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Basic Pharmaceutics
| Question | Answer |
|---|---|
| What kind of effects do drugs produce in the body? | desired or undesired |
| where are drugs circulated | throughout the body |
| what influences where the in the body the drug will go? | properties of both the drug and the body |
| site of action | the place where a drug causes an effect to occur |
| what is the objective of drug therapy | to deliver the right drug, in the right concentration, to the right site of action, and at the right time to produce the desired effect. |
| what happens when most drugs produce an effect? | they are interacting at a molecular level with cellular material or structure |
| Receptor | the cellular material directly involved in the action of the drug |
| how would you describe the receptor | a lock into which the drug molecule fits as a key, and only those drugs able to interact with the receptors in a particular site of action can produce effects at that site |
| specific cells only respond to certain drugs even though what | their receptors are exposed to any drug molecules that are present in the body |
| drugs are selective in their action meaning | they only act on specific targeted receptors and tissues |
| where are receptors located | the surface of cell membranes and inside cells |
| Selective action | the characteristic of a drug that makes its action specific to certain receptors and tissues |
| When drugs interact with the site of action they can: (7) | through physical action, react chemically, modify metabolic activity, change the osmolarity of blood, incorporate cellular material, join with other chemicals to form a complex, and modify the biochemical or metabolic process |
| some drugs work by what | changing the ability of ions to move into or out of cells |
| some drugs do what | modify the creation, release, or control of nerve cell hormones that regulate different physiological processes |
| Antagonists job | Block Action |
| Agonists job | Activate receptors |
| Antagonists | Drugs that bind with receptors but do not activate them. they block receptor action by preventing other drugs or substances from activating them |
| Agonists | drugs that activate receptors to accelerate or slow normal cellular function |
| What can happen when drug molecules bind with a receptor | they can cause a reaction that stimulates or inhibits cellular functions |
| what are the pharmacological effects of the interaction between molecules and receptors | agonism and antagonism |
| Examples of epinephrine-like drugs act on the heart to increase the heart rate, and acetylcholine-like drugs act on the heart to slow the heart rate | Agonists |
| What will the number of receptor available to interact with a drug mean | it will directly influence the effect |
| to produce an effect, what has to happen | a minimum number of receptors have to be occupied by drug molecules to produce and effect |
| what happens If there is little to no effect | there were too few drug molecules to occupy the necessary number of receptors |
| once all the receptors are occupied, what will increasing the dosage do? | increasing the dosage will not increase the effect |
| Can receptors be changed by drug use? | Yes |
| Extended stimulation of cells with an agonist can reduce the number/sensitivity of what? What happens? | receptors, the effect of the drug is reduced |
| Extended inhibition of cell functions with an antagonist can do what? | increase the number/sensitivity of receptors |
| if the antagonist is stopped abruptly, what happens? | the cells can have an extreme reaction to an agonist |
| it is difficult to measure the amount of a drug at the site of action and therefore what? | therefore to predict an effect based upon that measurement |
| what factors influence a drugs movement from site of administration to the site of action | Absorption, elimination, membrane permeability and that affect how a drug product behaves in them. more |
| why could it be impossible to measure the drug at the site of action | unknown location or small size |
| Dose response curve | a way to monitor the amount of a drug in the body and its effect at the site of action |
| what would you come to expect using a dose-response curve? | a certain effect for any given dose |
| human variability | different people have different characteristics that affect how a drug product behaves in them. |
| when are dose response curves not helpful? | when relating the amount of drug in the body to its effect |
| why is determining drug concentration in the bodys fluid | its a better way to relate the amount of drug in the body |
| why is blood generally used | because of its rapid equilibrium between the site of admin. and the site of action |
| what can knowing a drugs concentration in the blood be directly related to? | its effect; the most common way to analyze the potential effect of a drug |
| biopharmaceutics | the study of the factors associated with drug products and physiological processes and the resulting systemic concentrations of drugs |
| Minimum effective concentration (MEC) | the blood concentration needed for a drug to produce a response |
