Respi - Medicine for Cough & Cold

Question 1

Classes of cough & cold drugs used & examples

Answer 1

1. Cough Suppressants (Anti-tussives - Codeine, Dextromethorphan)
2. Cough Expectorants (Guaiphenesin)
3. Mucolytics (Carbocysteine, Ambroxol)
4. Antihistamines (1G - Diphenhydramine, Chlorpheniramine, Tripolidine, Promethazine, 2G - Cetirizine, Loratidine)
5. Decongestants (Pseudoephedrine, Phenylephrine, Oxymetazoline)

Question 2

Mechanism of action & uses of cough suppressants

Answer 2

Suppresses cough centre in the brain

Suppresses irritating, unproductive (no mucus) cough

Question 3

Toxicity of codeine (3)

Answer 3

Type A ADR, dose related

1. Addictive Potential - 10% converted to morphine
2. Constipation - due to reduced GIT motility (esp chronic)
3. Urinary Retention - due to increased bladder sphincter tone

Question 4

Mechanism of action of cough expectorants

Answer 4

1. Aids/promotes expulsion of mucus/exudate from the lungs, bronchi and trachea
2. Loosens phlegm/mucous secretion in the airway by increasing water content

Question 5

Mechanism of action of mucolytics

Answer 5

Breaks down chemical structure of mucus molecules - mucus becomes thinner, can be easily removed through coughing

Question 6

Mechanism of action of antihistamines

Answer 6

Binds to H1-receptor & eliminates histamine actions (competitive antagonist) - reduces nasal secretion + allergic response

Question 7

Uses of antihistamines (8)

Answer 7

1. Allergic Rhinitis
2. Common Cold (flu)
3. Allergic Conjunctivitis (red eye)
4. Allergic Skin conditions (rashes)
5. Urticaria (hives)
6. Angioedema (swelling of the deep layer of skin, usually affects eyes, lips, genitals, hands, feet)
7. Anaphylactic reactions (severe allergies)
8. Nausea & Vomiting (1G)

Question 8

Toxicity of antihistamines (3)

Answer 8

1. 1G - Sedation, dizziness, blurred vision, parasympathetic (constipation, urinary retention, confusion, dry mouth) - lack of selectivity for H1R, has anti-cholinergic activity
2. 2/3G - Drowsiness, fatigue, headache, nausea, dry mouth - more selective for peripheral histamine receptors, less ADRs
3. Terfenadine, astemizole - withdrawn due to cardiotoxicity

Question 9

Mechanism of action & uses of decongestants

Answer 9

Vasoconstriction in the nasal passage - relieves congestion

Relieves nasal congestion

Question 10

Considerations when using decongestants

Answer 10

Antihistamines should be taken with decongestants, or else nose will still be clogged with the stuck mucus (if only AH)

Question 11

Toxicity of decongestants (3)

Answer 11

1. Cardiac Arrhythmia
2. Tachycardia (palpitations)
3. Tremors