drugs for cough and cold

Question 1

what causes the cough and cold elements of infection

Answer 1

due to histamine release by mast cells

sore throat -> inflammation irritating throat
post-nasal dip -> excess mucus drip down back of throat, causing irritation and cough (result in rhinorrhoea)
excess mucus production -> nasal congestion

Question 2

how to administer nasal drops and sprays

Answer 2

LABA+iCS (combined inhaler)
1. gently blow nose
2. tilt head forward or all the way back (for spray not needed becase fine mist distributes drugs to nasal lining ->less risk of gravity redistributing meds)
3. insert spray bottle nozzle and press pump steadily and firmly
4. breather gently through nose and avoid blowing nose for 2-3min

Question 3

can you combine drugs of the same class

Answer 3

no because risk of additive AE

Question 4

antihistamine-decongestant combinations

Answer 4

common antihistamine: chlorpheniramine
common decongestant: pseudoephedrine
common analgesic: paracetamol

Question 5

MOA of antitussives

Answer 5

sensory inputs to brainstem nuclei regulate cough generation and anti-tussiv work in CNS to suppress cough

Question 6

AE of codeine

Answer 6

opioid antitussive

potential for abuse
CNS: sedation
respiratory depression on overdose

Contrindicated for <18
- respiratory centres in brain not fully developed so more sensitive to respiratory depression
- liver not fully developed so higher level of drug in body (codeine cleared by liver)

Question 7

effect of CYP2D6 on codeine

Answer 7

CYP2D6 are ultra rapid metabolisers
- codeine is a pro drug converted to more potent opioid, morphine
- with CYP2D6, codeine converted to morphine faster -> greater risk of AE

Question 8

AE of dextromethrophan

Answer 8

most potent non-opioid anti-tussives

• CNS: drowsiness, dizziness
  insomnia, excitement, nervousness at higher dose
  -GIT effects
  potential for abuse at higher dose (dissociative anaesthetic like effect)

Question 9

properties of diphenhydramine

Answer 9

MOA: antihistamine
(used as anti-tussive and anti-histamine)

no risk of addiction

AE:
sedative -> cross BBB

anticholinergic effects -> dry mouth, urinary retention, tachycardia

alpha adrenergic antagonism: hypotension, dizziness, reflex tachycardia
*1st gen antihistamines have ANS effect because block both alpha adrenergic and cholinergic receptors

Question 10

types of drugs to use for productive cough

Answer 10

expectorants like guaifenesin
mucokinetics
mucolytics

Question 11

MOA of guaifenesin

Answer 11

promote coughing by increasing fluid in airways to stimulate more coughing

Question 12

AE of guaifenesin (expectorant)

Answer 12

GIT disturbance
nausea

Contrindication
cannot for <2
caution for <6

Question 13

impt thing to take note for guaifenesin

Answer 13

must take enough fluid to make secretions less viscous to increase secretion of fluids into airways
+ protect kidney function (kidney stones reported on overdose)

Question 14

example of mucokinetic

Answer 14

bromhexine ->active metabolite is ambroxol

Question 15

MOA of bromhexine

Answer 15

• promote mucus clearance by stimulating surfactant production to prevent mucus from sticking
• local anaesthetic by blocking voltage gated Na channel to alleviate sore throat
• anti inflammatory

Question 16

AE of bromhexine

Answer 16

allergic reaction
cutaneous AE
Contraindication
cannot use < 2, caution <6
history of peptic ulcer disease and asthma

Question 17

example of mucolytic

Answer 17

acetylcysteine
carbocisteine (not for patients with peptic ulcer disease)

Question 18

MOA of acetylcysteine

Answer 18

free sulphydryl group open disulfide bonds in mucoproteins

break down mucus -> decrease mucus viscosity

-> help mobilise and clear mucus from airways (enable productive cough)

Question 19

AE of mucolytics

Answer 19

bronchospasm
anaphylaxis
GIT effects

Contraindication
elderly/ those with severe respiratory insufficiency
asthma (bronchospasm)