| onset of action | the time MEC is reached and the response occurs |
| therapeutic window | a drugs blood concentration range between its MEC and MTC |
| Which applications of Blood concentration do Manufacturers, pharmacy professionals, Researchers and clinicians, and physicians and pharmacists use? | Manufacturers use data to evaluate drug products,Pharm. prof. use them to see the consequences of incorrectly compounding a formulation/wrong route of administration, researchers/clinicians measure human variable, Physicians/Pharm. monitor drug therapy |
| Where does the blood concentration number begin? | At zero, at the time the drug is administered, before it has been absorbed in the blood |
| what happens when the drug leaves the formulation and enters the blood | it causes concentrations to rise |
| What has to happen to produce an effect in blood concentrations | they must achieve a (MEC)Minimum effective concentration |
| What happens during an MEC | there is enough drug at the site of action to produce a response |
| When the MEC happens, it is called | the onset of action |
| When blood concentrations increase what happens | so does the intensity of the effect, since blood concentrations at the site of action that produce the response |
| What is it called when some drugs have an upper blood concentration limit betond which there are undesired or toxic effects | the limit is called the MTC or Minimum toxic concentration |
| the range between the MEC and MTC is called | the therapeutic window |
| As absorption completes, what happens | blood concentrations are declining as absorbtion completes and eliminatation is proceeding |
| the time between the onset of action and when MEC is reached by declining blood concentrations is called | the is the duration of action |
| what is an advantage of using blood concentrations as a measure of the drug amount in the body | blood can be sampled repeatedly |
| When can a blood concentration time profile be developed | when sampling covers several hours or more |
| what else can be used for blood concentration time profiles? | serum or plasma |
| When changes in the blood concentration time profile reflect changes in the concentration at the site of action, what happens | changes effect |
| how are these drugs typically monitored? | by determining the the blood concentration Peak and Trough at the beginning and end of a doing interval |
| Examples of drugs that are monitored | vancomycin, phenytoin, gentamycin, digoxin, and valproic acid |
| ADME | Absorbtion, distribution, metabolism, excretion |
| Blood concentrations are the result of 4 simultaneously occurring processes | Absorbtion, distribution, metabolism, excretion |
| what is another name for the 4 processes other than ADME processes | Disposition |
| What are the metabolism and excretion processes combined called | elimination |
| Absorption | the transfer of drug into the blood from an administered drug product |
| what is the primary process when a drug product is first administered | Absorption |
| why do the processes of distribution, metabolism and excretion have much less of the drug available for the processes? | because absorption Is the primary process. |
| because distribution, metabolism and excretion use much less of the drug, what happens to the effect? | much less of an effect |
| where does blood deliver the drug | to the body tissue |
| what happens when the blood delivers the drug to the body tissue, if the drug cannot penetrate the tissues membrane | it will not interact with the receptors |
| when a drug is delivered to the body tissue, and is able to penetrate the membranes,what happens if there is not enough blood flow to the tissue? | little of the drug will be available |
| Distribution is influenced by what factor | a drug binding to proteins in the blood or tissues |
| ADME processes are illustrated by what | blood concentration time curves |
| Blood concentrations do what during absorption? | they rise |
| what happens as absorption begins completetion | metabolism and elimination become the primary processes |
| what happens as blood concentrations finish absorption, and metabolism and elimination become the primary processes? | they cause BC to decline |
| Why are the ADME processes studied separately as they occur simultaneously | to understand the critical factors responsible for each process |
| Half Life | the amount of time it takes for the blood concentration of a drug to decline to one-half an initial value |
| What should be done to estimate how long it takes to essentially remove the drug from the body via the process of eliminaton | 5x the half life is used |
| Why will most drugs dissociate and associate in solutions? | because they are weak organic acids and bases |
| Dissociate | come apart |
| Associate | Attach to other chemicals |
| What happens when acids dissociate? | they become ionized |
| What happens when bases dissociate | they unionize |
| why do unionized drugs penetrate biological membranes more easily than ionized drug | unionized drugs are: More lipid soluble,charges on biological membranes bind or repel ionized drugs,Ionized drugs associate with water molecules-creating larger particles with reduced penetrating capability |
