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Chapter 11
| Term | Definition |
|---|---|
| What can human variability in biopharmaceutics and disposition do | Significantly alter blood concentration time profiles and drug efficacy |
| What are variables to be considered in the differences in disposition and response to medications | Age, weight, height, genetics and gender |
| Age stages of humans | Neonates + infants, Children, Adolescent, Adults, The elderly |
| Neonates and infants age | birth-1yr |
| Children age | 1yr-12yr |
| Adolescent age | 13-19yrs |
| Adults age | 20-70 |
| Elderly age | over 70 |
| Why would you have variables in giving Neonates/Infants medicine | Drug distribution, metabolism and excretion are quite different because the oragans haven't quite fully developed |
| Why would you have variables in giving Children medicine | They metabolize certain drugs more rapidly than adults. |
| What age does the metabolism start to increase? | between 1 yr and 12 yr |
| When do metabolism rates decline | with age, to normal adult levels |
| Drugs eliminated faster in children | Clindamycin, valproic acid, ethosuximide, and theophylline |
| Why would you have variables in giving adults medicine? | They experience a gradual decrease in many physiological functions between 30 and 70 yrs |
| Which age range typically consumes more drugs than any other age group | the elderly |
| Why do the elderly consume a greater amount of drugs | Greater instance of chronic illness and multiple disease states |
| The elderly taking more drugs results in what | a higher incidence of side effects/drug interactions in this age group |
| What are some of the physiological changes an elderly person has that significantly affects drug action | Changes in gastric ph and emptying time, intestinal motility and gastrointestinal blood flow. Changes in Cardiovascular system. Decrease in liver production of enzymes, decline in kidney function |
| What will changes in intestinal motility and gastrointestinal blood flow do to an elderly body | slow the rate of absorption |
| What do changes in the cardiovascular system, including lower cardiac output tend to do to an elderly body? | Slows distribution of drug molecules to their sites of action, metabolism and excretion |
| What will a decline in kidney function do to an elderly body | tends to slow urinary excretion of drugs |
| Why were woman excluded from clinical drug investigation? | to avoid exposure to a fetus or potential fetus to unknown risks |
| What did the FDA and NIH issue guidelines in 1993-94 stating | Woman will be included in clinical drug investigations unless some clear and compelling reason is known not to do so |
| Acetaminophen and clofibric acid are eliminated more rapidly in | woman than men |
| What does some gender base difference in drug responses tend to be related to | hormonal fluctuations in woman during menstrual cycle |
| An obvious reason men and woman may vary with some results of drug distribution | Differences in body composition |
| What factors might A woman in late stages of pregnancy may have physiological changes that tend to change the rate of absorption: | Delayed gastric emptying, delayed gastrointestinal tract motitlity |
| What happens to drug plasma protein binding in pregnant women? | may be reduced and metabolism increased in a number of drugs |
| the rate of urinary excretion for a number of drugs is much greater in | pregnant woman |
| During pregnancy, drugs can also readily transport from where | from the maternal to the fetal circulation |
| Because the fetus has underdeveloped mechanisms to handle drug exposure,drug concentrations do what | may be greater in the fetus than in the mother |
| Pharmacogenetics | a field of study which defines the hereditary basis of individuals differences in absorption, distribution, metabolism and excretion |
| What does the human variability, genetics, determine | the types and amounts of proteins produced in the body |
| Why do genetic differences result in differences in drug action | drugs interact with proteins in plasma, tissues, receptor sites and elsewhere |
| Genetic differences can result in | differences in drug action |
| What is the largest contributing factor to inherited variability | metabolism |
| Dosage adjustments are not usually made for adults who are slightly overweight. Who are they made for? | People really underweight/emaciated/anorexic or obese |
| What is the body fat considered to be obese | body fat content greater than 30% of your total body weight |
| Why does the dose have to be changed for an obese patient? | because of significant changes in the distribution and renal excretion of a number of drugs |
| one example of psychological factors influencing individual response to drug administration | in clinical trials, where placebos are used, patients report therapeutic or adverse effects |
| The disposition of some drugs can be altered in one person but not in another due to the presence of what? | diseases other than the one for which a drug is used |
