activity 10

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Chapter 10
Drugs and the Older Adult

Objectives (1 of 3)

Discuss the physiologic changes that occur as we age that affect our response to drug administration, including absorption, distribution, metabolism, and excretion.

Describe the symptoms of anti-cholinergic syndrome and identify classes of drugs with anti-cholinergic side effects.

Objectives (2 of 3)

Describe the symptoms of serotonin syndrome and identify classes of drugs that have serotonergic activity.

Identify classes of drugs that should be avoided in the older patient as outlined in Beer’s criteria and STOPP.

Identify classes of drugs that are underutilized in the older patient, as described in START.

Objectives (3 of 3)

Discuss drugs of abuse in older adults.

Discuss the use of herbal therapy and supplements.

Describe the increase in drug side effects that occur as the result of taking an increased number of drugs

Discuss how to manage polypharmacy.

Discuss the principle of Go Low – Go Slow in the use of drugs in the older patient.

Introduction (1 of 4)

  • Number of drugs used by older patients has increased dramatically
  • People age 65 and older:
  • Make up 13% of the U.S. population
  • Buy 33% of the prescription drugs
  • 95% of 70-year-old Americans reportedly use at least one medication

Introduction (2 of 4)

Introduction (3 of 4)

  • Food and Drug Administration (FDA)
  • Responsible for approval of prescription and non-prescription drugs
  • Does not require drugs to be tested in older populations
  • Does not regulate the production of herbal medications and supplements

Introduction (4 of 4)

  • Many drug interactions are due to both pharmacokinetic and pharmacodynamic interactions
  • Phamacokinetics
  • What the body does to a drug
  • Pharmacodynamics
  • What the drug does to the body

Pharmacokinetics (1 of 15)

  • Drug absorption
  • Depends on how a drug is administered:
  • Oral, sublingual, intranasal, intravenous, intramuscular, topical, subcutaneous, or inhaled
  • Oral administration is most common
  • Each administration route could potentially be impacted by the aging process

Pharmacokinetics (2 of 15)

  • Oral administration
  • Most drug absorption occurs in the small intestine
  • Rate of gastric emptying needs to be considered
  • Slowed gastric emptying increases the amount of time it takes to attain maximal drug concentrations in the blood without a change in maximal drug concentration
  • Oral administration does not significantly affect the clinical response to drugs

Pharmacokinetics (3 of 15)

  • Transdermal administration
  • Administration through the skin
  • Convenient method for administering a steady amount of a drug over a prolonged period
  • Age-related changes in skin can impact absorption
  • May lead to lower concentrations in the blood

Pharmacokinetics (4 of 15)

  • Drug distribution
  • Drugs distribute throughout the body based on their physicochemical properties
  • Most important is the hydrophilicity or lipophilicity of the drug
  • Effect of aging on distribution is very much dependent on the specific drug

Pharmacokinetics (5 of 15)

  • Drug metabolism
  • Liver is the main organ of drug metabolism
  • Drug metabolizing enzymes are not significantly affected by aging (in the absence of disease)
  • Other changes are more significant
  • Decreased blood flow in the liver decreases extraction of drugs from the blood and slows metabolism

Pharmacokinetics (6 of 15)

  • Drugs with a high extraction from the blood are most affected with age
  • Increases half-life of these kinds of drugs
  • Example: half-life of diazepam (valium)
  • 20 hours in a person’s twenties
  • 80 hours in a person’s eighties

Pharmacokinetics (7 of 15)

Pharmacokinetics (8 of 15)

Pharmacokinetics (9 of 15)

  • Some drugs metabolize to active metabolites
  • Drug breaks down but is transformed into another active drug
  • Example: diazepam
  • Metabolizes to three active metabolites
  • Single dose may continue producing effects for 6 days

Pharmacokinetics (10 of 15)

  • Drugs are metabolized in the liver by a number of enzymes
  • Major group belongs to the class of cytochrome P450s, which has many subtypes
  • Vary considerably based on a person’s:
  • Genetic background, including ethnic background
  • Previous exposure to drugs
  • Current drug regimen

Pharmacokinetics (11 of 15)

  • Many therapeutically important drugs will inhibit the CYP450 enzymes
  • Slows metabolism of other drugs
  • Drug levels in blood will increase, potentially leading to toxicity

Pharmacokinetics (12 of 15)

  • Enzyme induction
  • Occurs when the liver produces more of the metabolizing enzyme after exposure to the drug
  • Leads to:
  • Increased metabolism of drugs metabolized by this specific enzyme
  • Lower blood levels of the drug
  • Decreased therapeutic efficacy

Pharmacokinetics (13 of 15)

Pharmacokinetics (14 of 15)

  • Drug excretion
  • Ability to excrete drugs and metabolites is altered as a person ages
  • Most are excreted in urine through the kidneys
  • Another route is through the bile into the intestines
  • Decreased kidney function with age further decreases excretion of drugs
  • Effect on drug excretion depends on properties of the drug

Pharmacokinetics (15 of 15)

Pharmacodynamics

  • Involves examining how drug responses change based on changes in cellular responses to drugs over the life span
  • Depends on the changes that occur in the drug’s targets
  • Knowing why a person responds to specific medications can help the physician make decisions about the best drug to prescribe

Pharmacogenomics (1 of 2)

  • Study of how a person’s genetic background determines the pharmacokinetic and pharmacodynamic responses to drugs
  • Widespread variability in how older adults metabolize drugs based on the levels of subtypes of cytochrome P450 enzymes
  • Lab tests are available to determine the levels of these enzymes in a patient

