Principles Of Drug Use In The Elderly Flashcards
Why is drug use in older people important?
Co-morbidities Polypharmacy (=/>4) Susceptibility to ADRs Hospital admissions increasing Compliance/adherence High cost
What is a drug interaction?
A situation in which a substance (usually another drug) affects the activity of a drug when both are administered together
What is an adverse drug reaction (ADR)?
Undesirable effect (i.e. injury) of a drug beyond its anticipated therapeutic effects occurring during clinical use (serious and growing public health problem in the elderly)
What are the risk factors for adverse drug reactions (ADRs)?
Polypharmacy
IP
Physiological affects of ageing
Comorbidities
What are adverse drug reactions (ADRs) related to?
DoTS classification:
- Dose
- Time-course
- Susceptibility
How can a dose of a drug ABOVE the therapeutic range cause adverse drug reactions (ADRs)?
Above therapeutic range = toxic reaction e.g. bleeding following too high dose of Warfarin
Treatment:
- Reduce dose
- Prevent by using min. effective dose
How can a dose of a drug WITHIN the therapeutic range cause adverse drug reactions (ADRs)?
Within therapeutic range = collateral reaction e.g. drowsiness with antihistamines
Treatment:
- May be unavoidable
- Try reducing dose w/o reducing desired therapeutic effect
- If this does not work change medicine
How can a dose of a drug BELOW the therapeutic range cause adverse drug reactions (ADRs)?
Below therapeutic range = hypersusceptibility reaction e.g. penicillin allergy
Treatment:
- Avoid by using foreknowledge of patient allergies - ask in history what allergies and what there reaction is
- Permanently avoid said drug
How can the time-course of a drug cause adverse drug reactions (ADRs)?
- 1st dose reaction
- Early reactions
- Intermediate reactions
- Late reactions
- Withdrawal reactions
- Delayed reactions
How can the dose of a drug cause adverse drug reactions (ADRs)?
- Above therapeutic range
- Within therapeutic range
- Below therapeutic range
Therapeutic range = specific to patient
What is a first dose reaction?
When a patient reacts after the first dose of a drug e.g. hypotension after 1st dose of ACEi so advise/special precautions are needed e.g. advice to take 1st dose at night when lying down so they do not fall over
What is a early reaction?
When a patient gets a side effect after being on the drug for a short amount of time but the patient becomes tolerant so the reaction wears off so the patient can continue with the treatment as the ADR should wear off e.g. nitrate-induced headache
What is an intermediate reaction?
When a reaction to a drug occurs within a specific time frame but vigilance can be relaxed if no reaction occurs after this time e.g. neutropenia due to carbimazole which may make patients have a sore throat short-term
What is a late reaction?
A longer term affect of a drug that persists so increases risk of ADR with continued/repeated exposure and implies the need for long-term monitoring +/- prevention e.g. bruising, weight gain and bone loss as a result of corticosteroids
What is a withdrawal reaction?
When patients get negative affects as a result of stopping a drug (SSRIs, corticosteroids, opioids)abruptly after being on them for a while so it is important to slowly withdraw or reduce the dose of some drugs to prevent ADRs e.g. SSRI AD discontinuation syndrome can cause flu-like symptoms, shock-like sensations, dizziness, anxiety, irritability, insomnia, vivid dreams etc.
What is a delayed reaction?
When a patient gets a long-term illness or disease e.g. carcinogenesis or teratogenesis as a result of long-term use of a drug so the drug should be avoided in patients with known susceptibility to these problems e.g. HRT, chemotherapy, radiotherapy and methotrexate (not as important in elderly but more so in younger patients)
What drug in the elderly shows an important delayed reaction?
Nitrofurantoin is used as a prophylactic for UTIs but can cause irreversible progressive pulmonary fibrosis
What factors make patients susceptible to adverse drug reactions (ADRs)?
- Genetics
- Age
- Sex
- Specific physiological states e.g. pregnancy
- Diseases e.g. hepatic/renal impairment
- Exogenous factors e.g. other drugs (interactions), diet etc.
If there is a suspected adverse drug reaction (ADR), where should it be reported?
Yellow Card Scheme using the electronic form online
What is ageing?
Gradual loss of function of cells and organs with the eventual outcome of death
What factors influence ageing?
Genetics Psychology Lifestyle Socio-economic factors Environment
Why is ageing important for doctors?
- Doctors care for lots of older people
- We want to improve QoL and longevity
- Resource issues for NHS