CHAPTER 2 Pharmacologic Principles Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.

CHAPTER 2CHAPTER 2

Pharmacologic PrinciplesPharmacologic Principles

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.

DrugDrug

Any chemical that affects the physiologic processes Any chemical that affects the physiologic processes of a living organismof a living organism


PharmacologyPharmacology

The study or science of drugsThe study or science of drugs


Drug NamesDrug NamesChemical nameChemical name Describes the drug’s chemical composition and molecular Describes the drug’s chemical composition and molecular

structurestructure

Generic nameGeneric name (nonproprietary name) (nonproprietary name) Name given by the United States Adopted Name CouncilName given by the United States Adopted Name Council

Trade nameTrade name (proprietary name) (proprietary name) The drug has a registered trademark; use The drug has a registered trademark; use

of the name restricted by the drug’s patent owner (usually the of the name restricted by the drug’s patent owner (usually the manufacturer)manufacturer)


Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.

Pharmacologic PrinciplesPharmacologic Principles

PharmaceuticsPharmaceutics PharmacokineticsPharmacokinetics PharmacodynamicsPharmacodynamics PharmacotherapeuticsPharmacotherapeutics PharmacognosyPharmacognosy


PharmaceuticsPharmaceutics

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


PharmacokineticsPharmacokinetics

The study of what the body does to the drugThe 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 for The use of drugs and the clinical indications for drugs to prevent and treat diseasesdrugs to prevent and treat diseases

Empirical therapeuticsEmpirical therapeutics Rational therapeuticsRational therapeutics


PharmacognosyPharmacognosy

The study of natural (plant and animal) drug The study of natural (plant and animal) drug sourcessources


PharmaceuticsPharmaceutics

Dosage form design affects dissolutionDosage form design affects dissolution



Pharmacokinetics: AbsorptionPharmacokinetics: Absorption

The rate at which a drug leaves its site of The rate at which a drug leaves its site of administration, and the extent to which administration, and the extent to which absorption occursabsorption occurs BioavailabilityBioavailability BioequivalentBioequivalent


Factors That Affect AbsorptionFactors That Affect Absorption

Absorption characteristics vary according to Absorption characteristics vary according to the dosage form and routethe dosage form and route 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


Routes Routes

A drug’s route of administration affects the A drug’s route of administration affects the rate and extent of absorption of that drugrate and extent of absorption of that drug Enteral (GI tract)Enteral (GI tract) ParenteralParenteral TopicalTopical


Enteral RouteEnteral Route

Drug is absorbed into the systemic Drug is absorbed into the systemic circulation through the oral or gastric mucosa circulation through the oral or gastric mucosa or the small intestineor the small intestine OralOral SublingualSublingual BuccalBuccal


First-Pass EffectFirst-Pass Effect

The metabolism of a drug and its passage from the The metabolism of a drug and its passage from the liver into the circulationliver into the circulation

– – A drug given via the oral route may be extensively A drug given via the oral route may be extensively metabolized by the liver before reaching the systemic metabolized 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, preventing The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the first-pass effect from taking place, and more drug reaches the circulationthe circulation



First-Pass Effect and Box 2-1 (Drug First-Pass Effect and Box 2-1 (Drug Routes and First-Pass Effect)Routes and First-Pass Effect)

Parenteral RouteParenteral Route Intravenous (fastest delivery into the blood Intravenous (fastest delivery into the blood

circulation)circulation) IntramuscularIntramuscular SubcutaneousSubcutaneous IntradermalIntradermal IntrathecalIntrathecal IntraarticularIntraarticular Transdermal can be considered parenteral, tooTransdermal can be considered parenteral, too


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


DistributionDistribution

The transport of a drug in the body by the The transport of a drug in the body by the bloodstream to its site of actionbloodstream 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, brain kidneys, brain

Areas of slow distribution: muscle, skin, fatAreas of slow distribution: muscle, skin, fat


MetabolismMetabolism(Also Known as Biotransformation)(Also Known as Biotransformation)

The biochemical transformation of a drug into The biochemical transformation of a drug into an inactive metabolite, a more soluble compound, or a an inactive metabolite, a more soluble compound, or a more potent metabolitemore potent metabolite

Liver (main organ)Liver (main organ) Skeletal muscleSkeletal muscle KidneysKidneys LungsLungs PlasmaPlasma Intestinal mucosaIntestinal mucosa




Metabolism/BiotransformationMetabolism/Biotransformation

Biologic transformation of a drug into:Biologic transformation of a drug into: An inactive metaboliteAn inactive metabolite A more soluble compoundA more soluble compound A more potent metaboliteA more potent metabolite



Metabolism/Biotransformation Metabolism/Biotransformation (cont’d)(cont’d)

Organs or body tissuesOrgans or body tissues Liver (main)Liver (main) Skeletal muscleSkeletal muscle KidneysKidneys Lungs Lungs PlasmaPlasma Intestinal mucosaIntestinal mucosa



Factors that decrease metabolismFactors 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 metabolismFactors that increase metabolism Fast acetylatorFast acetylator Barbiturate therapyBarbiturate therapy Rifampin therapyRifampin therapy



Delayed drug metabolism results in:Delayed drug metabolism results in: Accumulation of drugsAccumulation of drugs Prolonged action of the drugsProlonged action of the drugs

