Lecture 6 Drug Toxicity in Older People Flashcards
Define adverse drug reactions.
Any noxious, unintended, undesired effect of a drug, excluding therapeutic failures, intentional/accidental poisoning, and drug abuse
Define the classification of ADRs by concentration they occur at.
Hypersusceptible: occur at low dose
Collateral: occur at therapeutic range
Toxic: high dose
Have a read of the Assessment of Causality of ADRs
Are there any previous conclusive report on this reaction?
Did ADR occur after suspected drugs was administered?
Did ADR improve when drug was discontinued or a specific antagonist was administered?
Did the ADR reappear when drug was readministered?
Are there alternative causes that could explain reaction?
Did the reaction reappear when placebo was given?
Was the drug detected in blood in concentrations known to be toxic?
Was the reaction dose-related?
Did the patient have similar reaction to the same or similar drugs in any previous exposure?
Why is reporting ADRs important?
ADRs are often only found after the drug has been released onto the market, especially rare ADRs. So reporting will provide knowledge for future prescriptions.
What could be possible next steps after reporting of ADRs?
Amend the drug’s product information
Restricts drug’s availability
Remove medicine from market
Why is it important to understand drug toxicity in older people?
Older people use most drugs, high incidence of polypharmacy hence greater likelihood of toxicity especially severe toxicity.
TRUE OR FALSE: Elderly have multimorbidity thus result in drug-drug and drug-? interactions?
TRUE
? = disease
What are the geriatric giants? (major categories of impairment in elderly)
Immobility Instability Intellectual impairment Incontinence (involuntary urination or defecation) Polypharmacy
What is the interactive concentric model of geriatric syndromes? And give ane xample
It is the synergism of multiple independent risk factors, together causing a clinical phenotype.
e.g. visual impairment, instability of legs, poor muscle ability, autonomic degeneration, postural hypotension all contribute to a fall
What are the main causes leading to adverse effects in elderly?
Reduction in organ failure leads to altered pharmacokinetics and pharmacodynamics, which leads to adverse effects. In addition reduced haemostatic function also leads to altered pharmacodynamics and adverse effects. Finally multiple diseases causing multiple drugs is the main cause of adverse effects
What are the effects of old age on pharmacokinetics?
Pharmacokinetics is what the body does to the drug ADME:
Absorption: complete but slower
Distribution: less muscle, more fat, so less distribution of water soluble drugs
Metabolism: reduced esp. Phase 1
Elimination: reduced
What are the effects of old age on pharmacodynamics?
Pharmacodynamic is what the drug does to the body:
Changes in receptors and other drug targets changes the body’s sensitivity to drugs
-CNS: less muscarinic cholinergic receptors
-ANS: decrease in beta-adrenergic system
What measures can be taken to prevent drug toxicity?
Minimise drug use
Minimise use of high-risk drugs
Consider age, comorbidities, concurrent medication when choosing drugs and dose
Monitor frequently
What measures can be taken to diagnose drug toxicity?
Be very suspicious and cautious!
Any presentation could be at least in part due to drug toxicity
What is a prescribing cascade?
When you prescribe a drug, it causes a side effect. Then you prescribe another drug to treat this side effect. And this continues.
