Drugs and Polypharmacy Flashcards
What is polypharmacy?
The use of many drugs - one unnecessary medication can be enough to place an older person at risk of a toxic reaction
How many serious adverse drugs reactions are there annually in the US?
Over 2 million
How many deaths are there annually due to adverse drug reactions (US)?
100,000
Adverse drug reactions are the 4th leading cause of death, true or false?
True
What is the rate of ADRs in nursing home patients?
350,000 annually
What number of ADRs in ambulatory settings are preventable?
Nearly 1/3rd
What number of ADRs in nursing facilities are preventable?
Half
What are some common iatrogenic drug problems?
Confusion, dry mouth, constipation, blurred vision, urinary retention and orthostatic hypotension with anticholinergics
Confusion and unsteady gait with tricyclics
Digoxin toxicity with normal serum concentrations
CNS toxicity with long-acting benzodiazepines
Confusion with narcotics
What are the most costly medication-related problems/adverse drug reactions in the elderly?
Falls Cognitive loss/delirium Dehydration Incontinence Depression
What are possible end results of ADRs in older patients?
Loss of functional capacity
Poor quality of life
Nursing home placement
How many prescriptions do older adults get compared to those < 50?
Older adults (> 50) get 2-3 times as many prescription
What percentage of the population receiving prescription drugs, and percentage of prescription drugs in total do older adults account for?
12% of the population
> 32% of prescription drugs
How many drugs does a typical 85 year old take?
8-9 prescriptions and 2 OTC drugs at any one time
What common adverse drug reactions may be mistaken for ‘normal’ ageing?
Unsteadiness Dizziness Confusion Nervousness Fatigue Insomnia Drowsiness Falls Depression Incontinence
How many associated drug-drug interactions are there with type 2 diabetes mellitus, heart failure, and depression?
T2DM - 133
Heart failure - 111
Depression - 89
What are the healthcare provider factors that contribute to polypharmacy?
No medical review with patient on a regular basis
Presumes that patient expects medications
Prescribes without sufficiently investigating clinical situation
Evidence that a particular drug is the best drug for a problem, complicated by existence of many problems and multiple providers
Provides unclear, complex or incomplete instructions on how to take medications
No effort to simplify drug regimen
Ordering automatic refills
Lack of knowledge of geriatric clinical pharmacology
What are the drugs with the most adverse side effects?
Anticholinergics
Sedatives
What are some common peripheral side effects of antimuscarinic drugs?
Dry mouth Dry eyes Constipation Reduced peristalsis Inability to accommodate vision Pupillary dilatation Urinary retention Tachycardia Decreased sweating
What are some common central side effects of antimuscarinic drugs?
Memory impairment Confusion Disorientation Agitation Hallucinations Delirium Falls
How is absorption affected in old age? Give an example of this
Physiological changes occur that affect the rate but generally not the extent of absorption from the GI tract, this may lead to a delay in onset of action
e.g. reduction in saliva production may result in reduction in rate of absorption of bucally administered drugs like GTN
What is the exception to the effect of old age on absorption?
Levodopa - substantial mucosal metabolism of this drug occurs by enzyme dopa-decarboxylase, which is reduced in the elderly so there is a substantial increase in the absorption of levodopa in this age group
Why are there changes in drug distribution in the elderly?
Body composition changes
Reduced muscle mass
Increased adipose tissue, so fat-soluble drugs have increased Vd, half-life and duration of action
Reduced body water so water soluble drugs have reduced Vd and increased serum levels
Protein binding changes
Decreased albumin - reduced binding and increased serum levels of acidic drugs e.g. furosemide
Increased permeability across blood-brain barrier
How is drug metabolism affected in the elderly?
Hepatic metabolism affected by decreased liver mass and decreased liver blood flow
Results in toxicity due to reduced metabolism and excretion and reduced first-pass metabolism
How is drug excretion affected in the elderly?
Renal function declines with age
Reduces clearance and increases half-life of many drugs, leading to toxicity
How are pharmacodynamics affected in the elderly?
Increased sensitivity to particular medicines
Change in receptor binding
Decrease in receptor number
Altered translation of a receptor initiated cellular response into a biochemical reaction
e.g. diazepam - increased sedation
warfarin - increased anticoagulation
What are the principles of prescribing for older people?
Where possible, be clear about diagnosis to avoid prescribing a drug to manage an adverse effect
Consider whether drug therapy is the best therapeutic action
Lower doses generally needed, or reduced frequency of administration
Think about whether the drug causes particular problems in elderly patients
Check whether lower dose is recommended in the elderly
Start at lowest dose and titrate up slowly
Review new drugs and check if they are achieving their aim
Review all prescriptions regularly
Stop any medicines that are not beneficial
Try to keep regimens as simple as possible
Consider compliance issues
Elderly patients should not be denied a drug with proven benefits on the basis of age
Bear in mind that clinical trials are often preformed in a younger population so benefits may not translate to older age group
Where can drug information be found?
BNF
What prescribing tools and guidelines can be used?
Beers’ criteria
START-STOPP criteria
NHS Scotland polypharmacy guide
When is de-prescribing indicated?
To reduce, substitute or discontinue a drug
- adverse drug reaction
- drug-drug interaction
- drug-disease interaction
- better alternative
- not effective
- not indicated
- not evidence-based
- minimise polypharmacy
What is proactive deprescribing?
Systematic review of medication withdrawal trial in people > 65
Some evidence that it is safe and/or beneficial to stop antihypertensives, benzodiazepine and antipsychotics
What needs to be considered in prescribing for psychiatric conditions in the elderly?
Care with treating agitation
Sedatives are problematic
Increased effects of benzodiazepines
Anti-psychotics have increased adverse effects
Anti-depressants are less effective and potentially more dangerous
What needs to be considered in prescribing analgesia for the elderly?
Opioids - elderly are more sensitive to effects so lower doses needed
Pethidine and tramadol may be less useful
NSAIDs - increased adverse effects such as renal impairment and GI bleeding
What needs to be considered in prescribing digoxin for the elderly?
Increased toxicity
Lower doses needed
What needs to be considered in prescribing diuretics for the elderly?
Decreased peak effect but reduced clearance, so abnormal urea and electrolytes
Other issues around continence and mobility
Often inappropriate indication
What needs to be considered in prescribing anti-hypertensives for the elderly?
May have exaggerated effects on BP and HR
More likely to have issues with postural hypotension
ACEIs often pro-drugs which may not be metabolised into their active form
Renal adverse effects
What needs to be considered in prescribing anti-hypertensives for the elderly?
More sensitive to warfarin
Greater risk from warfarin e.g. GI bleeds, falls
What needs to be considered in prescribing antibiotics for the elderly?
Increased adverse effects Diarrhoea and c. diff infection Blood dyscrasias with trimethoprim and co-trimoxazole Delirium with quinolones Seizures Renal impairment
