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Two components ofPharmacoepidemiology
1.Pharmaco
2.Epidemiology
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1.Pharmacology is the study of the effects of
medicines.2. Clinical Pharmacology is the study of theeffects of medicines in humans.
Pharmacoepidemiology can be considered,therefore, to fall within clinical pharmacology.
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Clinical pharmacology divided in 2 basic
areas: Pharmacokinetics
Pharmacodynamics
Pharmacokinetics is the study of the relationshipbetween the dose administered of a medicine and theserum or blood level achieved (medicine absorbtion,distribution, metabolism, and excretion).
Pharmacodynamics is the study of the relationshipbetween medicine level and medicine effect.
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Pharmacoepidemiology VS. Epidemiology
Epidemiology is the study of the distribution and
determinants of diseases in populations.
Epidemiology is divided in 2 basic areas:
1. Infectious diseases
2. chronic diseases
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PharmacoepidemiologyA relatively new applied field
Bridging between clinical pharmacology and
epidemiologyApplies the methods of epidemiology to the content
area of clinical pharmacology.
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HISTORICAL 1906US law: the Pure Food and Drug Act, response to excessive
adulteration and misbranding of the food and medicines available atthat time.
1937over 100 people died from renal failure as a result of the
marketing of elixir of sulfanilamide disolve in diethylene glycol. 1938Food, Drug and Cosmetic Act: pre clinical and toxicity testing
was required for the first time, and submit clinical data about safetyto the FDA prior to drug marketing.
Litle attention to adverse drug reaction until 1950: Chloramphenicolcould cause aplastic anaemia.
1952: the first textbook of adverse drug reaction was published. TheAMA council on Pharmacy and Chemistry established the first officialregistry of adverse drug effects, to collect cases of drug inducedblood dyscrasias.
1960: FDA began collect reports of ADR.
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DESI (Drug Efficacy Study Implementation)conducted by the National Academy of Sciences
National Research Council with support from the FDA:removal from US market of many ineffective drugs anddrug combination.
1960s: publication of a series of utilization studies,
provide the first descriptive information on howphysicians use drugs, and began a series ofinvestigations of the frequency of poor prescribing anddeterminants of poor prescribing.
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1960s
is the begining of the field ofPharmacoepidemiology
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MEDICINE USE & FACTORS
INFLUENCING PRESCRIBING
Defining pharmacoepidemiology and
medicine utilizationProcess of pharmacotherapy
Factors influencing prescribing
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Aims of Pharmacoepidemiology
To examine and judge pattern of medicine use
To determine how efficacy in clinical trials translatesinto effectiveness in the population
To evaluate the extents of risks Adverse medicinereactions
To evaluate the extents of cost
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DEFINING
MEDICINE UTILIZATION
Medicine utilization is defined as the marketing,
distribution, prescription, and use of medicines withspecial emphasis on the resulting medical, social, andeconomic consequences (WHO, 1997)
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FOCUSED MEDICINE
UTILIZATION STUDIES?
To identify problems of medicine utilization
To identify possible causing factors
To identify intervention for improvement
To evaluate intervention strategy
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PROCESS OF
PHARMACOTHERAPY Making of diagnosis and defining patients problem
Defining therapeutic goal
Defining interventions: Medicines & Non medicines Selecting medicines
Determining dose, route, frequency, and duration ofmedicine administration
Writing prescription
Providing information
Monitoring and evaluation
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FACTORS INFLUENCING
PRESCRIBING
Levels of knowledge, skills, and competence of
prescribersAttitude
Information and promotion
Patients demand
Medicine supply and availability
Peers and environmental
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Framework for changing medicine
use practicesPurpose and content
There are many different ways to improve medicine use practices. This unitwill expose you to a number of different strategies which have been tried to
improve medicine use, ranging from providing information to restrictiveregulatory measures, and the evidence for or against their effectiveness.Not all strategies are relevant or feasible in specific area, in specificprogram, or for every medicine use problem. However, this session willenable students to identify and choose among the possible interventionstrategies which might be considered in a given situation.
