ADR + Interactions Flashcards
What is ADR
preventable or unpredicted medication event with harm to the patient.
Classification of ADRs - 3 sections
Onset
Severity
Type
Types of onset classification
Acute - within 1 hour
Sub-acute - 1-24hrs
Latent >2days
Types of severity classification
Mild - requires no change in therapy
Moderate - requires change in therapy, additional treatment, hospitalisation
Severe - disabling/life-threatening. Can result in death, prolongs hospitalisation, causes congenital abnormalities, requires intervention
How many types of ADRs are there?
5
ABCDE
Augmented Bizarre Chronic Delayed Endoftreatment
What happens in Type A ADR
Extension of pharmacologic effect
Dose dependent
Most ADRs
Examples of Type A ADR
o Atenolol (beta blocker) will slow the heart down but if you give too much of it, it may cause complete heart block
o Chronic use of NSAIDs can cause peptic ulcers
o Anticholinergics can lead to dry mouth
What happens in Type B ADR
Idiosyncratic/immunologic reactions
Allergy
Rare + unpredictable
Examples of Type B ADR
- Chloramphenicol can cause aplastic anaemia (1 in 10,000)- it is usually irreversible than fatal
- ACE inhibitors can cause angioedema
What happens in Type C ADR
More common
Assoc w long term use of drug
Dose accumulation over long period
Examples of Type C ADR
- Methotrexate – leads to liver fibrosis/ toxicity
* Antimalarials - ocular toxicity (can damage the optic nerve and retina)
What happens in Type D ADR
Delayed effects - sometimes dose independent
Examples of Type D ADR
o Carcinogenicity - e.g. immunosuppression
o Teratogenicity - e.g. thalidomide
What happens in Type E ADR
End of dosing/treatment reactions
o Withdrawal reactions (opiates, benzodiazepines, corticosteroids)
o Rebound reactions
o Adaptive reactions
What happens when u stop taking clonidine
Withdrawl - rebound reactions
It used to be antihypertensive- is an alpha2 agonist so it reduces release of NA from S neurones.
This leads to drop in BP. Without clonidine, can lead to large rise in BP = stroke/death. Long term use = compensatory upregulation in adrenergic receptors on post-synaptic neuron. Thus when inhibition of NA release by clonidine is removed, NA starts being produced again and more receptors = cause great affect = rise in BP
How many classifications of allergy are there
4
What is Type I alergy
Immediate - anaphylactic (IgE)
Lifethreatening + rapid onset
Treated as emergency
What is Type 2 allergy
Cytotoxic Antibody (IgG + IgM)
What is Type 3 allergy
Serum Sickness (IgG + IgM) Antigen-antibody complex
What is Type 4 allergy
Delayed hypersensitivity (T cell) Common
What pseudoallergy does aspirin/NSAIDs cause
Bronchospasm
- Inhibiting production of prostanoids + prostaglandings via COX pathway which are bronchodilators
- Arachidonic acid is diverted to make leukotrienes (proinflamm + bronchoconstriction = bronchospasm + mucus secretion in airways)
Thus giving these to asthmatics = caution
What pseudoallergy does ACE inhibitor cause
Cough/Angioedema
ACE inhibitor stops production of AT2, stops breakdwon of bradykinins (inflamm peptides). Thus these accumulate = triggers coughing as it acts on sensory nerves of lungs.
Angioedema - leads to bronchospasm, swelling of mouth + lips
Another way of classifying ADRs - DoTS
Dose
Time
Susceptibility
4 common causes of fatal ADRs
Antineoplastics
CV drugs
NSAIDs/analgesics
CNS drugs
