Pharmacological principles

Pharmacologic PrinciplesPharmacologic Principles


DrugDrug

• Any chemical that affects the processes of Any 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 molecular The drug’s chemical composition and molecular structurestructure

Generic name (nonproprietary name)Generic name (nonproprietary name)

• Name given by the United States Adopted Name given by the United States Adopted Name CouncilName Council

Trade name (proprietary name)Trade 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 owner of 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


• 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 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 for The 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 Various Drug 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 of The rate at which a drug leaves its site of administration, and the extent to which administration, 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

Pharmacokinetics: Absorption Pharmacokinetics: Absorption

RoutesRoutes

• A drug’s route of administration affects the rate A 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 circulation Drug is absorbed into the systemic circulation through the oral or gastric mucosa, the small through 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 passage The 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 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, The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and preventing the first-pass effect from taking place, and more drug reaches the circulation.more drug reaches the circulation.

First-Pass EffectFirst-Pass Effect

• 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 the The 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 into The biologic transformation of a drug into an inactive metabolite, a more soluble an 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

Pharmacokinetics: MetabolismPharmacokinetics: Metabolism

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

PharmacokineticsPharmacokinetics

Half-LifeHalf-Life

• The time it takes for one half of the original amount The 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 removed A measure of the rate at which drugs are removed from the body.from the body.


Drug actions:Drug actions:

• The cellular processes involved in the drug and The 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 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

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 produce The ways by which drugs can produce therapeutic effects:therapeutic effects:

• Once the drug is at the site of action, it can modify Once the drug is at the site of action, it can modify the rate (increase or decrease) at which the cells or the rate (increase or decrease) at which the cells or tissues function.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 perform.function it was not designed to perform.

Pharmacodynamics: Pharmacodynamics: Mechanisms of ActionMechanisms of Action

• Receptor interactionReceptor interaction

• Enzyme interactionEnzyme interaction

• Nonspecific interactionsNonspecific interactions

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 must The 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 side and 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 benefits The 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 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


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 the Inherent, not preventable event occurring in the

normal therapeutic use of a drugnormal therapeutic use of a drug

• Any reaction that is unexpected, undesirable, and Any reaction that is unexpected, undesirable, and occurs at doses normally usedoccurs at doses normally used


Some adverse drug reactions are classified as Some adverse drug reactions are classified as side effects.side effects.

• Expected, well-known reactions that result in little Expected, 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 to The 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 are Unintentional 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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Pharmacological principles