chapter 14 drugs: chemical cures, comforts, and cautions
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Chapter 14Drugs: Chemical Cures, Comforts,
and Cautions
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Chapter 19 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.
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Chapter 19 3
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
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Chapter 19 4
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
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Chapter 19 5
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
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Chapter 19 6
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
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Chapter 19 7
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
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Chapter 19 8
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
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Chapter 19 9
Antibacterial Drugs• Have lowered the
death rate for infectious diseases
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Chapter 19 10
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
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Chapter 19 11
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
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Chapter 19 12
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
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Chapter 19 13
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
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Chapter 19 14
Antiviral Drugs
• Cannot use antibiotics
• Need antiviral drugs
• Three classes
• Combinations of drugs more effective than individual drugs
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Chapter 19 15
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
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Chapter 19 16
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
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Chapter 19 17
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
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Chapter 19 18
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
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Chapter 19 19
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Chapter 19 20
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
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Chapter 19 21
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
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Chapter 19 22
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
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Chapter 19 23
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
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Chapter 19 24
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
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Chapter 19 25
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
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Chapter 19 26
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
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Chapter 19 27
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
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Chapter 19 28
Nerve Cells•Neurotransmitters cross synapse•Many different functions
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Chapter 19 29
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
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Chapter 19 30
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
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Chapter 19 31
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
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Chapter 19 32
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
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Chapter 19 33
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
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Chapter 19 34
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
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Chapter 19 35
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
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Chapter 19 36
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
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Chapter 19 37
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
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Chapter 19 38
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
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Chapter 19 39
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
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Chapter 19 40
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
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Chapter 19 41
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
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Chapter 19 42
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
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Chapter 19 43
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
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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
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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
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Chapter 19 46
End of Chapter 14