1. Medicines for Cough and Cold

Question 1

Classifications of drugs for common cold

Answer 1

Rhinorrhoea/Nasal congestion/Post-nasal drip:

1. Antihistamines
2. Decongestants
3. Mucoregulators (more severe)
4. Mast cell stabilisers (more severe)

Cough

1. Non-productive cough: Antitussive
2. Productive cough: Expectorant and Mucoactive

Question 2

Nasal congestion is associated with

Answer 2

1. decrease sympathetic vasoconstriction of submucosal blood vessels
2. increase parasympathetic stimulation of mucus secretion

Question 3

Example of mucoregulators

Answer 3

Ipratropium

Question 4

Uses of ipratropium

Answer 4

1. Controls severe cold symptoms

2. Decrease mucus hypersecretions from globet cells and submucosal glands

Question 5

MOA of ipratropium

Answer 5

1. SAMA
2. Blocks inflammation-induced parasympathetic cholinergic receptor (M3) activation of submucosal glands/globet cells
3. Decrease stimulated mucus output and sputum volume

Do not dry basal secretions
Do not increase normal viscosity

Question 6

Side effects of ipratropium

Answer 6

1. Few side effects as little enters systemic circulation via intranasal route
2. Unpleasant taste
3. Dry mouth
4. Urinary retention in the elderly

Question 7

Example of mast cell stabiliser

Answer 7

Cromoglicic acid

Question 8

Uses for cromoglicic acid

Answer 8

Intranasal or inhaled for severe cold symptoms

Question 9

MOA of cromoglicic acid

Answer 9

1. Mast cell stabiliser
2. Controls chloride channels to inhibit cellular activation
3. Decrease mast cell degranulation by IgE-mediated FcεRI cross linking
4. Decrease secretion of inflammatory mediators from eosinophils, neutrophils, and macrophages
5. Increase secretion of annexin A1
   - annexin A1 inhibits prostaglandins and leukotriene production

Question 10

Side effects of cromoglicic acid

Answer 10

1. Throat and nasal irritation, mouth dryness, cough

2. Unpleasant / bitter taste

Question 11

Examples of decongestants

Answer 11

phenylephrine, oxymetazoline, naphazoline, pseudoephedrine, ephedrine

Question 12

MOA of decongestants

Answer 12

1. Direct alpha adrenoceptor agonists
   - Alpha-1 selective → phenlyephrine (oral or intranasal)
   - Non-selective → oxymetazoline (intranasal) / naphazoline (intranasal)
2. Indirect increase in release of adrenaline/noradrenaline
   - Pseudoephedrine (oral) / Ephedrine (intranasal)
3. Vasoconstriction of nasal blood vessels
4. Reduce inflammation and secretion of mucus

Question 13

Examples of nasal glucocorticoids

Answer 13

fluticasone, mometasone

intranasal

Question 14

MOA of nasal glucocorticoids

Answer 14

1. Anti-inflammatory

2. Decrease inflammation → decrease congestion & mucus secretions

Question 15

Adverse effect of fluticasone

Answer 15

Some people report that intranasal fluticasone has a “rose water” odour that they cannot tolerate

Question 16

Adverse effects of sympathomimetic agents

Answer 16

1. Rebound congestion → occurs with prolonged (> few days) topical intranasal use
2. CNS stimulation
   - More likely with oral decongestants
   - Restlessness, tremors, irritability, anxiety and insomnia
3. Cardiovascular
   - More likely with oral decongestants
   - Hypertension due to vasoconstriction
   - Tachycardia (indirect sympathomimetics e.g. pseudoephedrine)
4. Dry mouth
   - Alpha-2 agonist effect on salivary gland

