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Therapeutics > L2 L3 and L4 Asthma Drugs > Flashcards

L2 L3 and L4 Asthma Drugs Flashcards

1
Q

Describe short acting beta-2 agonist drugs and their use in asthma treatment.

A

Short-acting beta-2 agonists such as salbutamol and terbutaline are used in the treatment of acute bronchospasm. Stimulate the relaxation of bronchial smooth muscle. Act within 5-15 mins for 3-6 hours.
First line of treatment for acute relief.
given as needed.
Increased use indicates lack of asthma control.
Doseage forms include metered dose inhaler, dry powder inhaler, nebuliser, oral liquid and injection.
Safe to use in pregnancy.

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2
Q

Describe non-steroidal preventers.

A

CROMOLYNS: Have no bronchodilator effect. Used to decrease airway hyperactivity over time (prevent late-phase of asthma). Preventative effect may take up to 1 month.
LEUKOTRIENE ANTAGONISTS: Leukotrienes are implicated in bronchoconstriction and oedema. Leukotriene antagonists are administered orally, are long-acting with a slow onset of action. They reduce airway inflammation.

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3
Q

Describe corticosteroid preventers.

A

Inhaled corticosteroids such as betamethasone reduce inflammation and bronchial hyperactivity over time, but have some systemic adverse effects.

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4
Q

What is theophylline?

A

Orally administered bronchodilator used for severe airway obstruction. Pharmacokinetic variability means patients require TDM. LABA.

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5
Q

Which preventer medication should be the initial choice in pregnancy?

A

budesonide.

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6
Q

What is the general mechanism of action of beta-2 agonists and theophylline?

A
  1. activate adenylyl cyclase which increases the production of cAMP in bronchial smooth muscle
  2. cAMP activates PKA
  3. PKA phosphorylates intracellular proteins, and this cascade leads to smooth muscle relaxation and bronchodilation.
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7
Q

Apart from directly relaxing bronchial smooth muscle through increasing cAMP concentration, what other effects do short acting beta-2 agonists have?

A

Inhibit the release of bronchoconstricting substances from mast cells, and may also inhibit microvascular leakage and increase mucociliary transport.

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8
Q

Describe long acting beta-2 agonists, including their use, 2 examples and comparison of 2 drugs.

A

Onset of action is 10-30 mins after administration, so not used for acute relief of symptoms. Long duration of action (more than 12 hours).
Eg Eformoterol and Salmeterol, which both come as Dry Powder Inhalers. Eformoterol has a faster onset of action than salmeterol.
These drugs are not recommended as sole asthma treatment as they do not address underlying airway inflammation.

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9
Q

What is a rare adverse effect of long-acting beta-2 agonist use in asthma?

A

1% chance of paradoxical bronchoconstriction due to propellants or dispersants in inhalers. This effect is worsened by the longer onset of action.

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10
Q

What are the indications for use of long acting beta-2 agonists?

A

Maintenance treatment of asthma (especially nocturnal) in patients receiving corticosteroids.
Adjunctive therapy in patients whose asthma is inadequately controlled by glucocorticoids.
Protection against exercise-induced asthma (give at least 30 mins before exercise), but effectiveness may decline with regular use..
Maintenance treatment of COPD

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11
Q

Can eformoterol or salmeterol be used in pregnancy?

A

Yes, however experience in pregnancy is limited

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12
Q

What is the mechanism of action of salmeterol?

A

Side chain of the molecule binds to a specific site of the beta-2 adrenergic receptor that results in prolonged receptor activation.

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13
Q

What is the mechanism of action of eformoterol?

A

Enters the lipid bilayer of the cell membrane, from which it gradually leeches out and is thus available over a long period of time to stimulate the beta-2 adrenoreceptor.

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14
Q

What are the effects of medications such as propanalol in asthmatics?

A

These medications are beta-2 receptor ANTAGONISTS, and prevent bronchodilation. This can cause wheezing, and may precipitate an acute asthmatic attack by interfering with the effect of endogenous adrenaline (beta-2 agonist)

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15
Q

List 5 side effects of beta-2 agonists.

A 
Tremor (most common SE)
Tachycardia
headache
hyperglycaemia
hypokalemia
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16
Q

How do beta-2 agonists cause tremor?

A

Direct stimulation of beta-2 receptors in skeletal muscle. Occurs frequently with oral beta-2 agonists, but rarely with inhaled ones.

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17
Q

How do beta-2 agonists cause tachycardia?

A

Stimulation of beta-2 receptors can cause vasodilation and reflex tachycardia (some beta 2 receptors present in ventricles and atria of heart. Cardiac symptoms are rare in patients on normal doses. In high doses, selective beta-2 agonists lose selectivity and may act on other adregenergic receptors outside the lungs.

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18
Q

What is hypokalemia, and how is it exacerbated?

A

Hyperkalemia is the presence of excess potassium in the blood. It may occur with high doses of beta-2 agonists, and may be exacerbated by concomitant treatment with methylxanthines, corticosteroids, diuretics and by hypoxia.

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19
Q

How dose tolerance to beta-2 agonists occur? What is the result of this, and how can tolerance be minimised?