| A pathological condition in any of these organs may have both, what | a direct effect on the drug action or a secondary effect through the other organs |
| there are a variety of Liver diseases that affect what | hepatic function |
| liver diseases that appear to decrease hepatic metabolism and diminish drug elimination | Cirrhosis and obstructive jaundice |
| How does acute viral hepatitis change disposition | changes are insignificant, and return to normal as soon as the condition clears |
| during absorption, when liver activity is decreased, what else is affected? | first pass metabolism is also reduced |
| When liver activity is decreased, and first pass metabolism is also reduced, how does that effect bioavailibility | results in increased bioavailability for drugs that are usually deverely degraded by first pass metabolism |
| What condition do patients with cirrhosis develop? | a condition in which a significsnt amount of blood coming from the intestine, bypasses the liver cells and directly enters the circulatory system |
| When the condition of significant amounts of blood bypassing liver cells and entering the circulatory system directly, what happens to the bioavailability? | the bioavailability of the drugs that would otherwise be degraded by first pass metabolism rises substantially |
| What can circulatory disorders at the extreme cause | either a change in magnitude of blood flow to and through an organ, or a regional - redistribution of the cardiac output. |
| Changes in blood flow influence what | drug absorption, distribution, and elimination and therefore have the potential to alter the effect of a drug |
| What can decreased blood flow from cardiovascular disorders can cause widespread effects on absorption, such as | Edema in the large intestine, decreased splanchnic blood flow, delayed gastric emptying, decreased intestinal motility, changes in GI ph, and changes to bacterial flora of the intestine |
| Decreased blood flow in the liver can effect what | metabolizing drugs that are hepatically eliminated |
| What would a diminished blood flow in the liver lead you to think | diminished blood flow = decreased clearance |
| What physiological changes does the liver go through if the blood flow is decreased | external and internal hepatic anastomoses are formed, which shunt the blood away from hepatic cells that contain metabolizing enzymes |
| What effect do changes in renal blood flow have on elimination | less effect in elimination of drugs than blood flow changes in the liver |
| What changes for renal excretion? | renal excretion can change significantly for those drugs that have a high renal clearance |
| What does reduced renal function, especially end stage renal disease affect | the elimination of many drugs and affect the plasma protein binding of drugs |
| What should be done as renal function decreases | the dosage of a drug that is eliminated by the kidney should be reduced to avoid accumulation of the drug in the body |
| how does reduced renal function affect plasma protein binding? | the plasma protein binding of acidic drugs is reduced in severe renal insufficiency |
| Normally the kidneys do not allow elimination of albumin but in chronic renal disease, what happens | excessive protein filtration may occur, which leads to loss of albumin in the body |
| What is albumin's role in protein binding | Albumin is the major plasma and tissue protein that is responsible for acidic drug binding |
| What is Orosomucoid | a plasma protein that is rapidly produced when the body is injured. Also a protein that many basic drugs bind to |
| How do orosomucoids come into play with chronic renal disease | Orosomucoid blood concentrations are higher than normal and this results in increased basic drug binding |
| How can decreased renal function be measured? | by monitoring the amount of creatine excreted in the urine |
| where is creatine created? | produced in the muscles in the body |
| How is creatine excreted? | at a constant rate primarily by glomerular filtration |
| What happens to creatine in diseased kidneys? | the rate of creatine excretion decreases |
| Cirrhosis | a chronic and potentially fatal liver disease causing loss of function and increased resistance to blood flow through the liver |
| Acute viral hepatitis | an inflammatory condition of the liver caused by viruses; the effects are less than in cirrhosis but long term exposure can progress into chronic disease with the same characteristics |
| Obstructive jaundice | An obstruction of the bile duct that causes hepatic waste products and bile to accumulate in the liver |
| Hypothyroidism | a condition in which thyroid hormone secretions are below normal, often referred to as an underactive thyroid |
| hyperthyroidism | a condition in which thyroid hormone secretions are above normal, often referred to as an overactive thyroid |
| what happens to the bioavailibility of drugs with hypothyroidism | the bioavailability of a few drugs is increased |
