2. Drugs/Agents and Factors Affecting Their Action
Chapter 1
Drugs/Agents and Factors Affecting Their Action

3. Pharmacology
Study of the history, sources, and physical and chemical properties of drugs
Also looks at the ways in which drugs affect living systems
Various subdivisions of pharmacology have evolved
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4. Pharmacodynamics
Study of the biochemical and physiological effects of drugs
Study of drugs’ mechanisms of action
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5. Pharmacokinetics
Study of the absorption, distribution, biotransformation (metabolism), and excretion of drugs
Four steps
Absorption
Distribution
Metabolism
Excretion
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6. Pharmacotherapeutics
Study of how drugs may best be used in the treatment of illnesses
Study of which drug would be most appropriate or least appropriate to use for a specific disease; what dose would be required; etc.
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7. Pharmacognosy
The study of drugs derived from herbal and other natural (plant and animal) drug sources
Studying compositions of natural substances helps to gain knowledge for developing synthetic versions
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8. Toxicology Study of poisons and poisonings
All drugs have the potential to become toxic.
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9. History of Pharmacology
Ancient Egypt: the cradle of pharmacology
These medical sources listed over 700 different remedies for different ailments.
First century: Dioscorides prepared De Materia Medica:
Listed and classified 600 different plants used for medicinal purposes; first time plants were ever classified
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10. Sources of Drugs Drugs derived from: Natural sources
Semisynthetic sources
Synthetic sources
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11. Drug Uses Symptomatic treatment Prevention Diagnostic drugs Curative
Health maintenance
Contraception
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12. Dosage Forms Tablets Timed or sustained release
Tablets or controlled release
Capsule
Troches
Suppositories
(continues)
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13. Dosage Forms Solutions Douche Suspensions Emulsions Topicals
(continued)
Dosage Forms
Solutions
Douche
Suspensions
Emulsions
Topicals
Patches
Drug implants
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14. Parenteral Product Packaging
Ampules
Sterile
Sealed glass or plastic container
Contain a single liquid dose
Vials: either single or multiple dose
Glass or plastic container
Sterile liquid dose
Sealed with a rubber diaphragm
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15. Drug Names Chemical name Generic name (nonproprietary name)
The drug’s chemical composition and molecular structure
Generic name (nonproprietary name)
Name given by the United States Adopted Names Council
Allows the drug to be marketed
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16. Brand Name Also called trade name (proprietary name)
The drug has a registered trademark; use of the name is restricted by the drug’s owner (usually the manufacturer)
Allows the drug to be commercially distributed
The superscript ® is registered by the U.S. Patent Office and approved by the FDA (Food and Drug Administration)
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17. Drug Names: Examples Chemical name Generic name Trade name
(+/-)-2-(p-isobutylphenyl) propionic acid
Generic name
Ibuprofen
Trade name
Motrin
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18. U.S. Drug Legislation Pure Food and Drug Act of 1906
Required all drugs to meet minimal standards
Federal Food, Drug, and Cosmetic Act of 1938
Required the drug to be safe before being distributed over state lines
(continues)
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19. (continued)
U.S. Drug Legislation
1970: Comprehensive Drug Abuse Prevention and Control Act
Also known as Controlled Substance Act: classified drugs according to their abuse potential
Regulates the manufacture and distribution of drugs causing dependence
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20. Controlled Substances Schedules
Schedule I
High potential for abuse
No medical use
Heroin
LSD
Schedule II
Accepted medical use
Morphine
Demerol
Schedule III
Lower potential for abuse
Librium, Valium, hydrocodone, Tylenol with codeine
Schedule IV
Librium
Valium
Schedule V
Lowest potential for abuse
Lomotil
Robitussin A-C
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21. Prescription Drugs Prescription drugs = legend drugs
Drugs prescribed by:
Physician
Nurse practitioner
Physician’s assistant
Dentist
Veterinarian
Others
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22. Principles of Drug Action
Drugs
Alter existing cellular or chemical functions
Exert their action by forming a chemical bond with specific receptors within the body
Referred to as a lock and key effect
(continues)
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23. (continued)
Drug receptor interaction. Binding with specific receptors occurs only when the drug and its receptors have a compatible chemical shape.
(continues)
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24. Principles of Drug Action
(continued)
Principles of Drug Action
Receptors
The better the fit, the stronger the drug’s affinity, thus
Drug effect occurs at lower doses
(continues)
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25. Principles of Drug Action
(continued)
Principles of Drug Action
Agonist effect
Antagonistic effect
Adverse drug effect
Therapeutic effect
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26. Pharmacokinetics: Absorption
Routes
Oral
Parenteral
Topical
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27. Metabolism: First-Pass Effect
The metabolism of a drug and its passage from the liver into the circulation
Metabolism occurs in the liver
Liver enzymes react with the drug
Increases the dosage requirement
The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation.
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28. Pharmacokinetics: Distribution
The transport of a drug in the body by the bloodstream to its site of action
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29. Elimination/Excretion
The elimination of drugs from the body
Kidneys (main organ)
Liver
Bowel
(continues)
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30. (continued)
Renal excretion of drugs. Note sites where drugs are secreted and reabsorbed.
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31. Pharmacokinetics: Measuring Drug Action
Half-life
The time it takes for one half of the original amount of a drug to be removed from the body
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