Question 17

Adverse effects of nasal glucocorticoids

Answer 17

1. Systemic side effects limited by intranasal delivery

2. Local mucosal dryness and irritation

Question 18

Types of antitussives

Answer 18

1. Opioid antitussives
   - Codeine
2. Nonopioid antitussives
   - Dextromethorphan
   - Diphenhydramine

Question 19

Uses for codeine

Answer 19

Most effective cough suppressant

Question 20

MOA of codeine

Answer 20

Acts in the CNS to suppress cough

Question 21

Adverse effects of codeine

Answer 21

1. CNS → sedation
2. Weak opioid but still has abuse potential at high dose
3. Respiratory depression
   - should not occur with normal clinical dose
   - risk on overdose
   - risk in patients with severe respiratory insufficiency
4. Do not combine with other CNS depressants
5. Caution in CYP2D6 ultra-rapid metabolisers → convert more codeine to morphine

Question 22

Age group in which codeine is not recommended

Answer 22

< 18 years old

Question 23

Uses of dextromethorphan

Answer 23

1. Most effective non-opioid antitussive

2. Used for non-productive cough

Question 24

MOA of dextromethorphan

Answer 24

Acts in CNS to suppress cough

Question 25

Adverse effects of dextromethorphan

Answer 25

1. CNS → drowsiness, dizziness, confusion, insomnia, excitement, nervousness 2. GIT → nausea, vomiting, stomach pain 3. Abuse potential at higher dose (dissociative anaesthetic-like effect)

Question 26

Age group in which dextromethorphan is not recommended

Answer 26

< 4 years old

Question 27

MOA of diphenhydramine

Answer 27

Antihistamine, MOA of antitussive action unknown

Question 28

Adverse effects of diphenhydramine

Answer 28

Sedative, anticholinergic

Question 29

Example of expectorants

Answer 29

Guaifenesin

Question 30

MOA of guaifenesin

Answer 30

Increase production of respiratory tract fluids to help liquefy and reduce the viscosity of tenacious secretions

Question 31

Adverse effects of guaifenesin

Answer 31

GI disturbances, nausea

Question 32

Age group in which guaifenesin is not recommended

Answer 32

Caution < 6 years old | Not indicated < 2 years old

Question 33

Advice that should be given to patients with the usage of guaifenesin

Answer 33

1. Not for persistent cough associated with asthma or smoking 2. Take adequate fluid to make secretions less viscous and protect renal function (nephrolithiasis reported on overdose)

Question 34

Examples of mucolytics

Answer 34

acetylcysteine, carbocisteine

Question 35

MOA of mucolytics

Answer 35

1. Free sulfhydryl group opens disulphide bonds in mucoproteins 2. Lowers mucous viscosity

Question 36

Adverse effects of mucolytics

Answer 36

1. Bronchospasm 2. Anaphylactoid reactions - rash, hypotension, dyspnea, wheezing 3. GI disturbances (carbocisteine contraindicated in patients with active peptic ulcer)

Question 37

Cautions with the usage of mucolytics

Answer 37

1. Elderly or debilitated patients with severe respiratory insufficiency 2. Patients with asthma

Question 38

Examples of mucokinetics

Answer 38

Bromhexine and its active metabolite ambroxol

Question 39

MOA of mucokinetics

Answer 39

1. Mucokinetic → promotes ciliary clearance - Increase ciliary beat frequency - Decrease adherence of mucus to cilia 2. Stimulate surfactant production → surfactant is an anti-glue factor to prevent mucus from sticking to alveolar and bronchial walls 3. Antioxidant as free radical scavenger 4. Anti-inflammatory by decreasing cytokines 5. Suppresses influenza virus multiplication 6. Local anaesthetic by blocking voltage-gated Na+ channel

Question 40

Potential side effects of mucokinetics

Answer 40

1. Allergic reactions 2. Cutaneous adverse effects 3. Avoid in patients with history of asthma and peptic ulcer disease 4. Caution < 6 years old 5. Not indicated < 2 years old

Question 41

Is cough and cold medication safe for paediatric use?

Answer 41

Generally unsafe, wait and see instead of giving meds

Question 42

Is cough and cold medication safe for geriatric use?

Answer 42

Generally unsafe