| what happens to the bioavailability of drugs with hyperthyroidism | the bioavailability is decreased because of the change in gastrointestinal motility |
| Changes that affected by thyroid conditions | Renal blood flow is decreased in hypothyroidism and increased in hyperthyroidism, the activity of metabolizing enzymes in the liver is reduced in hypothyroidism and increased in hyperthyroidism |
| Because of human variabilility, adverse drug reaction can.... | occur in one person but not another |
| adverse drug reaction | any undesired symptom and can involve any organ. common or rare, localized or widespread, mild or severe depending on the drug and the patient |
| CNS | Central nervous system |
| CNS side effects | may result from stimulation (agitation,confusion, delirium, disorientation, hallucinations), or CNS depression (dizziness, drowsiness, sedation, coma, impaired respiration and circulation) |
| Hepatoxicities | liver toxicities |
| types of hepatotoxicities | hepatitis, hepatic necrosis, biliary tract inflammation or obstruction |
| what kind of drugs are used to fight hepatotoxicities | hepatotoxic drugs like acetaminophen, halothane, isoniazid, chlorpromazine, methotrexate, nitrofurantoin, phenytoin and aspirin |
| any drud in any dose can cause an allergic reaction or hypersensitivity. why does this happen? | patients develops antibodies while previously taking the drug or a drug with a similar chemical structure.the drug will interact with the antibodies, releasing histamine and other substances that produce reactions |
| most severe form of rash/hypersensitivity | anaphylactic shock |
| how long does it take to see if you have an allergy or hypersensitivity | between minutes and weeks |
| Symptoms of anaphylactic shock | severe respiratory distress, and convulsions |
| How would you treat anaphylactic shock | immediate emergency treatment with epinephrine, antihistamines or bronchodilator drugs are required |
| Signs of adverse reactions in the Gastrointestinal area | anorexia, nausea, vomiting, constipation and diarrhea. more serious includes ulcerations and colitis/ IBS |
| Chronic usage of narcotic analgesics, sedative-hypnotic agents, antianxiety agents, and amphetamines can result in what kind of dependence | physiological and phycological |
| What is involved with physiological drug dependence | accompanied by unpleasant physical withdrawal symptoms when the dose is discontinued or reduced. |
| What is involved in psycological dependence | involves an emotional or mental fixation on drug usage |
| teratogenicity | the ability of a substance to cause abnormal fetal development when given to pregnant women |
| What drug groups are considered teratogenic | analgesics, diuretics, antihistamines, antibiotics and antimetics |
| Carcinogenicity | The ability of a substance to cause cancer |
| what kind of drugs are carcinogenic | several kinds of drugs, including hormones and anticancer drugs |
| a drugs effort can be altered by what | a drug-drug interaction |
| the probability of someone having a drug drug interaction increases with what | the number of drugs a person takes, and in certain disease states |
| Many drug-drug interactions can affect disposition of one or both drugs and result in what | increases or decreases in therapeutic or side effects |
| 4 means in which one drug may be affected by the extent or rate of GI absorption of another drug | Complexation, Gastric emptying, Gastric PH and intestinal metabolism |
| During absorption when complexation happens, what do drugs form by binding to other drugs | nonabsorbable complexes |
| What do nonabsorbable complexes result in | decreased absorption |
| What can affect the absorption of tetracyclines, methyldopa and levodopa by decreasing absorption | iron salts |
| What decreases the absorption of norfloxacin and ciprofloxacin | Antacids and sucralfate |
| How does propanthelene delay acetaminophen absorption | by slowing the rate of gastric emptying |
| Why use metoclopramide to increase acetaminophen absorption | it increases gastric emptying time |
| a problem with reducing gastric emptying time is | drugs that are to degraded by gastric acid, have a longer time to degrade, resulting in a decreased amount of drug available for absorption from the intestine |
| Drugs that alter the GI ph can have some varied effects on other administered drugs like what | the amount of unionized drug available for absorption, the rate of dissolution, intestinal motility and degradation |
| What drug-drug action is involved between birth control and oral antibiotic therapy | alterations in metabolism- the antibiotic kills the normal GI tract flora, which disrupts the enterohepatic recycling of the oral contraceptives estrogens |
| during distribution how does one drug increase the amount of free drug available during protein binding? | one drug displaces the other drug from a plasma protein binding it increases the pharmacological effect and its elimination because more of the drug is available for metabolism and excretion |
