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56 Cards in this Set
- Front
- Back
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Older ppl represent 12% of population but consume
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40% of all drugs prescribed
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Polypharmacy?
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- 4 or more drugs
- >12 doses/day - >2 drugs for same condition |
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Older ppl take an av of
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9 drugs
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Factors assoc. with multiple drug use
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-Age
-Female -no. of diagnoses -Recent hospitalisation -Depression |
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Rational polypharmacy
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-Meds acting on diverse aspects of a single disease or condition may provide synergistic benefits(CCF-diuretic,ACEI or osteoporosis-biphosphonate,Ca,vit D)
-combining 2 or more drugs in low dose to provide efficacy where a higher dose of a single drug would nt be tolerated(neuropathic pain:anticonvulsant,analgesic) -meds used for multiple comorbidities(b-blockers and ACEI for IHD,diabetes,HT,CCF) |
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Irrational polypharmacy
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-Trying to treat each diagnosis separately
-Lack of review of efficacy of a newly commenced drug -lack of review of continued need for a drug -multiple health providers who do not check each other's script |
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Prescribers unaware of
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Meds taken by pts
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ADR
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Adverse drug reactions
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ADR
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-Incidence increases with age
-15 % of elderly ppl seeing GP reported an ADR in previous 6 months -20% hospitalized elderly exper. ADR |
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ADRS from antihypertensives and diuretics
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-Postural hypotension(prazosin,terazosin,ACEIs,doxazosin)-->falls & fractures
-Constipation(verapamil) -Peripheral oedema(amlodipine,nifedipine,felodipine) -renal impairment(ACEI,ARA) -Hyperkalaemia(ACEI,ARA) |
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ADRs from Anti-HT and diuretics
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-Hypokalaemia(thiazide & loop diuretics)
-hyponatraemia(thiazide & loop) -Impaired glc tolerance(thiazide & loop) -Hyperuricaemia-->gout -urinary incontinence(doxazosin,prazosin,terazosin,diuretics) |
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ADRs from BENZOS
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-poor muscle coordination/balance --> falls and fractures
-over sedation -confusioon & memory impairment |
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In pt with insomnia,
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non-pharmacological therapy shoudl be tried before prescribing meds.
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ADRs from TCS
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-postural hypotension
-confusion -urinary retention -constipation -blurred vision |
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TCAs should not be used as
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Nocturnal sedatives in non-depressed patient.
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ADRs from Antipsychotics(phenothiazines)
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-Postural hypotension
-confusion -sedation -extrapyramidal adverse effects(parkisonism) -constipation -urianry retention -blurred vision |
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ADRs from anti-emetics(prochlorperazine,metoclopramide)
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-postural hypotension(prochlorperazine)
-dizziness(metoclopramide) -drowsiness -confusion -Parkinsonism(dopamine blocking drugs) |
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ADRs from Antiparkinson agents
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-Postural hypotension
-Confusion(esp. anticholinergics) -psychoses/hallucinations -constipation(anticholinergics) -urinary retention -blurred vision |
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AVoid
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Anticholinergics in elderly
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ADRs from NSAIDs(esp. non selective agents)
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-Gastric ulceration
-Na+ and h20 retention -exacerbation of HT and heart failure -Renal dysfunction -Dizziness |
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What's preferred for pain in osteoarthritis with few signs of inflam.?
