COUGH

	
Cough is a defensive reflex that is stimulated by the irritation of the 
respiratory mucosa in the lungs,the trachea or the pharynx. It is 
co-ordinated by the central cough centre of the medulla (Mason, 2002).
It is triggered by either mechanical or chemical stimulation of afferent
nerve endings located in the bronchial mucosa (Karlsson and Fuller, 1999).
This irritation manifests itself as impulses, which are propagated via the
vagus nerve with pathways ascending from the cough control centre in the 
brainstem to the cerebral cortex.  From the cortex, signals make their 
way, via descending pathways, to the cough control centre in the brainstem
to the respiratory muscles to initiate cough (Eccles, 1996).
       
Mediators of inflammation associated with URTI, such as bradykinin, are 
known to stimulate sensory nerve endings perhaps in the larynx and trachea
to initiate cough (Eccles, 1996).

Derived from Eccles, 1996

	
Cough can be classified as –

	ACUTE - 

		Acute cough lasts for 2 weeks or less and is usually caused
		by viral infections of the upper respiratory tract (URT) 
		(Mason, 2002).

	CHRONIC - 

		Chronic cough lasts for longer than that and is associated 
		with post-nasal drip syndrome (PNDS), secondary to a cold,
		sinusitis bronchitis, asthma, gastro-oesophageal reflux 
		disease or congestive heart failure (CHF) (Mason, 2002).

Patients with lung disorders such as asthma, emphysema, lung cancer and 
tuberculosis may also experience chronic cough. Angiotensin-converting 
enzyme (ACE) inhibitors can cause a dry, persistent cough in up to 10%
of patients (Mason, 2002).

TYPES OF COUGH
Cough can be described as either –

		Productive (ie. Chesty, producing sputum) 

			Productive cough is usually associated with 
			infection and inflammation of the lower 
			respiratory tract (Eccles, 1996)
 
			Patients suffering from productive cough should be 
			encouraged to cough, and to expel the secretions 
			from the LRT, thereby preventing impairment of 
			breathing and risk of infection (Mason, 2002)

		Non-productive (ie. Dry, with no sputum)

			Associated with acute upper respiratory tract 
			infection (URTI) (Eccles, 1996)
			
			Non-productive cough serves no useful physiological
			purpose.  It is generally caused by a viral 
			infection, although asthma, ACE inhibitors and lung
			cancer may be possible causes (Mason, 2002)

WHICH MEDICATION?
Drug therapy of cough is dependent on the type of cough present. 

		Productive coughs should be managed with expectorants 
		(pro-tussive agents) such as guanphenesin or mucolytics
		such as bromhexine

		Non-productive coughs should be treated with cough 
		suppressants (anti-tussive agents) such as dextromethorphan
		or the opioids – dihydrocodeine and pholcodine. 

	
Protocols for Use
A patient comes into the pharmacy requesting for some cough products.

Questions to ask patient:
-	Is it for you?
-	Is it for child/ adult?
-	What symptoms are you having?
-	Are you experiencing high temperature for 3 days or more?
-	Have you tried anything for the cough? Did it work?
-	Have you seen a doctor for it?
-	Do you know what may have caused the cough?
-	Do you know what makes the cough better or worse?
-	Are you currently taking any other medications?
-	Are you pregnant or breastfeeding?
-	Do you have any other medical conditions?