heart rate
- Increases cardiac muscle’s force of contraction
This is the adrenaline effect on the heart
What does the adrenergic receptor- beta (B-2) do?
- Relaxes the airway
- Dilates smooth muscles
This is the adrenaline effect on the lungs
What is biological specficity in therapeutic action
Right target
What is chemical specifcity in therapeutic action
Right target binding site
What is biolgical specficity in adverse/side effects?
Non-specific binding site
What is chemical specificity in adverse/side effects?
Non-specific binding site
What is specificity?
Target binding sites (receptors and its subtypes) provides the selectivity for the specific binding of drugs/ligands (Lock and Key system)
What are the key drug binding sites?
- Drugs as enzyme inhibitors- blocks the enzyme activity
- Drugs as enzyme substrates
Give examples of drugs and their enzymes and how they block the process.
Drugs as enzyme inhibitors
- Sildenafil- targets the phosphodisterase enzyme and it blocks the
enzyme, which function is intracellular breakdown - Neostigmine- enzyme is Acetylcholine esterase and it will inhibit neurotransmitter degradation
- Ibuprofen (reversible), Aspirin (irreversible)- enzyme is cyclo-oxygenase and its function is messenger synthesis.
So the medication blocks that enzyme and then that will block the enzyme function/activity
Which out of aspirin and ibuprofen binds to an enzyme and is reversible and which is irreversible?
Aspirin- irreversible
Ibuprofen- reversible
What is reversible antagonists?
Readily dissociate from their receptor
What is irreversible antagonists?
Form a stable, permanent or nearly permanent chemical bond with their receptor.
What is pseudo-irreversible antagonists?
Slowly dissociate from their receptor
Give an example of drugs as enzyme substrates
Dopamine- enzyme acting as a substrate.
E.g. dopamine precurosor L-DOPA for parkinson’s disease
What is competitive binding?
Drug competes for the ligand active site. Can be reversible and irreversible
Example of competitive inhibitor
Neostigmine (medication) is a comeptitive inhibitor with Acetylcholine which comeptes to bind with the Acetylcholine esterase
During competitive binding neostigmine will compete with _____ to bind to the ligand active site of Acetylcholine (Ach) esterase?
Acetylcholine
What is non competitive binding?
Drug binds at different site. Irreversible
Example of non competitive binding
Cycloxygenase enzyme (COX) is responsible for the synthesis and release of prostaglandins (a pro-inflammatory cytokine). The synthesis of prostaglandin required arachidonic acid.
The arachidonic acid binds to the COX enzyme and releases the prostaglandins.
Example
Aspirin binds to the COX and it will not allow the arachidonic acid binding to the COX.
The 3 class of drug targets
- Enzymes
- Drugs targeting transporters
- Drugs targeting voltage-gated ion channels
- Drugs targeting receptors
Cocaine mechanism
Blocking of the transporter reducing the uptake of noradrenaline constant stimulation
Drugs targeting transporters
The transporter is a protein, most of the drugs acting on the transporters are inhibitors. They block the transport
Example of drugs targeting voltage gated ion channels
Its a trans membrane channel, its not a receptor because it doesn’t require binding of drug. It just recognizes the membrane potential. They have specific sensors to detect the inside, outside electric environment.
Once the channels open, it allows the ions to mobilise so its exclusively for ion movement. Inward/outward of ions. Could be Na, K, Ca, F ions (depending on which ion channel). The fastest
Example of drug targeting ion channel
Lidocaine which is a local anesthetic. Blocks the Sodium (Na) channel.
What are drugs targeting receptors?
proteins which respond to a endogenous messenger by initiating a signal
could be hormones, peptides, cytokines, neutrotrasnmitters etc
What are the key types of receptors?
- Nuclear receptors
- Ligand gated ion channels
- Catalytic receptors
- G-protein coupled receptors
Benefits vs risk (market authorisation of clinical drugs
Thalomid- treatment used to treat nausea in pregnant woman, caused birth defects
Aspirin
Therapeutic action- COX inhibitor, anti-inflammatory (fever, pain, blood thinner)
Adverse effects- gastric upset, bleeding and ulcer. If given to children under 12, causes reyes syndrome which is liver and brain damage