| when displacement issues happen during plasma protein binding, how long before the displacement interactions generally occur | within a week or two of administration, could be self correcting after a few days |
| if displacement of one drug by another during plasma protein binding happen, and interactions occur but self correct, what happens to the concentration of the displaced drug | it often returns to pre-interaction levels, even if the patient continues to take both drugs |
| What is the biggest consequence of displacement interactions | changes in pharmacological effect |
| If drugs are higher protein bound what happens to the displacement | displacement tends to have a greater effect than drugs that are not highly bound |
| how plasma bound is warfarin? | 98% plasma bound 2% free or unbound |
| If drug interaction displaces only 2% of the 98% bound warfarin, what is the result | 96% bound warfarin with 4% free or unbound |
| Complexation | when two different molecules associate or attach to each other |
| displacement | a drug that is bound to a plasma protein is removed when another drug of greater binding potential binds to the same protein |
| Enzyme induction | the increase in hepatic enzyme activity that results in greater metabolism of drugs |
| Enzyme inhibition | the decrease in hepatic enzyme activity that results in greater metabolism of drugs |
| What does enzyme induction do to the metabolism of drugs | increases the metabolism of rugs that use the same enzyme system and usually results in a reduction in pharmacological effects |
| Examples of enzyme inducers | phenobarbital, carbamazepine, phenytoin and rifampin |
| What two recreational activities can also induce metabolism | cigarette smoking and alcohol consumption |
| What is the time course for enzyme induction | slower than many other tpes of intractions |
| other than being dose related what else can affect enzyme induction | age, genetics or liver disease |
| which alteration in metabolism which usually occurs when two drugs compete for binding sites on the same metabolizing enzyme | enzyme inhibition |
| Enzyme inhibition generally has what effect on plasma concentration and pharmacological effect | increases plasma inhibition and pharmacological effect of atleast one of the drugs |
| what is studied if a drug is known to be metabolized by the liver | manufacturers often study its potential for enzyme inhibition early in the drug development process |
| examples of enzyme inhibitors | allopurinol, cimetidine, erythromycin, disulfiram, isoniazid, ketoconazole and verapamil |
| Unlike enzyme induction that has a much slower time course, what is the time course with enzyme inhibition | rapid onset, generally within 24hrs and tends to disappear quickly, once the inhibitor is discontinued |
| Why is enzyme inhibition easier to predict? | it appears to be dose related |
| when drugs share a similar chemical structure, they often share the potential for what | enzyme inhibition |
| Drug interactions that change filtration are rare, and filtration changes are usually more likely to occur in what | specific drug- those that change systemic blood pressure |
| Changes in filtration rate will also change what | change the rate of drug excretion |
| there are different secretion sytems in the kidneys based on what | basic drugs and acidic drugs |
| Which form of drugs do not seem to compete for the acidic drug transport system | basic drugs |
| what form of drugs do not seem to compete for the basic drug transport system | acidic drugs |
| what does it take for basic and acidic drugs to fight over transport systems, and what does it cause | 2 basics or 2 acidics will fight, which causes one or both of the drugs to accumulate in the blood |
| what is used as a passive transport system and is influenced by the ph of urine and the extent of ionization of a drug | urinary reabsorption |
| in acidic urine what happens during urinary reabsorption | acidic drugs tend not to be reabsorbed while basic drugs are not |
| As a result of acidic drugs not being reabsorbed, what happens to basic drugs? | they are excreted in the urine |
| In alkaline urine, what happens to acidic drugs | they will not be reabsorbed but will be excreted in the urine. |
| In alkaline urine what happens to basic drugs | basic drugs will be reabsorbed |
| some drug interactions do not alter drug disposition, but interact where | at the site of action |
| Sometimes the drugs compete for the same receptor, other times the interaction is more indirect and involves interfering with normal physiological processes. what are the interactions called | additive, summative, synergistic or potentiation |
| Why are the definitions of the drug interactions basically used as synonyms | its difficult to quantify the extent of altered drug activity |
| when do Additive Effects occur | occur when two drugs with similar pharmacological actions result in an effect equal to the sum of the individual effect |
| Many drugs affect the electrical activity of the heart. Amiodarone + dofetilide two drugs that are used, why? | they prolong repolarization of the heart as part of their therapeutic effect |