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Paracetamol
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ADRs from DIGOXIN
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-nausea
-anorexia -confusion |
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ADRs from warfarin
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-increased risk of bleeding
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ADRs from Sulphamethoxazole/trimethoprim
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-Severe skin rns
-blood dyscrasias |
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ADRs from flucloxacillin
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-hepatic damage
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Incidence of ADRs
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Increasing
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Greatest increase in
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Over 80s
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Atypical presentation of ADRs
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-confusion,agitation(CNS active drugs,anticholinergics)
-falls(anti HT,CNS active drugs) -incontinence(diuretics,CNS active drugs) |
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ARDs misinterpreted as new disease
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-NSAID--> HT
-benzos--> dementia |
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Prescribing cascase
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-treat 1 SE of a drug with another drug
-NSAId--> HT-->antiHT -Ca channel blocker-->oedema-->diuretic -antiHT-->dizziness-->antiemetic |
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Consider any new sign or symptom to be
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A possible consequence of current drug therapy before adding new drug
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Factors contributing to ADRs in elderly
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-Polypharmacy
-Altered drug response(pharmacodynamics,kinetics) -Inappropriate choice of drugs -Suboptimal monitoring -Pt's inability to tak drugs -Under prescribing |
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Decline in renal function with
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Age
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Caution in use of serum creatinine conc. ALONE to measure
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Renal function in older ppl
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Serum creatinine may remain in NORMAL range despite
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Reduction in GFR
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Cockroft-Gault Equation
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-estimate GFR and pt's charateristics that influence muscle mass
-fairly accurate estimate of GFR |
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e-GFR
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-MDRD eqn
-not validated for assessing age-related decline in renal function -not validated for adjusting drug doses(use cockcroft instead) -routinely used by most path labs |
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Drugs most affected by declining renal function
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-Drugs that predom. renally cleared(DIGOXIN)
-drugs that have pharmaco. or toxico. active metabolites that rely on renal routes for their elimination(allopurinol) -drugs that have a longer t1/2 |
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GFR 50% lower in
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Old ppl than young ones
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Decline in Hepatic function with
age. |
-more variable and less predictable in renal function
-phase1 metabolism often decreased by 20-40%(propanolol,verapamil,citalopram) -phase 2 metabolism usually UNAFFECTED(oxazepam,paracetamol) |
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Absorption of drugs in old ppl
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-No significant change
-Increased bioavailability of some drugs highly metabolized on 1st pass through liver |
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Distribution of drugs in elderly
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-Increased fat:lean body mass ratio
-decreased total body water -drugs that are fat soluble accumulate and have longer t1/2(e.g diazepam,amitriptyline) |
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Pharmacodynamics
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way drugs affect body
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Old ppl are more sensitive of effects of drugs
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true
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Mechanisms for above ?
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-Altered homeostasis
-Altered receptor or tissue sensitivity |
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Altered homeostasis
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-Impaired balance & posture maintenance(by benzos)
-Impaired renal function(NSAIDS,diuretics,aminoglycosides) |
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Altered receptor or tissue sensitivity
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-CNS particularly vulnerbale due to brain atrophy,loss of active cells,reduction in cerebral blood flow,selective decline in some nerve pathways(cholinergic nerves)
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Elderly pts more sensitive to most CNS acitve drugs like
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-benzos,antipsychotics,anticholinergics
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Altered receptor or tissue sensitivity
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-Increased sensitivity to drug-effects in CNS may be dsiplayed as sedation,confusion,behavioural disturbances(agitation,aggression)
-may be misdiagnosed as dementia/psychosis -risk increases 9fold when pts take 4 or more meds |
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Some diseases may further modify drug disposition and drug response
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-Heart failure-->reduced perfusion of kidney & liver failure=decreased clearance of drugs
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Drug interactions may alter
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PK & PD
-PK: amiodarone,digoxin -PD:fruseminde,ACEI |
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Impact of PK and PD changes
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-Lower doses required
-Physiological variability increases with age & dosage must be INDIVIDUALISED. -START LOW AND GO SLOW -monitor closely for ADRs after new drug started -appropriateness of drug doses need to be revealuated at regular intervals as person ages. |
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Polypharmacy
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-may be unavoidable in many casees
-must be minimised -avoid unecessary drugs(drugs w/o valid indication-eg sedatives for insomnia OR drugs to treat ADRs like antiemetics for dizziness) -use 1 drug for 2 indications if possible(ACEI for HT and CHF) |
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Monitoring
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-Often neglected
-esp when new drug commence -also during regular med review(at least yearly) |
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50 % of older ppl dont take their meds as prescribed
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-deliberate non-adherence
-inadvertent non-adherence |
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RFs for non-adherence
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-polypharmacy
-complexity of therapeutic regimen -cognitive impairment(memory problems,confusion,dementia) -ability to manage dose forms(deteriorating sight/hearing,loss of manual dexterity,muscle weakness,inability to swallow solid,oral dose forms) -inadequate med knowledge -ADRs -finance |