The case study will also make clear the need for carefully considering eachapproachs unintended effects before widespread implementation.
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OBJECTIVES
Students will be able to:
1. Identify particular medicine use problems, and placethem in the perspective of the factors underlying
problems in medicine use.2. Identify any different approaches to improve
problems in medicine use which have been tried inthe past.
3. Understand some of strehgths and weaknesses ofdifferent approaches in terms of demonstratedeffectiveness, cost, and suitability for specific placecontexts and medicine therapy problems.
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FACTORS WHICH INFLUENCE MEDICINE USE
Problems in medicine use can be caused by a wide rangeof factors, which differ in importance from problem to
problem and from setting to setting. Before trying tocorrect any problem in medicine use, it is helpful toidentify which factors are most important in causingthe problem at hand. Unless the proposed
intervention targets the appropriate causes of theproblem, it is unlikely to be successful.
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Several categories of factors which
should be considered as possiblecauses of a problem in medicine use.
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1. Characteristic of providers of care
Lack of knowledge about diagnosis, therapeutics, theefficacy and risks of particular medicines.
Acquired habits in diagnosis and treatment which may notreflect what providers actually know, but the patterns of
behaviour they have come to adopt. Beliefs about illness and medicines such as the increased
power of injections over oral medicines, which also do notalways reflect their level of scientific knowledge.
Personal economic motivations for prescribing ordispensing particular medicines, for example, medicinecompany incentives, dispensing fees, referrals to privatepractice, ect.
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2. The Summary of Medicine
Utilization Research
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Proven Effectiveness:
Face to face education focused on a fewprescribing problems
Structured medicine order formsPrescription audits/procurement review
plus feedback
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Possible Effectiveness:Essential medicine lists plus education
Standard treatment schedules pluseducation
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Ineffective:
Printed materials alone
Arbitrary limits on number/quantity of
medicines per prescriptionUnfocused education
Essential medicine lists alone
Standard treatment schedules alone
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New Medicine Development
In vitro and Pre clinical Toxicity: animal testing
Phase I: Human clinical trials
Phase II and Phase III: Human clinical trials
Phase IV studies: Post marketing surveilance andmedicine use experience
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Premarketing Risk Analysis To detect overt toxicity
To establish dose-response estimation ofpharmacologic and toxic effects
To assess medicine distribution to organ system
To identify metabolic, kinetic, and eliminationpathways
To assess carcinogenic potential To assess reproductive toxicity and teratogenic
potentials
To direct clinical safety assesssments
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Premarketing clinical investigations
Phase I:
Usually in normal volunteers with attention topharmacokinetics, metabolism, and both single dose
and dose-range safer Phase II:
Limited size, closely monitored investigations designedto assess efficacy and relative safety
Phase III: Full-scale clinical investigations designed to provide an
assessment of safety, efficacy, optimum dose, and moreprecise definition of medicine-related adverse effects
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Postmarketing Medicine Evaluation Phase IV Studies, Postmarketing Surveilance and
Medicine Use Experience
Efficacy
Effectiveness
Safety
Adverse Medicine Reactions
Economic Analysis
PHARMACOECONOMICS
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PHARMACOECONOMICS
Economic analysis of Pharmaceuticals
Introduces the concepts of clinical economics
Review some methodologic issues
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Dimensions of Economic analysis
Types of analysis: Cost-identification
Cost minimization
Cost-effectiveness
Cost -utility Cost-benefit
Viewpoints of analysis Provider, Payer, Patient, Society
Types of cost Direct costs: medical and non medical cost
Indirect cost
Intangible cost
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Changing a Medicine Use Problem
An Overview of The Process1. Examine
Measure Existing Practices
Improve diagnosis 2. Diagnose
4. Follow up Identify SpecificMeasure changes in outcomes Problems & Causes
Improve intervention
3. TreatDesign & Implement
Interventions
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