11 - Drugs & Polypharmacy 2

Question 1

name a factor which may reduce the rate of absorption of a buccally administered drug - e.g. GTN?

Answer 1

reduction in saliva production

Question 2

what is an exception to decreased absorption of a drug in elderly people and what is this because of?

Answer 2

levodopa - used for Parkinson’s

this is because there is less dopa-decarboxylase (enzyme) which breaks down levodopa

Question 3

what are the 2 most important factors that affect drug distribution in the elderly?

Answer 3

changes in body composition

changes in protein binding

Question 4

what is changes in body composition and protein binding also accompanied by?

Answer 4

decrease in total body water

Question 5

how are fat soluble drugs distributed in elderly?

Answer 5

Vd is increased due to increased body fat - longer duration of action

Question 6

2 fat soluble drugs?

Answer 6

diazepam

haloperidol

Question 7

how are water soluble drugs distributed in the elderly?

Answer 7

Vd is decreased - resulting in higher serum levels

Question 8

2 water soluble drugs?

Answer 8

theophylline

atenolol

Question 9

what factor affects the pharmacological effects caused by a drug?

Answer 9

free drug concentrations - this is because a bound drug cannot bind to target tissues

Question 10

name 4 conditions which depress albumin in elderly?

Answer 10

heart failure
renal disease
rheumatoid arthritis
hepatic cirrhosis

Question 11

how much does serum albumin decrease by in elderly patients?

Answer 11

decreased by 12%

Question 12

what is the binding site for basic drugs?

Answer 12

α1-acid glycoprotein

Question 13

when does α1-acid glycoprotein change?

Answer 13

in acute illness, not with age

Question 14

name 4 acidic drugs?

Answer 14

diazepam
cimetidine
furosemide
NSAIDs

Question 15

how does age affect the permeability of the blood-brain barrier and what is the result of this?

Answer 15

it increases the permeabiity - therefore drugs are more readily available to be distributed in the CNS

Question 16

name a water-soluble drug with a high Vd and explain why this is?

Answer 16

digoxin - due to widespread distribution into muscle and reduced muscle mass in elderly populations

Question 17

what has to be altered about digoxin when given to older people?

Answer 17

loading dose has to be substantially reduced

Question 18

how does Vd affect how widely distributed a drug is?

Answer 18

drugs with low Vd are not widely distributed, drugs with high Vd are

Question 19

2 factors which affect hepatic metabolism?

Answer 19

Decreased liver mass

Decreased liver blood flow

Question 20

2 consequences of decreased hepatic metabolism?

Answer 20

Toxicity due to reduced metabolism/excretion

Reduced first pass metabolism

Question 21

how is excretion and renal function affected with age & what is the result of this?

Answer 21

renal function and therefore excretion decreases with age - also reduces the clearance and increases half-life of many drugs - leading to toxicity

Question 22

3 reasons which account for the increased sensitivity to some medicines as we get older?

Answer 22

change in receptor binding

decrease in receptor number

altered translation of a receptor initiated cellular response into a biochemical reaction

Question 23

in general, how are doses/ frequency of administration affected when prescribing for elderly people?

Answer 23

lower doses and lesser frequency of administration are recommended

Question 24

describe 5 principles of prescribing for older people?

Answer 24

Review all prescriptions regularly and stop any medicines that are not beneficial

Try to keep regimens as simple as possible

Consider compliance issues which elderly patients in particular may experience

‘start low, go slow’

Review the new drug and check whether it is achieving its aim

Question 25

what prescribing tool can be used for ruling out inappropriate drugs for older people?

Answer 25

Beers’ Criteria

Question 26

what research tool can be used for finding medical optimisation when prescribing in older people?

Answer 26

START-STOPP criteria