Abstract
Background
Promoting the absorption of COVID-19 pneumonia is critical for reducing pulmonary sequelae and improving prognosis. This study aimed to evaluate the efficacy and safety of nebulized unfractionated heparin, acetylcysteine, budesonide, and ipratropium bromide (HABIT) in hospitalized patients with COVID-19 pneumonia.
Methods
This single-center, open-label, randomized, parallel-group trial was conducted at a tertiary hospital in China. Participants were randomized 1:1 to receive either standard of care (SOC) or SOC plus nebulized HABIT. The HABIT protocol included daily quadruple nebulization for seven days, comprising 6000 units heparin sodium, 2 mg budesonide, 0.3 g acetylcysteine, and 0.5 mg ipratropium bromide. The primary outcome was the change in lung lesions assessed by chest CT scans on admission (Day 0) and post-treatment (Day 8).
Results
A total of 74 patients were randomized to the HABIT group (n = 37) or the control group (n = 37). Four patients per group were excluded during follow-up, leaving 66 patients for final analysis. Baseline CT scores were comparable between groups (10.55 ± 3.11 vs. 10.76 ± 2.85, p = 0.774). Post-treatment, the HABIT group showed significantly lower mean CT scores (6.6 ± 2.98 vs. 8.69 ± 2.53, p = 0.003) and greater lesion absorption (37.5% vs. 20%, p < 0.001) compared to controls. The HABIT group also exhibited a non-significant improvement in PaO2/FiO2 (75.27 vs. 51.23, p = 0.113). Safety analysis showed no significant differences in activated partial thromboplastin time or serious adverse events.
Conclusion
The adjunctive HABIT regimen demonstrates favorable efficacy and safety in treating COVID-19 pneumonia.
Trial registration
The clinical trial was registered with the Chinese Clinical Trial Registry (ChiCTR; www.chictr.org.cn; ID: ChiCTR2300073871) on July 24, 2023. Ethical approval was valid from May 2023 to May 2025.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12890-025-03824-5.
Keywords: Corona virus disease 2019 (COVID-19), Viral pneumonia, Pathophysiology, Nebulization therapy, Unfractionated heparin, CT severity scores
Introduction
Since the beginning of the COVID-19 pandemic, more than 776 million confirmed cases and nearly 7 million deaths have been reported worldwide [1]. COVID-19 has a wide spectrum of clinical severity, categorizing as mild (81%), severe (14%), or critical (5%) [2]. Patients with severe illness may experience dyspnea and hypoxemia following the onset of the disease, which can rapidly progress to acute respiratory distress syndrome (41.8%), a predominant cause of hospitalization and mortality [3–5]. The lungs are the primary target of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and may have long-term damage after infection [6–8]. For example, chest CT scanning revealed persistent irregular lines, traction bronchiectasis, subpleural lines, and ground-glass opacity in COVID-19 survivors at 3 years after discharge [7]. In another study, more than one-third hospitalised COVID-19 survivors continued to have persistent radiological lung abnormalities at 3-year follow-up, which were associated with respiratory symptoms and reduced diffusion capacity [9]. Therefore, early intervention in COVID-19 pneumonia to facilitate lung lesion absorption is crucial for reducing pulmonary sequelae and improving patient prognosis.
Currently, antiviral agents, prevaccination, supportive care and oxygen therapy remain key management elements of COVID-19 [10, 11]. Furthermore, local nebulization treatments are emerging as safe and effective adjunctive therapies for COVID-19 pneumonia, as it facilitates higher dosages, enhance local efficacy, reduce the risk of adverse drug reactions, and demonstrate greater overall effectiveness [12, 13]. The pathophysiology of lung injury associated with COVID-19 pneumonia is characterized by diffuse alveolar damage, hyperinflammation, coagulopathy, hyaline membranes, and microvascular thrombosis [14, 15]. Based on these complex pathogenesis processes, drug nebulization for COVID-19 pneumonia with different mechanisms of action have been investigated, including anticoagulants [15–20], antioxidants [21–23], corticosteroids [24–26], and bronchodilators [27, 28]. Studies have shown that, in addition to standard treatment, nebulised heparin, N-acetylcysteine, budesonide, and ipratropium bromide, when used individually, are beneficial for reducing mortality, suppressing inflammation levels, improving oxygenation, reducing the occurrence of severe respiratory failure, and shortening the length of hospital stay in COVID-19 patients [15, 17–19, 21, 24, 25, 29]. However, the high heterogeneity of existing nebulization protocols limits their widespread clinical application.
