Transcript Polypharmacy

POLYPHARMACY
Pio L. Oliverio, MD
Fellow, Geriatrics
SVCMC, Jamaica, NY
February 27, 2006
Definition
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POLYPHARMACY
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Use of several drugs or medicines together
in the treatment of disease, suggesting
indiscriminate, unscientific, or excessive
prescription
(Stedman’s Medical Dictionary)
Definition
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POLYPHARMACY
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The administration of many drugs at the
same time
DRUG
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is any substance that affects the physical
and mental functioning of a living organism
Epidemiology and Prevalence
2/3 of residents in long term care
facilities receive 3 or more medications
daily
 7 different medications per patient per
day
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Overall average per resident
Older adults spend $3 billion annually
on prescriptions
Epidemiology and Prevalence
Direct correlation between age of the
patient and the number of prescriptions
they take daily
 90% of older adults take at least one
prescription daily
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most take two or more prescriptions daily
Medication Underuse/Overuse
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UNDERUSE – when available drugs are
not used maximally for correct indication
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OVERUSE – when a particular
medication is used excessively even if
not properly indicated
Polypharmacy Admission
3 and 10% - in two studies
 Result in several billions of dollars in
yearly health care expenditures
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Commonly Prescribed
Medications
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Cardiovascular drugs
Antihypertensives
Analgesics
Sedatives
Anti-inflammatory
GI preparations (laxatives)
Definition
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PHARMACOKINETICS
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management of the drug by the body
PHARMACODYNAMICS
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target organ’s sensitivity to the drug
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Decreased drug absorption
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Small bowel resection
Malabsorption
Multiple drugs
Antacids
Active transport - e.g. in nutrients and
vitamins
 Passive transport – most common
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Antacids decrease absorption of
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Cimetidine
Digitalis
Tetracycline
Phenytoin
Quinolones
Ketoconazole
Iron
YOUNG
ELDERLY
Drug absorption
Faster
Slower/
decreased
Metabolism
Faster
Slower
Excretion
Faster
Slower
Fat: lean body
mass
Volume
distribution
 Duration
that a particular drug
exerts its effort depends on:
Volume distribution (Vd)
 Metabolism of the drug
 The clearance of the drug
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 All
three factors change with age
 Volume
distribution
 term
used to relate the amount of
drug in the body to the
concentration of drug in the
plasma
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Vd =
Dose
Cpo
 Vd
is determined by
Degree of plasma protein binding
 The patient’s body composition
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 Changes
substantially with age
 Adipose tissue increases
 18-36% in males
 36-48% in females
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Elderly
 ↓ body water and lean body mass 
lower Vd  ↑ drug concentration
 ↑ body fat  large Vd  prolongation
of half life unless the clearance
increases (unlikely in the elderly)
increase in adipose tissue 
larger Vd for lipid soluble drugs 
causing half life (T1/2) to be
prolonged  clinically important
with the CNS drugs i.e.
benzodiazepines and barbiturates
 The
 Total
body water composition
decrease by 15%, consequently the
Vd of water soluble drugs is
decreased  increased drug serum
concentration
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Plasma protein concentration also ↓ with age
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↑ increased amt of free (active) drug in the
body
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Drugs have ↑ concentration due to ↓ plasma
protein
 Digoxin
 Theophylline
 Phenytoin
 warfarin
DRUG METABOLISM
 Phase
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1
Cytochrome P – 450 enzyme system
 Oxidation,
reduction, hydrolysis
Declines with increasing age
 Drugs involved
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 Ketoconazole,
erythromycin, SSRI
DRUG METABOLISM
 Phase
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2
Conjugation/ biotransformation
 Acetylation,
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glucoronidation, sulfation
Usually not effected by age
 Not
safe to assume efficient drug
metabolism in geriatrics pt with
normal liver function
Effects Of Age
On Renal Function
Wide inter-individual variation in the rate
of decline in renal function with
increasing age
 i.e. renal function declines by 40-50%
between ages 20 and 90, - this is an
average decline
 Can cause over or under dosing
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Effects Of Age
On Renal Function
↓ muscle mass  ↓ creatinine
production
 Serum creatinine may be normal at a
time when renal function is reduced.
