Iatrogenic Flashcards
epidemiology
90% of older people have prescriptions
polypharmacy = 5 or more drugs
>50% of 65-74yo take 3+ (>70% >75y);
12.6% of interactions involve polypharma
30% of ADRs occur in elderly; 6-17% of elderly IP have ADR
10-12% of acute Ax due to prescriptions; 1in4 older adults over 5y; 6.5% of all Ax are ADRs; 30-55% avoidable
30% >65y, 50% > 80y have a fall each year: hyptnotics, ADD, APD, thiazides, NSAIDs
increased fracture risk: SSRIs, glitazones, CST, PPO
Inappropriate Prescribing
- contraindicated drugs
- inappropriate dose/duration
- adverse effect on prognosis
- failure to provide drug that could have positive outcomes
more common in older adults due to;
- more chronic disease
- more polypharmacy
- changes in pharmacokinetics and pharmacodynamics
pharmacokinetics in HCE
How body interacts with drug;
- Distribution
- increased distribution of fat soluble drugs
- decreased distribution of water soluble drugs
- less serum albumin so less binding to drugs - hepatic metabolism
- decreased liver volume and enzyme activity therefore metabolism decreases - renal elimication
- reduced GFR therefore less excretion/clearance
- eg digoxin should be reduced with age to prevent toxic accumulation
absoption changes are insignificant
pharmacodynamics in HCE
increased sensitivity: BZD, antiHTN, TCA, warfarin
decreased sensitivity: BA, BB
- Response to benzodiazepines is increased
- Response to warfarin is increased
- b1 and b2 receptor responsiveness is decreased (e.g. response to salbutamol and terbutaline)
- a2 receptors responsiveness is decreased (e.g. response to clonidine and methyldopa)
- Response to Opioid analgesics increased.
General exagerated response to CNS activated drugs
prescribing principles in HCE
- benefit should outweight the risks
- cost effective
- drug should be safe
- individual characteristics should be taken into account
medicines management (r/v)
stopp/start criteria: review systems
high risk situations
transfer
DH extensive
ABx (antibiotics) (C-diff: coamox, clinda, cipro, defuroxime)
high risk meds
NSAIDs: 29% of ADR Ax; GI, CVS, HTN, resp, AKI
diuretics: Na, HTN, AKI, falls, dehydration
warfarin: falls, cognition
anti-HTN: falls, K
ADD/APD: Na, seizure, cog, bleed, Loc, SS
hypnotics: falls
digoxin: arryhtmia, N&V
opitiates: sedation, constipation
vanc/gent: oto/nephrotoxic
RF for IP
- more chronic disease
- more polypharmacy
- changes in pharmacokinetics and pharmacodynamics
- longer Ax duration
- increased M/M
- increased ADRs/interactions
- decreased compliance
application
ID and treat medical issues r/v polypharmacy + consult: # and doses monitor MDT + CGA best evidence + lowest risk/SE
ADR risks
cognition (12x), 4+ comorbidities (8x) dependent (4x), non-adherence (2x) impaired renal function (2.5x) polypharma (2.7x)
poor mental health poor home support, poor dexterity/senses
altered physiology, pharmacodynamics, pharmacokinetics
Polypharmacy
5 or more drugs
1/3 patients affected
can result in;
- increased risk of side effects
- increase risk of drug-drug interactions and drug-disease interactions
- therapeutic cascade
- increased risk of medications not being reviewd throoughly
prescribing tips
- accureate med hx
- map Dx to PMH
- Current context (eg no diuretic in dehydrated)
- ensure essential meds (ABx, Antiepileptics, DM dx, and PD dx)
- look for other routes if some ruled out
- monitor for effectiveness and ADRs
- REVIEW REVIEW REVIEW
STOP CVD
-digoxin >125 microgram/day in impaired renal fx
- loop diuretic for ankle oedema or first line hypertension
-thiazide like for gout
-Beta blocker with COPD
-beta blocker with veramapril
-CCB with chronic constipation
-aspirin + warfarin WITHOUT STOMACH PROTECITON
ASPIRIN WITH GASTRIC ULCER HX OR > 150MG/DAY or no cvd hx
- thinners with a bleeding disorder
STOP CNS
- TCAs with dementia, glycoma, cardiac conductive abnormalities, constipation, opiate, ccb, protastism or hx of urinary retention
- long term neuroleptics as long term hypnotics
- long term neuroleptics in PDs
- Phenothiazides in epilepsy
- SSRIs with hyponatraemia hx
- metoclopromide or haliperidol in PD