To date, there are no published reports on the combined nebulization of unfractionated Heparin, Acetylcysteine, Budesonide and Ipratropium bromide (HABIT) for the treatment of hospitalised patients with COVID-19 pneumonia. Of note, it is a common practice to combine nebulised heparin, N-acetylcysteine, budesonide and ipratropium bromide in smoke inhalation-induced lung injury, which shared similar pathophysiology with COVID-19 pneumonia, including diffuse alveolar damage, hyperinflammation, coagulopathy, hyaline membranes and microvascular thrombosis [30–33]. Given these properties, we hypothesized that the combined nebulization heparin, N-acetylcysteine, budesonide, and ipratropium bromide might be a potential adjuvant therapy against COVID-19 pneumonia. This combined therapy is referred to as HABIT. Therefore, we conducted this prospective, single-center, open‐label, randomized, parallel group study to evaluate the therapeutic effect and safety of HABIT nebulization therapy in COVID‐19 patients.
Methods
Study design
This trial was an investigator-initiated, single-center, open-label, randomized, parallel group study conducted at Daping Hospital, ChongQing, China between August 1 st, 2023, and March 1 st, 2024. The study protocol was reviewed and approved by the Ethics Committee of Daping Hospital, Army Medical University, following the Declaration of Helsinki and good clinical practice guidelines. This study was registered with the Chinese Clinical Trial Registry (ChiCTR2300073871). All patients provided written informed consent. The study was conducted and reported following the recommendations of the Consolidated Standards of Reporting Trials (CONSORT) statement.
Participants
Hospitalised patients with moderate or severe COVID-19 pneumonia were screened for eligibility. Inclusion criteria were as follows: ages 18 to 80 years, positive result on a SARS-CoV-2 Reverse Transcription-Polymerase Chain Reaction test from a nasopharyngeal swab, presence of imaging features characteristic of COVID-19 pneumonia by chest CT, and within 5–7 days since the onset of symptoms. The clinical classification is based on the Diagnosis and Treatment Protocol for COVID-19 Patients, Trial Version 10, released by National Health Commission of People’s Republic of China. The Exclusion criteria included symptoms of hemoptysis, known hypersensitivity to heparin, acetylcysteine, budesonide, and ipratropium bromide or related compounds, signs indicating imminent ICU admission, and presence of coagulation dysfunction (meeting any of the following criteria): coagulation function tests showed a hypocoagulable state; platelet count < 50 × 109/L; hemorrhage in the skin or other organs.
Intervention
All patients received standard care regimens based on the Diagnosis and Treatment Protocol for COVID-19 Patients (Trial Version 10), which included antiviral, antibiotics, intravenous corticosteroids (dexamethasone, methylprednisolone), and anticoagulation (typically, enoxaparin sodium intravenous, IV), either in prophylactic or therapeutic doses. In addition to standard care, the HABIT groups received nebulization treatment through a nebulizer (KST-Y, China) every 6 h for 7 consecutive days starting on the second day of admission. Initially, 6000 units of heparin sodium diluted in 3 ml of 0.9% saline were administered, followed by a nebulised mixture containing 2 mg of budesonide, 0.3 g of N-acetylcysteine, and 0.5 mg of ipratropium bromide, with a filling volume of 9 ml, after a five-minute interval. The control group could be treated with nebulization without heparin at the discretion of the respiratory physicians.
Procedures
Eligible patients were randomly assigned (1:1) to the HABIT group or the control group. The randomization code was generated by the Department of Statistics, Army Medical University by a random number table. All patients underwent chest CT examinations in a supine position on admission (Day 0) and post-treatment (Day 8). CT scan examinations were performed with a 64-row detector CT scanner (GE MEDICAL SYSTEMS, LightSpeed VCT) and reviewed by two radiologists with 5 and 10 years of experience in thoracic imaging. To quantify the extent of lung lesions, a thin‐section CT involvement score was assigned based on all abnormal areas as previously reported. Briefly, each of the five lobes of the lung was assigned a visual score: score 0, no involvement; score 1, less than 5% involvement; score 2, 5-25% involvement; score 3, 26-49% involvement; score 4, 50-75% involvement; and score 5, greater than 75% involvement. There was a score of 0–5 for each lobe, with a total possible score of 0-25 [34].
