Chapter 14Drugs: Chemical Cures, Comforts,

and Cautions

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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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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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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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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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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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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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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Antibacterial Drugs• Have lowered the

death rate for infectious diseases

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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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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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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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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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Antiviral Drugs

• Cannot use antibiotics

• Need antiviral drugs

• Three classes

• Combinations of drugs more effective than individual drugs

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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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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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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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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 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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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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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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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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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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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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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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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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Nerve Cells•Neurotransmitters cross synapse•Many different functions

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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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End of Chapter 14