POLYPHARMACY

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POLYPHARMACY

• Pio L. Oliverio, MD
• Fellow, Geriatrics
• SVCMC, Jamaica, NY
• February 27, 2006

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Definition

• POLYPHARMACY
• Use of several drugs or medicines together in the
  treatment of disease, suggesting indiscriminate,
  unscientific, or excessive prescription
• (Stedmans Medical Dictionary)

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Definition

• POLYPHARMACY
• The administration of many drugs at the same time
• DRUG
• is any substance that affects the physical and
  mental functioning of a living organism

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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
• Overall average per resident
• Older adults spend 3 billion annually on
  prescriptions

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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
• most take two or more prescriptions daily

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Medication Underuse/Overuse

• UNDERUSE when available drugs are not used
  maximally for correct indication
• OVERUSE when a particular medication is used
  excessively even if not properly indicated

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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

• Cardiovascular drugs
• Antihypertensives
• Analgesics
• Sedatives
• Anti-inflammatory
• GI preparations (laxatives)

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Definition

• PHARMACOKINETICS
• management of the drug by the body
• PHARMACODYNAMICS
• target organs sensitivity to the drug

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• Decreased drug absorption
• 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
• Cimetidine
• Digitalis
• Tetracycline
• Phenytoin
• Quinolones
• Ketoconazole
• Iron

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YOUNG ELDERLY
Drug absorption Faster Slower/ decreased
Metabolism Faster Slower
Excretion Faster Slower
Fat lean body mass
Volume distribution
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• Duration that a particular drug exerts its effort
  depends on
• Volume distribution (Vd)
• Metabolism of the drug
• The clearance of the drug
• All three factors change with age

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• Volume distribution
• term used to relate the amount of drug in the
  body to the concentration of drug in the plasma
• Vd

Dose
Cpo
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• Vd is determined by
• Degree of plasma protein binding
• The patients body composition
• 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)

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• The 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

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• 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
• ? increased amt of free (active) drug in the body
• Drugs have ? concentration due to ? plasma
  protein
• Digoxin
• Theophylline
• Phenytoin
• warfarin

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DRUG METABOLISM

• Phase 1
• Cytochrome P 450 enzyme system
• Oxidation, reduction, hydrolysis
• Declines with increasing age
• Drugs involved
• Ketoconazole, erythromycin, SSRI

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DRUG METABOLISM

• Phase 2
• Conjugation/ biotransformation
• Acetylation, glucoronidation, sulfation
• Usually not effected by age
• Not safe to assume efficient drug metabolism in
  geriatrics pt with normal liver function

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Effects Of AgeOn 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 AgeOn 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
• Aminoglycosides
• Benzodiazepines
• Digoxin
• Haloperidol
• Metoclopramide
• Thyroxine
• Vitamin D

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Drugs with ? renal elimination

• Aminoglycosides
• ACE-I
• Digoxin
• Diuretics
• Lithium
• H2 blockers

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• Pharmacodynamics
• The study of the effects of drugs at the receptor
  level
• Changes in the end-organ response to a drug due
  to
• Change in the receptor binding
• Decrease in receptor number
• Altered translation response to a receptor

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Pharmacodynamics

• Increase in receptor response is noted
• Benzodiazepines
• Warfarin
• Opiates

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Adverse Drug Reactions

• Primum non nocere first do no harm
• Applicable when drugs are prescribed for
  geriatric population
• Older adults are more at risk
• Can be reduced by decreasing number of medications

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Adverse Drug Reactions

• Frequent symptoms
• Confusion (75)
• Nausea
• Loss of balance
• Change in bowel pattern
• Sedation

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Adverse Reactions Risk Factors

• Advanced age
• Female
• Hepatic/ renal insufficiency
• Polypharmacy
• Lower body weight
• History of prior drug reaction

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Reasons for inappropriate medication ordering

• Multiple problems and complaints may consult
  several health care professionals
• Use of multiple pharmacies
• OTC medication history
• Time limitations during office visits

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Consequences

• Non-adherence
• Adverse drug reactions
• Drug-drug interactions
• Increased risk of hospitalizations
• Medication errors
• Increased costs from treatment of adverse events

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Strategies for Elderly Compliance

• 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

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Strategies for Elderly Compliance

• 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

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Factors not affecting compliance

• Age
• Sex
• Education
• Disease severity

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Factors reducing compliance

• Multiple medications
• Frequent dosing schedules
• Complicated dosing instruction
• Expensive medications

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Promote compliance

• Reducing the number of prescribed drugs
• Simplifying dosage regime
• Evaluating patients functional ability to take
  medication

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Inability to self-medicate

• Cognitive impairment
• Decreased dexterity
• Sensory/motor deficits
• Number of medications

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Measures of Compliance

• Direct method
• drug concentration in the blood, urine, or
  saliva
• Indirect method
• Therapeutic response
• Self report
• Pill counts
• Pharmacy records

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Principles of Drug Prescribing

• 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

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Principles of Drug Prescribing

• 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

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Prescribing Practices

• Basic elements
• Reduction of polypharmacy
• Coordinated medication plan
• Clinicians, pharmacists, older person/ families
• Basic tenet
• Non pharmacologic therapy is always initiated
  first whenever appropriate

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Summary

• Polypharmacy epidemiology, prevalence,
  implications in terms of compliance
• Pharmacokinetics pharmacodynamics
• Pharmacology of drugs
• Principles of appropriate prescribing
• Strategies to improve compliance in the elderly

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THANK YOU
THANK YOU
ANY QUESTIONS?