Drug therapy in the elderly. Changes in drug pharmacokinetics and pharmacodynamics in patients with diabetes mellitus and thyroid gland dysfunction. Flashcards
who are the elderly
those defined by WHO as >65y.
are more likley to receive medication
mistakes when rx eldery
Prescription of higher dose ( lower doses more effective)
Prescription of more dangerous drugs
Use of drug combinations that lead to interactions and produce adverse effects
syndromes in elderly requiring unique drugs old ppl cant over use drugs
Orthostatic hypotension Poor nutrition Constipation Osteoporosis Urinary incontinence Dementia Stroke
why are age related phk difficult to produce
clinical trials usually use young healthy individuals in drug development
changes phK in elderly
slower rate of abs of oral drugs
decreased hep func- reduced first pass
-increased bioavailability
less plasma albumin- more free drug - increased effect
decreased CO and renal func reduces drug clearance
altered elimination half life d/2- changes in maintenance dose
what causes altered phD in elderly
loss of receptors
change in the secondary messengers
effects of altered phD on specific drug action
warfarin -increased coag
heparin
- increased bleeding
opiods
-more analgesic effect
long acting benzo
- longer lasting sedation
why are ADR’s more common in elderly
↑number of diseases
↑severity of disease
↑number of medications (also increases the chances of unintended drug reactions)
examples of increased adr from drug interxn
diuretics with digoxin
-increased risk of hypokalaemia
digoxin intoxication
drugs generally CI in elderly
Long-lasting benzodiazepines (confusion, sedation, falls)
Amitriptyline (excessive anticholinergic effect)
effects of DB on phd
increased SC insulin absorption
reduced IM drug abs
reduced drug binding
-d/2 glycosylation of pp
decreased CYP450A3 activity
- lower drug met of benzo’s
anti arythmics
reduced hepatic clearance
-fatty liver
initial elevated renal clearance followed by decline
Hyperthyroidism effect
increased drug metabolism
thyroid hormones activate cytp450
larger doses needed
decreased riboflavin abs
increased drug clearance d/2 increased renal BF
Hypothyroidism
decreased met, increases toxicity risk
decreased gutmotility increases riboflavin abs
decreased renal bf,
which drug induces thyrpid dysfunc
Amiodarone
because of its high iodine content
(which inhibits 5-deiodinase activity).