We collected the following baseline demographic and clinical data: age, sex, smoking history, symptoms, comorbidities, respiratory support level (type and fraction of inspired oxygen, FiO2), PaO2/FiO2(PFO), hematological and biochemical parameters findings, Chest CT images, other treatments reflecting the standard of care in use during the time of the trial, including the use of any prophylactic or therapeutic anti-coagulant treatment, intravenous corticosteroids. We also collected the following treatment-related information: nebulised unfractionated heparin, acetylcysteine, budesonide, and ipratropium bromide dose (daily and cumulative), treatment duration, administration technique (including nebulization device), and skipped doses and reasons for this.
Outcomes
Primary outcomes were measured in this study: the extent of absorption of lung lesions at the end of treatment. Chest CT scans were conducted at baseline (day 0) and at the end of treatment (day 8), with semi-quantitative scoring employed to assess lesion resolution. Secondary outcomes included changes in the PFO and days of hospitalization. Safety outcomes assessed included baseline and peak activated partial thromboplastin time, incidence of epistaxis, blood-tinged sputum, pulmonary bleeding, gastrointestinal hemorrhage, major bleeding, heparin-induced thrombocytopenia, anaphylaxis, bronchospasm, and respiratory deterioration during or immediately after administration of inhaled nebulised HABIT or any other adverse events. Additionally, we monitored ICU admission, mortality, dynamic changes of hematological and biochemical parameters before and after treatment.
Statistical analyses
The sample size for this study was based on a comparison of lung lesions absorption rates at Day8 between both groups. Previous studies have indicated that after 7 to 10 days of routine treatment for COVID-19 pneumonia, chest CT scores demonstrate a lung lesion absorption rate of 15–20% [35–37]. On the basis of routine treatment, nebulized adjunctive therapy can effectively promote the absorption of COVID-19 pneumonia [15, 21]. We hypothesized that adjunctive treatment with HABIT nebulization therapy could increase the absorption rate from 15 to 45%. A difference test is conducted, where the significance level (α) is set at 0.05 and the power at 0.80. The sample size per group is calculated to be 33. Accounting for a 10% loss to follow-up rate, it was determined that 37 patients would be included in the HABIT group and control group, respectively.
The Shapiro-Wilk test was used to test data normality. Normal distributed data were reported as mean and standard deviation for continuous variables and percentage (%) for categorical characteristics. Non-normal distributed continuous data were reported as median and interquartile range. Comparison of demographic characteristics and clinical variables between two study groups were assessed using χ2 Yates’s continuity correction or Fisher’s exact tests for categorical variables and Mann-Whitney u test for non-normally distributed continual variables. To compare symptoms as categorical variables, we used the χ2 test or Yates’s continuity correction between two groups and the McNemar test within groups pre and postintervention. The independent samples T-test was used for compare normal distributed continuous variables between groups and within groups pre and postintervention. Mann-Whitney u test and Wilcoxon Ranks test was used for comparing the non‐normal distributed continuous variables between groups and within groups pre and postintervention. All statistical analysis was carried out using SPSS version 26, and GraphPad Prism version 9.5. In all analyses, p Values less than 0.05 were considered significant.
Results
Participants and baseline characteristics
From Aug 2023 to Mar 2024, 74 out of 86 patients with COVID-19 pneumonia referred to Daping Hospital in Chongqing, China, met the inclusion criteria and were randomly assigned into the HABIT group (n = 37) or the control group (n = 37). Four patients in each group were eliminated during follow-up, and 66 patients completed the study and were included in the analysis. Figure 1 shows the flowchart of participants through each stage.
Fig. 1.
