Drugs and Polypharmacy Flashcards
Define polypharmacy
Use of 5+ medications but unnecessary medication
Which can place an older person at risk of avoidable toxic reaction
How many different drugs do you need to take before there is a guaranteed ADR?
9
What % of ADRs are preventable?
1/3rd in ambulatory settings
1/2 in nursing homes
What are some costly medication related problems/ARDs in older patients?
Falls Cognitive loss/dementia Dehydration Incontinence Depression
Leading to loss of functional capability, reduced QoL, nursing home placement
What is the typical drug consumption of a 85yo?
8-9 prescribed drugs
2 OTC
Why are elderly patients taking more drugs?
More acute and chronic disease
More doctor visits (may see diff doctors each time –> more and more drugs)
Drugs given to counteract SEs of other drugs
What are some ARD symptoms that may just get labelled as ‘getting old’?
Unsteadiness Dizziness Confusion Nervousness Fatigue Insomnia Drowsiness Falls Depression Incontinence
Describe the ‘prescribing cascade’ that often happens in the pharmacological management of an elderly patient
Drug 1 give, ADE interpreted as new medical condition, so drug 2 given and so on
What is stated in the SIGN guideline 116 for management of diabetes?
Aim for HbA1c <7% or individualised BP <130/80 ACEi>ARB>CCB>thiazide Avoid alpha and beta blockers Statins if <40 Aspirin for secondary prevention only Lifestyle advice
What is the problem with the sign 116 guidelines in elderly patients?
Very strict targets
If multimorbid will be very difficult to reach targets
Not much evidence that really tight glycaemic control is beneficial in elderly (only beneficial if started mid-life and long term)
Apart from diabetes, what other condition shows loss of benefit for tight control in geriatric populations?
HTN (tight BP control may be dangerous in these groups)
Beneficial only for those able to walk, for those unable if was detrimental to give anti-hypertensives
What are the problems with guidelines for those who are multi-morbid?
There are many guidelines for each individual condition but none to fit all of their conditions
Cross-referenced NICE guidelines for T2DM, depression, heart failure and 11 other specific diseases
How are elderly patients medicines meant to be checked?
All >75y meant to have annual medication review
What are some healthcare provider factors that contribute to polypharmacy?
No med review
Presumes patient expects meds
Prescribes without sufficient Ix
Evidence that a particular drug is best for a problem
Complications of many problems and multiple providers
Unclear, complex or incomplete instructions on how to take meds
No effort to simplify med regimen
Ordering automatic refills
Medications promoted and publication bias
Lack of knowledge of geriatric clinical pharmacology
How does absorption differ in older people?
Rate of absorption affected but not extent of absorption from GIT
Give an example of how absorption may differ in an older person
GTN
Delayed absorption due to changed physiology & reduced saliva production, so patient may take more drug than they need –> BP falls –> vasovagal syncope
What is the exception to the rule for how absorption differs in the elderly?
Levodopa
There is substantial mucosal metabolism of this by dopa-decarboxylase enzyme
Reduced dopa-decarboxylase as this is secreted in saliva and there is reduced saliva production
So increased absorption and higher peak level quicker than younger patients
What body compositional changes in elderly patients mean they have different distribution of drugs?
Reduced muscle mass and water content
Increased fat content
Particularly significant if drug highly lipid soluble, widely distributed into muscle/contained in water
How will the distribution of fat soluble drugs difer in an elderly patient?
Vd increased due to increased body fat
(e.g. fat soluble drugs - haloperidol, diazepam)
Adipose tissue acts as a reverse for these drugs, so enhanced t1/2
How will the distribution of fat soluble drugs differ in an elderly patient?
Tend to reduce Vd –> higher serum levels
E.g. of water soluble drugs - digoxin, theophylline, atenolol, propranolol, hydrochlorothiazide
How does protein binding differ in elderly patients?
Total serum albumin decreases by 12%
So more unbound, free drug
Common diseases in elderly depress albumin (HF, renal dx, RA, hepatic cirrhosis, some malignancies)
Give examples of protein bound drugs
Furosemide, diazepam, cimetidine, propanolol
How is the blood brain barrier affected by age?
More permeable so drug more easily distributed to CNS
Why must you be careful in dosing digoxin in the elderly?
Reduction of muscle mass means there is a significant reduction in digoxins Vd so loading dose must be substantially reduced
