Pharmacodynamics (my Cards) Flashcards
What is the definition of pharmacodynamics? (3)
1) ‘How the drug works’
2) The study of the drug mechanisms that produce biochemical or physiological changes in the body.
3) The interaction at the cellular level between a drug and cellular components.
What is MRNA?
MRNA is a molecule responsible for transfers g genetic information from DNA found in the nucleus of the cell to ribosomes floating in the cell cytoplasm.
What are amino acids?
Molecules that combine to form proteins .
What is a chain of amino acids called?
Polypeptide
Describe an amino acid group (2)
1) An amine group at one end (this is called the N terminal)
2) A carboxyl group on the other end (this is called the C terminal)
What causes a protein to change shape? (2)
1) PH
2) temperature
What is an Ion?
An Ion is an atom or molecule with electrical change due to the loss of gain of one or more electrons.
What is a Zwitterions? (2)
1) A Zwitterions is an ion possessing both negative and positive electrical charges.
2) Zwitterions are mostly electorally neutral.
What is a proton donor?
(Give an example)
Hydrogen ions (+ve) can donate to amine end
When measuring PH, what are you measuring?
Hydrogen ions because hydrogen ions are acid.
What does the lipid cell membrane do?
Provide a barrier against the transport of hydrophilic molecules into or out of the cell
A) what is hydrophobic?
B) what is hydrophilic?
A) (hydrophobic) water-fearing. Naturally repel water
B) (hydrophilic) water loving. Has an affinity to water
Drugs work by 4 main mechanisms, what are these?
RICE
1) Receptors
2) Ion channels
3) Carrier molecules
4) Enzymes
What are Receptors?
Receptors are protein molecules that are normally activated by transmitters or hormones
What are the 4 main types of receptors?
1) linand gated channel receptors
2) G protein coupled receptors
3) Kinase linked receptors
4) Nuclear receptors
What are the characteristics of a linand gated channel receptor? (5)
1) Agonist
2) response time of milliseconds
3) Inotropic (increasing or decreasing force)
4) Excitable tissue (nerve/cardiac)
5) examples (SHT3, ACh, GABAa)
What are the characteristics of a G protein coupled receptor? (4)
1) Metabotropic (action is mediated by metabolic functions)
2) linked to physiological response by second messengers
3) form a family of receptors with 7 membranes spanning helices
4) response time of seconds
7TMD = 7 transmembrane domain
What are the characteristics of nuclear receptors? (4)
1) present in the cell nucleus
2) Regulates transcription and protein synthesis
3) Bind to DNA and switches genes on and off
4) Response time of hours
(Example = steroids)
What are the characteristics of Kinase linked receptors? (4)
1) Surface receptors (extra cellular)
2) Enzyme amplifier
3) Possess intrinsic tyrosine kinase activity
4) Response time of hours
(Example - insulin)
(RTK = receptor tyrosine kinases)
What are the main characteristics of ion channels? (6)
1) can be closed, open or inactive
2) drugs either block or modulate channels (the binding of a drug to a site on the associated receptor can either increase or decrease ion channel opening
3) There are 4 main types of ion channels
4) Important for systems that require a rapid response (NS renal CVS)
5) Ions need the help of proteins to cross cell membrane (such as ion channels)
6) Don’t bind but form a channel through the membrane
What are the 4 main types of ion channels?
1) Ligand gated (activated by the binding of ligands to a specific receptor, which forms part of the ion channel (extra cellular)
2) as above but intracellular
3) Voltage gated (activated following a change in voltage)
4) Mechanically gated (weight or force of molecule hitting it open)
What are the main characteristics of carrier molecules? (5)
1) Transport a substrate across a cell membrane
2) Carrier molecules can be ion, glucose or amino acids
3) Carry a specific molecule/shape
4) Drugs can act to modulate the function of carrier molecules directly or indirectly
5) Some drugs target these carriers and block transport (common by inhibiting enzyme ATP, that provide energy to drive them)
Drugs can act to modulate the function of carrier molecules directly or indirectly
Explain….,
Direct - Bind completely to the carrier preventing the binding of ligands
Indirect - Bind to a separate site on the carrier and alter the 3D shape, preventing the binding of ligands.
Allosteric = change shape
What are the two types of carrier molecules?
1) Energy dependent (can work across a concentrated gradient)
-requires energy, usually ATP (adenosine triphosphate)
2) Energy independent (can only work down a concentrated gradient)
- Transporters (single molecule in one direction)
- Symporters (2 molecules in the same direction)
- Antiporter (2 molecules in opposite directions)
A) What is an agonist?
B) What is a partial agonist?
C) What is an antagonist?
