Cystic fibrosis is a genetic disorder which mainly affects the lungs. Chest infections recur in people with cystic fibrosis due to a build up of thick sputum (phlegm) in the air passages. Several treatments, including thiol derivatives, aim to loosen this sputum and so improve lung function and reduce the frequency of chest infections. Thiol derivatives may be either nebulized (breathed in) or oral (by mouth). They have been shown to help in other lung conditions, such as chronic obstructive pulmonary disease. This review aims to find out if there is enough evidence to recommend the nebulized or oral thiol derivatives for people with cystic fibrosis. We included eight trials; three assessed the effect of nebulized thiol derivatives. Of the nebulized studies, one compared 20% n-acetylcysteine to 2% n-acetylcysteine; another compared sodium-2-mercaptoethane sulphonate to 7% hypertonic saline; and the other compared glutathione to 4% hypertonic saline. Nebulized thiol derivatives were generally well-tolerated with no major adverse effects. However they showed no significant improvements in any of our outcome measures.
Five included studies assessed the effects of oral thiol derivatives.Three of these studies compared oral n-acetylcysteine to placebo; one compared oral n-acetylcysteine, oral ambroxol and placebo; and one compared oral carbocysteine and oral ambroxol (no placebo). None of the studies showed an overall significant benefit in any of the outcome measures of this review. Oral thiol derivatives were generally well-tolerated with no major adverse effects.
In summary, the studies included in the review did not provide any evidence that nebulized or oral thiol derivatives were either beneficial or harmful to people with cystic fibrosis. Further research investigating the effects of thiol derivatives in people with cystic fibrosis is required before their use can be recommended.