Older Adults

Question 1

How is absorption changed in the older individual and what factors affect absorption?

Answer 1

• amount absorbed/bioavailability does not change! Exception is drugs that undergo first pass metabolism, and these drugs will have a higher bioavailability since the liver extracts less
• in general, peak serum concentration may be lower or delayed
• factors affecting absorption are: route of administration, what is taken with drug, comorbid illnesses, presence of divalent cations, enteral feedings, increased gastric pH, drugs affecting GI motility

Question 2

How does aging change the volume of distribution?

Answer 2

• decreased body water (less VD for hydrophilic)
• decreased lean body mass (less VD for muscle binders)
• increased fat stores (more VD for lipophilic)
• decreased albumin (more unbound/active)

Question 3

How does aging affect metabolism of drugs? What type of drug metabolism is preferred for older adults?

Answer 3

• clearance of drug by liver is reduced

- Phase II pathway metabolism is preferred (drugs are converted to inactive metabolites and do not accumulate)

Question 4

What are some considerations to be aware of when prescribing NSAIDs to older adults?

Answer 4

• require hepatic metabolism

- increase risk of bleeding event

Question 5

How does kidney function affect prescribing medications in the older adult?

Answer 5

• most drugs are eliminated via kidney
• decreased renal function can lead to drug accumulation and toxicity
• in general, the kidney gets smaller, has reduced blood flow, decreased functioning nephrons, and decreased renal tubular excretion — this all leads to lower glomerular filtration rate

Question 6

How can you determine creatinine clearance in an older adult?

Answer 6

• do NOT assume serum creatinine reflects creatinine clearance (there is lower Cr production and lower GFR in adults)
• CrCl can either be measured with 24hr urine collection or estimated with Cockroft Gault equation

Question 7

What is the Cockroft Gault Equation?

Answer 7

[(Weight in kg)(140-age)] / [72 x serum Cr] ( x .85 if female)

• NOTE: this takes into account size, age, and gender!

Question 8

What is an important part of prescribing drugs in the older adult?

Answer 8

reviewing drug list on every visit to ensure that a drug is still needed

Question 9

What are the risk factors for an adverse drug event (ADE) in an older person?

Answer 9

• 6 or more chronic conditions
• 12+ doses of drugs / day
• 9+ medications
• prior ADE
• low BMI
• age 85+
• estimated CrCl < 50 mL/min

Question 10

What are some drugs that have high potential for severe ADEs?

Answer 10

• anticholinergics
• narrow therapeutic window (warfarin, digoxin)
• benzodiazepines
• CV or psychotropic

Question 11

Describe the ADE prescribing cascade

Answer 11

Drug 1 is given, and an ADE develops but is misinterpreted as a new medical condition
Drug 2 is given in addition to Drug 1
Lather, rinse, repeat

Question 12

What are the most common ADEs seen in older adults?

Answer 12

• confusion
• cognitive impairment
• arterial hypotension
• acute renal failure

Question 13

What are the principles for prescribing medications in older adults?

Answer 13

• start low and go slow

- avoid starting 2 drugs at same time

Question 14

What is the Beers criteria?

Answer 14

Highlights drugs that are high risk and should be avoided in older adults, including the quality of evidence against use