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Pharmacology
Chapter 1
| Question | Answer |
|---|---|
| 3 phases of drug action, in order | pharmaceutic, pharmacokinetic, pharmacodynamic |
| pharmaceutic phase | *1st phase of drug action *Dissolving process |
| disintegration | the breakdown of a tablet into smaller particles |
| dissolution | *Dissolving of the smaller particles in the GI fluid before absorption *Becomes a solution to cross cell membrane |
| excipients | *Fillers & inert substances *Allows the drug to take on a certain size & shape *Makes the difference between a generic & brand name drug |
| rate limiting | time it takes the drug to disintegrate & dissolve to become available for the body to absorb it |
| enteric-coated drugs | *Do not crush! *Resists disintegration in stomach; available in small intestine |
| pharmacokinetic phase | *Second phase of drug action *the process of drug movement to achieve drug action |
| 4 processes of pharmacokinetics, in order | absorption, distribution, metabolism(biotransformation), excretion(elimination) |
| absorption | movement of drug particles from GI tract to body fluids |
| 3 processes for absorption | *Passive *Active *Pinocytosis |
| passive absorption | *Occurs mostly by diffusion (movement from high conc grad to low conc grad) *The drug does not require energy to cross the cell membrane *Lipid soluble drugs pass rapidly |
| active absorption | Water soluble drugs require a protein or enzyme to cross the cell membrane |
| pinocytosis | *cells carry drugs across cell membrane by engulfing drug particles *"Pac-man" |
| first-pass effect | some meds aren't absorbed in GI tract, so they go through the portal vein to the liver |
| bioavailability | percentage of administered drug dose that reaches systemic circulation after first-pass effect |
| distribution | *the process by which the drug becomes available to body fluids & tissues *affected by blood flow, drug's affinity to the tissue & protein-binding effect |
| protein-binding | *as drugs are distributed in plasma, many are bound to varying % with protein (albumin & globulin) *the portion that is bound is inactive because its not available to receptors |
| free drugs | *the portion that remains unbound *active & can cause a pharmalogic response |
| volume of drug distribution (Vd) | *dependent on dosage & concentration in body *more Vd = more half-life |
| proteins usually bound by medications, two types | *albumin *globulin *FYI: albumin is made by the liver. If the liver is not working well & a protein-binding drug is to be used, the pt won't benefit much from it |
| metabolism(biotransformation) | the liver does a majority |
| half-life (t 1/2) | *the time it takes for one half of the drug concentration to be eliminated *affected by metabolism & elimination *short: 4-8 hrs, long: 24 hrs & longer |
| steady-state serum concentration | a constant level of a drug that is needed to be therapeutic |
| excretion(elimination) | *main route is through kidneys *other routes: liver metabolism (first-pass effect), bile, feces, saliva, sweat, breast milk *kidneys filter unbound, free drugs |
| creatinine clearance (CLcr) | *most accurate test to determine renal function *varies with age (elderly) & gender (women) d/t decreased muscle mass |
| pharmacodynamic phase | the study of drug concentration & its effects on the body |
| primary & secondary effects | *primary: desirable effect *secondary: desirable or undesirable effect Ex: diphenhydramine (Benadryl)- primary: antihistamine, secondary: undesirable if taken during the day d/t drowsiness or desirable at night d/t mild sedative effect |
| dose response | relationship between the minimal & maximal amount of drug dose needed to produce the desired drug response. *Ex: some people need higher dosages to get the desired response |
| maximal efficacy | *all drugs have a maximum drug effect *no matter how much is given, if the drug has already reached it maximal efficacy, it will not work any better |
| onset, peak & duration of drug action | *onset: time it takes to achieve minimum effective concentration *peak: when it reaches max blood or plasma concentration *duration: how long it lasts |
| receptor theory | *most receptors (proteins) are found on cell membranes *drug-binding sites are on proteins, glycoproteins, proteolipids & enzymes *drugs act through receptors by binding to initiate or block a response *Ex: similar to the fit of the right key in a lock |
| agonists | produces or initiates a response |
| antagonists | block a response |
| nonspecific drug effect | *drugs that affect various SITES (same type of receptor) *drugs that evoke a variety of responses throughout the body have a nonspecific response |
| nonselective drug effect | drugs that affect various types of RECEPTORS |
| 4 categories of drug action | *stimulation or depression *replacement *inhibition or killing of organisms *irritation |
| therapeutic index (TI) | estimates the margin of safety of a drug using a ratio that measures the effective dose (ED) & the lethal dose (LD) |
| low therapeutic index | *has a narrow margin of safety *drug levels need to be closely monitored because of the small safety range between ED & LD |
| high therapeutic index | *has a wide margin of safety *less danger of producing toxic effects; does not need to be routinely monitored |
| therapeutic range (therapeutic window) | *should be between minimum effective concentration & minimum toxic effect *if narrow window, monitor periodically to avoid drug toxicity |
| peak drug level | *highest plasma concentration at a specific time *indicates rate of absorption |
| trough drug level | *lowest plasma concentration *measures rate of elimination |
| loading dose | *large initial dose given to achieve rapid minimum effective concentration *given when an immediate drug response is desired *after initial dose, a dosage is prescribed daily to maintain that level |
| side effects | *physiologic effects not related to desired effects *usually predictable *desirable or undesirable (Ex: Benadryl) |
| adverse reactions | *severe, unintended side effects *occurs with normal dosages *always undesirable |
| toxic effects | *occurs with overdosing or drug accumulation *normally happens with drugs that have a narrow therapeutic index |
| pharmacogenetics | *effect of drug differs from predicted response d/t genetic factors or heredity *Ex: African Americans don't respond as well as Caucasians to some antihypertensives |
| tolerance | *decreased responsiveness over the course of therapy *Ex: someone that takes a pain med might have started out with only 1 pill, but over time, may take 2 because the 1 pill is no longer effective |
| tachyphylaxis | *acute decreased responsiveness or "acute tolerance" *happens faster than tolerance *occurs with: narcotics, barbiturates, laxatives & psychotropics |
| placebo effect | *psychologic benefit from a compound that should not have the chemical structure to cause the desired result *1/3 of people are susceptible *unethical if you don't tell the pt beforehand |
Created by:
orphans2001
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