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Pharmacology - Winter > 13 - Special Populations > Flashcards

13 - Special Populations Flashcards

1
Q

What are special populations?

A
  • Infants and children
  • Elderly people
  • Pregnant and breastfeeding women
  • Obese, underfed
  • Clinical issues (liver failure, kidney failure or dialysis, extracorporate membrane oxygention, therapeutic cooling)
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2
Q

What makes special populations different?

A
  • Different PK and PD
  • Different diseases
  • Use different drugs
  • High potential of damaging self or other (pregnant/breastfeeding)
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3
Q

Why should special populations be treated differently?

A
  • Less info about safety and efficacy
  • More complicated prescribing and dispensing
  • Higher risk of adverse drug events
  • Higher risk of ineffective therapy
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4
Q

What is ontogeny?

A

Development of an individual from the earliest stage to maturity

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5
Q

What do absorption and distribution describe?

A

How drugs get in the body and where they go

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6
Q

How are drugs absorbed in children?

A
  • Oral
  • Sublingual
  • Intramuscular
  • Percutaneous
  • Rectal
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7
Q

What are some factors that influence oral drug absorption?

A
  • Biliary function
  • Gastric emptying time
  • Intestinal motility
  • Microbial colonization
  • Intestinal drug transport
  • Intestinal surface area
  • Gastric pH
  • Splanchnic blood flow
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8
Q

What is distribution?

A

Apparent “space” where a drug molecule may travel to or reside in

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9
Q

What are some factors that influence distribution?

A
  • Extent (size of body water/adipose compartment; degree of plasma/tissue protein binding; permeability of cell membranes; acid-base balance
  • Rate (regional blood flow; organ perfusion pressure; cardiac output)
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10
Q

What do metabolism and elimination describe?

A

Getting rid of foreign molecules

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11
Q

What is drug clearance?

A
  • Volume of blood cleared of a substance per unit of time

- Relates to drug removal from the body by physiologic or extracorporeal methods

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12
Q

What is total clearance?

A

Additive term comprised of each route of metabolism or elimination (ex: kidney, bile, lung)

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13
Q

What are some factors that affect drug metabolism?

A
  • Herbal medicine (ex: St. John’s Wort)
  • Disease
  • Drugs
  • Genetics (ex: fast or slow metabolizers)
  • Age
  • Nutrition (ex: grapefruit juice)
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14
Q

What can cause increased toxicity and decreased toxicity in children?

A
  • Increased toxicity b/c of immature glucuronidation

- Decreased toxicity b/c immature CYPs (ex: CYP can’t produce toxic intermediate of acetaminophen)

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15
Q

Can half life of a drug change w/ age?

A

Yes, can be longer the younger a child is

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16
Q

Can an adult dose of a drug simply be scaled based on body weight or surface area for a child?

A

No b/c doesn’t account for developmental changes that affect drug disposition or tissue/organ sensitivity

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17
Q

Why is pediatric prescribing more complicated than prescribing for adults?

A
  • Specific and general aspects of pediatric px (side, immaturity)
  • Limitations of commercially available dosage formulations
  • Challenges of administering drugs
  • Lack of info about drug use in children
  • Inadequacy of clinical pharmacology training
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18
Q

What are the major principles of drug therapy in children?

A
  • Prescribe judiciously
  • Carefully select safest dosage regimen available
  • Educate px, caregivers, and staff about the choice and expected positive and negative effects
  • Carefully monitor px responses to therapy
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19
Q

When can prescriptions be considered as given “off-label”?

A

When given for a different age group, dosage, indication, dosage form, or route of administration

20
Q

Why are the majority of pediatric drugs prescribed off-label?

A
  • Lack of appropriate safety and efficacy data
  • Shortage of child-friendly formulations
  • Labels out of date
21
Q

What are some general considerations that should be made w/ pediatric formulations?

A
  • Administration route
  • Adequate palatability
  • Tablet size
  • Liquid formulations require dosing device and preservative
22
Q

What are the various sizes of tablets and what is the age limit for each?

A
  • Small tablet = 3-5 mm diameter; children 2 y/o and older
  • Medium tablet = 5-10 mm diameter; children at least 6 y/o
  • Large tablet = 10-15 mm diameter; children at least 12 y/o
  • Very large tablet = 15 mm or more diameter; adults 18 y/o and older
23
Q

What are the max recommended single dosing volumes for various age groups of children?

A
  • Max of 5 mL for children under 4 y/o

- Max of 10 mL for children 4-12 y/o

24
Q

What is normally the max number of drops per single intake?

A

10 drops

25
Q

Should pediatric medicines be coloured?

A

No

26
Q

What should be considered when adding sugar/sweeteners to pediatric medicines?

A
  • Effect of sugar content on teeth (dosing frequency and duration of medicine)
  • Side effects of larger daily exposure
  • Effect of the sweetening agent on absorption
27
Q

What is the intent of the Pediatric Regulation?

