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Chapter 14 Drugs: Chemical Cures, Comforts, and Cautions

Chapter 14 Drugs: Chemical Cures, Comforts, and Cautions. Drug. Chemical substance that affects the functioning of living things May treat, diagnose, and prevent disease Dates to ancient times Over 9900 drugs available in U.S. Antibacterial Drugs.

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Chapter 14 Drugs: Chemical Cures, Comforts, and Cautions

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  1. Chapter 14Drugs: Chemical Cures, Comforts, and Cautions

  2. Drug • Chemical substance that affects the functioning of living things • May treat, diagnose, and prevent disease • Dates to ancient times • Over 9900 drugs available in U.S. Chapter 19

  3. Antibacterial Drugs • Have lowered the death rate for infectious diseases Chapter 19

  4. Antibacterial Drugs • Sulfa drugs: inhibit use of folic acid by bacteria • First antibacterial drug developed • Penicillins: inhibit growth of microorganisms • Antibiotic • Group of related compounds • Inhibit enzymes used to make cell walls • Many people allergic Chapter 19

  5. Other Antibacterial Drugs • Cephalosporins: related to penicillin • Tetracycline: effective against wide variety of bacteria – broad spectrum antibiotic • Inhibits protein synthesis • Fluoroquinolones • Inhibit bacterial DNA synthesis Chapter 19

  6. Antibiotics • Save lives of many people every year • Large decline in death by infectious disease • Bacteria eventually develop resistance to antibiotics • Must continually search for new compounds Chapter 19

  7. Viruses • Unable to replicate on their own • Assemble to viruses once in host cell • DNA virus made of DNA and protein coat • RNA virus made of RNA and protein Chapter 19

  8. Antiviral Drugs • Cannot use antibiotics • Need antiviral drugs • Three classes • Combinations of drugs more effective than individual drugs Chapter 19

  9. Classes of Antiviral Drugs • Nucleoside analogs: replace nucleotides during replication • Reverse transcriptase: Convert RNA of virus to DNA • Reverse transcriptase inhibiters block enzyme • Protease inhibitor: new copies of the virus can’t infect new cells Chapter 19

  10. Chemicals Against Cancer • Main problem: chemicals that kill cancer cells can damage normal cells as well • Antimetabolite: usually a compound that inhibits synthesis of nucleic acids • Alkylating agents: transfer alkyl groups to compounds of biological importance • Some developed from original chemical weapons Chapter 19

  11. Miscellaneous Anticancer Agents • Some antibiotics • Sex hormones against cancers of reproductive system • Alkaloids from plants • Typically combine treatment with chemicals (chemotherapy) with other strategies • Surgery or radiation Chapter 19

  12. The Pill • Administer derivative of progesterone • Otherwise need to take hormone using injections • Fools body into thinking it is already pregnant • Prevents ovulation • Some risks: may experience hypertension, acne, or abnormal bleeding • Increases risk of blood clots • Especially in smokers Chapter 19

  13. Missed Period Pills • Diethylstilbestrol (DES) • low dosages may help maintain pregnancy • High dosages can induce abortion • Sons of women who took it may be sterile • RU-486 inhibits action of progesterone • Prevents establishment of pregnancy • Need to take 2nd shot with prostaglandin • Suffer from severe morning sickness during and shortly after treatment Chapter 19

  14. Pill for Males? • Problem: males produce sperm continuously • Have to reduce production of sperm but not libido • Several drugs have been tested on mice • Human trials have not been started Chapter 19

  15. Nerve Cells • Neurotransmitters cross synapse • Many different functions Chapter 19

  16. Hormones • Chemical messengers made in endocrine glands • Released in one part of body to send messages to other regions • Control growth, metabolism, reproduction, and other bodily functions Chapter 19

  17. Chapter 19

  18. Prostaglandins • Closely related to hormones • Act on target cells but are produced near site where used • Effects can differ on different tissues • Act as mediators of hormones Chapter 19

  19. Steroids • Based on structure for cholesterol • Occur widely in living organisms, but not all are hormones • Used to reduce inflammation, increase muscle mass, and the development of sexual characterstics Chapter 19

  20. Sex Hormones • Androgens: male sex hormones • Estrogen and progesterone: female sex hormones • Regulate sexual cycle before, during, and after pregnancy • Both sexes have small amounts of each Chapter 19

  21. Drugs for Heart • Lowering blood pressure • Normalizing heart rhythm • Arrhythmia: abnormal heartbeat • Treating coronary disease • Heart getting less O2 than needed • Typically use drugs that release NO in body Chapter 19

  22. Drugs and the Mind • Psychotropic drugs affect the mind • Stimulants increase alertness, speed up general mental process, and generally elevate moods • Depressants reduce level of consciousness and intensity of reactions to environment • Hallucinogenic drugs alter the way we perceive things Chapter 19

  23. Depression and Mania • Involve amines • Norepinephrine • High levels cause manic state • Low levels cause depression • Serotonin involved in sleep, sensory perception, pleasure sensations, and body temperature • Control levels of compounds in normal range Chapter 19

  24. Anesthetics • General anesthetic: acts on brain to produce unconsciousness and general insensitivity to pain • Developed in 19th century • Ether used but effective dose close to lethal dose • Modern mixtures use several different compounds to make it safer Chapter 19

