Adverse Drug Reactions Flashcards Preview

Y2 LCRS 1 - Pharmacology and Therapeutics - Laz > Adverse Drug Reactions > Flashcards

Flashcards in Adverse Drug Reactions Deck (24)
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1
Q

What is an adverse drug reaction?

A

Preventable or unpredictable medication event with harm to the patien

2
Q

Describe the classification of ADRs based on onset.

A
Acute = < 1 hour  
Sub-acute = 1-24 hours
Latent = > 2 days
3
Q

Describe the classification of ADRs based on severity of the reaction.

A

Mild – requires no change in therapy
Moderate – requires change in therapy
Severe – disabling or life-threatening

4
Q

Define Type A ADR.

A

Extension of pharmacological effect
This is usually predictable and dose-dependent
This is the most common type of ADR – 2/3
Example: atenolol can slow down heart rate but if you give too much you could cause heart block

5
Q

Define Type B ADR.

A

‘Bizarre’ type of ADR
Idiosynchratic or immunologic reactions – includes allergy or pseudoallergy
This is very rare and unpredictable
Example: chloramphenicol and aplastic anaemia

6
Q

Define Type C ADR.

A

Associated with long-term use
Involves drug accumulation
E.g. methotrexate and liver toxicity

7
Q

Define Type D ADR.

A

Delayed effects – sometimes dose independent

E.g. carcinogenicity and teratogenicity

8
Q

Define Type E ADR.

A

Withdrawal reactions
Rebound reactions
Adaptive reactions

9
Q

Describe and explain clonidine rebound.

A

Clonidine is an alpha-2 agonist so it suppresses the release of noradrenaline
Long-term use of clonidine leads to an upregulation in adrenergic receptors on the post-synaptic membrane
If the dose of clonidine is missed once or twice, it will cause an increase in noradrenaline release, which then acts on an increased number of receptors so has a greater effect
This causes a large increase in blood pressure

10
Q

What is the ABCDE classification of adverse drug reactions?

A
A – augmented pharmacological action   
B – bizarre 
C – chronic  
D – delayed  
E – end of treatment
11
Q

Describe the classification of allergies.

A

Type 1 – immediate, anaphylaxis (IgE)
Type 2 – cytotoxic antibody (IgG + IgM) ]
Type 3 – serum sickness (IgG + IgM)
Type 4 – delayed hypersensitivity (T cell)

12
Q

Give examples of pseudoallergies.

A

Aspirin/NSAIDs and bronchoconstriction
This occurs because aspirin and NSAIDs inhibit the production of prostanoids, which are bronchodilators
 They promote the production of leukotrienes, which are bronchoconstrictors
ACE inhibitors and cough/angioedema
 ACE inhibitors prevent the breakdown of kinins
 Kinins accumulate in the sensory nerves in the lungs and trigger cough

13
Q

What are the most common causes of ADRs

A

Antineoplastics
Cardiovascular drugs
NSAIDs/analgesics
CNS drugs

14
Q

What is the yellow card scheme?

A

A voluntary scheme allowing doctors, dentists, nurses, coroners and pharmacists to report serious adverse drug reactions

15
Q

Why is it difficult to determine the incidence of drug-drug interactions?

A

There is a lack of availability of comprehensive databases
Difficulty in assessing OTC and herbal drug therapy use
Difficulty in determining contribution of drug interaction in complicated patients

16
Q

What are the three types of pharmacodynamic drug interaction?

A

Additive effects
Synergistic effects
Antagonistic effects

17
Q

What are the different types of pharmacokinetic drug interaction?

A

Alteration in drug absorption
Protein binding effects
Changes in drug metabolism
Alteration in elimination

18
Q

What is an example of alteration of absorption?

A

Chelation

19
Q

Explain what is meant by protein binding effects.

A

Competition between drugs for protein or tissue binding sites
It can increase free unbound concentration of a drug thus leading to enhanced pharmacological effects (e.g. warfarin)

20
Q

Which cytochrome P450 enzymes are responsible for over half ofdrug metabolism?

A

CYP2D6

CYP3A4

21
Q

Give a few examples of CYP450 inhibitors.

A
Cimetidine  
Erythromycin  
Ketoconazole  
Ciprofloxacin  
Ritonavir  
Fluoxetine  
Grapefruit juice
22
Q

Give a few examples of CYP450 inducers.

A
Rifampicin  
Phenytoin 
Carbamazepine  
St. John’s Wort (hypericin) 
Phenobarbitone
23
Q

Describe the difference in the speed of inhibition and the speed of induction of CYP450 enzymes.

A

Inhibition is RAPID

Induction takes hours/days

24
Q

Give an example of a deliberate drug interaction.

A

ACE inhibitors and thiazides