Drug Therapy : Drug Interaction Flashcards
<p>What is a drug interaction?</p>
<p>Modification of a drugs effect by prior or concomitant administration of another drug</p>
<p>What are different things involved in drug interactions?</p>
<p>Drugs</p>
<p>Herbal</p>
<p>Food</p>
<p>Drinks</p>
<p>Pharmacogenetics</p>
<p>What is the object drug?</p>
<p>Drug which is effected by these interactions</p>
<p>What is the precipitant?</p>
<p>Agent which precipitants such a reaction</p>
<p>What are examples of drug interactions which are not always decremental?</p>
<p>Hypertension</p>
<p>Parkinson's</p>
<p>What is epidermiology?</p>
<p>Branch of medicine that deals with incidence, distribution and possible control of disease</p>
<p>What is the incidence of significant interactions?</p>
<p>Relatively low at 1%</p>
<p>What are some examples of drug involved in serious reactions?</p>
<p>Lithium</p>
<p>Warfarin</p>
<p>Erythromycin</p>
<p>Linezolid</p>
<p>What are drugs involved in serious interactions often?</p>
<p>Potent with a narrow therapeutic index, meaning a small change in blood levels induce toxicity</p>
<p>What do lots of foods interact with?</p>
<p>Warfarin</p>
<p>What happens to the probability of a drug-drug interaction with more medicaments?</p>
<p>Increases exponentially</p>
<p>Who are some people more likely to suffer from a drug-drug interaction?</p>
<p>Elderly</p>
<p>Young</p>
<p>Critically ill</p>
<p>Patients undergoing complicated surgery procedures</p>
<p>Patients on many medications</p>
<p>What kinds of conditions make people susceptable to drug interactions?</p>
<p>Chronic</p>
<p>What are examples of chronic conditions that make people more susceptable to drug interactions?</p>
<p>Liver disease</p>
<p>Renal impairment</p>
<p>Diabetes mellitus</p>
<p>Epilepsy</p>
<p>Asthma</p>
<p>Who usually experience severe interactions?</p>
<p>Patients with chronic conditions</p>
<p>What is pharmacodynamics?</p>
<p>Study of how a drug affects an organism</p>
<p>What is pharmacokinetics?</p>
<p>Study of how the organism affects the drug</p>
<p>What can drug interactions be?</p>
<p>Additive or synergistic</p>
<p>Antagonistic</p>
<p>What can interactions be due to?</p>
<p>Changes in drug transport</p>
<p>Fluid and elctrolyte disturbances</p>
<p>Indirect pharmacodynamics interactions</p>
<p>What are the 4 stages of pharmacodynamics?</p>
<p>Absorption</p>
<p>Distribution</p>
<p>Metabolism</p>
<p>Elimination</p>
<p>What can a drug do to the pharmacokinetics of another drug?</p>
<p>Alter it</p>
<p>Why is it possible to predict potential interactions?</p>
<p>Due to marked inter-individual variations in pharmacodynamics process</p>
<p>What is it not possible to predict?</p>
<p>Patients who will have a clinically significant interaction</p>
<p>What do absorption interactions mechanisms include?</p>
<p>Formation of insoluble complexes</p>
<p>Altered pH</p>
<p>Altered bacterial flora</p>
<p>Altered GIT motility</p>
<p>What do most absorption interactions lead to?</p>
<p>Change in absorption rate and not the extend of absorption</p>
<p>When is delayed absorption likely to have a great impact?</p>
<p>When the drug has a short half life or when we want high plasma levels quickly</p>
<p>How can absorption interactions be avoided?</p>
<p>2-4 hours are left between administration of drugs</p>
<p>What do some drugs do in the GI tract?</p>
<p>Bind to each other</p>
<p>What are examples of drugs that bind to each other in the GI tract?</p>
<p>Tetracycline and erythromycin complex with iron, calcium and magnesium</p>
<p>Cholestryamine resin used to bind cholesterol in the GI tract also binds to other drugs like warfarin</p>
<p>What is absorption affected by (relates to acids/bases)?</p>
<p>Degree of ionisation which is dependant on pH</p>
<p>Why do drugs increase pH?</p>
<p>Reducing the [H+] ions</p>
<p>What are some drugs that increase pH?</p>
<p>H2 antagonists</p>
<p>Proton pump blockers</p>
<p>Antacids</p>
<p>What destroys normal gut flora?</p>
