6: Pharmacology

Question 1

Pharmacokinetics: body’s action on the drug - ADME

(Absorption, distribution, metabolism, excretion)

Pharmacodynamics: drug’s action on the body

Question 2

A patient’s ___ has an effect on the concentration of drugs they are administered.

Answer 2

age

Question 3

Different drugs can ___ to change their metabolism.

Answer 3

interact

Question 4

The ___ of the environment a drug is in affects its absorption.

Answer 4

pH

acidic drugs require an acidic environment for absorption

basic “” for “”

Question 5

The route of delivery of a drug is important when talking about older patients.

Why?

Answer 5

Difficulty swallowing

Nasogastric or PEG tubes - tablets need to be suitable for them

Delirious patients won’t tolerate tablets, injections etc.

Pre-op patients may be nil-by-mouth

Question 6

? how much of this we need to know

Question 7

Name an example of an acidic drug.

Answer 7

Aspirin

Penicillin

Question 8

Name an example of a basic drug.

Answer 8

TCAs

Opioids

Benzos

Question 9

revise volume of distribution

high vd means more drug is stored in fatty tissue

dangerous when cachexic - fat broken down, drug released into circulation

Question 10

Older patients have greater ___ stores than younger patients.

Answer 10

fat stores

Question 11

high Vd means drug is lipophilic and most is absorbed into fat

low Vd means drugis hydrophilic and tends to be absorbed by the plasma

Question 12

biological half life is the time taken for the activity of a drug to half

t1/2 = 0.693 (or ln2) x Vd all over clearance

lipophilic drugs have a large Vd so therefore their t1/2 is greater

Question 13

older patients have a lower clearance and less body water (i.e plasma), so combined with a high Vd they take ages to clear lipophilic drugs

Question 14

older people have reduced liver and kidney function so excretion is impaired

Question 15

serum creatinine dependent on muscle mass, so not reliable for measuring renal function - use eGFR instead obviously

Question 16

therapeutic index = toxic dose / effective dose

narrow therapeutic index (i.e <2) is bad

drug dose required to produce an effect decreases as you age, so therapeutic index narrows as you age

Question 17

Opioids - think constipation

Steroids - think osteoporosis

Calcium supplements and T3 need to be taken at morning/night - interact with one another

Question 18

Avoid long-term NSAIDs, risk of peptic ulcers, renal impairment, gammy other drugs

Opioids and benzos (e.g lorazepam) increase risk of falls

4 Cs and C. diff

Question 19

ask about OTC medication and herbal remedies

Question 20

go over drug side effects

Question 21

stopp-start tool