Flow chart of the study
The baseline and clinical characteristics of all patients are summarized in Table 1. Of 74 participants, the median (IQR) age was 62 (53–71) years, 59.5% were male, and hypertension (24.3%), diabetes (18.9%) and cardiovascular diseases (17.6%) were the most common comorbidities. No significant differences were observed between the two groups in terms of age, gender, body mass index, smoking status, or comorbidities. Upon admission, the three most common symptoms in total participants were cough (89.2%), fever (78.4%), and sputum (75.7%). There were no differences in the frequency of symptoms between the two groups. All patients in the study received standard of care regimens based on the Diagnosis and Treatment Protocol for COVID-19 Patients (Trial Version 10). There was no significant difference in the proportion of patients receiving oxygen therapy (p = 1.000), antiviral therapy (p = 0.708), antibiotics (p = 1.000), and intravenous corticosteroids therapy (p = 0.06) between the two groups. The control group had a higher proportion of patients receiving systemic anticoagulant therapy (43.2% vs. 8.1%, p = 0.001) compared to the HABIT group. Regarding the clinical outcomes, there was no significant difference in the length of hospital stay between the two groups (p = 0.399). During hospitalization, no patients were transferred to ICU or died.
Table 1.
Baseline and clinical characteristics
| Total (N = 74) |
HABIT group (N = 37) |
Control group (N = 37) |
P value | |||
|---|---|---|---|---|---|---|
| Age, years | 62 (53, 71) | 61 (51, 69) | 64 (54, 71) | 0.449a | ||
| Sex | ||||||
| Male | 44 (59.5%) | 22 (59.5%) | 22 (59.5%) | 1.000b | ||
| Female | 30 (40.5%) | 15 (40.5%) | 15 (40.5%) | |||
| BMI, kg/m2 | 24 (22, 26) | 24 (23, 27) | 24 (22, 25) | 0.182a | ||
| Smoking status | ||||||
| Current/Former smoker | 15 (20.3%) | 7 (18.9%) | 8 (21.6%) | 0.772b | ||
| Never smoker | 59 (79.7%) | 30 (81.1%) | 29 (78.4%) | |||
| Comorbidities | ||||||
| Hypertension | 18 (24.3%) | 7 (18.9%) | 11 (29.7%) | 0.278b | ||
| Diabetes | 14 (18.9%) | 5 (13.5%) | 9 (24.3%) | 0.235b | ||
| Cardiovascular diseases | 13 (17.6%) | 4 (10.8%) | 9 (24.3%) | 0.222c | ||
| COPD | 2 (2.7%) | 0 | 2 (5.4%) | 0.493d | ||
| Other | 4 (5.4%) | 4 (10.8%) | 0 | 0.115d | ||
| Symptoms upon admission | ||||||
| Cough | 66 (89.2%) | 34 (91.9%) | 32 (86.5%) | 0.708c | ||
| Fever | 58 (78.4%) | 31 (83.8%) | 27 (72.9%) | 0.259b | ||
| Sputum | 56 (75.7%) | 31 (83.8%) | 25 (67.6%) | 0.104b | ||
| Fatigue | 26 (35.1%) | 10 (27.0%) | 16 (43.2%) | 0.144b | ||
| Dyspnea | 11 (14.9%) | 5 (13.5%) | 6 (16.2%) | 0.744b | ||
| Diarrhea | 3 (4.1%) | 2 (5.4%) | 1 (2.7%) | 1.000c | ||
| Treatments during hospitalization | ||||||
| Oxygen supply | 71 (95.9%) | 36 (97.3%) | 35 (94.6%) | 1.000c | ||
| Nasal cannula | 69 (93.2%) | 36 (97.3%) | 33 (89.2%) | 0.354c | ||
| HFNC | 2 (2.7%) | 0 | 2 (5.4%) | 0.493d | ||
| Antivirals | 66 (89.2%) | 34 (91.9%) | 32 (86.5%) | 0.708c | ||
| Antibiotics | 64 (86.5%) | 32 (86.5%) | 32 (86.5%) | 1.000b | ||
| Systemic anticoagulation | 19 (25.7%) | 3 (8.1%) | 16 (43.2%) | 0.001*c | ||
| Corticosteroids intravenous | 32 (43.2%) | 12 (32.4%) | 20 (54.1%) | 0.060*b | ||
| Hospital stay, days | 9 (8, 12) | 9 (8, 12) | 10 (8, 13) | 0.399a | ||
Data are N (%), or median (IQR)
Abbreviations BMI Body Mass Index, COPD Chronic obstructive pulmonary disease, HFNC High-flow nasal cannula for oxygen therapy
ap Value based on Mann–Whitney u test
bp Value based on χ2 test
cp Value based on Yates’s continuity correction
dp Value based on Fisher exact test
*p < 0.05 considered as significant
Evolution of chest CT findings and chest CT score
In the HABIT group, the most common lung abnormalities on chest CT scans preintervention were ground-glass opacities (n = 33, 100%) and reticulation (n = 16, 48.5%). Posttreatment, the lesions were not completely absorbed, with the proportions remaining unchanged. Similarly, in the control group, the predominant lung abnormalities both pre and postintervention were ground-glass opacities (n = 33, 100%) and reticulation (n = 12, 48.5%). The results of the tomographic evaluations pre and postintervention for both groups are presented in Supplementary Table 1.
