Pharmacodynamic Principles - 1 Flashcards
the study of what the drug does to the body
pharmacodynamics.
what does pharmacodynamics include? “HINT:3”
1- the action of the drug on the body (beneficial and harmful).
2- influence of drug concentrations on the magnitude of response.
3- modification of the action of one drug by another drug.
how do antacids work?
neutralization of gastric HCL
how do chelating agents work?
chelation of heavy metals.
give examples of chelating agents?
EDTA and dimercaprol.
when are chelating agents used?
in cases of heavy metal poisoning.
give an example diuretic?
mannitol.
give an example of a laxative?
mag. sulphate.
how do diuretics and laxatives work?
osmotic activity.
how does activated charcoal work?
adsorptive property.
give an example of a radioisotope?
l-131
how do radioisotopes work?
radioactivity.
majority of drugs act by binding to their _____ or _____________
targets or specific receptors.
a macromolecule or binding site located on the surface or inside the cell that serves to recognize the signal molecule/drug and initiate response to it, but itself has no other function.
receptor.
list the 4 receptor families?
1- ligand - gated ion channels.
2- G-protein coupled receptors.
3- enzyme linked receptors.
4- cytosolic (nuclear) receptors.
where are receptors found in ligand-gated ion channels?
coupled directly to membrane ion channels
speed of response in ligand-gated ion channels is?
millisecond.
give an example of a drug that acts on ligand-gated ion channels?
neurotransmitters.
where are receptors in G-protein coupled receptors found?
bound to cell membrane and coupled intracellular effector system by a g-protein.
speed of response in g-protein coupled receptors?
seconds.
give an example of a drug that acts on GPCR?
catecholamines.
binding of a drug to an enzyme linked receptor results in?
increased enzymatic activity.
speed of response in an enzyme linked receptor is?
minutes to hours.
give an example of a drug that acts on enzyme linked receptors?
receptors for growth hormone and insulin
what is the function of a cytosolic (nuclear) receptors?
regulate DNA transcription and protein synthesis.
speed of response in a cytosolic (nuclear) receptors?
hours to days.
give an example of a drugs that act on cytosolic (nuclear) receptors?
steroid receptors, thyroid receptors.
list the 4 different G proteins based on alpha subunit?
1- Gs
2- Gi
3- Go
4- Gq
what is the function of Gs?
adenylyl cyclase activation, Ca2+ channel opening.
what is the function of Gi?
adenylyl cyclase inhibition, K+ channel opening.
what is the function of Go?
Ca2+ channel inhibition.
what is the function of Gq?
phospholipase C activation.
list 5 examples of GPCRs?
1- muscarinic receptor (M2): Gi,Go.
2- muscarinic (M1): Gq.
3- B adrenergic: Gs.
4- Alpha 1 adrenergic: Gq.
5- alpha 2 adrenergic: Gi.
list the 4 mechanisms of drug action?
1- enzyme inhibition.
2- transporters.
3- alter microbial processes.
4- incorporation into larger molecules.
list 2 examples of drugs that inhibit enzymes?
1- aspirin inhibits cyclooxygenase enzyme.
2- allopurinol inhibits xanthine.
give an example of drug that uses transporters?
blockade of anion transport in renal tubule by probenecid increases uric acid excretion.
give an example of a drug that alters microbial processes?
penicillin interferes with formation of bacterial cell wall.
give an example of a drug that incorporates into larger molecules?
5-flurouracil, an anticancer drug, is incorporated in place of uracil.
list the 3 types of therapeutic biologics?
1- genetically engineered enzymes and monoclonal antibodies.
2- genetically modified viruses and microbes.
3- gene therapy products.
give an example of generically modified viruses and microbes?
genetically modified live oncolytic herpes virus to treat melanoma.
give an example of gene therapy products?
using viruses as vectors to replace genetic mutations.
Number of drug receptor complexes determines ______?
Amount of response
Receptors are responsible for _______?
