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Y3 Lecture weeks > ADR > Flashcards

ADR Flashcards

1
Q

What’s the other name for TYPE A adverse drug reactions?

A

Type A = augumented

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2
Q

What’s the other name for Type B ADR?

A

Type B = bizzaire/ idiosyncratic

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3
Q

What’s type A reactions?

A

Type A (augmented)

  • reactions that are predictable from the known pharmacology
  • often represent an exaggeration of pharmacological effect of the drug
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4
Q

What are Type B reactions?

A

Types B (idiosyncratic/ bizarre)

  • unpredictable from the knowledge of the basic pharmacology of the drug
  • show no dose-response relationship

May be : chemical, biochemical, immunological -> these complex processes influence the reaction

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5
Q

Phases in drug development

A

Phase I - healthy volunteers ->to understand bioavailability of the drug

Phase II - inpatient -> to identify dose, kinetics and dynamics of the drug

Phase III - patients -> 1st efficacy and safety studies (how effective under ideal condition) with exclusion and inclusion criteria (comparison to placebo)

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6
Q

When the drug company can apply for the license for the drug?

A

Once the drug got through phase 1, 2 and 3

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7
Q

Where can this be usually detected in drug development process:

Type A reactions

Type B reactions

A

Types A -> usually during phases 1 - 3

Type B -> usually during phase 4 *

* only with large exposure, when drug is on the market

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8
Q

What’s ‘role of 3’ in pre-marketing detection of the ADR?

A

Role of 3 in ADR

  • if 30 exposed persons -> 1 in 10 show ADR
  • if 300 exposed -> 1 in 100 will show ADR
  • 3000 espossed -> 1 in 1000 show ADR
  • 30 000 -> 1 in 10 000 show ADR

* Not all ADR will show up in the early phases of clinical trials (some rare reactions detected only with large exposure - when clinically available)

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9
Q

Are the long term effects detected in phase III pre-marketing testing?

A

Not, as it is short-lasting

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10
Q

What phase III for?

A

Phase III is for efficacy

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11
Q

How to recognise ADR?

A

When a patient develops new symptoms

T -> temporal relationship -> does the effect occur after the drug has started? (most ADR occur in first 3 months after the drug started)

R - re-challenge -> if you give same drug, same dose again -> pt will develop symptom again (done in mild ADR only)

E - exclusion of other causes -> to check if the symptom is not due to other cause

N - novelty -> check if someone else had same drug reaction; but maybe you will be first to identify the ADR

D - de-challenge -> dose reduction/ withdrawal (would reduction of drug improve the effect?)

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12
Q

What’s the yellow card?

A

To report suspected ADR -> MHRA* collects the data and assess the safety of the drug

MHRA = Medicine and Healthcare products Regulatory Agency

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13
Q

What is ADR with Warfarin?

  • MoA
  • antidote
A

Warfarin -> May cause hematoma

*higher the dose = higher risk of bleeding

  • MoA: warfarin prevents vit K -> vitamin K- dependant clotting factors (2, 7, 9 and 10) are decreased
  • antidote: vitamin K
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14
Q

What factors will determine the dosage of Warfarin )?

A

Warfarin doses

  • elderly -> lower doses -> this is because the liver get smaller with age
  • weight increase -> higher doses
  • gender
  • age
  • other meds
  • nutritional status
  • genetics

*to determine the dose -> we check INR

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15
Q

Direct Oral Anticoagulant

  • elimination depends on what organ?
A

DOAC

  • excreted by the kidney

Therefore in kidney impairment -> need to reduce the dose due to risk of bleeding

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16
Q

What is MoA of DOCS?

A
  • DOACs (Apibaxan and ‘…baxans’) -> Xa inhibitor
  • Dabigatran IIa (antithrombin)
17
Q

What type of ADR Toxic Epidermal Necrolysis is?

A

TEN is type B ADR reaction

18
Q

Toxic Epidermal Necrolysis

  • what happens?
A

Toxic epidermal necrolysis (TEN)

  • potentially life-threatening skin disorder
  • most commonly seen secondary to a drug reaction
  • the skin develops a scalded appearance over an extensive area
  • TEN is severe end of a spectrum of skin disorders which includes erythema multiform and Stevens-Johnson syndrome
19
Q

Clinical features (+ sign) of TEN

A

Features

  • systemically unwell e.g. pyrexia, tachycardic
  • positive Nikolsky’s sign: the epidermis separates with mild lateral pressure
20
Q

Examples of drugs that are known to cause Toxic Epidermal Necrolysis

A

Drugs known to induce TEN

  • phenytoin
  • sulphonamides
  • allopurinol
  • penicillins
  • carbamazepine
  • NSAIDs
21
Q

Management of TEN

A

Management of *TEN*

  • stop precipitating factor (drug)
  • supportive care, often in intensive care unit
  • intravenous immunoglobulin has been shown to be effective and is now commonly used first-line
  • other treatment options include: immunosuppressive agents (ciclosporin and cyclophosphamide), plasmapheresis
22
Q

The difference between SJS and TEN

A

SJS - 10% of the body is blistered

TEN - 30% or more blistered

23
Q

What is pathophysiology of TEN/SJS

A

Drug is recognised by the body as a foreign -> immune system response against them -> cytokines produced and skin attacked by T cells -> blisters

24
Q

What are Immune Check Inhibitors?

