Hanson 10e Pp Ts Ch05


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Hanson 10e Pp Ts Ch05

  1. 1. How and Why Drugs Work Chapter 5
  2. 2. Intended and Unintended Effects of Drugs <ul><li>Intended responses </li></ul><ul><ul><li>reason for using the drug </li></ul></ul><ul><li>Unintended responses </li></ul><ul><ul><li>side effects </li></ul></ul><ul><li>The main distinction between intended responses and side effects depends on the therapeutic objective. </li></ul>
  3. 3. Common Side Effects of Drugs <ul><li>Nausea or vomiting </li></ul><ul><li>Changes in mental alertness </li></ul><ul><li>Dependence </li></ul><ul><ul><li>Withdrawal </li></ul></ul><ul><li>Allergic reactions </li></ul><ul><li>Changes in cardiovascular activity </li></ul>© fred goldstein/ShutterStock, Inc.
  4. 4. Common Side Effects of Drugs (continued)
  5. 5. Dose-Response <ul><li>Many factors can affect the way an individual responds to a drug, including the following: </li></ul><ul><ul><li>Dose </li></ul></ul><ul><ul><li>Tolerance </li></ul></ul><ul><ul><li>Potency </li></ul></ul>
  6. 6. Dose-Response (continued) <ul><li>Additional factors </li></ul><ul><ul><li>Pharmacokinetic properties </li></ul></ul><ul><ul><ul><li>Rate of absorption </li></ul></ul></ul><ul><ul><ul><li>Manner distributed throughout the body </li></ul></ul></ul><ul><ul><ul><li>Rate metabolized and eliminated </li></ul></ul></ul><ul><ul><li>Form of the drug </li></ul></ul><ul><ul><li>Manner in which the drug is administrated </li></ul></ul>
  7. 7. Dose-Response Curve
  8. 8. Margin of Safety <ul><li>The range in dose between the amount of drug necessary to cause a therapeutic effect and a toxic effect </li></ul>
  9. 9. Potency vs. Toxicity Toxicity the capacity of a drug to do damage or cause adverse effects in the body Potency the amount of drug necessary to cause an effect
  10. 10. Drug Interaction <ul><li>Additive effects </li></ul><ul><ul><li>Summation of effects of drugs taken concurrently </li></ul></ul><ul><li>Antagonistic (inhibitory) effects </li></ul><ul><ul><li>One drug cancels or blocks effects of another </li></ul></ul><ul><li>Potentiative (synergistic) effects </li></ul><ul><ul><li>Effect of a drug is enhanced by another drug or substance </li></ul></ul>
  11. 11. Pharmacokinetic Factors That Influence Drug Effects <ul><li>Administration </li></ul><ul><li>Absorption </li></ul><ul><li>Distribution </li></ul><ul><li>Activation </li></ul><ul><li>Biotransformation and elimination </li></ul>
  12. 12. Forms and Methods of Taking Drugs <ul><li>oral ingestion </li></ul><ul><li>inhalation </li></ul><ul><li>injection </li></ul><ul><li>topical application </li></ul>© Oscar Knott/FogStock/Alamy Images
  13. 13. Distribution <ul><li>Most drugs are distributed throughout the body in the blood. </li></ul><ul><li>It takes approximately 1 minute for a drug to circulate throughout the body after it enters the bloodstream. </li></ul><ul><li>Drugs have different patterns of distribution depending on their chemical properties. </li></ul>
  14. 14. Required Doses for Effects <ul><li>Threshold dose —the minimum amount of a drug necessary to have an effect </li></ul><ul><li>Plateau effect —the maximum effect a drug can have regardless of the dose </li></ul><ul><li>Cumulative effect —the buildup of drug concentration in the body due to multiple doses taken within short intervals </li></ul>
  15. 15. Time-Response Factors <ul><li>The closer a drug is placed to the target area, the faster the onset of action. </li></ul><ul><li>Acute drug response </li></ul><ul><ul><li>Immediate or short-term effects after a single drug dose </li></ul></ul><ul><li>Chronic drug response </li></ul><ul><ul><li>Long-term effects after a single dose </li></ul></ul>
  16. 16. Biotransformation <ul><li>Biotransformation —the process of changing the chemical or pharmacological properties of a drug by metabolism. </li></ul><ul><li>The liver is the major organ that metabolizes drugs in the body. </li></ul><ul><li>The kidney is the next most important organ for drug elimination. </li></ul>
  17. 17. Physiological Variables That Modify Drug Effects <ul><li>Age </li></ul><ul><li>Gender </li></ul><ul><li>Pregnancy </li></ul>© Pixtal/SuperStock
  18. 18. Adaptive Processes <ul><li>Tolerance – changes causing decreased response to a set dose of a drug </li></ul><ul><li>Dependence – the physiological and psychological changes or adaptations that occur in response to the frequent administration of a drug </li></ul><ul><li>Withdrawal </li></ul>
  19. 19. Adaptive Processes (continued)
  20. 20. Tolerance <ul><li>Reverse tolerance (sensitization) </li></ul><ul><ul><li>Enhanced response to a given drug dose; opposite of tolerance </li></ul></ul><ul><li>Cross-tolerance </li></ul><ul><ul><li>Development of tolerance to one drug causes tolerance to related drugs </li></ul></ul>
  21. 21. Drug Dependence Physical dependence Psychological dependence
  22. 22. Psychological Factors Affecting Drug Effect <ul><li>Individual’s mental set </li></ul><ul><li>Placebo effects </li></ul>
  23. 23. Addiction and Abuse <ul><li>The term addiction has many meanings. It is often used interchangeably with dependence, either physiological or psychological in nature; other times, it is used synonymously with the term drug abuse. </li></ul>
  24. 24. Addiction and Abuse (continued) <ul><li>Factors affecting variability in dependence </li></ul><ul><ul><li>Hereditary factors </li></ul></ul><ul><ul><li>Drug craving </li></ul></ul>
  25. 25. Addiction and Abuse (continued) <ul><li>Other factors contributing to drug use patterns </li></ul><ul><ul><li>Positive versus negative effects of drug </li></ul></ul><ul><ul><li>Peer pressure </li></ul></ul><ul><ul><li>Home, school, work environment </li></ul></ul><ul><ul><li>Mental state </li></ul></ul>