L12 Respiratory Pharmacology Flashcards
What are the two types of cough?
Useful cough:
- Productive cough i.e. produces sputum to expel secretions.
- This is found in chest infections.
- Should not be suppressed
Non-useful cough:
- Persistent and non-productive cough. It is a dry cough. It has no benefit.
- Should be suppressed using antitussives.
- It is commonly associated with asthma, oesophageal reflux, sinusitis and psychogenic cough.
What is the mechanism of a cough?
The cough receptors or lung irritant receptors are stimulated. This sends an impulse via the vagus nerve to the medulla which results in a cough.
What treatment can be given in terms of the afferent side of a dry cough?
Afferent treatments include reducing stimuli e.g. stopping smoking. Treatments include:
- Linctuses which coat the mucosa with a protective layer and sooth the inflammation.
- Steam can be used to warm and sooth the inflamed areas below the larynx. You can add Menthol and Tinture Benozin to the steam to enhance this.
- Nebulised local anaesthetics.
What treatment can be given in terms of the efferent side of a dry cough?
- Opiods such as codeine, methadone and pholcodine
- Non-opiods such as dextromethorphan and noscapine
- Sedatives such as Diphenhydramine and cholorpheniramine
Give examples of expectorants.
Expectorant: A medication that helps bring up mucus and other material from the lungs, bronchi, and trachea. An example of an expectorant is guaifenesin, which promotes drainage of mucus from the lungs by thinning the mucus, and also lubricates the irritated respiratory tract.
What type of drugs are:
Acetyl cysteine, carbocystine and mecysteine and recombinant human DNAse?
Mucolytics
A 46 year old man is admitted to A&E with severe cough. He is producing yellow sputum and has fever. What is the best course of treatments?
Antibiotics
What are the most common causes of chronic cough?
- Bronchial asthma
- Upper airways cough syndrome
- COPD
- Gastroesphageal reflux disease
What are the types of bronchial asthma?
- Allergy induced asthma
- Intrinsic asthma
- Exercise Asthma
- Asthma associated with COPD due to the obstruction or destruction of the elastic tissue in the airways
What is the mechanism of allergy induced asthma?
- On exposure to the antigen, the antigen binds to the receptor in the lymphocytes activating them.
- The activation of Th causes the activation of B cells. Plasma cells can then produce IgE antibodies.
- IgE antibodies combine with mast cells activating them. This leads to the release of mediators such as histamine and other mediators which activate the arachidonic acid pathway leading to secretions of leuokines and prostaglandins.
- This leads to inflammation of the mucosa, swelling fo the mucosa and contrition of the smooth muscle leading to bronchoconstriction.
What are corticosteroids?
Corticosteriods can be used to reduce bronchial hyperactivity. Steroids are anti-inflammatory. They inhibit the influx of inflammatory cells after response. They reduce microvascular leakage and so decrease oedema. They inhibit the release of mediators such as cytokines. They inhibit the cyclooxygenase enzyme. They cause reduce bronchial activity. Steroids take time to work. They do not have a role in acute asthma. They reduce asthma exacerbations and so not relax smooth muscles.
Give examples of oral steroids?
Oral steroids can also be given: Prednisone, Methylprednisolone, Betamethasone and Triamcinolone.
What are the side effects fo long term steroid therapy? How can they be prevented?
Long term steroid therapy is associated with side effects
Gradual tapering is required.
▪ Iatrogenic Cushing’s syndrome
Diabetes, hypertension, Peptic ulcer, psychosis, delayed puberty
▪ Inhibition of hypothalamic pituitary axis
Other side effects
▪ Oropharyngeal candidiasis (on regular use)
▪ Hoarseness : direct effect vocal cords (in high doses)
▪ Cyclesonide: prodrug, less side effects
What drugs can be used to dilate narrowed bronchi?
- Sympathomimetics to mimic neurotransmitters
- Methylxanthines to direct acting bronchodilators
- Anticholinergics to block constrictor transmitters
Give examples of mast cell stabilisers? What are their properties?
Mast cell inhibitors prevent the release of mediators within mast cells.
Examples include:
Cromolyn sodium and Nedocromil sodium.
They are administered by inhalation but are very poorly absorbed. They are therefore not very effective. They have no effect on bronchial smooth muscle and so no use in bronchospasm. They should only be taken prophylactically.