A

Tolerance is the result of beta-2 receptor down-regulation due to chronic use of beta-2 agonists. This results in the shortening of duration of bronchodilation, however this is not clinically important to the short-acting drugs.
Steroids inhibit beta receptor downregulation. Glucocorticoids stimulate increased transcription of the gene for the beta-receptor.

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20
Q

What is an example of an anticholinergic bronchodilator?

A

Ipatropium (muscurinic receptor antagonist)

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21
Q

Compare ipatropium to it’s parent molecule.

A

Ipratropium is a derivative of atropine. It is a charged molecule so does not cross BBB, and is not well absorbed into the circulation and thus has minimal action at systemic muscurinic receptors.
Unlike atropine, it does not inhibit mucocilliary clearance (so less accumulation of secretions in lower airways)

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22
Q

Describe the mechanism of action of ipatropium?

A

Blocks the action of Ach at muscurinic receptors, inhibiting bronchomotor tone (promoting bronchodilation). Ach is an endogenous bronchoconstrictor.
Inhibits mucous secretion.
onset of action 30-60 minutes.
Muscurinic receptors are part of the parasympathetic pathway of bronchospasm, and so ipratropium is useful in patients who are intolerant to sympathomimetics or methylxanthines.
In severe asthma, ipratropium enhances bronchodilation produced by beta-2 agonists.

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23
Q

What are the indications for use of ipratropium?

A

Acute severe asthma and maintenance treatment of severe asthma.
adjunct to beta-2 agonists and steroids when these do not control asthma on their own.
treatment of severe acute asthma with SA beta-2 agonists.
COPD
In asthma with parasympathetic mediated reflex spasm.

24
Q

What are the side effects of ipratropium use?

A

Common: dry mouth and throat irritation
Rare: urinary retension, acute angle closure glaucoma.

25
Q

Describe counselling points for the use of anticholinergics in asthma?

A

Do not use for immediate relief of symptoms (i.e. in an acute asthma attack).
Do not reduce or stop inhaled corticosteroids, even if you feel better after starting this drug.
Do not get it into your eyes. Tell doctor if you have eye pain or discomfort, blurred vision, or visual halos.

26
Q

What is tiotropium and what is it used for?

A

Long-acting anticholinergic, which is only used in COPD.

27
Q

What are methylxanthines?

A

Theophylline derivative drugs.

28
Q

What is theophylline?

A

Bronchodilator drug that is administered orally, and used only in severe airway obstruction due to high pharmacokinetic variability and narrow TI.

29
Q

What is the mechanism of action of methylxanthines?

A

Adenosine receptor antagonists. Adenosine is an endogenous bronchoconstrictor and promotes release of histamine from mast cells.
Methylxanthines improve contractility of the diaphragm and stimulate the medullary respiratory centre.

30
Q

What is the mechanism of theophylline (specifically)?

A

Inhibits the enzyme phosphodiesterase, which is responsible for the breakdown of cAMP to AMP.
Has immunomodulatory, anti-inflammatory and bronchoprotective effects.

31
Q

What is the role of cAMP in bronchodilation?

A

cAMP is the second messenger molecule responsible for bronchodilation. It activates PKA, causing smooth muscle relaxation and bronchodilation.

32
Q

What are the indications for use of methylxanthines?

A

IV administration in severe acute asthma.
Maintenance treatment in severe asthma.
SR preps are more effective in treatment on nocturnal bronchospasm.

33
Q

What are the adverse effects associated with theophylline use?

A

Theophylline has the greatest potential of all anti asthmatic drugs for serious toxicity.
It has been associated with tachycardia, increased risk of seizures.

34
Q

What are the general side effects associated with methylxanthine use?

A

Nausea, vomiting and diorrhea, headache, insomnia, irritability, GI reflux, anxiety, tremor, palpitations.
seizures, cardiac arrhythmias (high plasma concentrations), tachycardia.

35
Q

What drugs do methylxanthines interact with?

A

CYP 1A2 inducers, such as omeprazole, phenobarbitone, phenytoin and tobacco smoking.
These decrease the plasma concentration of theophylline.
CYP1A2 inhibitors such as oral contraceptives, ciprofloxacin, fluvoxamine and cimetidine increase theophylline plasma concentration and may lead to serious side effects.
Erythromycin increases risk of arrhythmia as it prolongs QT interval.
Beta-2 agonists –> increased risk of hypokalemia.

36
Q

What conditions affect theophylline clearance?

A

INCREASE CL: hyperthyroidism and smoking

DECREASE CL: heart failure, pulmonary oedema, severe hypoxia, hypothyroidism.

37
Q

What are the different corticosteroids used for treatment of chronic asthma, and what dosage forms are they available in?

A

Beclomethasone (metered dose inhaler)
Fluticasone (metered dose inhaler, dry powder inhaler, nebuliser)
Budesonide (MDI, DPI, neb)
Ciclesonide (MDI)

38
Q

What are the indications for use of corticosteroids?

A

maintenance of persistent asthma. should be used when beta-2 agonists are used more than 3 times weekly.
Early use may prevent the severe, progressive inflammatory changes characteristic of chronic asthma.

