Geriatrics: Drugs and polypharmacy Flashcards
Give examples of medication related problems/ ARDs in older patients
○ Falls ○ Cognitive Loss /delirium ○ Dehydration ○ Incontinence ○ Depression ○ End result can be - Loss of functional capacity - Poor quality of life - Nursing home placement
What are some examples of adverse drug reactions?
○ Unsteadiness ○ Dizziness ○ Confusion ○ Nervousness ○ Fatigue ○ Insomnia ○ Drowsiness ○ Falls ○ Depression ○ Incontinence
What are the health care provider factors that contribute to polypharmacy?
○ No med review with patient on regular basis
○ Presumes that patient expects meds
○ Prescribes without sufficiently investigating clinical situation
○ Evidence that a particular drug is the “best” drug for a problem
○ Complicated by the existence of many problems and multiple providers
○ Provides unclear, complex or incomplete instructions about how to take meds
○ No effort to simplify medication regimen
○ Ordering automatic refills
○ Medications promoted and publication bias
○ Lack of knowledge of geriatric clinical pharmacology
Why might drug absorption be different in older people (also, give an example of this)?
○ Physiological changes occur that effect the rate but generally not the extent of absorption from the GI tract
- May lead to a delay in onset of action
○ Examples
- A reduction in saliva production may result in a reduction in the rate of absorption of buccally administered drugs e.g. glyceryl trinitrate (GTN)
How might drug distrabution be different in older people?
○ Body composition changes
- Reduced muscle mass
- Increased adipose tissue
□ Fat soluble drugs: ↑ Vd, ↑ T1/2, ↑ duration of action e.g. diazepam
- Reduced body water
□ Water soluble drugs: ↓Vd, ↑ serum levels e.g. digoxin
○ Protein binding changes
- Decreased albumin
□ ↓ binding, ↑ serum levels acidic drugs e.g. furosemide
○ Increased permeability across the blood-brain barrier
How might drug metabolism be different in older people?
○ Hepatic metabolism is affected by
- Decreased liver mass
- Decreased liver blood flow
○ Consequences
- Toxicity due to reduced metabolism/excretion
- Reduced first pass metabolism
- ↑ in bioavailability with some drugs e.g. propranolol
- Can cause ↓ bioavailability of pro-drugs e.g. enalapril
How might drug excretion change in older people?
○ Renal function decreases with age
○ Reduces clearance and increases half-life of many drugs leading to toxicity
Why might polypharmacodynamics change in older people (give examples of this)?
○ Increased sensitivity to particular medicines
○ Due to:
- change in receptor binding,
- decrease in receptor number,
- altered translation of a receptor initiated cellular response into a biochemical reaction.
○ Examples: diazepam (↑ sedation), warfarin (↑ anti-coagulation)
What are the principles of prescribing for older people?
○ Where possible, be clear about the diagnosis to avoid prescribing a drug to manage an adverse effect
○ Consider whether drug therapy is the best therapeutic action
○ Lower doses (or reduced frequency of administration) are generally needed
○ Think about whether the drug causes particular problems in elderly patients
○ Check whether a lower dose is recommended in the elderly: start at the lowest dose and titrate up slowly (‘start low, go slow’)
○ Review the new drug and check whether it is achieving its aim
○ Review all prescriptions regularly and stop any medicines that are not beneficial
○ Try to keep regimens as simple as possible
○ Consider compliance issues which elderly patients in particular may experience
○ Elderly patients should not be denied proven beneficial medicines on the basis of age
○ But bear in mind that clinical trials are often performed in a younger population which may mean that benefits do not translate to an older age group
What is deprescribing?
To reduce, subsitute or discontinue a drug
Why might you deprescribe?
- Adverse drug reaction
- Drug-drug interaction
- Drug-disease interaction
- Better alternative
- Not effective
- Not indicated
- Not evidence-based
- Minimise polypharmacy
