chapter 2
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Chapter 2. Pharmacokinetics and Pharmacodynamics. Pharmacotherapeutics. The study of how drugs are used to treat, prevent, and diagnose disease and illness Pharmacokinetics – how the body assimilates, incorporates, and eliminates a drug Pharmacodynamics – how a drug affects the body. - PowerPoint PPT PresentationTRANSCRIPT
PharmacotherapeuticsPharmacotherapeutics
The study of how drugs are used to treat, The study of how drugs are used to treat, prevent, and diagnose disease and prevent, and diagnose disease and illnessillness Pharmacokinetics – how the body Pharmacokinetics – how the body
assimilates, incorporates, and eliminates a assimilates, incorporates, and eliminates a drugdrug
Pharmacodynamics – how a drug affects the Pharmacodynamics – how a drug affects the bodybody
You will be able to You will be able to explain to an athlete…explain to an athlete…
Why it is important to take medications Why it is important to take medications as prescribed by a physicianas prescribed by a physician
How drugs workHow drugs work Why drugs workWhy drugs work How long a drug remains activeHow long a drug remains active What the potential drug adverse effects What the potential drug adverse effects
areare Other general questions they askOther general questions they ask
What is a Drug?What is a Drug?
A chemical that interacts with and affects A chemical that interacts with and affects living organisms to produce a biological living organisms to produce a biological responseresponse
A drug alters physiological functions by A drug alters physiological functions by replacing, interrupting, or potentiating replacing, interrupting, or potentiating existing cellular functionsexisting cellular functions
Primary or secondary effectsPrimary or secondary effects
PharmacodynamicsPharmacodynamics
Receptor Sites – a component of a cell to Receptor Sites – a component of a cell to which a drug binds to produce an effectwhich a drug binds to produce an effect
Most drugs act at specific locations in Most drugs act at specific locations in tissues or organstissues or organs
““lock and key” analogy (pgs 18-19)lock and key” analogy (pgs 18-19) Affinity – the force that makes 2 agents Affinity – the force that makes 2 agents
bind or unitebind or unite Efficacy – the capacity to elicit a Efficacy – the capacity to elicit a
responseresponse
Dose ResponseDose Response Threshold – lowest dose capable of Threshold – lowest dose capable of
producing a perceivable responseproducing a perceivable response Potency – amount of a drug necessary to Potency – amount of a drug necessary to
produce a desired effectproduce a desired effect Figure 2-2 Pg 19Figure 2-2 Pg 19
Time ResponseTime Response Determining the time response of a dose:Determining the time response of a dose:
LatencyLatency – “onset of action”, time required to – “onset of action”, time required to produce an observable effectproduce an observable effect
Maximal EffectMaximal Effect – time required to reach peak – time required to reach peak efficacyefficacy
Duration of ActionDuration of Action – time period over which – time period over which a drug produces a response after a single a drug produces a response after a single dosedose
Time ResponseTime Response Influenced by:Influenced by:
Route of administrationRoute of administration Solubility of the drugSolubility of the drug How fast the drug is distributed to action siteHow fast the drug is distributed to action site Time it takes to be inactivated and excreted Time it takes to be inactivated and excreted
from the bodyfrom the body
Therapeutic Index – the range in which Therapeutic Index – the range in which desired effects are produceddesired effects are produced
Used to determine the safety parameters Used to determine the safety parameters of dosesof doses
Half-Life – determined by the time required to Half-Life – determined by the time required to reduce by one-half the amount of the drug reduce by one-half the amount of the drug present in the bodypresent in the body
Drugs have different & distinct half-livesDrugs have different & distinct half-lives Comparison for drug elimination ratesComparison for drug elimination rates Determines frequency with which multiple Determines frequency with which multiple
doses of a drug can be safely administereddoses of a drug can be safely administered Half-life does not change with the drug doseHalf-life does not change with the drug dose
PharmacokineticsPharmacokinetics
