Treatment of Coughs and Colds 2 Flashcards
What is a cough?
A protective mechanism to remove an irritant or an airway obstruction from the respiratory tract. It can be potentially beneficial and it may be undesirable to suppress it in certain circumstances.
What is an acute cough?
- lasts for 3 weeks or less
- often caused by a cold, allergic rhinitis, acute bacterial sinusitis, asthma, pneumonia, congestive heart failure or Bordetella Pertussis infection
What is a sub-acute cough?
- lasts for 3-8 weeks
- post-infection cough, due to asthma, sub-acute bacterial sinusitis or Bordetella Pertussis infection
What is a chronic cough?
- Lasts for more than 8 weeks
- due to post-nasal drip, allergic rhinitis, vasomotor rhinitis, chronic bacterial sinusitis, asthma (kids), GERD< ACE inhibitors, smoking, physiological causes or habit
What constitutes a mild cough?
Due to airway irritation or inflammation
What constitutes a severe cough?
Persistent and distressing to patient, interfere with patient’s quality of life
What is a productive cough?
- associated with accumulation of secretions, phlegm and mucous from the respiratory tract
- protective cough, clear lungs, reduces congestion, reduces the potential sites for bacterial infection
What is a non-productive cough?
- dry and irritating
- due to irritation of mucous membranes in upper respiratory tract or post nasal drip or tracheitis
What 3 components are involved in the cough reflex?
- Cough centre in CNS (medulla)
- Cough receptors in URT (vagus and afferents to cough center)
- Diaphragm, abdominal and intercostal muscles
How should a cough related to bacterial infection be treated?
Antimicrobial agent
How should a cough related to bronchospasm be treated?
Bronchodilator
How should a cough be treated if there is no bacterial infection or bronchospasm?
Simple cough linctus or other demulcent, safe preparation
How should a dry, severe cough that disturbs sleep & is resistant to simple linctus be treated?
Rule out other serious underlying cause and prescribe an antitussive for a few nights
How should a chronic, tenacious, sputum producing cough be treated?
Mucolytic, expectorant
How should a cough following a viral infection be treated?
Bronchodilator aerosol may be useful (e.g. salbutamol or ipratropium bromide)
What are demulcents useful for?
Relieve dry, irritating coughs
How do demulcents work?
Form a protective coat over irritated mucosa
In what form are demulcents available?
As simple syrup or lozenges
- simple linctus (BP), glycerol, honey, cherry, licorice
What do humidifying aerosols and steam inhalers do?
Liquefy nasal secretions, rehydration of irritated oropharyngeal areas
What forms of humidifying aerosols and steam inhalers are available?
Volatile compounds
e.g. Friar’s Balsam, menthol, eucalyptus
What do expectorants do?
Help to expel bronchial secretions
- stimulate production of watery, less viscous mucous
- stimulate vagal system to increase respiratory secretions
What main side effect may be caused by expectorants?
Act indirectly via GIT, cause mild gastric irritation
What drug is an effective expectorant?
Guaiphenesin
Which expectorants are not recommended for clinical use?
Ammonium chloride, ipecacuanha & squill are sometimes included in compound mixtures - such polycomponent mixtures are not recommended for clinical use
What do mucolytics do?
- Reduce sputum viscosity, alter chemical structure of mucous
- Enhances sputum transport by the tracheobronchial cilia
What is important with mucolytics to reduce sputum viscosity?
Adequate hydration is important to reduce sputum viscosity
What are the main 5 mucolytics used in the treatment of cough?
- N-Acetylcysteine
- Bromhexine
- Carbocisteine
- Mesna
- Dornase alfa
What is N-Acetylcysteine used for?
Used in CF and other respiratory conditions that produce viscous mucous
Also used as an antidote in paracetamol poisoning
What is the mechanism of action of N-Acetylcysteine?
Split disulphide bonds in mucoproteins to reduce viscosity of secretions
N-Acetylcysteine: contraindications
Contraindicated in asthmatics and patients with a history of peptic ulceration
What are the adverse effects of N-Acetylcysteine?
Bronchospasm, nausea, vomiting, stomatitis, tinnitus, fever, urticaria, skin rashes, anaphylactic reactions (rare)
What does bromhexine do?
Reduces viscosity of bronchial secretions
Where should caution be used when giving Bromhexine?
Caution in patients with history of symptoms of peptic ulceration, asthma
What are some of the adverse effects of Bromhexine?
GIT effects, allergic reactions
- Transient increase in serum aminotransferase
What does Carbocisteine do?
Reduce viscosity of bronchial secretions
Also used as an antidote in paracetamol poisoning
What are contraindications and cautions for Carbocisteine use?
CI in active peptic ulceration
Caution in patients with a history of peptic ulcer disease and porphyria
What are the adverse effects of Carbocisteine?
Headache, GIT disturbances, skin rashes
What is Mesna used for?
Used topically to reduce sputum viscosity
- ampules, an endotracheal tube or tracheotomy cannula, also nasal spray
What should be done when giving Mesna to avoid complication?