 Serum creatinine does not reflect renal
function accurately in the elderly
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Use creatinine clearance to determine renal
function.
Formula to estimate renal function (Cockcroft
& Gault)
Creatinine clearance = (140 – age) X body
weight in kg / 72 X serum creatinine (x 0.85 in
females)
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Drugs given in reduced doses to elderly
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Aminoglycosides
Benzodiazepines
Digoxin
Haloperidol
Metoclopramide
Thyroxine
Vitamin D
Drugs with ↓ renal elimination
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Aminoglycosides
ACE-I
Digoxin
Diuretics
Lithium
H2 blockers
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Pharmacodynamics
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The study of the effects of drugs at the receptor
level
Changes in the end-organ response to a drug
due to
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Change in the receptor binding
Decrease in receptor number
Altered translation response to a receptor
Pharmacodynamics
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Increase in receptor response is noted
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Benzodiazepines
Warfarin
Opiates
Adverse Drug Reactions
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Primum non nocere “first do no harm”
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Applicable when drugs are prescribed for geriatric
population
Older adults are more at risk
Can be reduced by decreasing number of
medications
Adverse Drug Reactions
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Frequent symptoms
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Confusion (75%)
Nausea
Loss of balance
Change in bowel pattern
Sedation
Adverse Reactions – Risk
Factors
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Advanced age
Female
Hepatic/ renal insufficiency
Polypharmacy
Lower body weight
History of prior drug reaction
Reasons for inappropriate
medication ordering
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Multiple problems and complaints may
consult several health care professionals
Use of multiple pharmacies
OTC medication history
Time limitations during office visits
Consequences
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Non-adherence
Adverse drug reactions
Drug-drug interactions
Increased risk of hospitalizations
Medication errors
Increased costs from treatment of adverse
events
Strategies for Elderly Compliance
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Make drug regimens and instruction as
simple as possible
Instruct relatives and care givers on the drug
regimen
Make sure patient can get to a pharmacist,
can afford the prescription, and can open the
container
Strategies for Elderly
Compliance
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Enlist others (HHA, pharmacist) to help
ensure compliance
Use aids (special pill boxes and drug
calendars)
Keep updated medication record
Review knowledge of and compliance with
regimens regularly
Factors not affecting
compliance
 Age
 Sex
 Education
 Disease
severity
Factors reducing compliance
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Multiple medications
Frequent dosing schedules
Complicated dosing instruction
Expensive medications
Promote compliance
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Reducing the number of prescribed drugs
Simplifying dosage regime
Evaluating patient’s functional ability to take
medication
Inability to self-medicate
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Cognitive impairment
Decreased dexterity
Sensory/motor deficits
Number of medications
Measures of Compliance
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Direct method
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drug concentration in the blood, urine, or saliva
Indirect method
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Therapeutic response
Self report
Pill counts
Pharmacy records
Principles of Drug Prescribing
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Make a diagnosis before drug therapy is
initiated
Carefully weigh the risks versus benefits
Begin with low doses and slowly increase
until effect is reached, monitor for reactions
Inquire about the use of OTC and alternative
medications
Principles of Drug Prescribing
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Periodically review the list of medications
Simplify medication schedule
Suspect a medication as the cause of any
major medical or cognitive change
Discuss the benefits of the medication and
the consequences of non compliance
Inform the patient about potential reactions
Prescribing Practices
Basic elements…
 Reduction of polypharmacy
 Coordinated medication plan
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Clinicians, pharmacists, older person/ families
Basic tenet…
 Non pharmacologic therapy is always
initiated first whenever appropriate
Summary
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Polypharmacy – epidemiology, prevalence,
implications in terms of compliance
Pharmacokinetics + pharmacodynamics
Pharmacology of drugs
Principles of appropriate prescribing
Strategies to improve compliance in the
elderly