A

Immune Check Inhibitors

  • Blocking the binding of PD-L1 to PD-1 with an immune checkpoint inhibitor (anti-PD-L1 or anti-PD-1) -> T cells to kill tumor cells (
  • Immunotherapy uses the body’s immune system to fight cancer

Summary: these drugs allow the body’s immune system to attack the cancer

25
Q

What are examples of ADR associated with Immune Checkpoint Inhibitors?

A
  • thyroiditis
  • pituitary failure
  • adrenal insufficiency
  • lung inflammation
  • skin inflammation
26
Q

What are drug - drug interactions?

A

Drug-drug interactions

  • the alteration of the effect of one drug by co-administration of another

*these are common but only some of clinical importance

27
Q

What are Pharmaceutical interactions?

A

Pharmaceutical interactions

  • outside of the body
  • two different drugs are mixed together (e.g. IV bag) -> these drugs interact chemically -> crystalise each other out -> as a result patient does not get a drug
28
Q

What are Pharmacokinetic dinteractionsions?

A

Pharmacokinetic = what a body does to a drug

ADME: administration, distribution, metabolism and excretion

29
Q

What are types of pharmacodynamic drug interactions?

A

Pharmacodynamic drug interactions

What the drug does to the body

Types:

A. Synergistic -> positive effect (combining two drugs leads to larger effect than expected)

B. Antagonistic -> one drug inhibit action of the other

30
Q

Example of pharmacokinetic interaction (absorption)

A

Absorption affected

  • Microbiota in the gut is affected by antibiotic
  • If microbiota is dysregulated -> drugs may be affected

eg. oral contraceptives may not be as effective while taking antibiotics -> as microbiota dysregulated -> absorption of drug affected -> less effective oral contraception

31
Q

Example of pharmacokinetic reaction (metabolism)

A

Metabolism

Enzymes induction and inhibition

Drugs are metabolised by liver enzymes

  • Enzyme induction interaction -> enzyme is increased -> more metabolite

Effect: reduced effect of other (metabolised drugs)

  • Enzyme inhibition -> enzyme is decreased -> less metabolism -> accumulation of other drugs
32
Q

Examples of enzyme INDUCERS

A
33
Q

What ADR may St John’s Wort cause?

A

St John’s Wort -> it is an enzyme inducer -> more metabolism -> some drug effects is reduced (e,g, reduced immunosuppressants, steroids)

*ST John’s Wort -> herbal medication; anti-depressant and anti-viral properties

34
Q

What effects can grapefruit juice have on the drugs?

A

Grapefruit juice* contains substances (furanocoumarins) -> act as ‘suicide ‘of enzymes in the gut wall

Less enzymes -> less metabolism -> potential for drug overdose

*generally adviced to avoid citrous fruits

35
Q

Examples of drugs that may interact with grapefruit juice

A
  • statin e.g. simvastatin and atorvastatin
  • high blood pressure treatment -> nifedipine
  • organ-transplant rejection drugs -> cyclosporines
  • anti-anxiety drugs -> buspirone
  • corticosteroids -> Crohn’s disease or ulcerative colitis -> budesonides
  • Antiarrhythmics -> amiodarone
  • antihistamines -> fexofenadine
36
Q

Examples of ADR associated with excretion (3)

A

- digoxin

- lithium

- methotrexate

*narrow therapeutic index -> monitoring required

  • If other drugs given may lead to reduction in excretion of the above drugs -> OD)

Drugs are given with the drugs above: amiodarone, verapamil, quinidine NSAIDs, diuretics

37
Q

Interaction of Lithium and Bendrofluazide

A

Lithium is similar in terms of the structure to Na+

As diuretic will increase Na+ excretion -> Lithium will be retained instead

(as body tried to conserve Na+ -> conserve Lithium as similar structure)

38
Q

What type of ADR is the interaction between Spironolactone and ACE inhibitor?

A

Spironolactone and ACE Inhibitor

  • pahrmacodynamic/ synergistic type of reaction -> both lead to K+ retention -> hyperkalaemia
39
Q

What type of reaction is co-prescription of: NSAIDs and anti-hypertensives

A

NSAIDs and anti-hypertensives

  • antagonistic reaction -> reduced efficacy or toxicity
  • NSAIDs affect intrarenal prostaglandin levels (less dilation) while anti-hypertensives will usually dilate renal arteries

Y3 Lecture weeks (65 decks)

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