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Phar1 Test1
Pharm 1 test 1
| Question | Answer |
|---|---|
| What is Pharmacokinetics? | Describes quantitatively the rates of the steps of drug disposition dose and tissue concentration. Involves ADME process and explains things from a mathmatical point of view. |
| What does pharmacokinetics encompass? | encompasses ADME plus clearance |
| What is the standard Creatine clearance? | 125 ml/min |
| What is Clearance? | : the removal of a drug in units of volume/time |
| What kind of information does pharmacokinetics give you? | quantitative data important to detail fate of the drug, but also to be able to predict doses, routes, etc. |
| How does pharmacokinetics effect dose adjustments | allows individual adjustment based on individual pharmacokinetic assessment |
| Describe the flow of dosage of a drug to effect | Dosage ~ Conc. in plasma water ~ Conc. At site of action ~Intensity of effect |
| What is the intensity of effect related to? | Intensity of effect related to drug conc. at receptor sites |
| What is duration of action related to? | Duration of action related to how long drug conc. at receptor site remains high enough to provide response |
| how does drug concentration vary at receptor sites? | Conc. at receptor sites changes as drug enters, distributes, and is eliminated |
| Does pharmacokinetics have difficulty with Quantitation? | yes,Due to the difficulty of properly modeling so many processes occurring simultaneously |
| What are some problems quantifying pharmacokinetics? | Often make certain assumptions which do not greatly affect the data such as: Intensity of effect is correlated to the concentration of free drug in plasma |
| when is Modeling used | Used whenever the fate of a drug is described either qualitatively or quantitatively. |
| Describe modeling | Mathematical model encompassing known factors about drug (such as distribution, etc) hypothesized first, then proven (or modified) by real-life observation. |
| What is the easiest model to use? | One-Compartment Model easiest to use, and many drugs follow this scheme. |
| Describe One-Compartment Model | Assumes a single compartment which is in equilibrium which accounts for drug in plasma, and various tissues. |
| Describe 2(or more) compartment model | more difficult Seen when drug moves into tissues and is handled at different rates than central plasma compartment |
| Describe the mathmatics for first-order disposition | (rate at any time is proportional to concentration of the drug) |
| What is the appreviation for plasma concentration? | Cp |
| What is the appreviation for time? | t (lower case) |
| Abbreviation for initial concentration? | Co |
| What is K? | A constant |
| True or false... after IV administration, plasma concentration (Cp) decreases at a rate inversly proportional at all times (t) to the concentration at that time: | False, the concentration decreases at a rate proportional at all times to the concentration at that time. |
| Do anesthetics have a wide or narrow theraputic window? | Narrow |
| For a one compartment model what does the concentration log look like on a graph? | Diagonal line\ |
| on a graph what does the Concentration look like when you dont take the log? | Curve line (sloping down and then evens out) |
| If the dose is given, how can you calculate the volume of distribution? | Vd = D0/C0 |
| What is the abbreviation of volume of distribution? | Vd |
| abbreviation for half life | t 1/2 |
| give the formula for half life and K | t1/2 = 0.693/k |
| Describe the log plot for a two compartment model | Log plot does not give a single straight line, but instead shows two phases |
| Describe 2 compartment Model | Involves both distributive and elimination phases normally. |
| What 2 compartments do you have in a 2 compartment model? | now have a central compartment (ex.- plasma), and another compartment (ex.- tissue). |
| Why do the 2 compartments differ? | Differ because there are not an equal concentration thoughout the body and there are multiple concentrations. The tissue concentration can be preditive from the concentration in the plasma. |
| Can all drugs be properly estimated through pharmacokinetics? | No |
| Describe first Order Kinetics | The higher the concentration the faster drug is removed the lower the slower. If true first order then it will be a straight line |
| Describe zero Order Kinetics | no matter the concentration the time is still the same. Dependant of time not concentration |
| What is the difference on a graph when you give IV dose vs Oral dose? | IV dose starts up top. If oral dose then it would start at the bottom. |
| true or false, you don’t normally eliiminate drug from tissue, it has to get back into the plasma | TRUE |
| true or false, elmination does not occur during absorption | false! elimination does occur during absorption |
| What is Peak effect? | absorption rate and elimination rate are equal |
| What is theraputic minimum? | inorder to see effects in the body you have to get above this level |
| Define Zero order Kinetics | rate is INDEPENDENT of the concentration. no longer dependant on concentration, but instead becomes constant, at least until concentration falls below saturation. |
| What is bioavailability? | percentage of a drug or drug product that enters the general systemic circulation. Includes not only amount entering body, but also rate of entry |
| What is bioequivalence? | Bioequivalence – comparable bioavailability between drugs. |
| What is therapeutic equivalence? | comparable clinical effectiveness and safety between similar drugs |