Pharmacogenomics (2 of 2)

  • Advances are also being made in:
  • Understanding how genetics change the response to drugs
  • Precision dosing as a part of personalized medicine

Anti-Cholinergic Syndrome
(1 of 9)

  • Collection of symptoms related to the effects of agents that block acetylcholine in the nervous system
  • Greater risk of occurrence in older adults
  • Polypharmacy is an important contributor

Anti-Cholinergic Syndrome
(2 of 9)

  • Cholinergic system
  • Neurotransmitter acetylcholine is involved in:
  • Learning and memory in the brain
  • Central nervous influence on organs
  • Parasympathetic nervous system

Anti-Cholinergic Syndrome
(3 of 9)

  • Some classes of drugs have emerged from the large class of antihistamines
  • Antihistamines have widespread usage
  • Related classes of drugs act as antagonists at the muscarinic subtype of cholinergic receptors
  • Possible to take multiple medications for multiple conditions that all have antagonist effects at the muscarinic cholinergic receptor

Anti-Cholinergic Syndrome
(4 of 9)

Anti-Cholinergic Syndrome
(5 of 9)

Anti-Cholinergic Syndrome
(6 of 9)

  • Important concern is the effects of polypharmacy on cognition
  • Many species show a slow and continuous decline in the cholinergic forebrain system
  • A rapid decline of this system can result in dementia at an early age
  • If medications are used that work against these same receptors, the patient’s symptoms will worsen

Anti-Cholinergic Syndrome
(7 of 9)

  • Other syndromes
  • Serotonin syndrome
  • Medications that increase serotonin in the brain:
  • Antidepressants
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Some opioid pain relievers
  • Trazadone (used to help induce sleep)
  • Dextromethorphan (cold medication)

Anti-Cholinergic Syndrome
(8 of 9)

Anti-Cholinergic Syndrome
(9 of 9)

  • Symptoms of serotonin syndrome
  • Vary from very mild to life threatening
  • Hyperreflexia, clonus, and altered mental status are commonly seen
  • Symptoms resolve with discontinuation of the drugs

Drug Dependence, Misuse,
and Addiction (1 of 2)

  • Drugs used to treat older adults can:
  • Have serious side effects (pain relievers)
  • Lead to tolerance and dependence (sleep aids)
  • Discontinuation can result in symptoms of withdrawal
  • Strict limits should be placed on the use of drugs with misuse potential

Drug Dependence, Misuse,
and Addiction (2 of 2)

  • Alcohol misuse
  • Can lead to dependence and uncontrolled use
  • Health consequences:
  • Decreased cognitive function
  • Cardiomyopathy
  • Hepatitis and cirrhosis of the liver
  • Increased risk of falls when combined with sedatives
  • Can exacerbate the side effects of medications

Beers’ List and STOPP/START (1 of 3)

  • Beers Criteria for Potentially Inappropriate Medication
  • Identifies medications inappropriate for use by older adults
  • Important for healthcare practitioners to consider all drug classes before prescribing for older populations

Beers’ List and STOPP/START (2 of 3)

  • Screening Tool of Older People’s Potentially Inappropriate Prescriptions (STOPP)
  • Divides findings into nine systems
  • Indicates care with use of duplicate drug classes
  • Same team later developed the Screening Tool to Alert Doctors to Right Treatments (START)
  • Retained the same nine systems as STOPP

Beers’ List and STOPP/START (3 of 3)

Herbal Medicines and Supplements (1 of 5)

  • All age groups are using more nutraceuticals
  • Older adults consume more than any other age group
  • Purpose of use varies considerably depending on current popular and medical opinion
  • Women use more dietary supplements than men

Herbal Medicines and Supplements (2 of 5)

Herbal Medicines and Supplements (3 of 5)

  • Nutraceuticals may not be safe and effective
  • Not regulated by the FDA unless they are shown to be a significant risk to public health
  • Over-the-counter remedies are drugs and can have significant side effects and interactions with other medications

Herbal Medicines and Supplements (4 of 5)

Herbal Medicines and Supplements (5 of 5)

  • Manufacturers of nutraceuticals cannot advertise that they are treatments for any diseases
  • No dosage can be recommended for taking them
  • Consumers are expected to find the proper dosage themselves, for any given indication
  • More research needs to be done to determine how nutraceuticals can best be used

Polypharmacy (1 of 6)

  • Older patients take more medications than younger patients in part due to:
  • Increased incidence of chronic disease
  • Media pressure from the pharmaceutical industry
  • Iatrogenic component
  • Practitioners add additional medications to treat side effects

Polypharmacy (2 of 6)

Polypharmacy (3 of 6)

  • Basic common-sense steps are generally taken to reduce the number of drugs prescribed for a patient
  • First step is being aware of all medications (and dosages) being taken, including herbal and dietary supplements

Polypharmacy (4 of 6)

Polypharmacy (5 of 6)

  • Important to consider:
  • Clinical signs associated with each medicine
  • Possible side effects
  • How each drug is being taken
  • Review may lead to changing medications to obtain a more favorable side effect profile
  • Avoid treating side effects with another drug if possible

Polypharmacy (6 of 6)

  • If at all possible, only start one drug at a time
  • May take some time for the drug to reach therapeutic levels in the blood
  • Important to know whether the dose should be adjusted downward to account for hepatic or rental metabolism
  • Use the phrases “Go Low and Go Slow” and “KISS—Keep It Simple Seriously” when evaluating medications in older patients