pharmacologic principles

Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
Pharmacologic PrinciplesPharmacologic Principles

DrugDrug
• Any chemical that affects the processes ofAny chemical that affects the processes of
a living organisma living organism

PharmacologyPharmacology
• The study or science of drugsThe study or science of drugs

Pharmacologic Principles: Drug NamesPharmacologic Principles: Drug Names
Chemical nameChemical name
• The drug’s chemical composition and molecularThe drug’s chemical composition and molecular
structurestructure
Generic name (nonproprietary name)Generic name (nonproprietary name)
• Name given by the United States AdoptedName given by the United States Adopted
Name CouncilName Council
Trade name (proprietary name)Trade name (proprietary name)
• The drug has a registered trademark; useThe drug has a registered trademark; use
of the name restricted by the drug’s ownerof the name restricted by the drug’s owner
(usually the manufacturer)(usually the manufacturer)

Pharmacologic Principles: Drug NamesPharmacologic Principles: Drug Names
Chemical nameChemical name
• (+/-)-2-(p-isobutylphenyl) propionic acid(+/-)-2-(p-isobutylphenyl) propionic acid
Generic nameGeneric name
• ibuprofenibuprofen
Trade nameTrade name
• MotrinMotrin

Instructors may wish to useInstructors may wish to use
EIC Image #3:EIC Image #3:
The Chemical, Generic, and TradeThe Chemical, Generic, and Trade
Names for the CommonNames for the Common
Analgesic IbuprofenAnalgesic Ibuprofen

• PharmaceuticsPharmaceutics
• PharmacokineticsPharmacokinetics
• PharmacodynamicsPharmacodynamics
• PharmacotherapeuticsPharmacotherapeutics
• PharmacognosyPharmacognosy

PharmaceuticsPharmaceutics
• The study of how various drug forms influenceThe study of how various drug forms influence
pharmacokinetic and pharmacodynamic activitiespharmacokinetic and pharmacodynamic activities

PharmacokineticsPharmacokinetics
• The study of what the body does to the drug:The study of what the body does to the drug:
– AbsorptionAbsorption
– DistributionDistribution
– MetabolismMetabolism
– ExcretionExcretion

PharmacodynamicsPharmacodynamics
• The study of what the drug does to the bodyThe study of what the drug does to the body::
– The mechanism of drug actions in living tissuesThe mechanism of drug actions in living tissues

PharmacotherapeuticsPharmacotherapeutics
• The use of drugs and the clinical indications forThe use of drugs and the clinical indications for
drugs to prevent and treat diseasesdrugs to prevent and treat diseases

PharmacognosyPharmacognosy
• The study of natural (plant and animal) drug sourcesThe study of natural (plant and animal) drug sources

Drug Absorption of VariousDrug Absorption of Various
Oral PreparationsOral Preparations
Liquids, elixirs, syrupsLiquids, elixirs, syrups FastestFastest
Suspension solutionsSuspension solutions 
PowdersPowders 
CapsulesCapsules 
TabletsTablets 
Coated tabletsCoated tablets 
Enteric-coated tabletsEnteric-coated tablets SlowestSlowest

Pharmacokinetics: AbsorptionPharmacokinetics: Absorption
• The rate at which a drug leaves its site ofThe rate at which a drug leaves its site of
administration, and the extent to whichadministration, and the extent to which
absorption occurs.absorption occurs.
– BioavailabilityBioavailability
– BioequivalentBioequivalent

Factors That Affect AbsorptionFactors That Affect Absorption
• Administration route of the drugAdministration route of the drug
• Food or fluids administered with the drugFood or fluids administered with the drug
• Dosage formulationDosage formulation
• Status of the absorptive surfaceStatus of the absorptive surface
• Rate of blood flow to the small intestineRate of blood flow to the small intestine
• Acidity of the stomachAcidity of the stomach
• Status of GI motilityStatus of GI motility

RoutesRoutes
• A drug’s route of administration affects the rateA drug’s route of administration affects the rate
and extent of absorption of that drug.and extent of absorption of that drug.
– EnteralEnteral
– ParenteralParenteral
– TopicalTopical

Enteral RouteEnteral Route
• Drug is absorbed into the systemic circulationDrug is absorbed into the systemic circulation
through the oral or gastric mucosa, the smallthrough the oral or gastric mucosa, the small
intestine, or rectum.intestine, or rectum.
– OralOral
– SublingualSublingual
– BuccalBuccal
– RectalRectal

First-Pass EffectFirst-Pass Effect
The metabolism of a drug and its passageThe metabolism of a drug and its passage
from the liver into the circulation.from the liver into the circulation.
• A drug given via the oral route may be extensivelyA drug given via the oral route may be extensively
metabolized by the liver before reaching the systemicmetabolized by the liver before reaching the systemic
circulation (high first-pass effect).circulation (high first-pass effect).
• The same drug—given IV—bypasses the liver,The same drug—given IV—bypasses the liver,
preventing the first-pass effect from taking place, andpreventing the first-pass effect from taking place, and
more drug reaches the circulation.more drug reaches the circulation.