| Passive diffusion | The movement of drugs from an area of higher concentration to lower concentration |
| Active transport | The movement of drugs from an area of lower concentration to an area of higher concentration. Cellular energy is required. |
| What is a critical factor of drug concentration and effect | how drugs move through biological membranes |
| Biological membranes | complex structures composed of lipids and proteins |
| 3 types of biological membranes | those made up of several layers of cells (skin), those made up of a single layer of cells(intestinal lining),those of less than one cell of thickness (as in the membrane of a single cell) |
| How do most drugs penetrate biological membranes? | by passive diffusion |
| Drugs in the bodys fluids usually move from a higher area of concentration to a lower area of concentration, until the concentrations in each area are what | balanced or in a state of equilibrium |
| What is a primary factor in the distribution process | passive diffusion |
| The movement of higher drugs to lower concentration causes oral meds to do what | move from the intestine to the blood, and from the blood to the site of action |
| Other than drug concentration, what else is a factor influencing diffusion | Drugs that are lipid soluble- they will penetrate biological membranes better than those that will not |
| Membranes are | lipoidal or fat-like |
| Drugs that are lipoidal are | hydrophobic drugs, they hate or repel water |
| Hydrophilic drugs can also penetrate membranes, however they use | water filled passages called aqueous pores which allow water and any drug contained in it, to move through the membrane |
| Ways to carry other drugs through/across membranes other than passive diffusion | Specialized transport |
| Active transport is thought to explain what | how certain substances that do not penetrate membranes by passive diffusion nevertheless succeed in entertaining a cell |
| Absorption occurs with how many routes of administration | to some extent, with all administration routes |
| stomach ph | 1-2 |
| large intestine | 7-8 |
| small intestine | 5-7 |
| what is one of the primary factors affecting oral drug absorption | the gastric emptying time |
| Gastric emptying time | the time drug will stay in the stomach before it is emptied into the small intestine |
| what happens if a drug is left in the stomach too long | it can be degraded or destroyed and the effects decreased |
| What are some factors affecting gastric emptying times | the amount or type of food in the stomach,the presence of other drugs, the persons body position and their emotional condition |
| once a drug leaves the stomach how does it affect absorption | the rate of movement through the intestines |
| what does slower than usual movement of the drug through the intestines do to the rate of absorption? | can lead to increased absorption because the drug is in contact with the intestinal membrane longer |
| what does faster than usual movement through the intestines do to the rate of absorption? | it goes through the intestinal track too rapidly to be fully absorped |
| what factors from the intestinal track affect absorption? | Bile salts and enzymes |
| Bile salts | improve the absorption of certain hydrophobic drugs |
| Enzymes added to the intestinal tracts contents from pancreatic secretions do what | destroy certain drugs and consequently decrease their absorption; can also destroy drugs as they pass from the gut to the blood |
| why does the small intestine benefit absorption? | large surface area |
| protein binding | the attachment of a drug molecule to a plasma or tissue protein, effectively making the drug inactive, but also keeping it within the body |
| Complexation | when different molecules associate or attach to eachother |
| Protein binding can be considered what | a type of drug storage or depot within the body |
| When are drugs released after being bound exensively to proteins in fat and muscle, what happens to the blood concentration | the drug is gradually released as the blood concentration falls |
| What kind of duration to protein bound drugs have | they remain in the body a long time, and have a long duration of action |
| Once drugs become distributed in the blood stream, they have action that is | selective to certain tissues or organs |
| How can drugs be targeted for specific t herapeutic effects? | receptors have a specific nature about them which affects the distribution of the drug to the right tissue |
| Why would drugs have multiple effects | most receptors can be found in multiple tissues throughout the body and used for different therapies |
| Bolus | Rapidly administered intravenous solutions |
| What is something that a rapidly administered intravenous solution doesn't have | an absorption site |
| Distribution | involves the movement of a drug within the body once the drug has reached the blood |
| Where does blood carry the drugs | throughout the body, to the site of action, as well as to the organs responsible for metabolism and excretion |
