Geriatric Pharmacology Self Study

Question 1

What are the changes in absorption which occur in aging?

Answer 1

GI oral absorption is largely unchanged, but digestion slows

Question 2

What are the distribution changes that occur with age? (think of body composition changes) How does this influence halflife?

Answer 2

1. Decreased lean body mass -> increase plasma concentration of water soluble drugs (decreased half life)
2. Increased body fat -> higher Vd for lipophilic drugs (higher halflife)
3. Total body water decreases -> increased plasma concentration of water soluble drugs
4. Decreased serum albumin concentration -> decreased protein binding, can lead to toxicity if extra drug is given

Question 3

What are the metabolism changes which occur in the liver due to aging?

Answer 3

Decreased phase 1 activity, but phase 2 relatively unaffected

Hepatic size and blood flow is relatively diminished

Question 4

What happens to renal drug elimination with age, and creatinine levels?

Answer 4

Decreases due to a drop in GFR, scary for aminoglycosides / digoxin with narrow therapeutic window

Creatinine levels -> may stay the same due to drop in lean body mass

Question 5

What is the Cockroft-Gault equation?

Answer 5

Formula for adjusting drug doses for renal function, based on body weight parameters and creatinine concentration (Age > 75)

Creatinine Clearance = ((140-age) * wt / (Scr * 72))

Multiply by 0.85 only in women

Question 6

How should the pharmacodynamic changes in elderly patients be handled?

Answer 6

Start low, go slow

Start at low doses, and titrate up slowly while closely monitoring for abnormal response

-> responses to all drugs are increased across the board, except maybe a decreased sensitivity of baroreceptor reflex

Question 7

What is the Beers criteria?

Answer 7

A list of 53 medications or classes which should be taken into consideration before prescribing to elderly

Question 8

Can adverse drug reactions be preventable?

Answer 8

Yes, in fact 50% are in the US. 95% are predictable

->most common in polypharmacy

Question 9

What is an important physical sign / risk factor for falling? What can induce it?

Answer 9

Orthostatic hypertension -> diuretics, nitrates

Question 10

What other drug class is associated highly with falls?

Answer 10

Psychoactive drugs -> due to confusion, sedation, dizziness, and balance problems

Question 11

What is double incontinence?

Answer 11

Inability to control both stool and urine at wanted time

Question 12

What is the “prescribing cascade”?

Answer 12

A drug is given for a side effect of another drug, which causes more side effects

Question 13

What are the best types of drugs to give to the elderly?

Answer 13

Rapid onset, relatively brief duration, cleared by phase II metabolism

Question 14

What is inappropriate prescribing vs undertreatment?

Answer 14

Inappropriate prescribing - giving a drug which causes an ADR risk when there are safer alternatives

Undertreatments - failing to treat a druggable condition or prevention of condition

Question 15

What antibiotic is known to lead to an increase in warfarin activity by displacing it from proteins in plasma?

Answer 15

Sulfonamide antibiotics, like TMP/SMX

Question 16

What types of drugs should be titrated slowly in the elderly?

Answer 16

Narcotic analgesics, oral anticoagulants, antihypertensive agents, TCAs, and antipsychotics