Absorption – speed, rate, and extent of Absorption – speed, rate, and extent of absorption is dependant on its’ physical absorption is dependant on its’ physical and chemical propertiesand chemical properties Solubility of the drugSolubility of the drug Surface area of intended site of actionSurface area of intended site of action Specific route of administrationSpecific route of administration
EnteralEnteral
Oral ingestion - safest, most common, Oral ingestion - safest, most common, convenient, economical route of convenient, economical route of administrationadministration
Taken by mouth = onset of action within 1 Taken by mouth = onset of action within 1 hourhour
Oral mucosa – sublingual or buccal routesOral mucosa – sublingual or buccal routes Vast capillary blood supply = dissolve Vast capillary blood supply = dissolve
rapidlyrapidly
EnteralEnteral
Preliminary passage or “first-pass Preliminary passage or “first-pass metabolism” Figure 2-7 pg 24metabolism” Figure 2-7 pg 24
SolutionsSolutions Liquid form, syrups, elixirsLiquid form, syrups, elixirs
Capsules and tabletsCapsules and tablets Sustained-releaseSustained-release
ParenteralParenteral
Non-oral route of administrationNon-oral route of administration Drug delivered directly to target siteDrug delivered directly to target site Not subjected to first-pass metabolism Not subjected to first-pass metabolism Routes includeRoutes include
SubcutaneousSubcutaneous IntramuscularIntramuscular IntravenousIntravenous IntrathecalIntrathecal Intra-articularIntra-articular
InhalationInhalation
Form of gases or fine mistsForm of gases or fine mists Lungs: large surface area and rich blood Lungs: large surface area and rich blood
supply = effective means of absorbing supply = effective means of absorbing and transporting meds into blood supply and transporting meds into blood supply rapidlyrapidly
Special devices propel meds onto Special devices propel meds onto alveolar and bronchial tissuesalveolar and bronchial tissues
TopicalTopical
Applied to skin or mucous membranesApplied to skin or mucous membranes Difficult to reach systemic circulationDifficult to reach systemic circulation Used to treat skin problemsUsed to treat skin problems RoutesRoutes
OintmentsOintments CreamsCreams Transdermal patchesTransdermal patches
PharmacokineticsPharmacokinetics
Distribution – to act on a specific receptor Distribution – to act on a specific receptor site, the drug must pass through the site, the drug must pass through the different biological layers and then be different biological layers and then be transported to the site via the transported to the site via the bloodstreambloodstream
Cell membrane reviewCell membrane review
Modes of transportation across cell Modes of transportation across cell membranemembrane FiltrationFiltration DiffusionDiffusion Active transportActive transport
PharmacokineticsPharmacokinetics
Metabolism – process of ridding the body Metabolism – process of ridding the body of foreign substance (biotransformation)of foreign substance (biotransformation)
Breakdown of original drug compound Breakdown of original drug compound into metabolites, which are eliminatedinto metabolites, which are eliminated
Rate of metabolismRate of metabolism Liver is primary organ, specialized Liver is primary organ, specialized
enzymes that metabolize drugs or foreign enzymes that metabolize drugs or foreign compoundscompounds
PharmacokineticsPharmacokinetics
Excretion Excretion Routes of drug eliminationRoutes of drug elimination
Urine, bile, fecesUrine, bile, feces Lungs, salivary, sweat, mammary glandsLungs, salivary, sweat, mammary glands
Kidney is major organKidney is major organ Patient HealthPatient Health
Factors Affecting Drug Factors Affecting Drug ResponseResponse
AgeAge Infants & older adultsInfants & older adults
Weight & GenderWeight & Gender Men vs. womenMen vs. women Dosing based on weightDosing based on weight
Time of administrationTime of administration With food vs. before mealsWith food vs. before meals
Barriers to Drug Barriers to Drug DistributionDistribution
Blood-brain barrierBlood-brain barrier Placental barrierPlacental barrier Barriers inhibit certain chemicals in the Barriers inhibit certain chemicals in the
bloodstream that may be dangerous or bloodstream that may be dangerous or toxic to the individual or fetustoxic to the individual or fetus
Drug SafetyDrug Safety
Five Rights of Drug AdministrationFive Rights of Drug Administration Right drugRight drug Right patientRight patient Right doseRight dose Right routeRight route Right timeRight time