Drugs and Medicines 1 Version 1.01. Orgins of Pharmacology From earliest times people have used natural substances such as medicinal herbs to -- relieve.

Drugs and MedicinesDrugs and Medicines

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Version 1.01

Orgins of PharmacologyOrgins of Pharmacology

From earliest times people have used From earliest times people have used natural substances such as medicinal natural substances such as medicinal herbs to herbs to

-- relieve pain -- relieve pain -- heal injuries-- heal injuries-- cure diseases-- cure diseases

Some folk remedies contained certain Some folk remedies contained certain active ingredients that were of medicinal active ingredients that were of medicinal value.value.

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Examples of Folk Examples of Folk RemediesRemedies

Morphine Morphine – extracted from poppy used to treat pain in extracted from poppy used to treat pain in

the 19the 19thth century century

Salicyclic acid Salicyclic acid – extracted from willow bark as a precursor to extracted from willow bark as a precursor to

aspirin.aspirin.

Quinine Quinine – Used in South America to treat malariaUsed in South America to treat malaria

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Definition of a MedicineDefinition of a MedicineAny chemical substance thatAny chemical substance that

– Alters a physiological stateAlters a physiological state– Alters mood or emotionsAlters mood or emotions– Alters incoming sensory sensationsAlters incoming sensory sensations

Sometimes it is difficult to determine Sometimes it is difficult to determine whether a drug has any medicinal value.whether a drug has any medicinal value.The legitimate purpose of a drug is The legitimate purpose of a drug is usually to improve health.usually to improve health.Use of drugs in some cases is Use of drugs in some cases is controversial.controversial.

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The Placebo EffectThe Placebo Effect

Healing is a complex interaction betwe Healing is a complex interaction betwe en mind and en mind and body that is not entirely understoodbody that is not entirely understood

The The Placebo EffectPlacebo Effect–Merely taking any medicine may trigger Merely taking any medicine may trigger

responses in the body that result in responses in the body that result in changes in the mental/emotional or changes in the mental/emotional or physiological states of the person physiological states of the person without having any medicinal action.without having any medicinal action.

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Drugs and medicinesDrugs and medicines

Access to drugs and medicines is Access to drugs and medicines is controlled in most countries but the controlled in most countries but the definition of what constitutes a drug may definition of what constitutes a drug may varyvary

ExamplesExamples–MelatoninMelatonin–CodeineCodeine

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Methods of Administering Methods of Administering DrugsDrugs

Drugs must reach blood stream to be Drugs must reach blood stream to be transported to critical tissues.transported to critical tissues.The method of administration determines rate The method of administration determines rate at which the drug is absorbed in the blood.at which the drug is absorbed in the blood.Five common points of entry:Five common points of entry:

1.1. OralOral2.2. InhalationInhalation3.3. TopicalTopical4.4. InjectionInjection5.5. AnalAnal

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Methods of Administering Methods of Administering DrugsDrugs

Injection methodsInjection methods1.1. SubcutaneousSubcutaneous

2.2. IntramuscularIntramuscular

3.3. IntraveneousIntraveneous

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Research, Development Research, Development and Drug Testingand Drug Testing

Development of new drugs is long and Development of new drugs is long and expensive processexpensive process

Several stages in development include:Several stages in development include:1.1. Isolation or chemical synthesisIsolation or chemical synthesis

2.2. Laboratory studiesLaboratory studies

3.3. Animal testingAnimal testing

4.4. Clinical testingClinical testing

5.5. Approval by the FDA for marketApproval by the FDA for market

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Research, Development and Research, Development and Drug TestingDrug Testing

The development of a new drug is a time The development of a new drug is a time consuming processconsuming processDetermination of the Determination of the Lethal Dose or LDLethal Dose or LD5050. This . This is the concentration that will kill 50% of the is the concentration that will kill 50% of the animals in a test sampleanimals in a test sampleThe The Effective Dose or EDEffective Dose or ED5050. is the . is the concentration necessary to bring about a concentration necessary to bring about a noticeable effect in 50% of the test samplenoticeable effect in 50% of the test sampleThe The Therapeutic IndexTherapeutic Index is the ratio of is the ratio of

LDLD5050..EDED5050..