<p>Broad spectrum antibiotics</p>
<p>Where are most oral medicines absorbed?</p>
<p>Small intestine</p>
<p>What is the rate limiting step of most oral medicines?</p>
<p>Gastric emptying</p>
<p>What can some drugs do to gastric emptying?</p>
<p>Increase or decrease it and so impact absorption of other drugs</p>
<p>What is the drug interaction in distribution?</p>
<p>Protein-protein displacement</p>
<p>When does protein-protein displacement occur?</p>
<p>When there is a reduction in the extent of plasma protein binding of a drug caused by the presence of another drug</p>
<p>What does displacement of a drug from a plasma protein cause?</p>
<p>Increased bioavailability of that drug</p>
<p>What are the 2 most important plasma proteins?</p>
<p>Albumin</p>
<p>Alpha1-glycoprotein</p>
<p>What protect patients from distribution interactions?</p>
<p>Increased metabolism and excretion</p>
<p>What drugs cause distribution interactions?</p>
<p>Ones which are highly protein bound</p>
<p>What are examples of drugs which are highly protein bound?</p>
<p>Indomethacin</p>
<p>Warfarin</p>
<p>Ibuprofen</p>
<p>When do interactions involving metabolism occur?</p>
<p>When one drug induces or inhibits the metabolism of another</p>
<p>Where does metabolism of drugs commonly occur?</p>
<p>In the liver via the cytochrome P450 system</p>
<p>What are some drugs that can inhibit the cytochrome system?</p>
<p>Erythromycin</p>
<p>Cimetidine</p>
<p>What do drugs inhibiting the cytochrome system cause?</p>
<p>Inhibition of metabolism of drugs that use that cytochrome</p>
<p>What are drugs that can be affected by drugs inhibiting the cytochrome system?</p>
<p>Warfarin</p>
<p>Diazepam</p>
<p>What are some drugs that are potent inducers of cytochrome P450?</p>
<p>Barbiturates</p>
<p>Carbamazepine</p>
<p>How long does it take for the effects of enzyme induction to be seen?</p>
<p>2-3 weeks</p>
<p>What factors impact the effect of enzyme induction been seen?</p>
<p>Age</p>
<p>Disease</p>
<p>Genetics</p>
<p>Concurrent drug therapy</p>
<p>What are examples of drugs inducing the production of cytochrome P450 enzymes?</p>
<p>Rifampicin inducing CYP 3A4 increases metabolism of Ciclosporin</p>
<p>St John's wort induces CYP 3A4 to increase metabolism of ciclosporin</p>
<p>Where are most drugs excreted?</p>
<p>In urine or bile</p>
<p>What do interactions in excretion involve changes in?</p>
<p>Glomerular filtration rate</p>
<p>Tubular secretion</p>
<p>What is glomerular filtration rate?</p>
<p>How much blood passes through the glomeruli each minute</p>
<p>What is the glomeruli?</p>
<p>Tiny filters in the kidney that filter waste from blood</p>
<p>What is an example of a drug that inhibits excretion?</p>
<p>Calcium channel blockers</p>
<p>When do pharmacodynamic interactions occur?</p>
<p>When the action of a drug is changed due to another drug acting directly on the same receptor or indirectly on a different receptor</p>
<p>What can pharmacodynamic interactions be?</p>
<p>Direct</p>
<p>Indirect</p>
<p>Antagonistic</p>
<p>Synergistic/Agonistic</p>
<p>What is an example of pharmacodynamic direct antagonsm?</p>
<p>Beta blockers blocking the site of agonists</p>
<p>What is an example of pharmacodynamic synergistic interactions?</p>
<p>Two drugs with the same pharmacological effect acting on the same receptor are given concurrently</p>
<p>What is an example of a pharmacokinetic indirect agonism?</p>
<p>CNS depression</p>
<p>Warfarin and NSAIDs</p>
<p>What is an example of pharmacodynamic indirect antagonist?</p>
<p>NSAIDs and antihypertensive medication</p>
<p>NSAIDs and treatment for heart failure</p>
<p>What is the process of clinically dealing with an interaction?</p>
<p>1) Determine if the interaction is clinically important</p>
<p>2) Will altering the dose timing solve the interaction</p>
<p>3) Will using an alternative solve the interaction</p>
<p>4) If no for all of above, adjust the dosage and monitor the drug level and physiological function</p>
