Elderly Polypharmacy Flashcards
Old people take a lot of drugs
That means a lot of ADRs/drug interactions
Why might this be particularly complicated in the elderly?
A lot of ADRs from polypharmacy may resemble the symptoms of aging e.g. dizziness, confusion, fatigue, drowsiness, falls or incontinence.
If an elderly patient presents always think about their drugs before you assume it’s down to their age
Most treatment guidelines are designed for young people, what should you think about when applying such things to the elderly?
In many cases you should adjust what you’re doing.
For instance Tight glycaemic control is recommended in diabetes to avoid future cardiac events. However this doesn’t work if it’s started when someones already older, so don’t put an elderly person through the risks and stress of a complicated DM regimen. Similarly for tight BP control in hypertension.
Most treatment guidelines are designed in isolation, what should you think about when applying them to the elderly?
Most older people have multiple disorders and so multiple treatment regimens.
It’s important to consider the other medications a patient is on, instead of just putting them on all the “recommended” drugs
Pharamacokinetics and pharmacodynamics change with aging. How is absorption of drugs affected by aging?
Rate of absorption changes with age, while extent of absorption doesn’t really change
How GTN as an example of how absorption changes with age
Decreased saliva in the elderly means decreased rate of GTN absorption.
So elderly patient takes a puff, nothing happens, they take another and suddenly have way too much GTN and their BP drops dangerously
We said that while rate of absorption changes extent doesn’t really, there are some exceptions to this:
Levodopa:
- Elderly have less dopa-decarboxylase
- -> Less levodopa metabolism
- -> Faster absorption AND higher peak palsma level
How does distribution of drugs change with age?
More fat less muscle:
- Fat soluble drugs have greater Vd & greater duration of effect
- Water soluble drugs have less Vd & greater serum conc.
Also less albumin:
- less binding –> greater serum conc of acidic drugs e.g. furosemide
How does metabolism of drugs change with age?
Decreased liver mass & blood flow means hepatic metabolism decreases with age
–> Increased toxicity of drugs metabolised in the lvier
Also –> Reduced first pass metabolism –> Increased bioavailability of some drugs and less of some pro-drugs
How would excretion of drugs change with age?
Renal function declines
>Reduced clearance –> Increased half-life
> Toxicity
What effect does aging have on pharmacodynamics?
Changes in receptor binding, number and effect means older people have increased sensitivity to particular meds
E.g. Increased sedation on diazepam
E.g. Increased anti-coagulation on warfarin
What are the most dangerous drugs (for ADRs) re polypharmacy?
Anti-cholinergics
Sedatives
Here are some tips for prescribing for the elderly
- Be sure about the diagnosis so you don’t prescribe another drug to manage an ADR
- Consider non-drug therapies
- Lower doses/frequencies
- Look out for particular warnings about a drug in the elderly
- Review the med regularly
- Keep as simple as possible because compliance with many drugs is hard, especially for the elderly
