Prescribing in Older People Flashcards
Common Scenario:
85 yr old frail female admitted after a fall
Meds include: Warfarin, Perindopril, Diazepam, Ibuprofen, Furosemide, Sertraline, Amlodipine, Betahistine, Prochorperazine
What problem meds can you identify?
Warfarin and Ibuprofen = increased risk of bleeding
Ibuprofen/Diuretic/perindopril - affect ARF
Sertraline - low sodium/GI bleeds
Diazepam - sedation
Antihypertensives in those who fall (amlodipine)
Prochlorperazine - Parkinsonism
Patients over 65 years constitute …% of the population but use about …% of the medications
13% of population, 30-40% of medication
Elderly patients use … drugs and have … diseases
Elderly patients use multiple drugs and have multiple diseases
Greatly increased risk of drug … as well as … effects with multiple drugs
Greatly increased risk of drug interactions as well as adverse effects with multiple drugs
Drug absorption in the elderly
Reduced saliva Reduced gastric acid Decreased GI motility Reduced SA for absorption Reduced splanchnic blood flow overall - rate of absorption decreased and increased time to steady state
Levodopa competes with …
nutrients - plan dosing regimes to avoid meal times
Bisphosphonates - advise to take on a …
empty stomach, sitting up, 30 min before food
Drug distribution in the elderly
Decreased lean body mass (muscle)
Decreased volume of distribution for drugs that distribute into muscles e.g. digoxin
= increased plasma concentration
Digoxin toxicity
Cardiac (heart block, bradycardia, junctional tachycardia), Psychiatric (delirium, fatigue, malaise), Visual, GI side effects
Digoxin toxicity - Cardiac (3)
heart block, bradycardia, junctional tachycardia
Digoxin toxicity - A patient with normal digoxin levels (1-2 ng/mL), 6 hours post dose but renal insufficiency or severe hypokalemia may have more serious cardiotoxicity than a patient with high digoxin levels and no renal or electrolyte disturbances.
Treat how? withdrawing drug/correcting electrolytes
withdrawing drug/correcting electrolytes
Severe- digoxin specific antibody fragments (Digibind)
Drug Distribution in the elderly
increased body fat, increased volume of distribution for fat soluble drugs e.g. benzodiazepines, haloperidol = increased half life
e.g. diazepam - vol of distribution increased by x2 in elderly - half life increases from 24 hours to 90 hours in the elderly
Benzodiazepines side effects
Drowsiness, confusion, ataxia, dependence
Treat iv flumazenil 200mcg, antagonist, shorter half life than diazepam and so patient may become re-sedated
Drug distribution in the elderly - body water - what is the affect on distribution of water soluble drugs?
Decreased body water, decreased vol of distribution of water soluble drugs e.g. gentamicin
= increased plasma conc, loading doses are lower
Serum albumin - drug distribution in the elderly - what happens?
↓Albumin 12-25% - further depressed by heart failure, renal disease, rheumatoid arthritis, hepatic cirrhosis some malignancies
Drug binding capacity ↓ 12-25%
↑ free drug
Phenytoin toxicity
Nausea, vomiting, tremor, ataxia, nystagmus, coarse facies, hepatitis
Warfarin - Aspirin Interaction
Warfarin is highly bound to plasma albumin (99%)
Warfarin has narrow therapeutic index
Warfarin has a small volume of distribution
Aspirin can displace warfarin from plasma albumin
finish card
Adverse effects - antiplatelet agents e.g. aspirin
Antiplatelet agents - aspirin Peptic ulcer disease bleeding tendency fluid retention renal failure
Anticoagulants eg warfarin or DOAC adverse effects
Bleeding tendency
Interaction with other drugs
Digoxin toxicity - Psychiatric
delirium, fatigue, malaise, confusion, dizziness
Digoxin toxicity - Visual
blurred or yellow-green vision, halos, double vision, photophobia
Digoxin toxicity - Gastrointestinal
nausea, vomiting, anorexia, diarrhoea, abdominal pain
Drug distribution in the elderly - decreased body water - what is the affect on loading doses of water soluble drugs?
decreased body water = increased plasma conc, loading doses are lower
What drugs bind to albumin and require lower doses in the elderly?