39
Q

What is the mechanism of action of glucocorticoids?

A

attenuate prostaglandin and leukotriene synthesis via inhibition of phospholipase A2, leading to a significant bronchodilation effect.
increase responsiveness to beta-2 receptor agonists.
reduce mucus production.
effects take about 2-4 weeks to appear
Inhibit transcription of genes for cytokines implicated in asthma
up regulate beta-adrenoreceptors
inhibit IgE synthesis
decrease microvascular permeability of the bronchioles
suppress inflammatory processes

40
Q

What are some side effects of corticosteroid use?

A 
dysphonia, oropharangeal candidiasis, facial skin irritation after neb.
allergic reactions (rare) including bronchospasm, rash, urticaria and angiodena.
Systemic effects such as adrenal impairment, bonds density loss, cataracts, skin thinning, impaired growth.
41
Q

Describe corticosteroid dosing regimen.

A

Start at a dose that is likely to be effective, then reduce to minimum dose necessary to maintain control of asthma.
If control has been achieved, step down dose by 25% every 3 months. Dose needs to be lowest possible to minimise side effects but maintain control. this may require adjunctive use of long-acting beta-agonist or use of leukotriene receptor antagonists.

42
Q

How should corticosteroids be used?

A

Spacer should be used with MDI, and mouth should be rinsed after using a DPI to reduce oral deposition of drug (may lead to oral thrush).
Corticosteroids are of no use for immediate symptom relief in the event of an acute asthma attack.
They must be used every day, even if the patient is feeling better.

43
Q

Describe drug interactions of corticosteroids.

A

Fluticasone is metabolised by CYP3A4. Inhibitors of this enzyme, such as itraconazole and ritonavir will increase the concentration of fluticasone, which is likely to suppress the adrena-pituary-hypothalamic axis and may result in Cushing’s syndrome (hypercortisolism).
Beclomethasone can be used as an alternative.

44
Q

What is cortisol?

A

stress hormone. Increases gluconeogenesis, glucose levels in blood and lipolysis.
Regulates its own production by inhibiting secretion of CRH from hypothalamus and ACTH from anterior pituitary.

45
Q

Describe Latrogenic Cushing’s Syndrome.

A

Accounts for more than 98% of all cases of cushing syndrome.
Occurs with prolonged use of glucocorticoids, and includes diabetes, reduced infection resistance, osteoporosis, cataracts, increased appetite causing weight gain, hypertension.

46
Q

Why may abrupt cessation of glucocorticoids result in adrenal insufficiency?

A

The hypothalamus and pituitary gland require several weeks to re-establish adequate ACTH production after cessation of corticosteroids.

47
Q

Describe Symbicort Dry Powder Inhaler. And suitability for use.

A

Long acting beta agonist (eformetertol) combined with corticosteroid (budesonide).
Should only be used in appropriately selected patients. May not be suitable for patients who over-use relievers).
Patients with well controlled asthma should not switch to this new regimen.
Potential for adverse effects.

48
Q

What are some patient counselling points for Symbicort?

A

Should not take more than 6 inhalations on a single occasion, or more than a total of 12 inhalations in any one day.
If you require more than 12 inhalations in any day, you should see your doctor or go to the hospital the same day.

49
Q

What is Seretide, and what are its indications for use?

A

Combination of salmeterol and fluticasone (MDI, DPI).
Indicated for maintenance treatment of asthma in patients inadequately controlled with inhaled corticosteroids, or patients stabilised on salmeterole and fluticasone.
Cannon be used as a reliever, as salmeterol has a slow onset of action.

50
Q

Give 2 examples of cromolyns, and their indications for use.

A

Cromolyn sodium (disodium cromoglycate) as MDI, DPI or inhaled solution
Nedocromil as MDI
Indicated for maintenance treatment in persistent asthma, protection against exercise or antigen induced asthma.
Has no value in acute attacks
Prevents both early and late phase asthma.

51
Q

What is the mechanism of action of cromoglycate?

A

Depresses exxaggerated neuronal reflexes, and inhibits PAF interaction with platelets and eosinophils.

52
Q

What are some practice points for cromoglycate?

A

efficacy is difficult to predict, so patient must be assessed after 4 week trial on the drug.
Use may help reduce the dosage of inhaled corticosteroids.
Most likely to prevent attacks in extrinsic (allergen-induced) asthmatics, especially children.

53
Q

What are some adverse effects of cromoglycate?

A

Cromoglycate is the least toxic of asthma therapies.
Common adverse effects include cough, throat irritation, transient bronchospasm.
Rare: severe bronchospasm

54
Q

What are some adverse effects of nedocromil?

A

Common: cough, throat irritation, distinctive taste, headache, nausea, vomiting, abdo pain.
Rare: severe bronchospasm

55
Q

What are some counselling points for chromoglycate?

A

Do not use this medicine for the relief of acute asthma.
Do not reduce dose or stop taking this medicine unless your doctor advises you.
Regularly clean the mouthpiece of your metered dose inhaler to prevent the nozel blocking.

Therapeutics (8 decks)

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