Instructors may want to useInstructors may want to use

• Routes that bypass the liver:Routes that bypass the liver:
– SublingualSublingual TransdermalTransdermal
– BuccalBuccal VaginalVaginal
– Rectal*Rectal* IntramuscularIntramuscular
– IntravenousIntravenous SubcutaneousSubcutaneous
– IntranasalIntranasal InhalationInhalation
*Rectal route undergoes a higher degree of first-*Rectal route undergoes a higher degree of first-
pass effects than the other routes listed.pass effects than the other routes listed.

Parenteral RouteParenteral Route
• Intravenous*Intravenous*
• IntramuscularIntramuscular
• SubcutaneousSubcutaneous
• IntradermalIntradermal
• IntrathecalIntrathecal
• IntraarticularIntraarticular
*Fastest delivery into the blood circulation*Fastest delivery into the blood circulation

Topical RouteTopical Route
• Skin (including transdermal patches)Skin (including transdermal patches)
• EyesEyes
• EarsEars
• NoseNose
• Lungs (inhalation)Lungs (inhalation)
• VaginaVagina

Pharmacokinetics: DistributionPharmacokinetics: Distribution
The transport of a drug in the body by theThe transport of a drug in the body by the
bloodstream to its site of action.bloodstream to its site of action.
• Protein-bindingProtein-binding
• Water soluble vs. fat solubleWater soluble vs. fat soluble
• Blood-brain barrierBlood-brain barrier
• Areas of rapid distribution: heart, liver,Areas of rapid distribution: heart, liver,
kidneys, brainkidneys, brain
• Areas of slow distribution: muscle, skin, fatAreas of slow distribution: muscle, skin, fat

Pharmacokinetics: MetabolismPharmacokinetics: Metabolism
(also known as Biotransformation)(also known as Biotransformation)
The biologic transformation of a drug intoThe biologic transformation of a drug into
an inactive metabolite, a more solublean inactive metabolite, a more soluble
compound, or a more potent metabolite.compound, or a more potent metabolite.
• Liver (main organ)Liver (main organ)
• KidneysKidneys
• LungsLungs
• PlasmaPlasma
• Intestinal mucosaIntestinal mucosa

Factors that decrease metabolism:Factors that decrease metabolism:
• Cardiovascular dysfunctionCardiovascular dysfunction
• Renal insufficiencyRenal insufficiency
• StarvationStarvation
• Obstructive jaundiceObstructive jaundice
• Slow acetylatorSlow acetylator
• Erythromycin or ketoconazole drug therapyErythromycin or ketoconazole drug therapy

Factors that increase metabolism:Factors that increase metabolism:
• Fast acetylatorFast acetylator
• BarbituratesBarbiturates
• Rifampin therapyRifampin therapy

Delayed drug metabolism results in:Delayed drug metabolism results in:
• Accumulation of drugsAccumulation of drugs
• Prolonged action of the effects of the drugsProlonged action of the effects of the drugs
Stimulating drug metabolism causes:Stimulating drug metabolism causes:
• Diminished pharmacologic effectsDiminished pharmacologic effects

Pharmacokinetics: ExcretionPharmacokinetics: Excretion
The elimination of drugs from the bodyThe elimination of drugs from the body
• Kidneys (main organ)Kidneys (main organ)
• LiverLiver
• BowelBowel
– Biliary excretionBiliary excretion
– Enterohepatic circulationEnterohepatic circulation

Renal Drug ExcretionRenal Drug Excretion

PharmacokineticsPharmacokinetics
Half-LifeHalf-Life
• The time it takes for one half of the original amountThe time it takes for one half of the original amount
of a drug in the body to be removed.of a drug in the body to be removed.
• A measure of the rate at which drugs are removedA measure of the rate at which drugs are removed
from the body.from the body.

Drug Half-LifeDrug Half-Life

Drug actions:Drug actions:
• The cellular processes involved in the drug andThe cellular processes involved in the drug and
cell interactioncell interaction
Drug effect:Drug effect:
• The physiologic reaction of the body to the drugThe physiologic reaction of the body to the drug

OnsetOnset
• The time it takes for the drug to elicit aThe time it takes for the drug to elicit a
therapeutic responsetherapeutic response
PeakPeak
• The time it takes for a drug to reach its maximumThe time it takes for a drug to reach its maximum
therapeutic responsetherapeutic response
DurationDuration
• The time a drug concentration is sufficient to elicitThe time a drug concentration is sufficient to elicit
a therapeutic responsea therapeutic response

Pharmacodynamics:Pharmacodynamics:
Mechanisms of ActionMechanisms of Action
The ways by which drugs can produceThe ways by which drugs can produce
therapeutic effects:therapeutic effects:
• Once the drug is at the site of action, it can modifyOnce the drug is at the site of action, it can modify
the rate (increase or decrease) at which the cells orthe rate (increase or decrease) at which the cells or
tissues function.tissues function.
• A drug cannot make a cell or tissue perform aA drug cannot make a cell or tissue perform a
function it was not designed to perform.function it was not designed to perform.