The comparison of chest CT scores pre and postintervention between the two groups is shown in Fig. 2. On day 0, both groups had similar mean CT scores (HABIT group vs. control group: 10.55 ± 3.11 vs.10.76 ± 2.85, p = 0.774, Fig. 2A), indicating no significant difference in radiological severity between participants of the two groups. On day 8, the mean score of chest CT was significantly lower in the HABIT group than in the control group postintervention (6.6 ± 2.98 vs. 8.69 ± 2.53, p = 0.003, Fig. 2A). Although there was a significant decrease in CT scores pre and postintervention in both groups, the decrease in the HABIT group was significantly greater than that of the control group [37.5% (28.6%, 50%) vs. 20% (9%, 28.6%), p < 0.001, Fig. 2B]. Representative pre and postintervention chest CT images of two patients from each group are shown in Fig. 2C-D. According to the study protocol, control group patients could receive nebulization without heparin. We categorized the control group into three subgroups based on nebulization regimes: 9 patients received no nebulization, 7 received 1–2 drug nebulization, and 21 underwent combined budesonide, acetylcysteine, and ipratropium nebulization. The pre- to post-treatment CT score change rates for these subgroups were 18.2%, 28.6%, and 20% respectively, all significantly lower than the HABIT group. To establish a “pure” standard of care (SOC) cohort, we conducted a subgroup analysis excluding control patients who received any nebulization. In this analysis, the HABIT group (N = 33) demonstrated significantly greater CT score percentage reduction compared to the refined control group (N = 9, no nebulization), with median (IQR) values of 37.5% (28.6%, 50%) vs. 18.2% (9.1%, 27.3%), respectively (p = 0.0014, Supplementary Fig. 1). Details of the nebulization treatment for the control group are shown in Supplementary Table 2.
Fig. 2.
The comparison of chest CT scores and representative chest CT images pre and postintervention between the two groups. A Comparison of chest CT scores between the HABIT group and the control group at Day 0 and Day 8. On Day 8, there was a significant difference in chest CT scores between the two groups. B Graph illustrating the percentage change in chest CT scores from Day 0 to Day 8 between the HABIT group and the control group. There was a significant decrease in CT scores pre and postintervention in both groups, the decrease in the HABIT group was significantly greater than that of the control group. C-D Presentative chest CT images from the HABIT group C and control group D at Day 0 and Day 8. The HABIT group shows a marked reduction in CT score from 14 to 2, indicating significant lung improvement. In contrast, the control group exhibits a less pronounced decrease in CT score from 13 to 7
PaO2/FiO2 (PFO), biochemical and hematological findings
Next, we compared the improvement in PFO pre and postintervention both two groups (Fig. 3A-C). Before treatment, there was no significant difference between HABIT group and the control group in terms of mean PFO (294.34 ± 55.45 vs. 287.73 ± 55.65, p = 0.633, Fig. 3A) or the proportion of patients with PFO greater than or equal to 300 mmHg (44.1% vs. 41.9%, p = 0.859, Fig. 3C). After treatment, a mean increase of 75.27 mmHg in the PFO was noticed in the HABIT group, which was numerically higher than that of 51.23 mmHg in the control group, but the difference was not statistically significant (p = 0.113, Fig. 3B). Also, the proportion of patients with PFO greater than or equal to 300 mmHg was slightly higher in the HABIT group than the control group (88.2% vs. 74.2%, p = 0.255, Fig. 3C). Of note, significantly higher 32.3% of patients reached PFO greater than or equal to 400 mmHg in the HABIT group, which was than that of the control group (6.5%, p = 0.022, Fig. 3C).