| When 2 drugs that prolong repolarization as part of their therapeutic effect are used together, what is the result | repolarization may be delayed too long and arrythmias may occur |
| when does Synergism occur | Occurs when two drugs with similar pharmacological actions produce greater effects than the sum of the individual effects |
| Example of synergistic drugs | asprin + warfarin= Anticoagulation |
| What does asprin do to anticoagulaed patients? | increases the risk of bleeding because it inhibits platlet function and causes gastric erosions |
| what is a large dose of asprin | 3g/day or more |
| what does a large dose of asprin do | can increase entire anticoagulation response |
| What dose a low dose of asprin do | appear to primarily increase minor bleeding |
| Additive effects | the summation in effect when two drugs of similar pharmacological actions are taken |
| potentiation occurs | when one drug with no inherent activity of its own increases the activity of another drug that produces an effect |
| antidote | a drug that antagonizes the toxic effect of another |
| if Amoxicillin+ Clavulanic Acid are used for increased duration of amoxicillins antibiotic effect, why is the clavulanic acid used? | it inhibits the enzyme that degrades amoxicillin, and then allows amoxicillin to be more potent than if used alone |
| Naxalone+Morphine How does Naxalone act as an antidote to Morphine distress? | displaces morphine from its receptor sites, preventing the morphine from causing further depressive effects |
| Ways to receive Vitamin K | through a drug or by eating grees like spinach, brussel sprouts or broccoli, or liquid supplements |
| Why is protamine sulfate given as an antidote to heparin overdose | Protamine combines with heparin to form a stable complex, which leads to the decrease in the anticoagulant activity of both drugs |
| How is Flumazenil an antidote for the sedative effects of Diazepam, Midazolam, and zolpidem | Flumazenil is a benzodiazepine antagonist that reverses the side effect by competing for the same receptors as the benzodiazipines and displaces them |
| when does the time course of drug interaction occur | varies substantially, sometimes almost immediately, or can be a week |
| What does knowing the time course of interaction allow | quick identification and treatment of potential interactions, also allows clinicians to evaluate the relative importance of an interaction from 2 drugs compared to their therapeutic effects |
| How do differences in diet come into play with drug-diet interactions | differences in the diet maybe attributed to various factors including food preferences and availability, diets designed for weight gain and loss, and variations for seasonal, religious, and therapeutic reasons |
| How does the physical presence of food effect absorption | interacting chemically, improving the solubility of some drugs by increasing bile secretion, affecting the performance of the dosage form, altering gastric emptying/ intestinal motility and altering liver blood flow |
| When is the bioavailability of a drug generally decreased | when the presence of food slows absorption |
| How does tetracycline interact with dairy products | the calcium in the dairy and the tetracycline combine to form an insoluble drug-food complex |
| what is an insoluble drug-food complex and how is it eliminated | it is an insoluble nonabsorbable compound that is excreted in the feces |
| what does dietary fiber do to the absorption of drugs | decreases the absorption of drugs |
| How can high fat meals influence drug distribution | high fat meals increase fatty acid levels in the blood. the fatty acids bind to the same plasma protein binding sites as many drugs and displaces the previously bound drug and increases the free concentration of that drug, leading the the increased effect |
| How can interactions that alter drug absorption be minimized | by separating the administration of drugs and food intake by about 2 hours |
| Drug-diet interactions | when elements of ingested nurtrients interact with a drug and this affects the disposition of the drug |
| What are high protein diets associated with | accelerated metabolism |
| what are high carbohydrate diets associated with | to decrease metabolism |
| what effect does the substitution of fat calories for carbohydrates have | doesn't affect drug metabolism rates |
| What kind of metabolism do mild or moderately undernourished adults have | normal or enhanced metabolisms |
| Severely malnourished adults have what kind of metabolism | decreased |
| What effect does increasing protein in the diet have on distribution | appears to increase glomerular filtration, decrease reabsorption and decrease secretion in the kidneys |
| Increased protein diet | increased metabolism |
| increased carbohydrate diet | decreased metabolism |
| increased fat diet | no effect |
| decreased calories | decreased metabolism |
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