Drugs in the elderly Flashcards
Define Pharmacodynamics
How a drug alters the body
Define Pharmacokinetics
How the body alters the drug
Define polypharmacy
When the patient is taking 4 or more medications
What is an adverse drug reaction?
An injury caused by taking a medication
Name 2 risk factors associated with adverse drug reactions
Polypharmacy
Inappropriate prescribing
Name the 3 factors related to adverse drug reactions
DoTS classification
Dose
Time course
Susceptibility
What is the name for a reaction occurring below the therapeutic range?
Give an example of a drug where this may occur.
What would you do if this did occur?
Hyper-susceptibility
Penicillin
Completely avoid the drug permanently
What is the name for a reaction occurring within the therapeutic range?
Give an example of a drug where this may occur.
What would you do if this did occur?
Collateral
Antihistamines cause drowsiness
Nothing normally, as minimal and manageable side effects would be outweighed by the benefits of taking the drug - unavoidable
May not be reduced without reducing the therapeutic effect, even by reducing the dose
What is the name for a reaction occurring above the therapeutic range?
Give an example of a drug where this may occur.
What would you do if this did occur?
Toxic
Bleeding caused by Warfrin
Treat by reducing the dose being given
Prevent by using the minimal effective dose
Name 6 factors that have a effect on a patients susceptibility to a drug
Age - Old and young are more susceptible
Disease state - hepatic/renal impairment
Physiological state - pregnancy
Genetic susceptibility - Ethnicity
Sex
Exogenous factors - drug interactions/diet
Name 7 factors leading to increased drug reactions in the elderly
Decreased organ function
Co-morbidity
Poly-pharmacy
Altered Pharmacokinetics (moving substances through the body)
Altered Pharmacodynamics (receptor sensitivity/decrease in hormones)
Decreased homeostatic function
Decreased compliance
Name 3 things that should be carried out to achieve safe prescribing in the elderly
Improved compliance
(Simplify, educate, monitor) (Blister packs)
De-prescribe
(Discontinue drugs that aren’t of benefit/have adverse effects that require additional drugs to alleviate)
Medication reviews
(>75yo = annual reviews, and 6 month reviews if >75 yo and poly-pharmacy)
A reaction occurs immediately on taking a drug, what name is given to this?
Give an example of a drug that may cause this
First dose reaction
Ramapril causes hypertension (ACEi)
A reaction occurs 2 weeks into taking a drug, what name is given to this?
Give an example of a drug that may cause this and the action that should be taken.
Early reaction
Nitrates cause headaches
Patients may become tolerant to these reactions
ADR should wear off, so continue with medication
A reaction occurs 1 month into taking a drug, what name is given to this?
Give an example of a drug that may cause this and the action that should be taken.
Intermediate reaction
Neutropenia due to carbimazole
If no reaction occurs within a specific time frame then vigilance can be relaxed
A reaction occurs AFTER one month of taking a drug, what name is given to this?
Late reaction
Bruising due to corticosteroids
Risk of ADR increases with increased exposure
Need for long term monitoring
If a drug is stopped at 2 months, and a reaction occurs a week after this, what is this reaction called?
Withdrawal
SSRI anti-depression discontinuation
Slow withdrawal or reduction of dose to prevent
If a drug is stopped at 2 months, and a reaction occurs a month after this, what is this reaction called?
Delayed reaction
Carcinogenisis/teratogenesis
Avoid use of drug in patients that are susceptible
Roughly, how many older people take at least 1 medication
4 in 5
What percentage of the elderly take 4 or more medications
36%
Elderly people are 3 times more likely to suffer from adverse drug reactions.
What percentage of hospital admissions are due to this?
5-12%
What percentage of older patients do not take their medicines and prescribed?
Up to 50%
What is a drug interaction?
A situation in which a substance affects the activity of a drug when both are administered together
What is the normal therapeutic range for a drug?
1-1.5mg
How do you report suspected severe drug reactions?
The yellow card scheme
What is ageing?
Gradual loss of function of cells and organs with the eventual outcome of death
Name 5 factors that influence ageing
Genetics
Psychology
Lifestyle (diet/exercise)
Socio-economic factors
Environment
What are the 4 main pharmacokinetic processes?
How do these relate to the older population?
ADME
Absorption
Swallowing/gastric emptying/intestinal motility/blood flow/surface area
Distribution
Tissue perfusion an blood flow/plasma protein binding/volume distribution
Metabolism
Hepatic mass decrease/hepatic blood flow decrease/thyroid function decrease/genetics
Excretion
Assumption most older people have some degree of renal impairment.
Renal blood flow decreases, and GFR decreases
Give 3 aging changes that occur in pharmacodynamics
Changes in receptor sensitivity (B-adrenoceptor sensitivity decreases with age)
Changes in receptor number
Changes in hormone levels (menopause)
Give 7 common drugs that
ACE inhibitors
Diazepam
Digoxin
NSAIDS
Opiates
Oral hypoglycaemics
Warfrin
Give 3 ageing changes in homeostasis
Decreased postural control
Decreased thermo-regulation
Decreased immune response
Why does multi-morbidities increase the chance of adverse drug reactions?
More drugs needed so more chance of drug-drug interactions
More chance of drug-disease interactions
(Benzodiazepines may precipitate delirium in a patient with dementia)
How much of the drug budget do older people take up?
40%
What percentage of over 65’s are on regular medication?
66.6%
Why can polypharmacy be a problem?
Loss of patient compliance (50%)
Prescription errors (5-20%)
Increased ADR’s and interactions
Inappropriate prescribing