| What is the formula for bioavalibility? (F) | F = AUC (oral) / AUC (IV) |
| What is AUC | Area under the curve. Mathmatical way to determine the amount of drug that has been in the blood stream. (area under the curve is the total amt that gets into blood stream over the life of the drug. |
| What is volume of distribution(VD) | Vd, is the apparent or “virtual” volume into which a drug distributes. |
| Can Vd be larger than the total plasma volume in the body? | yes, ex:heparin = 5 liters (plasma only) |
| Why is Vd (volume of distribution) important? | knowledge of the Vd is also important in estimating the loading dose. |
| What is clearance? | Quantitative measure of the removal of endogenous or exogenous substances from the body or a specific organ. |
| How are the mathmatical models of clerance useful | help define proper dosing regimes. |
| what is the abbreviation for total body clearance | Cltot |
| K is the elimination rate constant, what is it equal to? | K= T 1/2 |
| What is the goal for IV dosing | is to provide a constant plasma level while supplying drug at the same rate as elimination. |
| What is a loading dose used for? | Used to reach steady state plasma concentration (Cpss) immediately, instead of waiting the normal 5 half-lives. |
| what is CPss | steady state plasma concentration |
| Why repeat iv dosing? | Can not maintain a constant Cpss, but instead maintain an average Cpss |
| What does IV dosing interval determine? | Dosing interval will determine severity of fluctuation above and below average Cpss |
| Describe the ideal dosing regimen | Determine the maintenance dose which will keep plasma level in therapeutic window |
| What is the most practical dosing regimine for compliance? | Once a day (2nd best is q12) over 4 times a day is NOT practical |
| describe maintenance dosing intervals | Maintenance doses are frequently given at intervals equal to their t1/2 , but must also be given at manageable times |
| True or false Drugs with a t1/2 less than 6 hours require a very wide therapeutic window to use them in repeated doses. | True |
| True or false Drugs with a t1/2 less than 6 hours require a very wide therapeutic window to use them in repeated doses. | true |
| What do you need to know in order to determine repeat oral dosing? | one must take bioavailability (F, the fraction entering general systemic circulation) into all calculations. |
| the amount of drug removed by an organ is dependant on | perfusion and extraction ratio (Concentration in venous minus arterial will give you the percent removed as it moves through) |
| Can first pass be saturable? | yes, and like all liver metabolism may increase due to enzyme induction. |
| Hepatic clearance is strongly related to.... | Blood flow |
| reabsorbtion vs flitration... | reabsorption= puts it back in the body and flitration puts it in the urinary fluid |
| Rate of renal excretion | = Rate of filtration + Rate of secretion – Rate of reabsorption |
| What is normal bile flow? | 0.5-0.8 ml/min |
| What does ADME stand for? | Absorption, Distribution, Metabolism and Elimination |
| What is drug absorption dependeant on? | Dependant on route, MW (size), solubility, availability of carrier molecules, etc. |
| Absorption greatly affects... | how quickly a drug elicits its biological response. |
| What are the most common routes of absorption? | Topical, Oral, Rectal, Pulmonary, Subcutaneous, intramuscular, intravenous, intra-arterial, intrathecal |
| Describe topical absorption | (influenced by blood flow, dermal thickness, lipid solubility) |
| describe oral absorption | (dependant on pH, solubility, formulation, stability) |
| describe rectal absorption | wide variation in absorption, but useful in comatose patients, or if drug is easily destroyed by GI pH or digestive enzymes) |
| describe pulmonary absorption | rapid absorption of many compounds, also for local treatment |
| describe subque absorption | under dermis, nonirritating drugs only, slow absorption |
| describe intramuscular absorption | into muscle, nonirritating only, faster absorption, depot injections |
| describe intravenous absorption | into vein, irritating drugs OK if given slowly, instant absorption |
| describe intra-arterial absorption | into artery, good for local therapy) |
| describe intrathecal absorption | into CSF, bypassing BBB |
| Does glucose move well across membranes | No (180) |
| Why is the Octanol coeff used? What is it similar to? | Cell Membrane |
| what is the composition of tight junctions between adjacent cells? | a neclace of membrane proteins |
| What is Distribution | Phase following absorption. Phase following absorption |
| What is distribution influenced by | Influenced by solubility, body water, protein binding, tissue binding, specific carriers. |
| What percent of total body water is intracellular | 40% |
| What percent of your total body water is extracellular? how is is broken down? | 20% (15% is interstitial and 5 % is vascular) |
| Can you take a sample at Zero time0 | No, if you have 1 Cp value and you know elimination rates and clearance you can get Cp0 |
| What is the #1 drug that proteins bind to? | Albumin |
| What are metabolism and Elimination | How a drug gets removed (or changed) from body. |
| What is a prodrug? | Prodrugs utilize metabolism to form active compounds |
| How many primary types of metabolism are there? What are they? | 2 types Phase 1( breakdown) Phase 2 (synthetic) |
| name 6 metabolic locations | Liver, lungs, skin, kidneys, blood and most all other tissues to a small degree |
| What is the #1 metabolizing organ in the body? | Liver |
| Can a drug pass through a phase 1 reaction and then the product be eliminated or further metabolized by phase 2? | yes |