Stimulating drug metabolism causes:Stimulating drug metabolism causes: Diminished pharmacologic effectsDiminished pharmacologic effects



Cytochrome P-450 enzymes Cytochrome P-450 enzymes

Also known as microsomal enzymesAlso known as microsomal enzymes


ExcretionExcretion

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 recirculationEnterohepatic recirculation



Half-lifeHalf-life

The time it takes for one half of the original amount of The time it takes for one half of the original amount of a drug in the body to be removeda drug in the body to be removed

A measure of the rate at which drugs are removed A measure of the rate at which drugs are removed from the bodyfrom the body

Most drugs are considered to be effectively removed Most drugs are considered to be effectively removed after about five half-livesafter about five half-lives

Steady stateSteady state


The Movement of DrugsThe Movement of DrugsThrough the BodyThrough the Body

Drug actionsDrug actions The cellular processes involved in the drug and cell The cellular processes involved in the drug and cell

interactioninteraction

Drug effectDrug effect The physiologic reaction of the body to the drugThe physiologic reaction of the body to the drug


Onset, Peak, and DurationOnset, Peak, and Duration

OnsetOnset The time it takes for the drug to elicit a The time it takes for the drug to elicit a

therapeutic responsetherapeutic response

PeakPeak The time it takes for a drug to reach its maximum The time it takes for a drug to reach its maximum


DurationDuration The time a drug concentration is sufficient to elicit a The time a drug concentration is sufficient to elicit a




Therapeutic Drug MonitoringTherapeutic Drug Monitoring

Peak LevelPeak Level Highest blood levelHighest blood level

Trough LevelTrough Level Lowest blood levelLowest blood level


Ways Drugs Produce Ways Drugs Produce Therapeutic EffectsTherapeutic Effects

Once the drug is at the site of action, it can Once the drug is at the site of action, it can modify the rate (increase or decrease) at modify the rate (increase or decrease) at which the cells or tissues functionwhich the cells or tissues function

A drug cannot make a cell or tissue perform a A drug cannot make a cell or tissue perform a function it was not designed to performfunction it was not designed to perform


Pharmacodynamics: Pharmacodynamics: Mechanisms of ActionMechanisms of Action

Receptor interactionsReceptor interactions Enzyme interactionsEnzyme interactions Nonspecific interactionsNonspecific interactions




Pharmacotherapeutics: Pharmacotherapeutics: Types of TherapiesTypes of Therapies

Acute therapyAcute therapy Maintenance therapyMaintenance therapy Supplemental/replacement therapySupplemental/replacement therapy Palliative therapyPalliative therapy Supportive therapySupportive therapy Prophylactic therapyProphylactic therapy Empiric therapyEmpiric therapy


ContraindicationContraindication

Any characteristic of the patient, especially a Any characteristic of the patient, especially a disease state, that makes the use of a given disease state, that makes the use of a given medication dangerous for the patientmedication dangerous for the patient

It is important to assess for contraindications!It is important to assess for contraindications!


MonitoringMonitoring

The effectiveness of the drug therapy must The effectiveness of the drug therapy must be evaluatedbe evaluated

One must be familiar with the drug’s:One must be familiar with the drug’s: Intended therapeutic action (beneficial)Intended therapeutic action (beneficial) Unintended but potential adverse effects Unintended but potential adverse effects

(predictable, adverse reactions)(predictable, adverse reactions)


Monitoring (cont’d)Monitoring (cont’d)

Therapeutic indexTherapeutic index Drug concentrationDrug concentration Patient’s conditionPatient’s condition Tolerance and dependenceTolerance and dependence InteractionsInteractions Adverse drug effectsAdverse drug effects



Therapeutic indexTherapeutic index– – The ratio between a drug’s therapeutic The ratio between a drug’s therapeutic

benefits and its toxic effectsbenefits and its toxic effects



ToleranceTolerance – – A decreasing response to repeated drug dosesA decreasing response to repeated 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 of Drug 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



Drug interactionsDrug interactions Additive effectAdditive effect Synergistic effectSynergistic effect Antagonistic effectAntagonistic effect IncompatibilityIncompatibility



Adverse Drug EventsAdverse Drug Events

Medication errorsMedication errors Adverse drug reactionsAdverse drug reactions



Adverse Drug ReactionsAdverse Drug Reactions Pharmacologic reactions, including adverse effectsPharmacologic reactions, including adverse effects Hypersensitivity (allergic) reactionHypersensitivity (allergic) reaction Idiosyncratic reactionIdiosyncratic reaction Drug interactionDrug interaction



Adverse effectsAdverse effects Predictable, well-known reactions that result in little Predictable, well-known reactions that result in little

or no change in patient managementor no change in patient management Predictable frequencyPredictable frequency Occurrences are related to the size of the doseOccurrences are related to the size of the dose Usually resolve when the drug is discontinuedUsually resolve when the drug is discontinued


Other Drug-Related EffectsOther Drug-Related Effects

TeratogenicTeratogenic MutagenicMutagenic CarcinogenicCarcinogenic


PharmacognosyPharmacognosy

Four main sources for drugsFour main sources for drugs PlantsPlants AnimalsAnimals MineralsMinerals Laboratory synthesisLaboratory synthesis



ToxicologyToxicology

The study of poisons and unwanted responses The study of poisons and unwanted responses to drugs and other chemicalsto drugs and other chemicals



CHAPTER 2 Pharmacologic Principles Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.

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