Drug Therapy : Absorption Flashcards
<p>What is pharmaceutical process?</p>
<p>Getting the drug into the patient</p>
<p>What is pharmacokinetic process?</p>
<p>Getting the drug to the site of action</p>
<p>What is pharmacodynamics process?</p>
<p>Producing the correct pharmacological effect</p>
<p>What is therapeutic process?</p>
<p>Producing the correct therapeutic effect</p>
<p>What are the 4 basic factors that determine pharmacokinetics?</p>
<p>Absorption</p>
<p>Distribution</p>
<p>Metabolism</p>
<p>Elimination</p>
<p>A knowledge of the factors of pharmacokinetics enables an understanding of what?</p>
<p>Dosage</p>
<p>Drug administration</p>
<p>Drug handling</p>
<p>Patient variability</p>
<p>Potential for harm</p>
<p>What must most drugs do to have biological action?</p>
<p>Enter the blood stream and be distributed to a site of action</p>
<p>What are different methods of administration?</p>
<p>Oral</p>
<p>Intra-venous (IV)</p>
<p>Subcutaneous (applied under the skin)</p>
<p>Intramuscular</p>
<p>Other GI (sublingual, rectal)</p>
<p>Inhalation</p>
<p>Nasal</p>
<p>Transdermal (delivered across the skin)</p>
<p>What is absorption?</p>
<p>Process of movement of unchanged drug from the site of adminstration to the systematic circulation</p>
<p>What does absorption depend on?</p>
<p>Properties of the drug</p>
<p>Dosage used</p>
<p>Anatomy and physiology of the drug absorption site</p>
<p>What is the relationship between plasma concentration and the therapeutic response?</p>
<p>There is a correlation between the two</p>
<p>What is Cmax?</p>
<p>The peak concentration</p>
<p>What is T max?</p>
<p>The time to peak concentration</p>
<p>What does the area under the curve of a concentration/time graph represent?</p>
<p>Total amount of drug that reaches systematic circulation</p>
<p>What does Tmax tell us?</p>
<p>How quickly the drug is going to get into our circulation to produce an effect</p>
<p>What does Cmax tell us?</p>
<p>Whether the effect of a drug may be toxic or ineffective</p>
<p>What does increasing the dose do in relation to Tmax and Cmax?</p>
<p>Does not increase Tmax but increases Cmax</p>
<p>What is the therapeutic range?</p>
<p>The range of concentration that a drug is active</p>
<p>What happens above the therapeutic range?</p>
<p>The drug is toxic</p>
<p>What happens below the therapeutic range?</p>
<p>The drug is ineffective</p>
<p>What is bioavailability?</p>
<p>The amount of a drug that gets into circulation and is available for biological activity</p>
<p>What is the bioavailablity of a drug given intra-venously?</p>
<p>100% bioavailability</p>
<p>How is bioavailability determined?</p>
<p>By giving the drug and working out the toal amount over time then comparing this to the IV route</p>
<p>What are some factors that affect bioavaiability?</p>
<p>Formulation</p>
<p>Ability of drug to pass physical barriers</p>
<p>Gastrointestinal effects</p>
<p>First pass metabolism</p>
<p>What impacts a drugs ability to cross physical barriers?</p>
<p>Particle size</p>
<p>Lipid solubility</p>
<p>pH and ionisation</p>
<p>What must a drug be to dissolve in lipids?</p>
<p>Unionised</p>
<p>What does first pass metabolism refer to?</p>
<p>Removal of the drug by the liver</p>
<p>What is bioavailability used to work out?</p>
<p>The best dosage of a drug for the desired effect</p>
<p>What are different kinds of transport across physical barriers?</p>
<p>Passive diffusion</p>
<p>Filtration</p>
<p>Bulk flow</p>
<p>Active transport</p>
<p>Facilitated transport</p>
<p>Ion-pair transport</p>