Question 20

thing to take note of when taking anti-histamines

Answer 20

avoid taking with anti-depressants (CNS depressants) because can lead to respiratory depression

Question 21

types of drugs to give for rhinorrhoea

Answer 21

mucoregulator
mast cell stabiliser
H1 antihistamines
nasal corticosteroids (anti-inflammatory)

Question 22

example of mucoregulator

Answer 22

ipratropium

Question 23

MOA of mucoregulator

Answer 23

decrease mucus hypersecretion from goblet cells and submucosal glands

*not for acute cough and cold but reserved for more severe cases of rhinorrhoea
- inhaled bronchodilator for subacute/chronic cough (Eg post infection persistent cough)

Question 24

AE of mucoregulator

Answer 24

unpleasant taste
dry mouth
urinary retention in elderly (elderly more sensitive to AE -> urinary retention sign that too much ipratropium enter systemic circulation)

Question 25

example of mast cell stabiliser

Answer 25

cromoglicic acid

Question 26

MOA of mast cell stabiliser

Answer 26

PK: intranasal control Cl- channels to inhibit cellular activation - decrease mast cell degranulation induced by IgE mediated FceRI cross linking -decreased secretion of inflammatory mediators - increase annexin A1 (anti-inflammatory mediator) -> inhibit prostaglandin and leukotriene production

Question 27

AE of cromoglicic acid

Answer 27

nasal and throat irritation dry mouth cough unpleasant taste

Question 28

types of H1 antihistamines

Answer 28

1st gen: Dont cook the pig Diphenhydramine Chlorpheniramine Tripolidine Promethazine 2nd gen: (30% sedation) cetrizine -> levocetirizine (no sedation) loratadine -> desloratadine fexofenadine

Question 29

MOA of H1 antihistamines

Answer 29

reduce inflammation and nasal secretions by blocking effects of histamine (vasodilation and degranulation of mast cells)

Question 30

thing to take note for mucolytic

Answer 30

strong sulphur smell and taste which can affect patient compliance

Question 31

why is nasal corticosteroids administered intranasally

Answer 31

intranasal to reduce risk of systemic distribution and systemic AE

Question 32

example of nasal corticosteroids

Answer 32

fluticasone -> rose water scent mometasone

Question 33

MOA of nasal corticosteroids

Answer 33

increase expression of anti-inflammatory genes (eg annexin A1) decrease pro-inflammatory genes (eg Cox-2) decrease inflammation -> decrease congestion and mucus secretion

Question 34

AE of nasal corticosteorids

Answer 34

nasal throat dryness and irritation

Question 35

what causes nasal congestion

Answer 35

part of the inflammatory response - decrease sympathetic vasoconstriction of submucosal blood vessel - increase parasympathetic stimulation of mucus secretion

Question 36

types of decongestants

Answer 36

nasal corticosteroids adrenergic agonist

Question 37

direct adrenergic agonists

Answer 37

alpha agonist: phenylephrine non-selective: oxymetazoline, naphazoline

Question 38

MOA of alpha agonist

Answer 38

oral/intranasal more effective alpha adrenoceptors on submucosal blood vessels promote vasoconstriction to counteract vasodialtion occuring as partof inflammatory response + reduce blood supply to nose to reduce activity of secretory cells -> less secretions

Question 39

AE of adrenergic agonists

Answer 39

1. rebound congestion upon withdrawal after prolonged used - compensatory upregulation of parasympathetic system when intranasal adrenergic agonist is stopped -> excess parasympathetic activity continues, promoting mucosecretions 2. CNS stimulation -> if drug enter systemic circulation and cross BBB - more likely to have systemic AE when take orally (restlessness, tremors) 3. CVS stimulation -> adrenergic agonsits can cause vasoconstriction and increase BP

Question 40

can intranasal delivery result in systemic AE

Answer 40

if adminsutered wrongly, drug can be swallowed and exposed to systemic circulation -> cross BBB

Question 41

indirect adrenergic agonist

Answer 41

ephedrine -> more potent so delivered intranasally to reduce systemic AE pseudoephedrine