Test 1 Flashcards
Receptors, Pharmacodynamics, Pharmacokinetics
Receptor
A protein or other substance that binds to an endogenous chemical or drug. They are sensitive, selective, and specific.
Signal transduction
A process by which a cell converts one kind of signal or stimulus into another.
Competitive antagonist
Has a weak affinity for the same receptor protein and may be displaced by an agonist.
Non-competitive antagonist
has a strong affinity for the receptor protein and cannot be displaced by an agonist.
Physiologic antagonism
Two agonist drugs that bind to different receptors. They bind to specific unrelated receptor proteins and elicit individual tissue responses. Responses generate opposing forces.
Chemical antagonism
When a drug action is blocked and no receptor is activated.
Down-regulation
Continued stimulation of cells with agonists generally results in a state of desensitization.
Pharmacokinetics
Quantitative state of absorption, metabolism, distribution, and excretion of injected and inhaled drugs.
“What the body does to the drug”
Pharmacodynamics
Quantitative study of the body’s response to a drug.
“What the drug does to the body”.
Efficacy
Is a measure of the intrinsic ability of a drug to produce a given physiologic or clinical effect.
ED50
The dose of drug required to produce a specific desired effect in 50% of individuals receiving the drug
LD50
The dose of drug required to produce death in 50% of patients.
Therapeutic index
the ratio between LD50 and ED50. the larger the therapeutic range, the safer the drug.
Stereochemistry
Study of how molecules are structured in three-dimension.
Chiral
A molecule that has a center (or centers) of 3D asymmetry
Enantiomers
A pair of molecules existing in two forms that are mirror images of each other but cannot be superimposed.
Clearance (Cl)
Clearance (Cl)= k (rate constante) X V (Volume of distribution)
Central compartment
Elements of the body that dilute the drug within the first minute after injection:
1) venous blood volume of the arm
2) the volume of great vessels, the heart, the lungs, and upper aorta
3) whatever uptake of drugs occurs in the first passage through the lungs.
Vessel rich group
Tissues that received the bulk of arterial blood flow: the brain, heart, lungs, kidneys, and liver
Intrinsic clearance
The ability of the liver to remove a drug from the blood in the absence of any limitation imposed by blood flow or drug binding
First-order kinetics
A constant fraction of the drug is removed during a finite period of time regardless of the drug amount or concentration.
Half-lives
The time required for the concentration to change by a factor of 2.
Elimination clearance
Theoretical volume of blood from which the drug is completely and irreversibly removed in a unit of time.
Elimination half-time
The time during which the amount of drug in the body decreases by 50%
Two compartment model
1) Rapid decrease in concentration (due to passage of drug from plasma to tissue)
2) Drug distribution within the central compartment is instantaneous.
Minimum effective concentration (MEC)
The minimum concentration of drug plasma required to produce the therapeutic effect
Minimum toxic concentration (MTC)
Minimum concentration in which toxicity usually occurs
pKa
A pH in which a drug is 50% ionized
Zero-order kinetics
A constant amount of drug is eliminated per unit time
Volume of distribution
Amount of drug administered/initial drug plasma concentration
Partial agonist
A drug that is NOT capable of producing the maximal effect even at a very high concentration
Potency
The dose required to produce a given effect
Content-sensitive half time
The time required by the drug concentration of the plasma to decrease by 50%
Steady state
A stable plasma concentration of a drug is achieved
Pharmacogenetics
Study of variations in human genes that are responsible for different responses to drug therapy
Polymorphism
Variations in the DNA sequence that occur at 1% of the population
Types of receptors
1) Ion channel-gated receptors
* Ligand-gated receptors
* Voltage-gated receptors
2) G-protein coupled receptors (GPCRs)
3) Intrinsic enzyme-linked receptors
* Tyrosine kinase
4) Intracellular receptors
Alpha 1 receptors
Increases IP3 + DAG via activation of phospholipase.
Found: POST-SYNAPTIC in peripheral tissues (vascular smooth muscle, glands)
*Causes increased systemic arterial BP, mydriasis, hyperglycemia, bronchoconstriction, GI relaxation
Alpha 2 Receptors
Inhibits adenylyl cyclase, thus decreasing cAMP.
Found: PRE-SYNAPTIC nerve terminals of sympathetic postganglionic neurons
POST-SYNAPTIC membranes in the brainstem and peripheral tissues
*Causes inhibition of NE synthesis and release (presynaptic), sedation, analgesia, decreased insulin secretion