Fig. 3.
Changes in PaO2/FiO2 (PFO), Biochemical and hematological findings pre and postintervention between the two groups. A Comparison of PFO between the HABIT group and the control group at Day 0 and Day 8. On Day 8, there was a significant difference in PFO between the two groups. B Graph showing the percentage change in PFO between the HABIT group and the control group. No significant difference was observed in the percentage change of PFO between the two groups. C Distribution of patients by PFO categories at Day 0 and Day 8 in the HABIT group and control group. The HABIT group showed a significant shift towards higher PFO categories by Day 8, with a decrease in the proportion of patients with PFO < 300 mmHg and an increase in the proportion of patients with PFO ≥ 400 mmHg. In contrast, the control group exhibited minimal changes in PFO ratio distribution over the same period. D-F Panels D, E and F display the changes in white blood cell count (WBC), lymphocyte count (LYM), and C-reactive protein (CRP) levels from Day 0 to Day 8 in the HABIT group and the control group. No significant differences were observed in WBC and LYM counts between the groups over time. However, on Day 8, the CRP levels in the HABIT group were significantly lower than the control group
Comparison of hematological parameters and biochemical parameters pre and postintervention between two groups of study are shown in Fig. 3D-F. There were no differences between the two groups in terms of the median of WBC or lymphocytes either pre and postintervention. Also, no significant change of WBC or lymphocyte was noticed after treatment in either group. Besides, the results for median CRP (29.48 vs. 40.34, p = 0.203, Fig. 3F) showed no significant differences before treatment between the two groups. However, after treatment, patients in the HABIT group had significantly lower levels of median CRP (1.69 vs. 3.52, p = 0.03, Fig. 3F) and a much lower percentage of patients with CRP ≥ 10 (6.06% vs. 21.87%, p = 0.137, Supplementary Table 3).
Safety outcomes
No laboratory measurements showed abnormal findings attributable to nebulised HABIT treatment, particularly in terms of activated partial thromboplastin time (APTT) and platelet count (PLT) (Fig. 4). Before treatment, there were no significant differences in the median APTT between the two groups (29.4 vs. 30, p = 0.799, Fig. 4A). The results indicate a slight decrease in the mean APTT for both groups after treatment, with no significant differences noted (28.9 ± 3.4 vs. 29.5 ± 4.5, p = 0.573, Fig. 4A). Moreover, the platelet count increased in both groups after treatment, with no significant differences observed in the post-treatment platelet count (268.47 vs. 265, p = 0.869, Fig. 4B).
Fig. 4.
The safety outcomes pre and postintervention in both groups. A Activated partial thromboplastin time (APTT) values at Day 0 and Day 8 in the HABIT group and the control group. No significant differences were observed between the groups over time. B Platelet count (PLT) measurements at Day 0 and Day 8 in the HABIT group and the control group. No significant differences were observed between the groups over time
During the study period, no patients discontinued HABIT nebulization therapy due to adverse events. Three patients in the HABIT group experienced minor bleeding events (epistaxis, n = 1; oral bleeding, n = 1; blood-tinged sputum, n = 1), all of whom were concomitantly receiving systemic anticoagulant therapy during the study period. In 2 patients, a total of 4 inhaled nebulised HABIT doses were skipped. 2 doses were skipped due to patient refusal (n = 1), another 2 were because of too close to previous dose (n = 1). 1 patient in the control group developed a minor epistaxis. There were no cases recorded of pulmonary bleeding, gastrointestinal hemorrhage, major bleeding, heparin-induced thrombocytopenia, anaphylaxis, bronchospasm, and respiratory deterioration during or immediately after administration of inhaled nebulised HABIT or any other adverse events.
Discussion
Nebulised medications are the preferred delivery method for pulmonary disorders, owing to the lungs’ extensive surface area, highly vascularized parenchyma, and substantial absorptive capacity [20]. This prospective study demonstrated that nebulised HABIT in addition to standard of care in hospitalised patients with COVID-19 pneumonia accelerates lung lesion absorption and improves oxygenation, and no serious hemorrhages and other adverse effects were noticed during the treatment.
