Geriatric Pharmacology

Question 1

Methods to improve successful pharmacology in elderly?

Answer 1

Prescribe 1 drug at a time
Start Low and titrate up
Look at drug interactions
Monitor closely
Use good resources for selection
Avoid over/under treating

Question 2

What are resources for evaluating proper meds?

Answer 2

Beers list (High/Med/Low risk drugs)
STOPP (screening tool of Older Persons with potentially inappropriate Prescriptions)
START (Screening Tool to Alert doctors to Right Tx)

Question 3

What are age related changes in:
Body composition?
Liver FUnction?
Cardiac Function?
Kidney Function?

Answer 3

Body comp: Dec TBW, Dec body mass, Inc Body fat
Liver: Dec in size, Dec in hepatic blood flow
Cardiac: Dec myocard sens to Beta stim, Dec baroreceptor activity, Dec CO, Inc TPR
Kidney: Dec GFR, Dec RBF, Dec FF, Dec Tubular secretory function, Dec Renal mass

Question 4

How age related changes affect pharmakodinamics?
Absorption?
First Pass?
Distribution?
Clearance?

Answer 4

Absorption: Doesnt’ affect that much
First Pass: Signif reduced - Give lower dose if Liver deactivates the drug; Higher dose if liver activates Drug (prodrug)
Distribution: Higher Vd with lipophilic drugs, Lower Vd with hydrophilic drugs
Clearance: Reduced kidney function, Dec blood flow to liver combined with decreased Phase 1 enzyme activity. Dec GFR, Polypharmacy inc competition for active transporters.

Question 5

How do pharmakokinetic affect:
T1/2?
Loading Dose?
Maintenance Dose?

Answer 5

T1/2: 0693x(Vd/CL) - lipophilic drugs, combined with Dec CL will have a much higher T1/2 than younger kids
Loading DOse: (VdxTC)/F. Hydrophilic drugs will have a lower Loading Dose due to dec Vd.
Maintenance Dose: Will only have to change dose of Capacity LImited drugs metabolized by Phase 1 enzymes. Flow dependent drugs will need to be decreased regardless of how they are metabolize dure do decreased flow to the liver. amount you put in has to equal the amount coming out.

Question 6

Why can Creatinine Clearance Estimates and Measurements be used for dosing?

Answer 6

Plasma has predictable concentration of Creatinine from muscle - all is filtered and none is reabsorbed. Measuring in urine tells you about GFR. and CL through the kidney

Question 7

What is the purpose of the Cockcroft and Gault Equation?

Answer 7

Gives creatinine clearance, taking into account decreased muscle mass to calculate GFR

Question 8

What are the adverse effects of the following in the elderly?
NSAIDS
Anticholinergic drugs
Antihyerglycemics
Anxiolyics/Sedatives
Opioids
Digoxin

Answer 8

NSAIDs: CL primarily by kidney and they lead to kidney damage - PGE helps inc renal flow.
Anticholinergics: Risk of Inc Delirium, falls, dry mouth, dec gut motility, Dec bladder, orthostatic hypotension
Antihyperglycemics: risk of hypoglycemia increased. use shorter acting drugs for this.
Anxiolytics/Sedatives: Inc risk of delirium
Opioids: Inc risk of delirium
Digoxin: Inc risk of toxicity due to Dec CL, renal down, Dehydration, drug drug interactions, ARRHYTHMIA, FATIGUE, CONFUSION

Question 9

What are classes of drugs with high anticholinergic activity?

Answer 9

Anticonvulsants
Antidepressants
Antipsychotics
Antihistamines
Cardiovascular drugs
Antispasmodics - GI
H2 Antagonists
Muscle Relaxants
Parkinsons Drugs
Antispasmodics - Urinary
Vertigo drugs