Bronchial aspiration in patients unable to cough or expectorate to avoid pooling of secretions in lung
What is the main adverse effect of Mesna?
Bronchospasm can occur, especially in asthmatics
What is Dornase alfa?
Recombinant human DNase
- administered via IH
What is Dornase alfa used for?
Used in cystic fibrosis patients
What are negative effects of Dornase alfa?
- Voice alteration
- Expensive
What are useful combinations to use for a productive cough?
- Mucolytic and bronchodilator (Bisolvon Linctus)
2. Mucolytic and expectorant
Antitussives: where do they have potential benefit?
Seldom required to suppress a cough
- Non-productive cough may have benefit
- Productive cough: may cause retention of mucous, promote stasis, encourage development of infection (treat with antimicrobials)
What are the main side effects of antitussives?
Constipation and respiratory depression
What is another significant concern with the majority of antitussives?
Abuse and addiction may be a problem
- some cough mixtures contain up to 40% alcohol = aggravates or may lead to alcoholism
When are antitussives contraindicated?
Contraindicated in liver disease
Antitussives come in combination with what other drugs?
Sympathomimetics, antihistamines, expectorants, etc.
Which class of antitussives is centrally acting?
Opioid derivatives
What is the mechanism of action of the opioid derivative antitussives?
Act on cough center
- decreased efferent impulses
= cough suppression
What are the three opioid derivative antitussives?
- Dextromethorphan
- Pholcodine
- Codeine
What effect does Dextromethorphan have on the body?
Direct action on cough center in the medulla
- effect equal to codeine
- no analgesic and little sedative effect
What are the pharmacokinetics of Dextromethorphan?
Oral absorption rapid
Duration: 6 hours
Excreted in urine
In which patients should Dextromethorphan be used with caution?
Asthma, emphysema, liver impairment, respiratory depression
What are adverse effects of Dextromethorphan?
Dizziness, GIT effects
What are the drug interactions with Dextromethorphan?
- Alcohol, benzo’s, phenothiazines, TCA
- Severe reactions with MAOI
- Drugs inhibiting cytochrome P450 2D6
What are the symptoms of Dextromethorphan overdose?
Confusion, excitation, respiratory depression
What is the risk of dependency with Pholcodine use?
Pholcodine is a semi-synthetic derivative or morphine, but it is not metabolized into morphine in the liver
= little if any analgesic or euphoria - not often abused
What are the pharmacokinetics of Pholcodine?
- Rapid absorption after oral administration
- Effect = 4-5 hours
- Long T1/2 - 1x or 2x daily dosing
What is the efficacy of Pholcodine?
At least as effective as Codeine
What are the adverse effects of Pholcodine?
- Nausea and vomiting
- Constipation
- Biliary colic, epigastric pain
What are the adverse effects of Pholcodine when given in high doses?
HIGH DOSES: sedation, paradoxical excitement, ataxia, respiratory depression
What is an important drug reaction with Pholcodine?
Pholcodine cough suppressants have been associated with anaphylaxis in some patients given NMBs during general anesthesia.
- Pholcodine purported as a potent stimulator of IgE production
- IgE had apparent cross-reactivity with suxamethonium (a neuromuscular blocking agent)
= increased incidence in anaphylaxis
For which patients can Codeine be used?
Chronic bronchitis patients, not URTI
What are some of the side effects of Codeine?
Greater SE
- constipation, drowsiness, no analgesia, ABUSE POTENTIAL HIGH
What is a side effect of Codeine that only occurs at high doses?
Increases histamine release
In which age group is Codeine contraindicated?
C/I in children under 2 years of age
Which is the cough suppressants is the most likely to be abused?
Codeine
- be aware of codeine addicts
What is the action of Codeine in the lungs?
Decreases secretions in bronchioles - thickens sputum - decreases ciliary activity
What is the MOA of peripherally acting antihistamines (1st generation)?
Block cholinergic nerve impulses - dry up secretions - mucous plug formation
- dry up nasal secretions
What should peripherally acting antihistamines (1st generation) not be used for?
Not for productive cough or asthmatics
What is important about Promethazine?
Causes sedation
What is important about Chlorpheniramine?
Less sedation
What is important about Diphenhydramine?
Potent antitussive, sedative
What is important about Tripolidine?
Acts for up to 12 hours
What are the side effects of the peripherally acting antihistamines (1st generation)?
Anti-cholinergic SE:
- dry mouth
- urine retention
- constipation
- blurred vision
Which bronchodilators are used in the management of coughs and colds?
- Selective beta-2 adrenoreceptor agonists e.g. Salbutamol
- Methylxanthines e.g. Theophylline
- Ephedrine, indirect acting sympathomimetic
Which bronchodilator is often found in OTC preparations?
Ephedrine
Where is chest physiotherapy useful?
Chest physiotherapy is very useful especially in chronic bronchitis, cystic fibrosis & recovery phases of severe chest infection