Heparin, N-acetylcysteine, budesonide, and ipratropium bromide target various aspects of the pathophysiology of COVID-19. When nebulized individually, they can achieve local benefits while minimizing systemic side effects. The anti-coagulant activities of nebulised unfractionated heparin limit the fibrin deposition and microvascular thrombosis [18, 34]. In addition, unfractionated heparin exhibits anti-inflammatory, mucolytic and anti-viral properties and, specifically, it has been demonstrated to inactivate the SARS-CoV-2 virus and prevent its entry into mammalian cells, thereby inhibiting pulmonary infection caused by SARS-CoV-2 [15]. An exploratory study demonstrated that nebulised unfractionated heparin, combined with standard care, provided clinical benefits for hospitalised COVID-19 patients, including reduced mortality rates and improved outcomes in MOCS scores and mechanical ventilation rates [17]. Another study indicated that nebulised heparin in the early phase of COVID-19 pneumonia, especially for patients with mild to moderate ARDS, could enhance oxygenation [38]. N-acetylcysteine, recognized for its mucolytic properties, also demonstrates antioxidant activity, immune cell response restoration, inflammatory modulation, thrombotic state reduction, and antiviral effects [22]. These pharmacological actions position N-acetylcysteine as a viable therapeutic for COVID-19. Preliminary study showed that inhalation of N-acetylcysteine was beneficial in reducing the mortality rate and inflammatory parameters, and the incidence of severe respiratory failure in COVID-19 patients [21, 39]. Inhaled corticosteroids are also known to be beneficial for COVID-19 as they could reduce the expression of key proteins that facilitate virus entry host cells and downregulate COVID-19-related genes [40]. The STOIC study showed that early administration of inhaled budesonide reduced the likelihood of needing urgent medical care and shortened recovery after early COVID-19 [24]. Another study revealed that inhaled budesonide could improve time to recovery and potentially reduced hospitalization or death in patients with COVID-19 in the community who are at higher risk of complications [25]. Inhaled bronchodilators have been considered as a viable treatment for hospitalised patients with COVID-19, relaxing the bronchus and antagonizing bronchospasm [28, 29]. Beyond smoke inhalation-induced lung injury, the efficacy and safety of partial combination nebulization with four drugs have been demonstrated in other infectious pneumonias. In refractory mycoplasma pneumonia, combined nebulization with acetylcysteine and budesonide can accelerate lesion absorption and reduce inflammatory markers [41, 42]. In bacterial bronchopneumonia, combined nebulization with ipratropium bromide and budesonide can shorten symptom relief time and improve pulmonary function indices [43].
In this study, the HABIT group showed significantly better resolution of pulmonary lesions after intervention, with more pronounced absorption of ground-glass opacities and consolidation on chest CT. Previous studies have demonstrated that the characteristic CT findings of COVID-19, such as ground-glass opacities and consolidation, are determined by its comprehensive pathophysiological processes—including gas-blood barrier dysfunction, microthrombosis, cytokine storm, oxidative stress, hyaline membrane formation, and bronchospasm—which are also associated with the development of post-COVID pulmonary fibrosis [14, 44–46]. Thus, the observed CT changes not only reflect the efficacy of HABIT therapy in targeting multiple pathophysiological mechanisms of COVID-19 but also indicate the accelerated resolution of fibrotic processes.
The current study has several limitations. First, one notable limitation of our study is the small sample size, which may reduce the generalizability of the findings to a broader population and prevented the possibility to conduct sub-group analysis. Second, due to the open-label design, both the investigators and participants were aware of the treatment allocation, which could systematically influence the evaluation of therapeutic efficacy. Consequently, to minimize detection bias, we implemented a blinded assessment of the primary endpoint, wherein chest CTs were scored independently by radiologists blinded to treatment allocation. Third, treatment heterogeneity in the control group may increase outcome variance and reduce statistical power. Therefore, we conducted a subgroup analysis. The results showed that the percentage reduction in CT scores for the HABIT group was significantly higher than that for each subgroup of the control group, suggesting that the HABIT therapy demonstrates superior efficacy compared to other nebulization regimens. Further clinical trials are warranted to confirm these results. The inability to rule out drug synergies with other components of the standardized protocol-driven care suggests the need for further controlled, larger scale study of nebulised HABIT.
