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64 Cards in this Set
- Front
- Back
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What is therapeutics?
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Clinical use of drugs to treat disease
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What is pharmacokinetics?
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Study of the effects of the body on drugs. Deals w/ absorption, distribution, metabolism and excretion
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What is pharmacdynamics?
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Study of the effects of drugs on the body and mechanisms of action
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What is an agonist?
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Drug + receptor = effect
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Most drugs show a plateau effect or a ceiling at which an increase in the drug no longer causes an increase in effect. What is a type of drug that does not show this type of relationship?
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Narcotics. Narcotic dose and response have a direct relationship.
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What is efficacy?
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Ability of a drug to produce a therapeutic affect. Ex. of efficacy vs. potency: Morphine and Meprinidine have the same efficacy despite difference in potency.
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What is an antagonist?
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Drug + receptor = no effect
Prevent agonist from binding to receptor. Binds to the same receptor or next to it, changing it so that the agonist can't bind. |
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What is synergy?
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Effect of 2 drugs = greater than expected or greater than the additive effects of the two drugs alone.
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What occurs when foods high in Tyramine are ingested by a patient taking MAO inhibitors?
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Tyramine causes a presynaptic release of norepi which is normally broken down by monoamine oxidizers. Someone on MAOIs, the MAOI prevents the breakdown of norepi and the result is hypetension.
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What is the therapeutic index?
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LD50/ED50: dose that produces lethal effects in 50% of ppl divided by the dos that produces therapeutic effects in 50% of people. Compares the benefits and risks of a drug. Lower the therapeudic index, the more dangerous.
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What is a side effect?
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Bothersome but not serious.
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What is an adverse drug event?
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Potentially serious, unpredictable, infrequent.
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What are teratogenic effects?
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Birth defects caused by a drug taken by the mother while pregnant. Categorized. Category A are ok to take, category X do not take.
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What is a hypersensitivity reaction?
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Allergy. Requires previous exposure to develop the antibodies, but there can be instances where it appears it is the first exposure, but exposure could have been through ex: food and the patient is unaware.
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What is cross reactivity?
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Hypersensitivity reaction to drugs chemically or pharmacologically related to drugs exposed to in the past. Ex: pts w/ pen allergy, 10-15% react to cephalosporins because they are similar.
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What are 4 examples of drugs that cause a reduced extent of GI absorption whcih causes a decreased serum concentration of object drug?
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Antacids, Kaolin-pectin, calcium cholestyramine, iron
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What are 4 drugs that cause displacement from plasma protein binding sites which causes a transient increase in free serum drug concentration of both drugs?
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Oral anticoags, Salicylate, Phenytoin, Sulfonamides
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What are 6 examples of enzyme inducers which cause reduced serum concentration of the object drug?
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Barbituates, Carbamazepine, Rifampin, Phenytoin, Cigarettes, St. Johns Wort
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What are 8 examples of enzyme inhibitors that cause increase serum concentration of object drug?
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Cimetidine, Erythromycin, Clarithromycin, INH (isonicotinylhydrazine), Propoxyphene, Grapefruit juice, SSRIs (selective serotonin reuptake inhibitor), statins
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What are 4 drugs that reduce renal elimination which causes an increased serum concentration of one or both drugs?
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Methotrexate, NSAIDs, Probenecid, Penicillins
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What is drug induced Torsades de Pointe?
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Prolongation of the QT interval caused by ventricular arrhythmia - possibly fatal
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What are 3 drugs that can be associated with drug induced Torsades de Pointe at therapeutic concentrations?
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Amiodarone, Sotolol, Procainamide
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What are 3 drugs that can be associated with drug induced Torsades de Pointe at elevated concentrations?
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Clarithromycin, Erythromycin, Quinolone abx
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What are the 4 components of pharmacokinetics?
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Absorption, Distributions, Metabolism, Excretion
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What are the 3 physiochemical factors that affect absorption?
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Lipid solubility, molecular size and degree of ionization.
Ionization: lipid soluble vs water soluble - most drugs are weak acids or bases which make it easier for them to be absorbed |
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What are 2 phsiologic factors that affect drug absorption?
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Absorptive surface area and circulation to the absorptive surface
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What is first pass metabolism?
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Drug from the GI tract goes through the portal system before reaching the systemic circulation. Sometimes a large portion of drugs can be metabolized before reaching the systemic circulation. This decreased the bioavailability
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What are 4 factors that affect distribution?
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Protein binding (Phenytoin 90% boutn, only 10% can interact w/ receptor), Tissue perfusion, Blood brain barrier (drug needs to be highly lipophilic to cross), Placental barrier (poor barrier)
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What are 5 outcomes of drug metabolism?
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Inactivate the drug, Increase the drug potency, Alter the structure so the kidney can excrete it, Make the drug more toxic, Activate the drug (Prodrug - needs to go through liver to produce effect. Prodrug = no activity)
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What are 4 types of metabolic reactions?
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Oxidation - p450 system (can be induced or inhibited by many drugs), Reduction, Hydrolysis, Conjugation
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What is the first metabolic reaction that fails in liver disease?
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Oxidation
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What are 6 factors that influence metabolism?
