Chronic cough is a common symptom but only a fraction of patients seek medical attention. Addressing the causes of chronic
cough may lead to control of cough; however, this approach is not always successful since there is a certain degree of failure
even when the cause(s) of cough are adequately treated; in idiopathic cough, there is no cause to treat. Persistent cough
may be associated with deterioration of quality of life, and treatment with cough suppressants is indicated. Currently available
cough suppressants include the centrally acting opioids such as morphine, codeine, and dextromethorphan. Peripherally acting
antitussives include moguisteine and levodropropizine. Early studies report success in reducing cough in patients with chronic
bronchitis or COPD; however, a carefully conducted study showed no effect of codeine on cough of COPD. Success with these
cough suppressants can be achieved at high doses that are associated with side effects. Slow-release morphine has been reported
to be useful in controlling intractable cough with good tolerance to constipation and drowsiness. There have been case reports
of the success of centrally acting drugs such as amitryptiline, paroxetine, gabapentin, and carbamezepine in chronic cough.
New opioids such as nociceptin or antagonists of TRPV1 may turn out to be more effective. Efficacy of cough suppressants must
be tested in double-blind randomised trials using validated measures of cough in patients with chronic cough not responding
to specific treatments. Patients with chronic cough are in desperate need of effective antitussives that can be used either
on demand or on a long-term basis.
Keywords Cough suppressants - Chronic cough - Codeine - Morphine - Dextromethorphan - Moguisteine