| how do blood flow rates effect distribution with different organs? | drugs are rapidly distributed to the organs with higher blood flow such as heart, liver, kidneys. distribution to areas with lower blood flow would be less |
| High blood flow organs | kidneys,liver,heart |
| Ares with low blood flow | muscle, fat and skin |
| Why is the permeability of the tissue membranes to a drug important? | most tissue membranes are easily penetrated by most drugs. Small drug molcules + hydrophobic drugs diffuse through tissue membranes easily. |
| What assists the tissue membrane in letting the drugs penetrate | Specialized transport mechanisms |
| The blood-brain barrier | Limits drug access to the brain and the cerebral spinal fluid |
| Protein binding can also affect distribution by: | drugs binding to proteins and forming a complex, which prevents the bound drug from entering its sites of action, metabolism and excretion, making the drug inactive |
| What kind of drugs can move through tissue membranes and cellular openings | Only a free or unbound drug |
| What makes a weaker drug unbound from a protein and what does it do | another drug with a stronger binding capacity can displace a weaker bound drug from a protein, making the weker bound drug unbound and available for pharmacological activity |
| What does metabolism refer to | the bodys process of transforming drugs |
| metabolite | the substance resulting from the bodys transformation of an administered drug |
| what are most metabolites | inactive molecules that are excreted |
| What do metabolites of some active drugs do | they will produce effects in the patient until they are further metabolized or excreted |
| What is the primary site of drug metabolism in the body | the liver |
| Enzymes | complex proteins that catalyze chemical reactions |
| What do the enzymes in the liver do? | interact with drugs and transform them into metabolites |
| How does the liver respond to chronic administration of certain drugs | the liver will increase its enzyme activity |
| What does an enzyme induction result in? | Greater metabolism of the drug |
| What is a result of enzyme induction | Larger doses of the drug must be administered to produce the same therapeutic effect |
| Enzyme inhibition | When some drugs decrease enzyme activity |
| What needs to be done for enzyme inhibition | smaller doses of the drug will be needed to avoid toxicity from drug accumulation |
| Where would the liver secrete drugs or metabolites | into the bile that is stored in the gallblader |
| What is the gallbladders job | to empty bile with any drugs or metabolites in it, into the intestinal tract. |
| What happens to any drugs or metabolites contained in the bile | they may be reabsorbed or simply eliminated within the feces |
| enterohepatic cycling | If the drugs or metabolites are reabsorbed back into the blood circulation |
| enzyme induction | the increase in hepatic enzyme activity that results in greater metabolism of drugs |
| first pass metabolism | the substantial degradation of an orally administered drug caused by enzyme metabolism in the liver before the drug reaches the systemic circulation |
| What happens if the kidneys process of excretion becomes impaired | excretion is reduced and some drugs will accumulate in the blood. |
| What do you do when there is a build of of a drug in the blood due to impaired excretion from the kidneys | dose must be decreased or the dosing interval lengthened |
| Factors affecting urinary excretion | drug accumulation if kidney excretion is impaired, some drugs affect the excretion, the ph of urine can affect the reabsorption of some drugs, |
| the amount of drug excreted in the urine is | the amount filtered + the amount secreted - the amount reabsorbed |
| High Ph in the urine has what effect | will decrease excretion of weak bases |
| What does a high PH increase | excretion of weak acids such as salicylates and phenobarbital |
| glomerular filtration | the blood filtering process of the nephron |
| Most drugs and their metabolites are | excreted in the urine by the kidneys |
| What is the result of some orally administered drugs not being absorbed by the gastrointestinal tract | as a result, they are significantly excreted into the feces |
| If enteroheptic cycling does not occur, what can happen | excretion can also occur through the bile, and certain drugs are removed through the lungs in the expired breath |
| What is the kidneys main job | they filter the blood and remove waste materials in it, including drugs and metabolites |
| As blood flows through the kidney, what happens | plasma water if filtered from the kidney into the nephron tubule, creating the process of glomerular filtration |
| What does filtered plasma water contain | waste materials and drugs from other parts of the body |
| Urinary reabsorption | when some drugs can be reabsorbed back into the blood from the urine/waste |
| What 3 processes have to happen for the remaining fluid in the kidneys to be excreted from the body as urine | 1.glomeruler filtration 2.renal secretion 3.urinary absorption |
| Which is faster, urinary excretion or fecal excretion | urinary excretion |