| What is the family of metabolic enzymes responsible for phase 1 metabolism? | CYP= cytochrome p 450 family |
| Where are CYP enzymes located? | On the smooth spots of the E.R. |
| T/f if the drug picks up a proton it will decrease water solubility | Fase, picking up a proton will increase water solubility. |
| Glucuronidation... phase 1 or 2? | Phase 2 |
| Glutathione Conjugation... Phase 1 or 2? | Phase 2 |
| Sulfate conjugation...Phase 1 or 2? | Phase 2 |
| Non microsomal systems (ex: Non microsomal hydrolysis using cholinesterase) Phase 1 or 2? | Phase 1 |
| 2 most common CPY enzymes | . #1: Cyp 3a45 #2: cyp2d6 |
| What is Chirality? | Chiral refers to molecule with a center of three-dimensional asymmetry. |
| What are the chiral pairs named and what form does the body mostly use for amino acids and glucose? | D&L forms. The body uses D-glucose and L- Amino acids |
| Approx what percentage of all drugs are chiral? | >50% |
| What are enantiomers? | (molecules having opposite shapes) are pairs of molecules existing in forms that are mirror images of each other (right-& left-hand) but that cannot be superimposed. |
| What is Structure Activity Relationship (SAR) | Understanding the relationship between drug structures and biological activities forms the basis of rational drug design. |
| What is a racemic mixture? | A mixture of the D and L form |
| Why would you have racemic mixtures? | D&L compounds are VERY difficult to separate them and can become cost prohibitive. |
| What are the Three major types of chemical forces/bonds | Covalent, electrostatic, Hydrophobic interactions |
| Rank the major types of chemical bonds in order of strength | Covalent> Electrostatic > Hydrogen bonding > induced-dipole interactions(van der waals forces)>Hydrophobic interactions. |
| Why do we use Henderson-Hasselbach equation? | useful for determining how well an ionizable drug will cross biological membranes. |
| t/f drug ionization increases a drug's ability to cross a lipid bylayer. | False, it reduces it, you need the unionized form to cross the bilayer |
| What is the most common buffer in the blood? | Bicarb |
| what is a drug? | Mimics endogenous ligand (usually) |
| What is Pharmacology? | Study of drugs and how they act on systems. |
| Where do drugs act? | Most drugs work at receptor sites and most sites are PROTEINS |
| What Phase do you bipass when you give a drug IV? | Absorption |
| Define Absorption | moving of drug across a membrane |
| Where are most drugs absorbed? | small intestine |
| Define Pharmacodynamics | The effects of a drug on the body. Relates the drug concentration to its effect |
| What is an Agonist | A substance which interacts at a receptor to elicit a response. |
| What is an Antagonist | A substance which blocks the response of an agonist at a receptor. |
| What are the 4 types of antagonsists | Competetitve, non-competetitive, Negative antagonsist(inverse antagonist) and Partial agonist/antagonist |
| How are receptors usually named? | Usually named for the agonist and antagonist which the interact with |
| Where are 3 receptor locations? | Cell Membrane(inside and out), cell cytoplasm, nuclear envelope |
| Do all drugs exert their effects via receptor-mediated response | No (ex: mannitol-osmotic diuretic, methylcellulose-osmotic laxative, Dextrans |
| T/F receptors are responsible for the transduction of biological signals? | true |
| Can enzymes be drug receptors? | yes, Many enzymes have been shown to be specific drug receptors (ex.- digitalis acts on Na+/K+ ATPase in heart muscles, |
| Will alterations in ligand structure effect affinity and/or intrinsic activity? | yes, Due to required fit at binding site |
| name some drugs that dont act on receptors | alcohols, osmotically active drugs, antiseptics, Acidifying/alkalinizing agents Some anesthetics, hypnotics, and sedatives |
| what is the difference in drug concentration required to block receptors for both specific and non specific receptors. | Usually, nonspecific receptors (such as those for ethanol) require high drug concentrations for effect (millimolar to molar), whereas specific receptors require only low concentrations (nanomolar to millimolar). |
| What is an ionophore? | receptor system that has a ion channel attached to the receptor system. |
| What is a metabphore? | receptor is bonded to an enzymatic system. A metabolic receptor system. (metabolic conversion of one compound to another) |
| What is a protein coupled receptor system: | a receptor site with a g protein,Bind ligand to the system the protein couples with GTP( energy source) then proteins migrates away from the receptor zone and activates another membrane and activates or deactivevates that particular enzyme |
| What is Transduction? | Taking a signal and passing it on to the cell. |
| What is the shape of the standard dose response curve you see with a drug | Sansordal or sigmodial curve. (s shape |
| Which direction does competetive inhibition shift the Max effect curve | To the right |
| What does an Allosteric inhibitor do? | changes the ability of the agonist to bid to that site. Increase amount of inhibitor decreases ability of agonist to bind to the site. |
| Which direction does allosteric potentiation shift the dose curve? | To the left, decreases the dose necessary to illicit the response. |
| What is the association constant? (KA) | The affinity of drug binding |
| What is KD (dissociation constant)? | is the concentration at which 50% of the receptors are occupied |
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shamus22
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