Pharmacodynamics:Pharmacodynamics:
Mechanisms of ActionMechanisms of Action
• Receptor interactionReceptor interaction
• Enzyme interactionEnzyme interaction
• Nonspecific interactionsNonspecific interactions

Instructors may wish to insertInstructors may wish to insert
Drugs and ReceptorsDrugs and Receptors
and possiblyand possibly
Drug-Receptor Interactions: DefinitionsDrug-Receptor Interactions: Definitions

Pharmacotherapeutics:Pharmacotherapeutics:
Types of TherapiesTypes of Therapies
• Acute therapyAcute therapy
• Maintenance therapyMaintenance therapy
• Supplemental therapySupplemental therapy
• Palliative therapyPalliative therapy
• Supportive therapySupportive therapy
• Prophylactic therapyProphylactic therapy

Pharmacotherapeutics: MonitoringPharmacotherapeutics: Monitoring
• The effectiveness of the drug therapy mustThe effectiveness of the drug therapy must
be evaluated.be evaluated.
• One must be familiar with the drug’sOne must be familiar with the drug’s
• intended therapeutic action (beneficial)intended therapeutic action (beneficial)
• and the drug’s unintended but potential sideand the drug’s unintended but potential side
effects (predictable, adverse drug reactions).effects (predictable, adverse drug reactions).

• Therapeutic indexTherapeutic index
• Drug concentrationDrug concentration
• Patient’s conditionPatient’s condition
• Tolerance and dependenceTolerance and dependence
• InteractionsInteractions
• Side effects/adverse drug effectsSide effects/adverse drug effects

Therapeutic IndexTherapeutic Index
• The ratio between a drug’s therapeutic benefitsThe ratio between a drug’s therapeutic benefits
and its toxic effectsand its toxic effects

ToleranceTolerance
• A decreasing response to repetitive drug dosesA decreasing response to repetitive drug doses

DependenceDependence
• A physiologic or psychological need for a drugA physiologic or psychological need for a drug

Interactions may occur with other drugs or foodInteractions may occur with other drugs or food
• Drug interactions: the alteration of action ofDrug interactions: the alteration of action of
a drug by:a drug by:
– Other prescribed drugsOther prescribed drugs
– Over-the-counter medicationsOver-the-counter medications
– Herbal therapiesHerbal therapies

InteractionsInteractions
• Additive effectAdditive effect
• Synergistic effectSynergistic effect
• Antagonistic effectAntagonistic effect
• IncompatibilityIncompatibility

Medication MisadventuresMedication Misadventures
Adverse drug eventsAdverse drug events
• ALL are preventableALL are preventable
• Medication errors that result in patient harmMedication errors that result in patient harm
Adverse drug reactionsAdverse drug reactions
• Inherent, not preventable event occurring in theInherent, not preventable event occurring in the
normal therapeutic use of a drugnormal therapeutic use of a drug
• Any reaction that is unexpected, undesirable, andAny reaction that is unexpected, undesirable, and
occurs at doses normally usedoccurs at doses normally used

Some adverse drug reactions are classified asSome adverse drug reactions are classified as
side effects.side effects.
• Expected, well-known reactions that result in littleExpected, well-known reactions that result in little
or no change in patient managementor no change in patient management
• Predictable frequencyPredictable frequency
• The effect’s intensity and occurrence is related toThe effect’s intensity and occurrence is related to
the size of the dosethe size of the dose

Adverse Drug ReactionAdverse Drug Reaction
An undesirable response to drug therapyAn undesirable response to drug therapy
• IdiosyncraticIdiosyncratic
• Hypersensitivity reactionsHypersensitivity reactions
• Drug interactionsDrug interactions

Iatrogenic ResponsesIatrogenic Responses
Unintentional adverse effects that areUnintentional adverse effects that are
treatment-inducedtreatment-induced
• DermatologicDermatologic
• Renal damageRenal damage
• Blood dyscrasiasBlood dyscrasias
• Hepatic toxicityHepatic toxicity

Other Drug-Related EffectsOther Drug-Related Effects
• TeratogenicTeratogenic
• MutagenicMutagenic
• CarcinogenicCarcinogenic

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