| How long does it take to excrete drugs through feces | a day or 2 |
| How long does it take to excrete drugs through urine | within hours |
| what is called the bioavailability of a drug | the amount of a drug the is delivered to the site of action and the rate at which it becomes available |
| How does the FDA measure bioavailability | by determining the relative amount of an administered dose of a drug that reaches the general systemic circulation and the rate at which this occurs |
| what tool is used to measure bioavailability | blood concentration profile |
| how is bioavailability often determined | by comparing blood concentration time profiles from a product to that of an intravenous solution, called absolute bioavailability |
| How is relative bioavailability determined | by comparing blood concentration time profiles of a product to any other product that is not an IV solution |
| What does comparing one bioavailability to another determine | their bioequivalency |
| The fda requires manufacturers to do what to do what to their products before they are approved for marketing | they have to preform bioavailability studies |
| how do you compare the bioequivalency of two drugs | the bioavailability of the active ingredient in a test formulation is compared to that in a standard formultion |
| Uses for bioequivalency studies | to compare bioavailability between different dosage forms, different manufacturers and different production lots |
| A pharmaceutical equivalent or alternative, which has essentially the same rate and extent of absorption when administered in the same dose of active ingredients under similar conditions | Bioequivalent drug products |
| Why does bioequivalency between drug products not occur? | to many variables contribute to the differences between product. the particle size may be different or manufacturing process may also produce different results in size hardness or other characteristics |
| Changes in some factors affect Bioavailability. There can be differences in bioavailability of different products when | the changes are not significant, the products are bioequivalent |
| Bioavailability | the relative amount of an administered dose that reaches the general circulation and the rate at which this occurs |
| Bioequivalency | the comparison of bioavailability between two dosage forms |
| Pharmaceutical equivalents | Same active ingredient/salt form, same amount of active ingredient, Same dosage form, Inactive ingredients can be different |
| Pharmaceutical equivalents have the following characteristics | do not have to contain the same inactive ingredients, or have the same physical shape, release mechanisms,packaging, or expiration time |
| Pharmaceutical equivalents may have different inactive ingredients, different pharmaceutically equivalent products and may not be equally suitable for a given patient. Why | one drug formulation may preform differently enough to change the overall effect |
| Pharmaceutical alternatives | Same active ingredient/diff. salt form, Amount of active ingredient can be different,Dosage form can be different,Inactive ingredients can be different |
| Pharmaceutical alterntives have the following characteristics | they do not have to have the same inactive ingredients or have the same shape, release mechanisms, packaging or expiration time |
| Therapeutic equivalents | therapeutic equivalents are pharmaceutical equivalents which produce the same therapeutic effect in patient |
| What is the name of "the orange book" that the FDA publishes annually | Approved Drug Products With Therapeutic Equivalence Evaluations |
| Def. Pharmaceutical equivalent | drug products that contain identical amount s of the same active ingredients in the same dosage form |
| Def. Phrmaceutical Alternative | Drug products that contain the same active ingredient, but not necessarily the same salt form, amount or dosage form |
| Def. Therapeutic equivalent | Pharmaceutical equivalents that produce the same effects in patients |
| When can therapeutic drug monitoring be useful? | when the blood concentration of the drug reflects the concentration at the site of action |
| Blood concentrations are the result of four simultaneously occurring processes- | absorption, distribution, metabolism and excretion |
| Beside the 4 processes, what is a critical factor of drug concentration and effect | How drugs move through the biological membranes. |
| Most drugs pass through biological membranes by | passive diffusion |
| One of the primary factors affecting oral drug absorption is | the gastric emptying time |
| Where are the proteins that many drugs bind to, found? | in the blood plasma |
| Why do drugs bind to proteins in the blood plasma? | to form a complex that is too large to penetrate biological membranes, essentially making a drug inactive |
| What is used as a catalyst in the transformation of drugs to metabolites | Enzymes |
| Most metabolites are | inactive molecules that are excreted |
| Urinary excretion formula | glomerular filtration + renal secretion - Urinary reabsorption |
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