L13 Adverse Drug reaction Flashcards
Adverse Drug reaction and events
Adverse drug reaction and adverse drug event are
terms that refer to harmful or undesirable response
to a drug
Adverse drug event
an adverse drug event is harm caused by appropriate
or inappropriate use of a drug
Adverse drug reaction
adverse drug reactions are a subset of these events, wherein harm is directly caused by a drug under appropriate use (i.e., at normal doses)
Adverse drug event vs reaction
an adverse drug event is harm caused by appropriate or inappropriate use of a drug whereas adverse drug reactions are a subset of these events, wherein harm is directly caused by a drug under appropriate use (i.e., at normal doses)
Adverse drug reaction (ADR) on health system
a significant burden to the health system and economy
- hospitalisation and/or prolonged hospital stay
- number of incidents continue to increase
top leading medications for ADR
Anticoagulants
Opioids and analgesics
Antineoplastic antibiotics
Elderly patients are at increased risk of ADRs
- changed pharmacokinetic and pharmacodynamic properties due to ageing
- polypharmacy - drug-drug interactions
- inappropriate prescribing (risk > benefit)
Elderly patient change in absorption
little clinical impact despite reduced surface area and slowed gastric emptying
Elderly patient change in metabolism
impaired CYP-mediated metabolism (conjugation is less affected)
* consideration for hepatically cleared drugs (P1).
* Because liver function decreases with age.
Elderly patient change in distribution
*↑ body fat and ↓ total body water
* ↑ Vd for lipophilic drugs but ↓ Vd for hydrophilic drugs
Elderly patient change in excretion
reduced GFR due to reduced renal size and nephron functions
* consideration for renally cleared drugs
Elderly patient change in protein binding
decreased plasma albumin level.
↓ drug binding and therefore ↑ free drug level for action
Elderly patient change in drug action
More sensitive to medications
Pregnant women are at increased risk of ADRs
- changed pharmacokinetic properties
- the main concern is drug teratogenicity - prenatal toxicity
º placenta is a partial barrier
º prescribing medicines in pregnancy (TGA categorisation)
Pregnant women change in Absorption
increased gastric pH alters ionisation of drugs
* absorption of weak bases ↑ and weak acids ↓; slower GI mobility ↓ absorption
Pregnant women change in Distribution
↑ body fat and total body water
* can increase Vd
for lipophilic drugs and hydrophilic drugs
Pregnant women change in Metabolism
↑ cardiac output leads to ↑ hepatic metabolism; ↑ activity of drug-metabolising enzymes, e.g., key CYP enzymes and UGT
Pregnant women change in excretion
↑ cardiac output leads to ↑ renal clearance
Pregnant women change in protein binding
decreased plasma albumin level
* ↓ drug binding and therefore ↑ free drug level for action
Pediatric patients at increased risk of ADRs
- ontogeny of drug-metabolising enzymes, receptors, and transporters
- development of drug clearance capacity
- dosing based on adult formula (per kg body weight) may be inappropriate
- drugs are poorly studied in this group - off-label prescription
polypharmacy
- complex or multiple diseases, e.g., autism spectrum
disorder - risk of drug-drug interactions
pharmacogenetics
- e.g., anticancer treatment
Pharmacovigilance
Detection, assessment, understanding and prevention of ADRs.
Certain, likely, possible
Unlikely, unclassified, unclassifiable
TGA (Therapeutic Goods Administration), Australia
- Blue card adverse reaction reporting form
- Medicines Safety Update - provides information on drug safety and emerging safety
issues
