Drugs: Chemical Substances for Cures and Comforts

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