Elderly Pharmacology Flashcards
Considerations when prescribing for elderly patients
- Pharmacokinetics reduced, increase drug level
- Volume of distribution – Diazepam (increase in body fat –skeletal muscle )
- Natural decline in renal function – decrease drug clearance (lithium)
- Age related change in liver function – variable drug metabolism/ polypharmacy – Adverse Drug Reaction /Interaction
- Pharmacodynamics - Physiological effect of drugs – increase sensitivity to certain drugs – benzodiazepine and opiates
Prescribing in elderly Case Study
- Gerald Smith 84 years- Alzheimer’s
- Donald her husband is main her carer
- Donepezil 10mg once daily
- Experiencing incontinence
- Two courses of antibiotics for UTI in 3 months
- Started on Mirabegron by GP
- What is going on ?
- What impact does this have on Gerald
- What impact does this have on her husband
- Which healthcare professionals are involved and what would you do differently
- Incontinence is an uncommon side-effect of Donepezil
- Not picked up by GP, and not seeing memory clinic till 3 months
- Loss of dignity for the patient
- Strain on Donald from the extra housework and personal care
- Always consider whether the symptoms are caused by a disease or by one or more medicines
Why are anti-cholingeric drugs concerning in the elderly?
- Review drugs that score high on Anticholinergic burden scale
- For every additional ACB point scored, the odds of dying increased by 26%.
- What are the side effects of these medications
- Prescribed with caution as elderly patients are more likely to experience adverse effects
High Risk Drugs in the elderly
- 75 years or older - prescribed an antipsychotic medicine
- 75 years - prescribed an NSAID without gastro protection
- 65 years or older currently taking an ACE inhibitor/angiotensin receptor blocker and a diuretic, who is prescribed an NSAID (the ‘triple whammy’)
- Aspirin or clopidogrel, who is prescribed an NSAID without gastro protection
- Current anticoagulant user prescribed an NSAID without gastro protection
- Current anticoagulant user prescribed aspirin or clopidogrel without gastro protection
High Risk Drugs in the elderly: Drugs that cause Dehydration
- STOP ACE inhibitors/angiotensin - II receptor antagonists
- NSAID’s
- Diuretics
- Metformin In Dehydrated
- Adults For example those suffering from more than minor vomiting/diarrhoea. Restart when well (e.g. 24 to 48 hrs eating and drinking normally).
Prescribing in elderly: drugs that increase risk of falls
Drugs that can cause: •Sedation and drowsiness •Dehydration •Confusion • Hypothermia •Impaired balance and stability •Hypoglycemia •Visual impairment (dry eyes and/or blurred vision) •Parkinson like symptoms •Orthostatic hypotension •Tinnitus/deafness
Prescribing in elderly Case Study
- Paul Johnson 78, recently had a fall
- 4 A/E attendances in the last year.
- A fractured left distal radius.
- Mobilises using a Zimmer frame.
- Past medical history includes hypertension, type 2 diabetes, BPH (benign prostatic hypertrophy), age-related macular degeneration and osteoarthritis
Medications: Amlodipine, Amitriptyline, Bendroflumethiazide, Finasteride, Furosemide, Gliclazide, Morphine sulphate oral solution, Omeprazole, Paracetamol, Ramipril, Sertraline, Simvastatin, Tamsulosin, Zopiclone
Which of the above medications could contribute to Paul’s falls risk?
TBD from discussion
Common causes dysphagia in the elderly
Stroke, neurodegenerative disease and learning disability are common causes
Pharmacokinetics: Absorbtion changes in elderly
With aging comes :
• Decrease in small-bowel surface area • Slowed gastric emptying,
• Increase in gastric pH,
Changes in drug absorption tend to be clinically inconsequential
for most drug
Ca CO3 requires acid pH for absorption ; Enteric coating on some drugs require acid to disolve coating
Pharmacokinetics: Distribution changes in elderly
- With Age comes :
- Increase in body fat ratio
- Reduction proportional water content
- Reduced serum Albumen : protein binding for drugs eg Phenytoin and Warfarin Toxicity when serum albumen is low eg acute illness
- Increase in Alpha-1-Acid Glycoprotein The direct impact of these is unclear
Pharmacokinetics: Hepatic metabolism changes in elderly
• Hepatic metabolism of many drugs through the Cytochrome P- 450 enzyme system decreases with age
• Hepatic clearance of drugs metabolized by phase I reactions : oxidation, reduction, hydrolysis is more likely to be prolonged in the elderly
• Usually, age does not greatly affect clearance of drugs that are metabolized by conjugation (phase II reactions).
• First-pass metabolism decreasing by about 1%/yr after age 40.
• Maintenance doses should be reduced in the elderly.
Individually tailored according to response
• High-protein binding: Phenytoin, Warfarin
• Lipophilic drugs : Benzodiazepines
• 1st-pass metabolism: Aspirin, TCA, ACE-inhibitors(some), Nitrates, some Beta-Blockers
The Cockcroft and Gault formula (1973)
Reduced Creatinine clearance means reduced elimination of Drugs!
CCr={((l 40–age) x weight[kg]) x Constant / Serum Creatinine (micromol/L)
Male (constant = 1.23
Female (1.o4)
Serum creatinine levels normal despite a decrease in GFR due to reduced muscle mass and less physical activity and thus produce less creatinine
Define Pharmacodynamics - considerations in elderly
- What the drug does to the body or the response of the body to the drug
- Depends on receptor binding, post-receptor effects, and chemical interactions
- Similar drug concentrations at the site of action (sensitivity) may be greater or smaller than those in younger people : dosing considerations and intervals of administration
- Closer monitoring
List some Anticholinergic drugs
Anticholinergic drugs
Many drugs eg,
tricyclic antidepressants,
sedating antihistamines, urinary antimuscarinic agents, some antipsychotic drugs, antiparkinsonian drugs,
OTC hypnotics and cold preparations have anticholinergic effects.
Drugs to use with special caution in the elderly
- Analgesics
- Anticoagulants
- Antidepressants
- Oral Hypoglycaemic agents • Antihypertensives
- Antiparkinsonian drugs
- Antipsychotics
- Anxiolytics and hypnotics
- Diuretics and Digoxin
