Question | Answer |
Potency | The drug dose needed to produce a given effect - usually 50% of maximum |
Efficacy | The goal dose for response. Usually refers to maximal effect. |
The potency or efficacy can be quantifed as | the quantal response or the number of patients who respond to a drug |
Therapeutic index is another name for | safety |
Therapeutic Index is | the relationship between the toxic dose and the effective dose. |
Equation for Therapeutic Index | Toxic Dose over Effective Dose or TD50/ED50 |
ED50 is | the potency |
the graded dose response relationship is | the drug receptor complex that results in biological effect |
the magnitude of the biological effect is proportional to | the number of receptors occupied |
affinity is | the strength of binding between the drug and its receptor |
an agonist is | something that binds and activates a recptor |
an antagonist is | something that binds and prevents receptor activity |
full agonist is | something that activates the receptor to full extend and mimics endogenous |
partial agonist is | something that causes a less than full response despite receptor saturation |
partial agonists can result in | antagonism |
an inverse agonist is | something that results in reverse activity of receptors and stabilize receptors in an inactive format |
a competitive antagonist | competes with agonist for receptor - like narcan and morphine |
irreversible antagonist | binds covalently to receptor and inactivates it - blocking the amount of receptors available |
allosteric antagonist | prevents receptor transformation when drug binds to a site that is different than an agonist site. |
allosteric agonist example | benzos bind to ion channels activated by GABA and enhance effects of GABA |
chemical agonist | drug binds directly to substance so substance cant interact with receptor ex. iron chelators |
small therapeutic index | monitor more frequently because less safe |
threshold for a toxic therapeutic index | 2.0 |
pharmakokinetics is | the actions of the body on the drug; absorption, distribution, metabolism and excretion of the drug in the body |
first order kinetics is the same as | first order elimination |
first order elimination is | enxymes that metabolize a drug for elimination that do not become saturated so the rate of elimination is directly proportional to the concentration of free drug |
zero order kinetics is | the enzyme system is saturated so rate of metabolism is constant - regardless of drug concentration. it is not affected by the rate of concentration |
first pass metabolism is | when a drug is administered orally and visits the liver via the bloodstream and is metabolized before going to the organ of disease |
lipophillic drugs | not excreted but their hydrophilic metabolites are excreted |
hydrophilic drugs leads to | increased renal excretion and decreased tubular reabsorption |
bioavailability is | determination of equivalence - the percent of drug that reaches systemic circulation, calculated by plasma level - effective dose/bioavailability. IV dose is 100% bioavailable, oral is 70% bioav. |
factors that influence bioavailability | first pass metabolism, solubility of drug, chemical instability, physical properties of drug |
most drugs are secreted by | passive diffusion |
antibiotics are brought into bacteria by | endocytosis |
drug distribution is when | a drug reversibly leaves the bloodstream and enters the interstitium and tissues/cells |
when plasma proteins are lower than normal | then total drug concentrations will be lower but unbound concentration will not be affected |
a large volume of distribution is associated with | low excretion/long half life |
metabolism is the | termination of drug action and has three portions - bioinactivation, detoxification and elimination |
biotransformation is | metabolism. both occur in the liver |
most liver metabolism converts meds to | more polar, less lipophilic compounds that can be eliminated by kidneys |
biotransformation occurs in two phases | phase 1 results in oxidation, reduction and hydrolysis, phase two results in conjugation products and are inactive |
An example of a phase 1 drug metabolism is the | CYP 450 system in liver mostly but also in GI and lung |
you have to love this to get in the brain | fat |
ionic forms of drugs are more easily excreted by | the kidneys |
polypharmacy is | 5 or more drugs |
grapefruit does this | inhibits CYP 450 enzyme |
milk pH is | 7.08 |
nicotine does this | induce cyp450 enzymes |
acidic medications are more likely to end up in this (lactating women) | breast milk |
alcohol and caffeine | induce cyp450enzymes |
grapefruit permanently does this | inactivates cyp3a4 enzymesand takes 48-72 hours |
half life is | the amount of time it takes for 50% of the drug to be out of your system |
this many half lives should be used to calculate clearance | 3.3 |
pharmacodynamics is | potency, efficacy and safety - how the drug causes a response in the body |
most drugs are excreted in | the kidneys |
clearance | refers to renal clearance - rate of drug elimination by metabolism and excretion |
pharmacogenetics | inherited drug response - look at phenotypes |
g linked receptor interactions include | prostaglandins alpha or beta receptors |
refractory receptors | require a rest period - ion channels only |
desnsitized receptors | no longer responsive to ligand - think smell |
downregulated receptors | receptors are sequestered, even downgraded and unable to interact (morphine + dilaudid) |
tachyphylaxis | rapid unresponsiveness with repeated dosing (nitro 4th dose) |
phase 1 clinical trial | determine max dose, toxicity 15, ppl |
phase 2 clinical trial | disease oriented only 50 ppl |
phase 3 clinical trial | |