A) An agonist activates/initiated a response
B) A partial agonist can still cause full therapeutic effect
C) An antagonist inhibits/blocks receptor
A) What is a competitive antagonist?
B) What is a non competitive antagonist?
A) A competitive antagonist binds reversibility with receptor and tissue response can be returned to normal by increasing the dose of agonist (reversible)
B) Non competitive antagonist do not bind but act downstream (non reversible)
A) What is a chemical antagonist?
B) What is a physiological antagonist?
A) A chemical antagonist binds to active drug and inactivates
B) A physiological antagonist has two agents with opposite effects which cancel one another out
What is a metabotropic receptor? (3)
- A type of receptor that initiates a number of metabolic steps to modulate cell activity
- Utilises system of second messenger effector systems
- G protein coupled receptor
What is a nuclear receptor? (4)
- Intracellular receptor
- Regulates DNA transcription (turns genes on and off)
- Ligands must enter cell to bind
- Powerful
What are the characteristics of Enzymes? (4)
- Biological catalyst that spreads up chemical reaction
- Enzymes are mostly proteins
- Enzymes have an active/catalyst site that binds substrates specifically. Substrate fits the shape (like a key in a lock). This causes a chemical reaction then substrate forms into product.
- Acts on specific substances known as substrates
Drug/Enzyme interaction may involve? (4)
1) Substrate analogues
2) False substrates
3) Conversion of pro drugs
4) Reversible and irreversible inhibitors
What does a substrate analogue do (how does it work)? (2)
1) Mimic the substrate/feature of a substrate
2) Can act as a competitive inhibitor or a non competitive inhibitor
What are the characteristics of a competitive inhibitor? (4)
1) Has a similar chemical structure (shape) and slows down a reaction rate
2) The inhibitor competes with the substrate to slow down the reaction
3) Binds at the active site
4) Drugs help prevent harmful products or growth of foreign cells (eg penicillin inhibits an enzyme which help bacteria grow)
What are the characteristics of a non competitive inhibitor? (3)
1) Bind to the enzyme but not at the active site
2) Still inhibits the reaction
3) Work by changing the enzyme shape, thus making it inactive
What does a false substrate do (how does it work)? (3)
1) Transformed by an enzyme to produce an abnormal non functioning product
2) Targets a specific point in a pathway and often has less side effects as it’s more targeted
3) Fools the enzyme into thinking it’s metabolising
What is conversion of pro drugs? (2)
1) Most oral drugs are in the non active form. They rely on conversion by enzymes (usually in the liver) to activate drug
2) pro drug is an active metabolite
(Example = codeine -morphine)
What are reversible and irreversible inhibitors?
Drugs are either reversible or irreversible inhibitors
REVERSIBLE - temporarily binds to the catalytic site
IRREVERSIBLE- binds permanently to the enzyme making it inactive. This requires production of new enzymes to re start activity
Examples: aspirin - irreversible and penicillin - reversible
What is a ligand? (2)
1) A ligand is a substance that normally binds to the receptor
2) Ligand is to the receptor as substrate is to the enzyme
1) What is an Action potential?
2) What is a resting potential?
1) Action potential is a rapid sequence of changes in the voltage across a membrane. The membrane voltage or potential is determined by the ratio of ions (extracellular and intracellular)
2) Resting potential is the electrical potential difference across the plasma membrane when the cell is in a non excited state
What is Ach? (4)
1) Acetylcholine (Ach) is a receptor that carries messages from your brain to your body through nerve cells
2) Able to transduce chemical signal into electrical signal
3) neurotransmitter gated ion channel
4) it is an excitatory neurotransmitter (excites nerve cells)
What is NFKB
Nuclear Factor Kappa - light chain enhancer of activated B cells
NFKB is a protein complex that controls transcription of:
- DNA
- cytokine production
- cell survival
What is transcription?
The process of copying a segment of DNA into RNA
What is tachyphyaxis and what could cause this? (5)
A sudden acute decrease in response to a drug. This could be caused by:
1) Change in receptor (shape)
2) Loss of receptor (aging)
3) exhaustion of mediators (second messengers)
4) Increased metabolic degradation
5) Physiological adaption (get used to the drug)
What is synergism?
Combined effect of giving two or more drugs is greater than giving one drug on its own
What is antagonism?
2 or more drugs having opposite effects on the body
a) what is up regulation?
b) what is down regulation?
a) Decreased exposure to an agonist results in an increase to the number of receptors (up regulation)
b) Increased exposure to an agonist results in a decrease in the number of receptors (down regulation)
What is a drug response curve? (2)
- A drug response curve refers to the relationship between the amount of drug given and the effect of the drug
- It is essential to understand drug safety and hazardous levels
