Geriatrics Flashcards
What problems in medication can you identify in this patient?
85 yr old frail female admitted after a fall
Meds include
Warfarin, Perindopril, Diazepam, Ibuprofen, Furosemide, Sertraline, Amlodipine, Prochorperazine, Betahistine
- Warfarin/Ibuprofen>>bleeding
- Ibuprofen/Diuretic/Perindopril>>ARF
- Sertraline>>Low sodium/GI bleeds
- Diazepam>> sedation
- Antihypertensives (Amlodipine) in those who fall
- Prochlorperazine (anti-emetic) >> Parkinsonism
How is drug absorption different in the elderly and how does this apply clinically?
reduced rate of absorption and decrease the time of steady-state of the drug in circulation
- Levodopa- competes with nutrients
- plan dosing to avoid meal times
- Bisphosphonates
- advise to take on empty stomach sitting up 30 minutes before food
How is drug absorption different in the elderly and how does this apply clinically?
reduced rate of absorption and decrease the time of steady-state of the drug in circulation
- Levodopa- competes with nutrients
- plan dosing to avoid meal times
- Bisphosphonates
- advise to take on empty stomach sitting up 30 minutes before food
how is volume of distribution measured
amount of drug in the body/ concentration in plasma
Vd affects the half-life and duration of effect of the drug
How does muscle mass in elderly people affect the volume of distribution?
Give a clinically significant drug
- as you get older you lose more lean muscle mass
- therefore drugs that distribute into the muscle have less muscle to go to →
- increased plasma concentration of that drug
- Digoxin distributes well into the muscle however can result in digoxin toxicity in the elderly due to reduced lean muscle mass
What are the side effects of Digoxin toxicity?
Cardiac
- heart block, bradycardia, junctional tachycardia
Psychiatric
- delirium, fatigue, malaise, confusion, dizziness
Visual
- blurred or yellow-green vision, halos, double vision, photophobia
Gastrointestinal
- nausea, vomiting, anorexia, diarrhoea, abdominal pain
How do you safeguard for Digoxin toxicity?
How would you treat it?
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 by withdrawing drug/correcting electrolytes
Severe- digoxin specific antibody fragments (Digibind)
How does body fat in elderly people affect the volume of distribution?
Give a clinically significant drug
- increased body fat → increased Vd for fat-soluble drugs e.g BZD, Haloperidol
- this increases the half-life of the drug
- the Vd of Diazepam is double in elderly
- the half-life also increases from 24 hours to 90 hours in the elderly
What are symptoms of Benzodiazepines?
Drowsiness
Confusion
Ataxia
Dependence
How can Benzodizapine overdose be treated/ reversed?
Flumazenil 200mcg
How does Body water in elderly people affect the volume of distribution?
Give a clinically significant drug
- decreased body fat → decreased Vd for water-soluble drugs e.g Gentamicin
- resulting in increased plasma concentration
- therefore a lower loading dose should be prescribed
How does serum albumin in elderly people affect the volume of distribution?
Give a clinically significant drug
- ↓Albumin 12-25% - further depressed by heart failure, renal disease, rheumatoid arthritis, hepatic cirrhosis some malignancies
- Drug binding capacity ↓ 12-25%
- ↑ free drug e.g
- Phenytoin, warfarin, propranolol, diazepam, levothyroxine, digoxin, furosemide
What are signs and symptoms of Phenytoin toxicity?
- Nausea, vomiting
- Tremor
- Ataxia
- Nystagmus
- Coarse facies
- Hepatitis
What is the interaction between warfarin and Aspirin?
- 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
What are the adverse effects of antiplatelet agents?
Aspirin
- Peptic ulcer disease
- Bleeding tendency
- Fluid retention
- Renal failure
What are the adverse effects of anticoagulant agents?
Warfarin or DOAC
- Bleeding tendency
- Interaction
Explain how Liver metabolism is affected 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
How is Excretion affected in the Elderly?
what are its therapeutic implications?
- Renal blood flow
- ↓ Renal mass (20%)
- ↓ Renal function (nephrons 30%)
- GFR declines by 1% per year from age 40
therefore reduced clearance of drugs that are more than 60% excreted by kidneys
- reduce dose in once-daily preps
- increase dosage in more frequently administered drugs
Lithium (may need dialysis) and Morphine (conjugated product are more potent not indicated in renal failure)
What are signs of Morphine toxicity?
treatment?
- Nausea, vomiting
- Constipation
- Drowsiness
- Respiratory depression
- Hypotension
treat with Naloxone IV 400mcg
What are some drugs that are pharmacodynamically increased in the elderly?
- Alcohol causes increase is drowsiness and lateral sway in older people than younger people at same serum levels
- Benzodiazepines (↑) – enhanced sedation
- Warfarin (↑)
- Hypotensives (↑) – postural hypotension
- GI effects of NSAIDs (↑)
- Central effects of anticholinergics (↑)
What are some drugs that there effects are pharmacodynamically decreased in the elderly?
- ß1 modulators in cardiac tissue (↓)- down regulated by 1/3
- Reduced & delayed bronchodilatory response to β-agonists
- Calcium channel blocking effect on PR interval (↓)
What are side effects of ACE inhibitors
- Hypotension
- Potassium increase
- Renal failure
- Cough
What are side effects of Calcium channel blockers?
- Hypotension
- Fluid retention
- Negatively Inotropic
What are side effects of Diuretics?
- Hypotension
- Hypokalemia
- Hyponatraemia
- Confusion
- Dehydration