phenytoin, warfarin, propranolol, diazepam levothyroxine,digoxin, furosemide
Phenytoin toxicity symptoms
Nausea, vomiting Tremor Ataxia Nystagmus Coarse facies Hepatitis
Warfarin – Aspirin interaction
Warfarin is highly bound to plasma albumin (99%)
Warfarin has narrow therapeutic index
Warfarin has a small volume of distribution
Aspirin can displace warfarin from plasma albumin
Displacement of 1-2% of bound warfarin doubles or triples concentration of free warfarin
↑ bleeding
Adverse effects - Antiplatelet agents (5)
aspirin Peptic ulcer disease Bleeding tendency Fluid retention Renal failure
Adverse effects - Anticoagulants warfarin or DOAC (2)
Bleeding tendency
Interaction with other drugs
Liver metabolism in the elderly
↓ liver volume – up to 30% reduction
↓ liver blood flow 12-40% (extremely variable)
↓ first-pass metabolism due to ↓ blood flow
↓ enzyme activity CP450 (frail elderly)-
↓ clearance of drugs = ↑ t1/2
Eg. antidepressants, antipsychotics, beta blockers, opiates, benzodiazepines, calcium channel blockers, theophylline, warfarin, phenytoin, NSAIDS, paracetamol, erythromycin
Excretion in the elderly
Renal blood flow
↓ Renal mass (20%)
↓ Renal function (nephrons 30%)
GFR declines by 1% per year from age 40
Excretion in the elderly
Drugs that are more than 60% excreted by kidneys are affected by a reduction in renal function
t1/2 prolonged
↑ serum levels
Drugs excreted primarily by kidneys include: digoxin, atenolol, sotalol, lithium, allopurinol & many antibiotics
Excretion in the elderly - Therapeutic implications
Reduce dose in once daily preps
Increase dosage interval in more frequently administered drugs
Lithium - toxicity
12 hour post dose 0.4-0.8 mmol/l
Early toxicity Li 1.5 mmol/l tremor, agitiation, twitching
Intermediate – lethargy
Late Li >2 mmol/l coma, fits, arrhythmia, renal failure – haemodialysis may be needed
Morphine undergoes phase II metabolism by …
conjugation
Morphine
Undergoes phase II metabolism by conjugation
Morphine-6-glucuronide 40x more potent
Approx 80% analgesic action derives from Morphine-6-glucuronide
Renal impairment results in accumulation of metabolite
Prolonged effect, ↑ toxicity
NB S/C morphine = 2x potent po
Morphine toxicity symptoms (5)
Nausea, vomiting Constipation Drowsiness Respiratory depression Hypotension
Treatment naloxone iv 400mcg
Morphine toxicity treatment
naloxone iv 400mcg
Pharmacodynamics - aging
Effects of aging on biochemical and physiologic effects of drugs and their mechanisms of action are not clearly known
Progressive decline in homeostatic mechanisms
? Due to receptor affinity or number
? Alterations in second messenger function
? Alteration in cellular & nuclear responses
drug effects in the elderly - alcohol?
Alcohol causes increase is drowsiness and lateral sway in older people than younger people at same serum levels
drug effects in the elderly - benzos?
Benzodiazepines (↑) – enhanced sedation
drug effects in the elderly - warfarin?
Warfarin (↑)
drug effects in the elderly - Hypotensives?
Hypotensives (↑) – postural hypotension
drug effects in the elderly - NSAIDS?
GI effects of NSAIDs (↑)
drug effects in the elderly - anticholinergics?
Central effects of anticholinergics (↑)
drug effects in the elderly - ß1 modulators in cardiac tissue?
ß1 modulators in cardiac tissue (↓)- down regulated by 1/3
drug effects in the elderly - bronchodilatory response to β-agonists?
Reduced & delayed bronchodilatory response to β-agonists
drug effects in the elderly - Calcium channel blocking effect?
Calcium channel blocking effect on PR interval (↓)
Elderly patients medicines should be … …
Elderly patients medicines should be reviewed regularly
Frail patients may have difficulty swallowing tablets – if left in the mouth … may develop
Frail patients may have difficulty swallowing tablets – if left in the mouth ulceration may develop
Encourage patients to take medication with enough …, in an upright position, consider … preparation
Encourage patients to take medication with enough fluid, in an upright position, consider liquid preparation
Antihypertensive medication (ACE inhibitors –eg. ramipril) – side effects
Hypotension
Potassium increase
Renal failure
Cough
Antihypertensive medication (Calcium channel blockers – e.g amlodipine) – side effects
Hypotension
Negatively inotropic
Fluid retention
Antihypertensive medication (Diuretics) – side effects
Hypotension Hypokalaemia Hyponatremia Confusion Dehydration
‘Traditional’ antipsychotics – haloperidol - side effects (elderly)
Confusion Sedation Parkinsonism Tardive dyskinesia Neuroleptic malignant syndrome
How to prescribe in the elderly
Consider risk/benefit ratio Pharmacokinetic/dynamic factors Start low, go slow Review the effect Communicate with patient,relative,other healthcare professionals Use the BNF
AF Risk of stroke - what score?
NICE CHA2DS2-VASc – treat men >1
Assess bleeding with HASBLEED – high risk >3 (European Society Guidelines AF)
Assess bleeding risk with what score? (AF)
Assess bleeding with HASBLEED – high risk >3 (European Society Guidelines AF)
What to do about compliance - elderly
Consider cognitive problems – carer to prompt patient with medications
Simplify regimes as much as possible to once or twice daily
Dossit boxes
Consider manual dexterity and vision of the patient
Check inhaler techniques
Syrups if dysphagia for large tablets
Adverse drug reactions - elderly
Prevalence increases with age, length of stay, number of medications
15.3% of admissions are due to ADR
What % of admissions are due to Adverse drug reactions - elderly
15.3% of admissions are due to ADR
Steroid 3 adverse affects (elderly)
Osteoporosis
Gastric irritation/ulcers
Hyperglycaemia
Tricyclic antidepressants - 5 adverse affects (elderly)
Cardiac arrhythmias Drowsiness Dry mouth Constipation Urinary retention
Non steroidal anti inflammatory drugs - 3 adverse effects (elderly)
Renal failure
Gastric irritation
Fluid retention
Selective alpha blockers - 4 adverse effects (elderly)
urinary retention (relax smooth muscle in BPH)
drowsiness
hypotension
syncope
STOPP/START criteria for potentially … prescribing in older people: version 2
STOPP/START criteria for potentially inappropriate prescribing in older people: version 2
Key Learning Points - prescribing in the elderly
Physiological changes in the elderly alter drug responses
Assess the risks and benefits when prescribing
Side effects are common and can be life threatening
Think about polypharmacy and compliance issues
Use the BNF