A
  • Increase number of pediatric formulations
  • Rapidly increase knowledge to quality aspects of pediatric medicines
  • Improve availability of info on the use of medicinal products in various pediatric populations
28
Q

What are challenges of geriatric pharmacotherapy?

A
  • New drugs available each year
  • Increasing popularity of “nutraceuticals”
  • HC approved and off-label indications expanding
  • Multiple co-morbid states
  • Effects of aging physiology on drug therapy
  • Changing managed-care formularies
  • Polypharmacy
  • Medication cost
  • Advanced understanding of drug-drug interactions
  • Medication compliance
29
Q

What are the effects of aging on absorption?

A
  • Lower peak concentration
  • Delayed time to peak concentration
  • Overall amount absorbed (bioavailability) is unchanged
30
Q

What is the effect of aging on hepatic first-pass metabolism?

A

Decreased liver mass and blood flow, so bioavailability may increase for drugs w/ extensive first-pass metabolism b/c less drug is metabolized by the liver

31
Q

What are the factors that affect absorption?

A
  • Route of administration
  • What is taken w/ the drug (divalent cations, food/enteral feedings, drugs that influence gastric pH, drugs that promote or delay GI motility)
  • Co-morbid conditions
  • Increased GI pH
  • Decreased gastric emptying
  • Dysphagia
32
Q

What are the effects of aging on volume of distribution?

A
  • Decreased body water = decreased Vd for hydrophilic drugs
  • Decreased lean body mass = decreased Vd for drugs that bind to muscle
  • Increased fat stores = increased Vd for lipophilic drugs
33
Q

Medications undergoing phase __ hepatic metabolism are generally preferred in elderly due to _____

A

Phase 2; due to inactive metabolites, so no accumulation

34
Q

What are the effects of aging on the kidney?

A
  • Decreased kidney size
  • Decreased renal blood flow
  • Decreased number of functional nephrons
  • Decreased tubular secretion
  • Result = decreased glomerular filtration rate (GFR) => decreased drug clearance
35
Q

How can you estimate GFR (glomerular filtration rate) in the elderly?

A
  • Creatinine clearance
  • Serum creatinine alone isn’t accurate in the elderly b/c decreased lean body mass = lower creatinine production, but serum creatinine stays in the normal range
36
Q

What is the equation for determining creatinine clearance?

A

[(IBW in kg * 140-age) / 72 * Scr in mg/dL] * 0.85 for females

37
Q

What are some age-related changes in pharmacodynamics?

A
  • Increased sensitivity to sedation and psychomotor impairment w/ BZDs
  • Increased level and duration of pain relief w/ narcotics
  • Increased drowsiness and lateral sway w/ alcohol
  • Decreased HR response to beta-blockers
  • Increased sensitivity to anti-cholinergics
  • Increased cardiac sensitivity to digoxin
38
Q

PK and PD changes generally result in decreased ___ and increased _____ to medications in older adults

A

Decreased clearance and increased sensitivity

39
Q

What should be done to decrease the risk of drug intolerance and toxicity in the elderly?

A

Lower doses, longer intervals, and slower titration

40
Q

What are the most common medications associated w/ ADEs in the elderly?

A
  • Opioids
  • NSAIDs
  • Anti-cholinergics
  • BZDs
  • CV, CNS, and musculoskeletal agents
41
Q

What is the purpose of the Beers Criteria?

A

Classifies drugs into high potential for severe ADE or high potential for less severe ADE

42
Q

What are some px risk factors for ADEs?

A
  • Polypharmacy
  • Multiple co-morbid conditions
  • Prior adverse drug event
  • Low body weight or BMI
  • Age over 85 y/o
  • Estimated CrCl < 50 mL/min
43
Q

What are the most common drug-drug interactions?

A

CV and psychotropic drugs

44
Q

What are the most common drug interaction effects?

A
  • Confusion
  • Cognitive impairment
  • Hypotension
  • Acute renal failure
45
Q

What are some common drug-disease interactions?

A
  • Obesity alters Vd of lipophilic drugs
  • Ascites alters Vd of hydrophilic drugs
  • Dementia may increase sensitivity to drugs w/ CNS or anti-cholinergic activity
  • Renal or hepatic impairment may impair metabolism and excretion of drugs
  • Drugs may exacerbate a medical condition
46
Q

What are the 5 principles for prescribing in the elderly?

A
  • Avoid prescribing prior to diagnosis
  • Start w/ low dose and titrate slowly
  • Avoid starting 2 agents at the same time
  • Reach therapeutic dose before switching or adding agents
  • Consider non-pharms
47
Q

What can be done to enhance medication adherence?

A
  • Avoid newer medications not shown superior to less expensive to less expensive generic alternatives
  • Simplify the regimen
  • Utilize pill organizers or drug calendars
  • Educate px on medication purpose, benefits, safety, and potential ADEs

Pharmacology - Winter (18 decks)

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