Mechanism of drugs used in the treatment of respiratory disease Flashcards

1
Q

Aim of bronchodilators

A

Rescue patient from bronchospasm

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2
Q

Aims of anti-inflammatories

A

Reduce frequency of attacks
Reduce severity of attacks
Limit structural remodelling

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3
Q

Examples of bronchodilators

A
B-adrenoceptor agonists
Xanthines e.g. caffeine
Muscarinic receptor antagonists
Leukotriene receptor antagonists
Histamine receptor antagonists
Methods all involve inhibition of contraction
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4
Q

Anti-inflammatory classes

A

Glucocorticoids
Cromoglicate and nedocromil
Anti-IgE
Mechanisms all involve inhibition of inflammation

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5
Q

B-adrenoceptor agonists mechanism

A

cAMP dependent, causes smooth muscle relaxation

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6
Q

Short acting B2-adrenoceptor agonists

A

E.g. salbutamol, terbutaline

Hydrophilic in nature, short duration of action (4-6 hours)

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7
Q

Long acting B2-adrenoceptor agonists

A

E.g. salmeterol, formoterol
Lipophilic in nature
Leech out of membrane prolonging duration of action (>12 hours)
Must not be given in the absence of a corticosteroid

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8
Q

(Old) mechanism for xanthines

A

Phosphodiesterase metabolises cAMP
Methylxanthines inhibit PDE, maintaining high cAMP levels
Achieves bronchial smooth muscle relaxation

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9
Q

Examples of xanthines

A

Theophyline

Aminophyline

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10
Q

Muscarinic receptor antagonists mechanism

A

Aim is to block post-synaptic M3 receptors
Effects are limited by lack of selectivity leading to antagonism of M2 autoreceptors (prevents ACh release)
Blocking M2 knocks out benefit of blocking M3 as more ACh released

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11
Q

Muscarinic receptor antagonist examples (best for COPD)

A

Ipratropium: onset of action 30 mins, lasts 3-5 hours, not selective for M receptor subtypes, may decrease mucus secretion and increase mucociliary clearance
Tiotropium: longer acting, once daily dosing

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12
Q

Adverse effects of muscarinic receptor antagonists

A

Minimal when inhaled, anti-muscarinic side effects e.g. dry mouth, sedation

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13
Q

Leukotriene receptor antagonists

A

Cysteinal leukotrienes (very potent) act on CysLT1 receptor in respiratory mucosa, montelukast and zafirlukast antagonise the receptor, prevents bronchiolar contraction mediated by LTs, inhibits early and late phase responses to irritants

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14
Q

Anti-inflammatory drugs

A

Used to reduce severity and frequency of asthma attacks
Limit progression of disease by inhibiting remodelling
Reduce night-time asthma attacks by preventing late-phase

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15
Q

Glucocorticoids

A

No immediate effect

Step 1 inhalation therapy when bronchodilator is used more than once daily

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16
Q

Glucocorticoids immunosuppression

A

Il-10 decreases cytokine formation which decreases the recruitment and activation of inflammatory T cells

17
Q

Glucocorticoids anti-inflammatory action

A

Induces lipocortin-1 synthesis which decreases inflammatory mediators
Suppresses COX-2 induction thus decreases inflammatory prostanoid production
Can reduce severity of early phase response and prevent late phase response

18
Q

Glucocorticoids mechanism

A

Two glucocorticoid receptors bind a glucocorticoid molecule, forming a functional unit, which enters the nucleus of the cell, which decreases pro-inflammatory gene products and increases anti-inflammatory gene products

19
Q

Steroid cards

A

initial dose: card not needed
Intermediate dose: card considered
High dose: card needed

20
Q

Cromoglyacte and nedocromil

A

Not in common use, poor/variable efficacy shown in antigen-, exercise- and irritant- induced asthma, weak anti-inflammatory effects, mechanism unclear

21
Q

If anti-inflammatories don’t work?

A

Steroid-sparing agents/ cytotoxic immunosuppressants e.g. azathioprine, methotrexate, cyclophosphamide, ciclosporin
Continuous subcutaneous terbutaline infusion
Omalizumab (attacks human IgE)

22
Q

Omalizumab mechanism

A

Binds to free IgE, reducing cell-bound IgE
Reduces high affinity receptors, reduces mediator release, reduces allergic inflammation
Prevents asthma exacerbations and reduces symptoms