Block 1 Bolded Terms Flashcards
Receptor
Any macromolecular component in an organism that binds a drug/ligand
Affinity
The substance’s ability to form a complex with a receptor. In other words, how strong the ligand and receptor bind
Ligand
A molecule that binds to a receptor (a drug)
KD
The dissociation equilibrium constant
Rt
The total number of receptors bound (bound [LR] + free [R])
Agonist
A substance that mimics the regulatory effects of the endogenous signaling compound
Antagonist
A substance that binds to the receptor without regulatory effect
Partial agonist
Partial agonists may act as agonists when no full agonist is around or they may act as antagonists if a full agonist is present - A partial agonist may have higher affinity for a receptor than a full agonist, but it can never produce Emax
Intrinsic Activity
The ability of a ligand to produce a cellular effect after it has bound to a receptor
Spare Receptors
The relationships between the amount of ligand bound and the effect on the cell is not linear but rather a rectangular hyperbola in most systems because very small amounts of receptor occupancy produce large effects because there are spare receptors available
EC50
The ligand concentration at which the effect is 50% Emax
Potency
The relationship between the amount of drug administered and its effect, the less drug needed to produce an effect, the more potent the drug
Maximal efficacy
The maximum effect of a particular drug on the patient
ED50
The dose of drug that is effective in 50% of the population - ED50 tells how potent a drug. A lower ED50 indicates that the drug is more potent and less is necessary to produce the desired effect
TD50
Toxic dose in 50% of people
LD50
Lethal dose in 50% of people
Therapeutic Index
TD50:ED50 ratio. Ideally this is a large number to ensure if the patient takes too much drug it will be less likely that they will suffer toxic consequences
Log-normal distribution
Represents most drug effects. The curve shows the number of people in the population that respond to a given dose of the drug
Hyporeactive
Patients who did not respond until the dosage of the drug was very high
Hyperreactive
Patients who responded with very little drug dosage
Hypersensitivity
People that have an allergic or inflammatory response to the drug
Bioavailability
Fraction of a drug administered that reaches the systemic circulation
First pass effect
The amount of drug metabolized or excreted on its first pass through the liver before it reaches the systemic circulation - Reduces bioavailability
Bioequivalence
Two preparations that have:
- Same drug (active ingredients)
- Same route of administration
- Same amount of drug
- Same rate of entry into the circulation
Redistribution
Drug action is terminated because the drug redistributes from its site of action into other tissues
Therapeutic window
The concentration of a drug in the body that is high enough to produce the desired effect with a minimum of toxicity
Volume of distribution (Vd)
A measure of the apparent space in the body available to contain the drug
Clearance
Rate of elimination/concentration
Rate of elimination
Directly proportional to drug concentration. As the concentration increases, the elimination increases proportionally so the clearance stays the same
Half life
The time required to decrease the concentration of the drug by one half