Geriatric Pharmacology

Question 1

GI Absorption

Answer 1

What is bioavailability of drug

• dec gastric emptying, intestinal motility, intestinal blood flow, inc gastric pH
• despite all of this, no significant change in quantity absorbed, just may delay time to onset

Question 2

Distribution

Answer 2

Inc body fat, dec muscle mass, dec body water, dec CO, altered regional blood flow

inc Vd of lipid soluble medications (benzos, digoxin)- time of response will be longer becaause meds will be deposited in tissues

dec Vd of water soluble meds

Question 3

Vd

Answer 3

Vd=drug dose/concentration

Question 4

Loading dose

Answer 4

LD= desired concentration x Vd

Question 5

1/2 life

Answer 5

t1/2=.7Vd/clearance

=.7/k

Question 6

Protein binding

Answer 6

Dec serum albumin, dec protein affinity, inc alpha1 acid glycoprotein

inc free fraction of highly protein bound meds

Question 7

Distribution

Answer 7

Usually Vd is more significant
but plasma protein binding is significant when there are changes in enzymes, metabolism, long half life drugs, total vs free drug in lab values

Question 8

Metabolism

Answer 8

dec hepatic mass and blood flow
dec phase 1- oxidation and reduction (prodrugs may not be as effectively activated)

phase 2 and CYP 450 activity-unchanged

Question 9

Renal elimination

Answer 9

dec RBF, renal tubular secretion, GFR,

avg renal function of 80 yearold os 50% of 20 yo

Question 10

Cockcroft Gault Equation

Answer 10

CrClmen= ((140-Age)x LBW)/Scr x 72

CrClwomen= CrClmen x .85

LBWmen= 50 kg + (2.3x inches>5 ft)
LBWmen= 45.5 kg + (2.3 x inches >5 ft)

Question 11

Consensus on Dosing (avoid if <30 ml/min)

Answer 11

Chlorpropamide, colchicine, cotrimoxazole, glyburide, meperidie, nitrofurantoin, propyxyphene, probenecid, spironolactone, triamterene

Question 12

Pharmacodynamics

Answer 12

Changes in numbers and sensitivity of receptors, counter regulatory mechanisms

Benzos- much more sensitive to these meds because inc receptor sensitivity. more likely to produce side effectives

dec renin and aldosterone levels

inc sens of Na/K ATPase (inc toxicity to digoxin)

inc sensitivity to warfarin, inc sensitivity to anti cholinergic effects (1st gen antihistamines)

Question 13

Decreased receptor sensitivity

Answer 13

beta-adrenergic receptors

Question 14

Decreased baroreceptor sensitivity

Answer 14

orthostatic hypotension w/ vasodilators, TCA’s, antihypertensives

Question 15

Drug- drug interactions

Answer 15

-if highly protein bound drugs, drugs metabolized by CYP450, enzyme inducers or inhibitors

BZD+ antidepressants cause confusion, sedation, falls

ACE inhibitors + diuretics cause hypotension/hyperkalemia
ACE inhibitors + K+ - hyperkalemia
Antiarrythmic + diuretics- electrolyte imabalnces

Question 16

Adverse Drug Reactions

Answer 16

many preventable
-most meds- CV, diuretics, non-opioid analgesics, hypoglycemics, anticoagulatints

preventable- renal, gi, hemorrhagic, metabolic, neuropsych

Question 17

10 PIRx Older adults should avoid

Answer 17

NSAIDs
Digoxin
Certain diabetes drugs
Muscle relaxants
Certain meds for anxiety/insomnia
Certain anticholinergic drugs
Meperidone
OTC combo products containing anticholinergics
Antipsychotics
Estrogen patches/pills