Selectivity of drug action
Any molecule which attaches selectively to particular receptors or sites?
Ligand
List the 4 types of ligands?
1- agonist.
2- antagonist.
3- partial agonist.
4- inverse agonist.
Agent which activates the receptor to produce an effect similar to the psychological signal molecule?
Agonist
Which ligand has both affinity and a maximal intrinsic activity (IA=1)?
Agonist
Give an example of a drug and which receptor is it an agonist to?
Salbutamol (B2 agonist).
Which drug produces longer bronchodilation than adrenaline?
Salbutamol
An agent which prevents the action of an agonist on a receptor but does not have any effect of its own?
Antagonist
Which ligand has affinity and zero intrinsic activity (IA=0)?
Antagonist
Give an example of a drug and which receptor are they an antagonist to?
Propanol is a B antagonist (B blocker)
An agent which activates the receptor to produce submaximal effect but antagonizes the action of a full antagonist?
Partial agonist
Which ligand has affinity and submaximal intrinsic activity (IA between 0 and 1)?
Partial agonist
Give an example of a partial and which receptor?
Pindol is a partial agonist at B receptor.
An agent which activates a receptor to produce an effect in the opposite direction to that of the agonist?
Inverse agonist
Which ligand has affinity and intrinsic activity (IA = between 0-1)
Inverse agonist
Give an example of an agonist, their inverse agonist , which receptor do they work on, and their effects?
Benzodiazepines, produce sedation, anxiolysis and control convulsions (GABA receptor agonist).
B-Carbolines (inverse agonist of GABA receptor), produce stimulation, anxiety and convulsions.
Increase in number of receptors
Up regulation of receptors
Decrease in number of receptors
Down regulation of receptors
Up regulation happens by continued presence of an ______ or absence of _______
Presence of Antagonist.
Absence of Agonist.
MI can be precipitated on abrupt withdrawal of which drugs?
Beta-blockers
How can abrupt cessation of B-blockers cause MI?
Continuous use of beta-blockers, up regulation of beta receptors, on abrupt cessation, endogenous epinephrine acts on large number of beta receptors, MI
Down regulation of receptors happiness because of a continued presence of an _____
Presence of an agonist
List the 2 factors that can bring about down regulation of receptors?
1- internalization of the receptor.
2- decreased synthesis/ increased destruction of the receptor.
Asthma patients treated continuously with ______ become ______ responsive to them
Beta agonist.
Less.
Dose response curve is which shape?
Rectangular hyperbola
When response is plotted again log(dose), the curve becomes which shape?
Sigmoid.
Linear response is seen in the ______% response zone
30-70%
Amount of drug needed to produce the same response
Potency
Potency is important for what?
Choosing the dose of the drug
10 mg of morphine = 100 mg of pethidine as an analgesic.
Which drug is more potent?
Morphine
The maximal response that can be elicited by the drug
Efficacy
Efficacy is important for what?
Choosing the drug
10 mg of morphine can relive chest pain of MI. Very high dose of aspirin is not able to relieve the same chest pain.
Which drug has higher efficacy?
Morphine
Small increase is dose will markedly increase the response
Steep slope.
Little increase in response occurs over a wide dose range?
Flat slope
Gap between therapeutic effect DRC and the adverse effect of DRC
therapeutic index
Therapeutic index is expressed by what?
TI = LD50/ED50
LD50 = dose which kills 50% of recipients.
ED 50= dose which produces specified effect in 50% recipients.
List the 2 factors that bound the therapeutic window/ range?
1- dose which produces minimal therapeutic effect.
2- dose which produces maximal acceptable adverse effect
Drugs with wide therapeutic range are _____ at high doses?
Safe
Give an example of a drug with wide therapeutic range which are safe at high doses
Paracetamol
Drugs with a narrow therapeutic range can be _____ at slight increase in dose
Toxic
Give an example of a drug with a narrow therapeutic range which can be toxic at slight increase in dose?
Theophylline.
