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Flashcards in Adverse reactions Deck (43):
1

Drug classes ordered in prevalence of adverse reactions?

NSAIDs (29.6%); Diuretics (27.3%) ; Warfarin (10%)

2

Side effects to NSAIDs

Bleeding, renal impairment and wheezing

3

Side effects Diuretics

Hypotension (biggest cause of falls); electrolyte disturbances (monitor plasma potassium!)

4

What is a useful response to dealing with a type A adverse reaction?

Reduce the dosage, since these are predictable

5

Side effects TCAs? (type a)

anti-muscarinic

6

Side effects Beta blockers (type a)

cold peripheries

7

Beta blockers (type a)

bradycardia (below 60)

8

Opioids (type a)

constipation or hallucinations

9

Antibiotics (type a)

diarrhoea

10

Ivabradine (type a) used for IHD and HF (blocks pacemaker current)

Monitor HR, risk of bradycardia

11

Cimetidine or Spironolactone (type a)

Gynaecomastia

12

NSAIDs (type a)

Asthma caution and GI damage

The biggest burden of ADR. insidious because OTC and abundant. 2000 deaths per year
Prescribe with caution, consider alternative
Who is at risk of GI damage? Co-prescribe a PPI if suspicious

13

Digoxin (type a)

Nausea, vomiting and visual disturbances

14

Cytotoxics (type a)

Myelosuppression

15

beta blockers (type a)

asthma: beta 1 selective, can block beta adrenoreceptors. risk of bronchospasm.
HF + COPD: add beta-1 block brosoprolol for HF, but monitor lung function if they have COPD

16

Describe pharmacokinetic mechanism

Absorption; elimination (renal and hepatic clearance)

17

To avoid an ADR, what key consideration should you make when prescribing digoxin?

renal function

18

How does diazapam's half-life change with age?

one hour increase per year beyond 20 y/o

19

When should you be cautious in who to prescribe diazepam to?

Neonates; elderly; enzyme defect populations (10% genetic defect to p450 enzyme); hepatic (LFT poorly predicts metabolism)

20

What are type B ADRs?

unpredictable, severe, un-related to pharmacology, rare, genetic or immunological
Respond not by reducing dose, but stopping the medication

21

What is agranulocytosis ? common examples?

Type B ADR; reduction in WBCs (absence of neutrophils, increased susceptibility to mouth ulcers, infections).
Clozapine is a common example. These patients require freq monitoring
Carbimazole
Carbamazepine

22

Thrombocytopaenia?

Bruising, easy bleeding- Type B ADR.

23

Are NSAIDs a risk to people with CV disease?

yes, it can worsen it. This is due to fluid retention, exacerbation of hypertension.
diclofenac is a no no!!!! (when used topically as a skin preparation it is ok)

24

Does NSAIDS increase risk of renal failure?

Yes, reduction of eGFR

25

Statins

Myopathy (actual muscle damage--> rarely, rhabdomylosis--> kidney failure)
'Routinely say that ''it can cause muscle pain, if so, require blood test to see if there's muscle damage''

26

Skin reactions

irritation--> life threatning*

*Urticaria
Erythematous erruptions: reddening, may resemble measles or maculopapular
Toxic epidermal necrolysis: rare but often fatal with blistering and skin peels off
Stevens-Johnson syndrome: fever, rash, blisters

27

Sumatriptan

Green blood. Once in a career occurrence

28

Monitor what with ACE-I?

renal function

29

Risk of drug interactions exacerbated by what?

Polypharmacy
Renal impairment (ageing patient)
Drugs with narrow therapeutic window pose greatest problem (lithium, warfarin, digoxin)

OTC does not necessarily = safe
Drug-food interactions
Elicit drugs important to rule out

30

Stomach interactions

tetracycline: binds Fe, calcium in milk. Not absorbed.
Avoid taking with dairy products
PPIs, antacids, H2 antagonists raise pH, can affect absorption of certain drugs

31

CYP related metabolism

Interaction
Induction or Inhibition

32

Examples of drug induction.. how does this occur?

Rifampicin
Phenytoin
Carbamazepine
Alchohol
St. John's Wart (weakly effective anti-depressant)


Conc of barbiturates, carbamazepine, rifampicin increase metabolism of OCs
May take a week or 2 for effect
Effect may persist on stopping inducer

33

Example of drug inhibition. How does this occur?

erythromycin / clarithromycin (avoid with simvostatin--> increases in conc, muscle damage)
ciclosporin
Psoralen (from grape fruit juice)


i.e. macrolide + warfarin- patient bleeds, or even h.stroke.

Rapid onset : 1-2 days
Often reverse quickly on stopping

34

Drugs to avoid with simvostatin

verapamil, diltiazem
For amlodipine plus statin:
Pravastatin does not interact
Use 20mg simvastatin as maximum dose

35

Key counselling point for methotrexate?

Do not self-prescribe with aspirin or NSAIDs: competition for renal elimination, toxicity risk. Also risk of impaired renal perfusion

rhuematologists might be happy to co-prescribe becaue they monitor blood count.
Drug interactions can be acceptable if carefully monitored

36

Heart failure patient on diuretic are you safe to use ACE-I??

Risk of first dose hypotension: stop diuretic for a few days

37

Another risk of diuretics?

Risk of hypokalaemia: digoxin risk. Take K levels beforehand

38

Asthma and beta-blockers?

Salbutamol's effectivity (B2 agonist) reduced due to beta blocker activity

39

Calcium channel blockers?

Verapamil etc can act on calcium heart channels. Thus using this drug and beta blocker could stop the heart!!
Dihydropyridine does not act on Ca channels of heart, limited to smooth muscle Ca channels.

40

Dangers of using Warfarin. Named alternatives

Anticoagulant
So many interactions: inducers and inhibitor susceptibility
INR: monitor (1 in healthy patient, value increases when blood coagulating less). i.e. measure 3 days after prescribing with macrolide, if it increases, reduce warfarin dose.
Increased actions lead to bleeding:
gastric
cerebral
haemoptysis
blood in faeces
blood in urine
easy bruising


Reasons why it's being used less.
eg Rivaroxaban
Direct Oral Anticoagulants
Factor X inhibitor
Fewer interactions
No requirement to monitor

41

Examples of alcohol interactions

Labels 2 & 4 (avoid if affected or avoid)
Mostly CNS depressant / sedating actions enhanced
E.g. TCAs, sedating antihistamines, benzodiazepines
Few antibiotics actually interact
Metronidazole leads to disulfiram-like effect
Gastric effects
Avoid aspirin containing products for hangover

42

Food interactions

Cranberry juice thought to potentiate warfarin leading to fatalities
Grapefuit juice interacts with simvastatin and some Ca-antagonists

43

1. Warfarin and NSAIDs:
2. Warfarin and antibiotics (esp erythromycin and ciprofloxacin):
3. NSAIDs and methotrexate:
4. ACE inhibitors and potassium/potassium sparing diuretics
5. Verapamil and beta-blockers
6. Digoxin and amiodarone:
7. Digoxin and verapamil:
8. Oral contraceptives and certain inducing agents (e.g. rifampicin, carbamazaepine and phenytoin):
9. Statins and macrolides:

1. leading to enhanced bleeding
2. leading to enhanced bleeding
3. leading to methotrexate toxicity
4.: risk of hyperkalaemia
5.: risk of asystole
6. risk of digoxin toxicity
7. risk of digoxin toxicity
8. risk of failure of contraception
9. risk of myopathy