Prescribing

Question 1

absorption principles

Answer 1

acidic drugs need acidic (ph<7.35) environment for absorption, e.g. phenytoin, aspirin, penicillin
basic drugs require a basic (ph>7.35). environment for absorption e.g. diazepam, morphine, pethidine

Question 2

absorption changes with. increased biological age (3)

Answer 2

increased gastric pH (less acid),
decrease small bowel surface area,
more likely to have had previous GI surgery or NG tube etc.

Question 3

In line with absorption which drugs are absorbed better in older people? acidic or basic

Answer 3

basic drugs increased absorption

Question 4

distribution principles

Answer 4

protein binding for must drugs - albumin basic so binds to acidic and alpha-1 acid glucoportein acidic binds to basic,
lipid binding

Question 5

distribution changes in old patients

Answer 5

elderly often low albumin but higher A-1 AG so bind more to basic drugs,
increased fat proportional to muscle mass so increases volume of lipophilic drugs e.g. diazepam, anaesthetics,
decreased body water by about 10-15% so hydrophilic drugs lower Vd so lithium, digoxin

Question 6

Volume of distribution

Answer 6

theoretical volume into which all of drug is fully dissolved in plasma

Question 7

volume of distribution indicates what?

Answer 7

indicates lipophylicity of drugs

Question 8

biological halflife

Answer 8

time for drug concentration to fall to half of its maximum concentration directly proportional to Vd

Question 9

drugs that are lyphophylic and have high Vd

Answer 9

long half-life

Question 10

lypophylic drugs clear faster/sloer than one that cleared by kidney/liver

Answer 10

slower

Question 11

How can sometimes old patients distribution be fine

Answer 11

lower Vd AND clearance both low so balance each other out so half life unaffected

Question 12

metabolism

Answer 12

hepatic metabolism,

renal metabolism

Question 13

metabolism old people changes

Answer 13

reduced liver function due to decreased size, blood glue, ,
lower CP yfoj ????,
lower GFR, but serum creatinine not reliable so use egfr

Question 14

reduced liver function in old people reduces what type of metabolism and give example of drug

Answer 14

first pass metabolism reduced e.g. propranolol

Question 15

general principle of older people

Answer 15

lower doses achieve same effect in older people but some effects are decreased e.g. beta blockers

Question 16

therapeutic index

Answer 16

drug with narrow therapeutic index be careful and it narrows as you grow older

Question 17

Drugs most often associated with adverse reactions

Answer 17

warfarin, 
digoxin, 
insulin, 
Benzos, 
diuretics, 
NSAIDs, 
steroids, 
anti-hypertensive agents, 
opioids, 
theophylline

Question 18

side effects old people with opioids, Benzes, steroids and levothyroxine

Answer 18

opioids -> laxatives prophylactically, psychomotor function, falls and confusion,
benzos -> psychomotor function, falls and confusion so low dose short time
steroids -> osteoporosis prevention, steroid induced diabetes,
levothyroxine -> calcium interferes with absorption of drug and lots of old people on calcium tabs

Question 19

problems with NSAIDs in oldies

Answer 19

decreased effectiveness of diuretics, anti-hypertensives,
decline in GFR,
GI haemorrhage

Question 20

antibiotics in oldies

Answer 20

resistance and c.diff diarrhoea use only when objective evidence of infection e.g. +ve blood culture, urine culture, pyrexia or consolidation on CXR

Question 21

average use of person >65 yrs is

Answer 21

4 prescription,

2.5 over-the-counter medicines

Question 22

poylpharmacy prevention

Answer 22

review meds regularly & discontinue unnecessary e.g. NSAIDs,
avoid treating s/e with more drugs e.g. amlodipine causing oedema,
attempt to get one drug to treat two things e.g. CCB/BB for HTx and angina

Question 23

diarrhoea

Answer 23

loperamide or codeine phosphate

Question 24

start-GI

Answer 24

PPI,

fibre supplements

Question 25

STOPP-CV

Answer 25

BB w/ verapamil

Question 26

STOPP-CV

Answer 26

non-cardioselective BB

Question 27

STOP-CV CCB

Answer 27

don’t use with chronic constipation,

diltiazem or verapamil with later stage heart failure

Question 28

STOPP-XCV

Answer 28

??

Question 29

START-CV

Answer 29

antihypertensive,
ACEi,
???

Question 30

old people prescribing basics

Answer 30

start low go slow, lower doses