Prescribing in the elderly Flashcards
DRUG INTERACTIONS
i) what is a patient at risk of if warfarin and ibuprofen are combined?
ii) which organ may ibu/diuretics/perindopril affect?
iii) name two things sertaline is associated with
iv) what is prochlorperazine used for? what can it induce if prolonged?
i) bleeding
ii) can cause acute renal failure
iii) sertraline is assoc with low sodium and GI bleeds
iv) prochlorpromazine = good anti emetic > drug induced parkinsonism if prescribed prolonged
DRUG ABSORPTION
i) name five things that are reduced and may impact on drug absorption
ii) what is the overall affect of this on rate of abs and time to steady state?
iii) what does levodopa compete with? when should doses be planned?
iv) should bisphosphonates be taken with or without food?
i) reduced saliva, gasttric acid secretion, GI motility, SA for abs and splanchnic blood flow
ii) overall decreased rate of abs and increased time to steady state
iii) levodopa competes with nutrients so avoid meal times
iv) bisphos should be taken on an empty stomach, sitting up
VOLUME OF DISTRIBUTION
i) what is it?
ii) what effect does a large Vd have on half life and duration of effect of a drug?
iii) how does reduced muscle in elderly affect Vd? why? what does this ultimately lead to
i) amount of drug in body / conc in plasma
ii) large Vd = increased half life and inc duration of effect (takes longer to clear)
iii) reduced muscle mass = reduced Vd as many drugs distrib through muscle
- leads to higher plasma concs
DIGOXIN TOXICITY
i) name three cardiac tox? name two things that may cause a patient to have more serious cardiotox
ii) name three psych tox
iii) name three visual tox
iv) name three gastro tox
v) how is dig toxicity treated (2) what is given in severe tox?
i) heart block, bradycardia, junctional tachycardia
- renal insufficiency or severe hypokal can increase cardiotox
ii) delirium, fatigue, malaise, confusion, dizzy
iii) blurred or yellow/green vision, halos, diplopia, photophobia
iv) nausea, vom, anorexia, diarrhoea, abdo pain
v) withdraw drug and correct electrolytes
- give digibind in severe tox (dig specific antibody frags)
BODY FAT AND DRUG DISTRIBUTION
i) name two fat soluble drugs? how may Vd be affected in incresed body fat?
ii) how much is Vd of diazepam increased in elderly?
i) benzos and haloperidol
- increased body fat = increased Vd of fat sol drugs
ii) Vd of diazepam is increased x2 in elderly (half life can be 90hrs)
BENZOS
i) name three side effects
ii) what is given in overdose? why must this be on parenteral infusion?
i) drowsy, confused, ataxia, dependence
ii) 200mcg flumazenil - shorter half life than diazepam so give on cont infusion
BODY WATER
i) do elderly people have more or less body water? how does this affect Vd of water sol drugs?
ii) name a water soluble drug (abx)
iii) are loading doses therefore higher or lower?
i) less body water
- therefore lower vd of drugs
ii) gentamicin
iii) lower loading doses
ALBUMIN
i) by how much % is albumin lowered in elderly?
ii) name three conditions that further lower it
iii) what does less albumin in the blood mean for amount of free drug?
iv) name three drugs that can become toxic due to lower albumin levels
i) 12-25%
ii) HF, renal disease, rheumatoid, hepatic cirrhosis
iii) less albumin to bind drug = more free drug
iv) phenyttoin, warfarin, propanolol, diax, digox
PHENYTOIN TOXICITY
i) what is it used for?
ii) give four symptoms of toxicity
i) treatment for epilepsy
ii) nausea, vomiting, tremor, ataxia, nystagmus, deranged LFT
WARFARIN - ASPIRIN INTERACTION
i) which one is highly bound to plasma albumin? which one displaces the other from plasma albumin
ii) what does this displacement cause?
iii) name three adverse effects of anti plat agents (aspirin)
iv) name two adverse effects of anticoags (warfarin or doac)
i) warfarin is highly bound to albumin and aspirin can displace it
ii) displacement of just 1% causes conc of free warfarin to double/triple leading to increased bleeding
iii) aspirin - peptic ulcer disease, bleeding tendency, fluid reeen, renal fail
iv) bleeding and interaction with other drugs
LIVER METABOLISM/EXCRETION IN THE ELDERLY
i) why is first pass metabolism decreased?
ii) which enzyme may have decreased activity?
iii) name three dugs that have decreased clearance and increased half life
iv) what % does GFR decline per year from the age of 40?
v) name three drugs excreted by the kidneys? how may these be altered if renal func is decreased
i) decreased first pass metab due to decreased blood flow
ii) decreased CP450 activity
iii) anti deps, antipsychotics, beta blockers, opiates
iv) GFR declines by 1% per year from age of 40
v) digoxin, atenolol, lithium, allopurinol
- reduce doses in once daily preps or increase dose intervals
LITHIUM
i) what is it given for?
ii) name three symptoms of early Li tox? at what level is this seen?
iii) what is seen at intermediate tox
iv) what level is seen in late tox? name three symptoms
i) mood stabiliser
ii) early (1.5) = tremor, agitation, twitching (mild and hard to pick up)
iii) intermed = lethargy
iv) late >2 - coma, fits, arrhythmia, renal fail
- haemodialysis maay be needed
MORPHINE
i) what happens to it when it undergoes phase II metabolism?
ii) what is 80% of morphine analgesic action derived from?
iii) what may lead to accumulation of morphine metabolites? when should it therefore not be given
iv) give four symptoms of toxicity
v) what can be given to treat toxicity?
i) phase II > conjugated > morphine 6 glucuronide (40x more potent)
ii) 80% action from M6G
iii) renal impair can lead to accumulation therefore dont give in renal failure
iv) nausea, vom, constipation, drowsy, resp dep, hypotension
v0 give naloxone IV 400mcg
PHARMACODYNAMICS
i) name four drugs where effects are increased in elderly
ii) name three drugs where effects are decreased
iii) what may happen if someone has difficulty swallowing and the tablet is left in their mouth?
i) alcohol, benzo, warfarin, GI effects of NSAIDs, centraal effecys of anticholinergics
ii) B1 modulators in cardiac tissue, beta agonists (bronchodilator response), calcium channel blocking
iii) get mouth ulceration
ANTI HYPERTENSIVES
i) name three common side effects of ACE inhibitors
ii) which type of medication may worsen HF?
iii) how may diuretics affectt sodium and potassium levels?
i) hypotension, hyperkalemia, renal failure
ii) amilodpine
iii) low