  25. Local Anesthetic • Renders a part of the body insensitive to pain • Blocks nerve conduction • First developed in 19th century • Some of the more powerful ones developed from cocaine • No longer used as extensively because of problems with toxicity Chapter 19

  26. Dissociative Anesthetics • Dissociates person’s perception from his or her senses • May induce hallucinations • Phencyclidine (PCP) • Stored in fatty tissue • Used as animal tranquilizer • 1 in 1000 develop severe form of schizophrenia Chapter 19

  27. Depressants • Ethanol most widely used • Slows both physical and mental activity • Probably first synthetic chemical made by humans • Potentially fatal • Potent teratogen • Barbiturates • Similar effects to alcohol • Synergistic effect with alcohol Chapter 19

  28. Narcotics • Produce narcosis and relief of pain • In U.S., if also addictive, legally classified as narcotics • Opium – source of morphine • Potent painkiller, cough suppressant • Side effects: constipation, addictive, euphoria, … • First isolated in 1805 • Codeine and heroin are just chemically modified morphine Chapter 19

  29. Synthetic Narcotics • Attempts have been made to make pain reliever as good as morphine but not addictive • Best known is Demerol • Less effective than morphine • Still addictive • Methadone does not produce intoxication • Highly addictive Chapter 19

  30. Natural Opiates • Endorphins: naturally produced morphine-like substances • Short peptides, rapidly digested • Synthetic versions that are not easily broken down have been produced • Still addictive Chapter 19

  31. Antianxiety Agents • Antipsychotic agents for treatment of maniacal forms of depression • Reduced number of patients confined to mental hospitals • People will relapse if they go off medication • Antidepressants • Original medication is dose sensitive • Work by enhancing serotonin uptake Chapter 19

  32. Stimulants • Amphetamines: mimic natural brain amines • Based on phenylethylamines • Used for weight reduction • Large illegal drug market • Cocaine: first used as local anesthetic • Powerful stimulant • Works by preventing reabsorption of dopamine Chapter 19

  33. Caffeine and Nicotine • Caffeine probably most common stimulant • Mildly addictive • May cause chromosome damage • Nicotine: toxic to animals • Used as insecticide • Transient effect as stimulant • Toxic, especially when injected Chapter 19

  34. Psychedelics • Change way we perceive things • Most powerful probably lysergic acid diethylamide (LSD) • Exact mechanism of action unknown • Need only very small doses: 10–100 g Chapter 19

  35. Marijuana • Second only to alcohol in popularity as intoxicant • Principal active ingredient: tetrahydrocannabinol (THC) • Hard to quantify effects because of variable amount of THC in different samples • Increases heart rate, distorts sense of time, and impairs complex motor functions Chapter 19

  36. Marijuana and the Brain • Activates brain’s reward system • Causes euphoric feeling by releasing dopamine • Legitimate medical uses • Treat glaucoma • Relieves nausea of cancer patients Chapter 19

  37. Drug Problems • Legal drugs • May be overprescribed • Faulty prescriptions • Costs of drugs • Illegal drugs • Expensive and addictive • Not always what they claim to be • Societal costs Chapter 19

  38. Nonsteroidal Anti-inflammatory Drugs (NSAIDs) • Most widely used: acetylsalicylic acid • Trade name: aspirin • Effective pain reliever (analgesic), antipyretic (fever reducer), and anti-inflammatory • Also anticoagulant • Good for heart attack and stroke prevention • Side effects: stomach distress and bleeding Chapter 19

  39. Other NSAIDs • Ibuprofen, ketoprofen, and naproxen • Similar shape to aspirin • Similar properties to aspirin • Acetaminophen not NSAID • Has all but anti-inflammatory properties of NSAIDs Chapter 19

  40. How NSAIDs Work • Inhibit cycloxygenases (COX) • COX-1 found in stomach and kidney tissue • Gives rise to side effects • COX-2 found in tissue where inflammation occurs • Older drugs affect both enzymes • Newer drugs affect only COX-2 Chapter 19

  41. Acetaminophen • Neither anti-inflammatory nor anticoagulant • Overuse linked to liver and kidney damage • Affects COX-3 • May represent mechanism to decrease pain and fever • No role in inflammation Chapter 19

  42. Combination Pain Relievers • Combine with caffeine or other NSAIDs • Buffered aspirin: contains antacids to prevent stomach problems • Usually available in two strengths: regular and extra strength Chapter 19

  43. Common Cold Remedies • Antihistamines: relieve symptoms of allergies • Cough suppressants • Expectorants: bring up mucus from bronchial passages • Nasal decongestants: repeated use may lead to rebound effect Chapter 19

  44. Placebo Effect • Placebo: inactive substance given in the form of medication to a patient who thinks it is the real thing • People given placebo report that it works • For some, they actually get better • Keep positive attitude Chapter 19

  45. New Uses for Old Drugs • Cost of developing a drug ~$800 million • Cheaper to use existing drug • Aspirin: original developed as painkiller • Prevents strokes and heart attacks • May show promise in fighting cancer and in delaying onset of Alzheimer’s disease Chapter 19

  46. End of Chapter 19 Chapter 19

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