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

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 1 - 2 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Pharmacodynamics Study of the biochemical and physiological effects of drugs Study of drugs’ mechanisms of action 1 - 3 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Pharmacokinetics Study of the absorption, distribution, biotransformation (metabolism), and excretion of drugs Four steps Absorption Distribution Metabolism Excretion 1 - 4 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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. 1 - 5 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 6 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Toxicology Study of poisons and poisonings All drugs have the potential to become toxic. 1 - 7 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 8 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Sources of Drugs Drugs derived from: Natural sources Semisynthetic sources Synthetic sources 1 - 9 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Drug Uses Symptomatic treatment Prevention Diagnostic drugs Curative Health maintenance Contraception 1 - 10 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Dosage Forms Tablets Timed or sustained release Tablets or controlled release Capsule Troches Suppositories (continues) 1 - 11 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Dosage Forms Solutions Douche Suspensions Emulsions Topicals (continued) Dosage Forms Solutions Douche Suspensions Emulsions Topicals Patches Drug implants 1 - 12 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 13 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 14 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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) 1 - 15 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Drug Names: Examples Chemical name Generic name Trade name (+/-)-2-(p-isobutylphenyl) propionic acid Generic name Ibuprofen Trade name Motrin 1 - 16 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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) 1 - 17 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

(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 1 - 18 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 19 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Prescription Drugs Prescription drugs = legend drugs Drugs prescribed by: Physician Nurse practitioner Physician’s assistant Dentist Veterinarian Others 1 - 20 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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) 1 - 21 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

(continued) Drug receptor interaction. Binding with specific receptors occurs only when the drug and its receptors have a compatible chemical shape. (continues) 1 - 22 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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) 1 - 23 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Principles of Drug Action (continued) Principles of Drug Action Agonist effect Antagonistic effect Adverse drug effect Therapeutic effect 1 - 24 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Pharmacokinetics: Absorption Routes Oral Parenteral Topical 1 - 25 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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. 1 - 26 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Pharmacokinetics: Distribution The transport of a drug in the body by the bloodstream to its site of action 1 - 27 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

Elimination/Excretion The elimination of drugs from the body Kidneys (main organ) Liver Bowel (continues) 1 - 28 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

(continued) Renal excretion of drugs. Note sites where drugs are secreted and reabsorbed. 1 - 29 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.

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 1 - 30 Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.