Various functions of ambroxol and N-acetylcysteine.
1. Expectorant effect
Ambroxol: It reduces sputum viscosity by increasing serous fluid secretion. It also enhances ciliary beating, promoting the secretion and release of alveolar surfactant, thereby facilitating sputum excretion.
NAC: Its molecular structure contains sulfhydryl groups, which can break the disulfide bonds between mucin complexes, reduce the viscosity of sputum, and make it easier for patients to cough up sputum.
2. Antioxidant Effect
Ambroxol: It activates the glutathione system in cells. The synthesis of glutathione in cells will be promoted, which can remove active peroxidation products. It has a destructive effect on oxygen free radicals.
NAC: Its molecular structure contains sulfhydryl groups. These groups can interact with hypochlorous acid, hydroxyl radicals, hydrogen peroxide and other substances to directly scavenge oxygen free radicals. Binding to glutathione peroxidase reduces the production of lipid peroxides. It can also serve as a precursor for the synthesis of glutathione, thereby maintaining sufficient glutathione levels in lung tissue and protecting cells from damage by cytotoxins.
3. Anti-inflammatory effects
Ambroxol: It inhibits the release of inflammatory factors such as histamine and leukotrienes by eliminating free radicals, which can effectively inhibit the inflammatory effects of white blood cells and macrophages.
NAC: It acts as an antioxidant. It inhibits oxidative stress-mediated inflammation. It can reduce the damage of oxidative stress to lung tissue and inhibit airway remodeling. It can also reduce the impact of inflammation on lung function.
4. Antibacterial effect
Ambroxol: When ambroxol used in combination with antibiotics such as amoxicillin, cefuroxime and erythromycin, it can increase the concentration of these drugs in lung tissue. This will increase the bacterial clearance rate of antibiotics in the lungs, thereby reducing the duration and dosage of antibiotics.
NAC: It reduces the adhesion of Haemophilus influenzae and Streptococcus pneumoniae to oropharyngeal epithelial cells, making it more difficult for the bacteria to grow in the airways. It also inhibits the replication of influenza virus and respiratory syncytial virus.
5. Other
NAC: It is used as an antidote for acetaminophen poisoning and hemorrhagic cystitis caused by cyclophosphamide.
Indications for ambroxol and N-acetylcysteine.
1. COPD
GOLD Guidelines: For patients with COPD not using ICS, routine use of expectorants and antioxidants can reduce the frequency of acute exacerbations of COPD and modestly improve health status.
NAC: It has strong expectorant, anti-inflammatory, and antioxidant properties. It can reduce sputum viscosity and promote expectoration. It can also improve cough, sputum production, and associated dyspnea in COPD patients. It can also reduce oxidative stress, decrease the frequency of acute exacerbations, and reduce bacterial colonization in the respiratory tract. It improves the patient's quality of life. Therefore, NAC is more suitable for COPD patients than ambroxol.
2. Bronchiectasis
Various pathogenic factors can lead to increased secretions in the airways of patients with bronchiectasis. The patient's airway clearance will be impaired and causing sputum accumulation. This can lead to airway obstruction and recurrent bacterial infections.
Guidelines recommend that patients with bronchiectasis who have difficulty expectorating and whose symptoms cannot be controlled by conventional airway clearance can use mucosal active drugs for long-term treatment (> 3 months). The current research results show that bromhexine combined with antibiotics or nebulized NAC can help clear sputum. Ambroxol, the active ingredient in bromhexine, can help improve lung function and shorten hospital stays in patients with bronchiectasis and infection.
3. Idiopathic interstitial pneumonia
Patients with idiopathic interstitial pneumonia mainly present with dry cough and progressively worsening dyspnea. Conventional expectorants do not seem to be of much use for patients with idiopathic interstitial pneumonia.
As a glutathione precursor, NAC can increase glutathione levels in the lining fluid of lung epithelial cells, exerting an antioxidant effect. NAC monotherapy has a certain effect on some patients with idiopathic interstitial pneumonia with TOLLIP gene phenotype, and NAC combined with pirfenidone is superior to pirfenidone alone in the treatment of patients with intermediate and late stage idiopathic interstitial pneumonia. Patients already receiving NAC monotherapy can continue maintenance therapy.
4. Bronchial asthma
There is limited research evidence on the effects of ambroxol and NAC in the treatment of patients with bronchial asthma. Currently, there is insufficient evidence to support the benefit of expectorant therapy in patients with asthma.
5. Acute respiratory distress syndrome
Currently, there is insufficient evidence to support the use of antioxidants such as NAC in the treatment of acute respiratory distress syndrome. Expectorants are also not recommended as a routine treatment for acute respiratory distress syndrome.