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Clinical TrialsClinical Trials

All drugs that are approved for market All drugs that are approved for market must be clinically tested multiple times must be clinically tested multiple times

Most clinical tests are done on volunteers Most clinical tests are done on volunteers using a double blind.using a double blind.

Neither the researcher know in advance Neither the researcher know in advance who is receiving the therapeutic medicine who is receiving the therapeutic medicine and who is receiving a placeboand who is receiving a placebo

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Drug DevelopmentDrug DevelopmentAll medicines have some side effects and All medicines have some side effects and the appropriate dosage must be the appropriate dosage must be determined,determined,To determine the following must be To determine the following must be consideredconsidered– Lethal Dose or LDLethal Dose or LD5050

– Effective Dose or EDEffective Dose or ED5050

– Therapeutic IndexTherapeutic Index– Toxic RangeToxic Range– Theraputic LevelTheraputic Level– Subtheraputic levelSubtheraputic level

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Contraindications or Side Contraindications or Side EffectsEffects

Contraindications are additional and often Contraindications are additional and often undesirable effects that result from the use undesirable effects that result from the use of a particular drug to treat a particular of a particular drug to treat a particular condition.condition.

Side effects are somewhat relative Side effects are somewhat relative depending on the reason the drug is depending on the reason the drug is prescribedprescribed

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Risk to Benefit RatioRisk to Benefit Ratio

The prescribing physician must weigh the The prescribing physician must weigh the benefits from the use of a drug against the benefits from the use of a drug against the undesirable side effects when determining undesirable side effects when determining a suitable level of riska suitable level of risk

The level of risk that is acceptable is The level of risk that is acceptable is related to the severity and the degree to related to the severity and the degree to which the condition is life threateningwhich the condition is life threatening

Examples: Chemotherapy, Pain Killers etcExamples: Chemotherapy, Pain Killers etc

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ToleranceTolerance

Over time the body adapts the Over time the body adapts the presence of a drugpresence of a drug

1.1. The person receiving the drug needs The person receiving the drug needs ever larger doses to achieve the original ever larger doses to achieve the original effecteffect

2.2. Increased risks of Increased risks of dependency/addictiondependency/addiction

3.3. Increased risks of toxic levelsIncreased risks of toxic levels4.4. Possibility of immunity in anti-Possibility of immunity in anti-

bacterials.bacterials.

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Thalidomide --An Example of Thalidomide --An Example of Improper Drug ApprovalImproper Drug Approval

Developed in Germany in the 1953 Developed in Germany in the 1953 Used as a tranquilizer (1957-1962)Used as a tranquilizer (1957-1962)Prescribed to combat morning sickness in Prescribed to combat morning sickness in the early months of pregnancythe early months of pregnancyMarketed widely in Europe but never Marketed widely in Europe but never approved by the FDA in the USAapproved by the FDA in the USACaused major birth defects in ABOUT Caused major birth defects in ABOUT 10,000 children whose mothers had taken 10,000 children whose mothers had taken thalidomide.thalidomide.

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ThalidomideThalidomide

Has two optical Has two optical isomers, one of isomers, one of which is a which is a powerful powerful teratogen.teratogen.

Used to treat Used to treat some symptoms some symptoms of Hansen’s of Hansen’s disease disease (Leprosy) (Leprosy)

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Chiral Carbon

Drug ClassificationDrug Classification

Drug CategoriesDrug Categories 1.1. DepressantsDepressants

2.2. StimulantsStimulants

3.3. AntacidsAntacids

4.4. AnalgesicsAnalgesics

5.5. AntibacterialAntibacterial

6.6. AntiviralAntiviral

7.7. Mind Altering DrugsMind Altering Drugs

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