Adverse drug reactions Flashcards
Recall how ADRs are classified by timeframe of reaction
Acute (<1hr)
Subacute (1-24hrs)
Latent (>2 days)
Recall how ADRs are classified by severity
Mild: no change in therapy required
Moderate: Change therapy + add treatment
Severe: disabling/ life-threatening
Recall the 5 classes of conventional classification for ADRs
Augmented Bizarre Chronic Delayed End
Into which category of ADR do carcinogenic drugs fall?
Type D
Into which category of ADR do allergies and pseudo-allergies fall?
Type B
Which class of ADR classifications is most predictable?
Type A
Which of the ADR classifications is most likely to be dose-dependent?
Type A
Under which class of ADR does foetal-damage resulting from thalidomide fall?
Type D
What is the underlying cause of Type A ARDs?
These ADRs are due to the PHARMACOLOGICAL effect of the drug (and so are often dose-dependent)
What are the main 2 types of reaction that fall under the Type B classification of ADRs?
Idiosyncratic or immunological
Give an example of a pseudoallergy
Angiodema associated with ACEi use - due to reduced bradykinin breakdown
Recall an example of a very rare but very acute Type B ADR
Chloramphenicol: causes severe aplastic anaemia in about 1 in 10,000
Give 2 examples of Type C ADRs
Methotrexate –> liver fibrosis
Anti-malarials –> ocular toxicity
What is the name of the scheme that allows anybody to record side effects of drugs and when + why was it introduced?
Yellow card
1964
Thalidomide
What is a type E ADR?
Withdrawal, rebound or “adaptive” reaction
Give 3 commonly-implicated drugs for withdrawal reactions
BDZs
Corticosteroids
Opiates
Give 3 commonly-implicated drugs for rebound reactions
Clonidine
Beta blockers
Corticosteroids
What sort of drug is clonidine?
Antihypertensive
Give an example of an “adaptive” reaction
Neuroleptic tranquiliser
Recall 2 drugs associated with pseudoallergy and the main symptom of each of these ADRs
- NSAIDS - bronchospasm
2. ACEi - cough + angiodema
Why is bronchospasm in response to NSAID use a pseudoallergy?
It is a totally pharmacological response so not sure why only some peopke react
How do NSAIDS cause bronchoconstriction?
Increase leukotriene production
How does ACEi use cause cough and angiodema?
Descreases bradykinin breakdown
What is a pseudoallergy?
An ADR that is mediated pharmacologically rather than immunologically
What are the 4 main factors affecting ADRs?
Polypharmacy
Diet
Age
Renal fx
What are the 3 types of drug-drug interaction?
Pharmacodynamic, pharmacokinetic and pharmaceutical
What are pharmacokinetic drug drug interactions?
DDIs that relate to the body’s effect on the drug
Give an example of a pharmacokinetic DDI
Impaired absorption due to chelation occurs when quinolones are absorbed alongside dairy products
What are pharmacodynamic DDIs?
DDIs that are related to the drug’s effect on the body
Recall 3 examples of phamacodynamic DDIs
- Synergistic action of antibiotics
- Overlapping toxicities of drugs eg BDZs and ethanol
- Antagonistic effects eg amitryptiline and ACEi
What is a pharmaceutical DDI?
Drugs ineracting outside the body eg precipitating in IV solution
What is the main difference between enzyme-induced and enzyme-inhibited changes in drug metabolism?
Drug inhibition can occur within minutes but induction takes hours/ days
Recall 5 key examples of CYP450 inhibitors
- SSRIs
- HIV drugs
- Anti-fungals
- Antibiotics
- Grapefruit juice
Recall 3 key examples of CYP450 inducers
- Rifampicin (antibiotic)
- Carbamazepine (anti-epileptic)
3, St John’s Wort
Recall 2 key examples of where drug elimination is inhibited by a DDI
- Penicillin excretion reduced by probenecid
2. Lithium reduces thiazide clearance
Recall 4 examples of where drugs are coprescribed deliberately for their interactions
- Levodopa and carbidopa
- ACEi and thiazides
- Penicillin and gentamycin
- Salbutamol and ipratropium