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Amount of free drug available (unbound), Hepatic disease, Liver blood flow, Enzyme induction, Enzyme inhibition, Protein binding displacement
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What is the equation for creatinine clearance?
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(140-age)(Lean body weight kg)/ (Scr)(72)
Multiply by 0.85 for female |
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What is renal clearance?
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Filtration + secretion - reabsorption
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What is linear kinetics?
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Serum drug concentrations change proportionately w/ chronic drug dosing. Dbl the dose, dbl the serum drug concentration at a steady state.
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What is non-linear kinetics and what is an example?
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Serum drug concentrations rise out of proportion to an increase in dose. Double the dose, much greater than dbl the serum drug concentration. Ex Phenytoin (Dilantin) - important not to dbl dose when you need dbl effect -> end up in toxic level
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What is extraction ratio?
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Rate of plasma drug removal by an organ of elimination, divided by the rate at which it is presented to this organ. 0 to 1. Close to 0, most of the drug escapes elimination on first pass of organ. Close to 1, most of the drug is eliminated on first pass.
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What are 2 drugs that have a low extraction ratio?
Reminder - low extraction ratio = most drug not eliminated on first pass |
Phenytoin, warfarin
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What are 3 drugs that have a high extraction ratio?
Reminder - high extraction ratio = most drug IS eliminated on first pass |
Lidocaine, propranolol, morphine
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What are 4 characteristics of low extraction ratio?
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Liver enzymes have limited capacity to metabolize drug, extent of protein binding affects clearance, decreases in protein binding will increase clearance because more is available to be cleared, total drug conc will decrease, but free conc remains unchanged
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What are 4 characteristics of high extraction ratio?
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Large first pass metabolism, Enzymes have a large capacity to metabolize drug, Changes in liver blood flow affect clearance, Nearly all drug presented to liver will be cleared regardless of protein binding
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What is the half life?
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Time required for serum concentration to decline by 50%
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What is steady state?
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Drug accumulation w/ repeated doses of a drug. Time to get to steady state depends on half life. Usually 3-5 half lifes. Serum conc levels will rise until equilibrium reached btwn dose admin and amt eleminated. Plateau is where steady state is reached.
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What is implantation - route of administration?
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Pellette under the skin. Allows for slow, sustained release over months. Hormone contraceptive, etc.
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What are the three types of drug classes (in terms of needing prescription)?
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Legend drug (controlled, non-controlled substances), otc, third class of drugs
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What are legend drugs?
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Drugs that need a prescription
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What are third class of drugs?
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Select few of prescription drugs sold w/out a prescription but must be sold by a pharmacist.
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What are schedule I drugs?
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High abuse potential. Not legally prescribed in US. I.e. heroine, LSD
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What are schedule II drugs?
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High abuse potential, but they are sold in the US. Can't prescribe over phone except in emergency. In emergency, 72 hour supply given - no refills! Phys DEA # required.
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What are schedule III drugs?
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Lower abuse potential. Rx must be re-written Q 6 months or 5 refills. Phone Rx allowed. DEA # required.
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What are schedule IV drugs?
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Lower abuse potential than III. But same regulations.
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What are schedule V drugs?
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Lower abuse potential than IV. Can be dispensed w/out Rx in some states but not CT.
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What are the 7 things required on a prescription?
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Date, Name address age of pt, Name of drug dose and quant, "sig," (how to take medication including what drug is being used for) refill info, prescriber's signature, DEA #
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What errors can occur when prescribing for children or elderly?
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Dosage based on body weight, elderly often have decreased liver or kidney function. Also, elderly can have communication or cognitive errors.
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How long does it take to bring a drug to market?
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Development time ranges from 2-12 years
Ave cost $1.8 bil, 1 in 10,000 compounds reach market, 1 in 3 drugs recapture development costs |
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What are the phases of drug development?
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Preclinical - in vtiro & animal testing, then human testing, Phase 1 trial - small group of healthy ppl to determine normal pharmacokinetics (how the drug is metabolized), Phase 2 - pts that have the disease, Phase 3 - placebo, blind, etc, Post marketing surveillance
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What happens after the drug development phases?
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If no red flags, all data submitted to FDA in new drug application. FDA approves labeling (not sale of drug).
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How long does it take for a new drug application to be reviewed by the FDA? Exceptions?
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About a year. Some expedited if the compound is unique w/ documented survival benefit. Ex: many anti-virals for HIV were expedited.
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What is post marketing surveillance?
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When a drug has a wide spread usage in a population, adverse events are monitored and drugs can be recalled. Medwatch.
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When can generic drugs be developed?
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After the patent has expired on the brand drug. Generic drug must gain FDA approval with abbreviated new drug app, but they don't have to redo clinical studies. Process is cheaper --> generic cheaper.
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What must generic drugs show to be approved by the FDA?
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Must show bioequivalence: Contain same active ingredient, same dosage form and route of administration, identical in strength and concentration.
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What is a misconception about generics?
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That they can vary by 20% from brand. Not true. If FDA agrees w/ bioequivalence --> AB rated and substitution can occur
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How much do generics actually usually vary from brand?
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Less than 4% in the US. 98% of all meds, generic substitution is clinically the same.
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Are herbal supplements regulated by the FDA?
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No
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