NAC in COPD

Q: Inhaled N-acetylcysteine (NAC) is used as a mucolytic in COPD patients due to its quick effect within minutes. What's its drawback?

Answer: Bronchospasm

NAC can sever disulfide bonds in mucoproteins and DNA, reducing mucus viscosity. It also has an antioxidant property. It starts working within a minute and lasts up to 10 minutes.

That said, inhaled NAC may induce fatal bronchoconstriction, so it should be used with caution. It's recommended to add a bronchodilator with it.

Oral NAC largely bypasses this direct effect. The dose is 600 mg twice daily.

#pulmonary

References:

1. De Benedetto F, Aceto A, Dragani B, Spacone A, Formisano S, Pela R, Donner CF, Sanguinetti CM. Long-term oral n-acetylcysteine reduces exhaled hydrogen peroxide in stable COPD. Pulm Pharmacol Ther. 2005;18(1):41-7. doi: 10.1016/j.pupt.2004.09.030. Epub 2004 Dec 8. PMID: 15607126.

2. Sadowska AM, Verbraecken J, Darquennes K, De Backer WA. Role of N-acetylcysteine in the management of COPD. Int J Chron Obstruct Pulmon Dis. 2006;1(4):425-34. doi: 10.2147/copd.2006.1.4.425. PMID: 18044098; PMCID: PMC2707813.

3. Rhee CK, Lim SY, Lee WY, et al. The effect of nebulized N-acetylcysteine on the phlegm of chronic obstructive pulmonary disease: the NEWEST study. BMC Pulm Med 2024; 24:434.