Pharmacodynamics Flashcards
What is a ligand?
A molecule that can bind to a complex with a receptor to produce a response. Can be endogenous or exogenous
List in order from weakest to strongest bonds (4 of them)
Van De Waals, Hydrogen, Ionic, Covalent
What is a Van De Waals bond?
2 molecules with electrostatic attraction will have a weak bond
What is a hydrogen bond?
Occur frequently when you have a molecule with a negative charge that has an electrostatic attraction to a positively charged hydrogen molecule
What is an ionic bond?
a positively charged ion and a negatively charged ion form a double bond
What is a covalent bond?
a chemical bond that involved sharing of electrons between atoms. Irreversible. Strongest bond
Explain a ligand gated receptor
A ligand binds to receptors and allows passage through the phospholipid bilayer. ex. acetylcholine receptors
Explain a G-protein coupled receptor
A ligand binds and causes structural changes to the G protein inside the cell. It becomes activated, finds an effector protein and causes a response. Ex. GABA receptors
Explain an enzyme linked receptor
A drug or hormone binds causes an enzyme to be activated inside the cell. That enzyme travels to an effector protein, and causes an affect. ex. tyrosine kinase
Explain Intracellular receptor
Something can pass through the phospholipid bilayer because: it lacks polarity (non-ionized), small enough to go directly through
What is the Law of Mass Action?
Drug + Receptor = Drug-receptor complex
What are the affects of the Law of Mass Action?
Elimination, concentration
What is the X axis on a drug-response curve?
Dose or Concentration
What is the Y axis on a drug-response curve?
Result or Effect
What is the Emax?
Maximal amount of effect
What does a full agonist do and what is an example?
Binds to a receptor and mimics an endogenous ligand. Reaches full Emax. Ex: Fentanyl (IV narcotics)
What does a partial agonist do and what is an example?
Binds to a receptors and partially activates a response Doesn’t reach full emax. It competitively blocks other agonists. Ex. nalbuphine.
Describe competitive agonist:
Reversible or irreversible antagonism?
Increased concentration can or cannot overcome effect?
They bind to a receptor and block activity. Increasing drug concentration will kick antagonist blocker off.
Reversible antagonism
CAN overcome
Describe competitive agonist:
Reversible or irreversible antagonism?
Increased concentration can or cannot overcome effect?
Binds to a receptor, blocks it, drugs cannot offset it.
Irreversible antagonism (Covalent bond)
CANNOT overcome
What is an inverse agonist?
It binds to a receptor and does the opposite effect ex. flumazenil
What is potency?
The amount of drug needed to produce an effect
What is efficacy?
Ability of a drug to produce a physiologic or clinical effect. More important than potency. We want drugs that WORK.
How do you calculate therapeutic index?
ToxicDose50/EffectiveDose50
Combination Therapy: Addition: Synergism: Potentiation: Antagonism:
Addition: 1 + 1=2
Synergism: 1 + 1 = 3
Potentiation: 1 + 0 = 3
Antagonism: 1 + 1 =0
Explain addition:
using 2 different drugs, you get expected results. Usually have the same mechanism of action
Explain synergism:
using 2 different drugs results in a greater effect. Ex. fentanyl and versed
Explain potentiation:
Combining a drug that normally doesn’t have an effect with a drug that has an expected effect and the effect is greater. Ex. NSAIDS and Coumadin
Explain antagonism:
Combine 2 drugs and get no results, they cancel each other out. Ex. protamine and heparin
What is down regulation?
Requires increased dose to have same effect. Physiologic tolerance. Ex: caffeine, nicotine, opiods, alcohol
What is tachyphylaxis?
an acute rapid decrease in response to a drug after its administration.
What is stereochemistry?
Study of 3D structures of molecules
What is a chiral model?
Molecules with 3D asymmetry. Almost always centered around carbon.
What is enantiomerism?
Pairs of molecules that are mirror images of each other
What is a racemic mixture?
50/50 mixture of “left” and “right-handed” enantiomers of a chiral molecule