<p>Endocytosis</p>
<p>What does the degree of ionisation depend on for a drug and why?</p>
<p>The environment because most drugs are weak acids or bases</p>
<p>When does an unionised drug stop crossing a membrane?</p>
<p>Once equilbrium is reached</p>
<p>What may happen whilst a drug is in the middle of crossing a membrane?</p>
<p>Ion trapping</p>
<p>What is ion trapping?</p>
<p>Drug crosses the first membrane but then is ionised and cannot cross the second</p>
<p>Where do acidic drugs get stick?</p>
<p>In compartments with a high pH</p>
<p>What is the ability of a drug to diffuse across a lipid barrier expressed as?</p>
<p>Lipid-water partition coefficient</p>
<p>What must a drug be to diffuse across a lipid membrane?</p>
<p>In solution</p>
<p>Lipid soluble</p>
<p>What is the lipid-water partition coefficient?</p>
<p>Ratio of the amount of drug which dissolves in the lipid an water phase when they are in contact</p>
<p>How are drugs given that cannot diffuse across lipid membranes?</p>
<p>By IV to skip most of these barriers</p>
<p>Where does passive diffusion occur?</p>
<p>Along concentration gradients (requires no energy)</p>
<p>What does passive diffusion depend on?</p>
<p>Lipid solubility</p>
<p>Degree of ionisation</p>
<p>Where does facilitated diffusion occur?</p>
<p>Along the concentration gradient but requires carriers</p>
<p>What are examples of things that use facilitated diffusion?</p>
<p>Monosaccharides</p>
<p>Amino acids</p>
<p>Vitamins</p>
<p>Where does active transport occur?</p>
<p>Against concentration gradients (requires energy)</p>
<p>What are examples of things that use active transport?</p>
<p>Ions such as K, Na and Ca</p>
<p>Where does filtration occur?</p>
<p>Through channels in the cell membrane</p>
<p>What is the driving force of filtration?</p>
<p>Hydrostatic pressure or osmotic pressure difference across the membrane</p>
<p>What uses filtration?</p>
<p>Urea</p>
<p>What are gastrointestinal factors that affect drug absorption?</p>
<p>Motility (speed of gastric absorption)</p>
<p>Food (can enhance or impair absorption)</p>
<p>Illness (can increase or decrease absorption)</p>
<p>Where are most drugs absorbed?</p>
<p>Small intestine</p>
<p>What is first pass metabolism?</p>
<p>Metabolism of drug prior to reaching systematic cirulation</p>
<p>What are some places involved in first pass metabolism?</p>
<p>Gut lumen (acid, enzymes)</p>
<p>Gut wall (metabolic enzymes)</p>
<p>Liver (hepatic enzymes)</p>
<p>What does absorption from subcutaneous/intramuscular sites depend on?</p>
<p>The blood flow at these sites</p>
<p>What do drugs given subcutaneously or intramuscularly avoid?</p>
<p>First pass metabolism</p>
<p>What do sublingual drugs avoid?</p>
<p>First pass metabolism</p>
<p>What is sublingual?</p>
<p>Under the tongue</p>
<p>What do drugs given via the rectum bypass?</p>
<p>First pass metabolism</p>
<p>What is the absorption of a drug from the rectum like?</p>
<p>Slow</p>
<p>What kinds of drugs are often given via the rectum?</p>
<p>Ones that cause irriation to the stomach</p>
<p>What is inhalation best for?</p>
<p>Volatile agents</p>
<p>How much of an inhalation drug is absorbed?</p>
<p>5-10%</p>
<p>What are the advantages of transdermal drugs?</p>
<p>Avoids first pass metabolism and can provide a controlled release</p>
<p>What should be considered when deciding the mode of administration?</p>
<p>Purpose and site of drug action</p>
<p>Disease effects</p>
<p>Patients ability to take medicine</p>
<p>Speed of action</p>
<p>Reliability of absorption</p>