Conclusions
The current study offers insights suggesting that the combined nebulization of unfractionated heparin, N-acetylcysteine, budesonide, and ipratropium bromide in individuals with COVID-19 pneumonia may enhance lung lesion resorption, leading to improved oxygenation and a reduction in systemic inflammation during the disease’s acute phase. Despite this, the HABIT regimen did not demonstrate any impact on hospital stay duration or the necessity for ICU admission. Moreover, the administration of heparin-based nebulised medications was found not to interfere with systemic coagulation or to trigger adverse events such as bleeding. While these results await validation from future prospective clinical trials, the favorable safety profile, proven efficacy, and cost-effectiveness of HABIT warrant its consideration as a potential adjunctive treatment for COVID-19 pneumonia.
Supplementary Information
Acknowledgements
We would like to thank the patients and staff for their valuable contributions.
Abbreviations
- COVID-19
Corona virus disease 2019
- HABIT
Heparin, acetylcysteine, budesonide, and ipratropium bromide
- SOC
Standard of care
- CT
Computed tomography
- SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2
- ICU
Intensive care unit
- FiO2
Fraction of inspiration O2
- PFO
Ratio of partial pressure of O2 in arterial blood to fraction of inspired oxygen, PaO2/FiO2
- WBC
White blood cell
- CRP
C-reactive protein
- APTT
Activated partial thromboplastin time
- PLT
Platelet count
- MOCS
WHO modified ordinal clinical scale
- ARDS
Acute respiratory distress syndrome
Authors’ contributions
L. L., G. C., K. L. conceived and designed the study, and drafted the article. J. G., N. N., and M. J. contributed to data acquisition, supervised data collection, data analysis, interpretation of the data and writing the manuscript. X. Y., Q. W., J. D., and J. K. contributed to the sample collection and data management and provided logistic support. X. L., L. Z., Y. Z., N. L., X. D., L. W., W. Z., and H. C. collected the data. All authors have read and agreed to the published version of the manuscript.
Funding
This work was supported by the Outstanding Youth Science Fund of Chongqing Municipal Science and Technology Bureau (CSTB2023NSCQ-JQX0033), Chongqing Municipal Health Commission (2023jstg012), Army Medical University (2022XL004, ZXAIZD001).
Data availability
The datasets in this study are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
The study was approved by the Ethics Committee of Daping Hospital, Army Medical University (NO.2023-137-01). All patients provided written informed consent. The study was conducted and reported following the recommendations of the Consolidated Standards of Reporting Trials (CONSORT) statement.
Consent for publication
Not Applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Junhui Gong, Naifu Nie and Minrui Jiang contributed equally to this work.
Contributor Information
Kunlin Li, Email: li676@sina.com.
Guoqiang Cao, Email: cgq1963@tmmu.edu.cn.
Li Li, Email: dpyyhxlili@tmmu.edu.cn.
References
- 1.Nigro M, Valenzuela C, Arancibia F, et al. A worldwide look into long COVID-19 management: an END-COVID survey. ERJ Open Res. 2024;10(6):00096-2024. [DOI] [PMC free article] [PubMed]
- 2.ÇELİK İ ÖZTÜRKR. From asymptomatic to critical illness: decoding various clinical stages of COVID-19. Turk J Med Sci. 2021;51(7):3284–300. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Grasselli G, Tonetti T, Protti A, et al. Pathophysiology of COVID-19-associated acute respiratory distress syndrome: a multicentre prospective observational study. Lancet Respir Med. 2020;8(12):1201–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Selickman J, Vrettou CS, Mentzelopoulos SD, Marini JJ. COVID-19-Related ARDS: key mechanistic features and treatments. J Clin Med. 2022;11(16):4896. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Wu C, Chen X, Cai Y, et al. Risk factors associated with acute respiratory distress syndrome and death in patients with coronavirus disease 2019 pneumonia in wuhan, China. JAMA Intern Med. 2020;180(7):934–43. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Huang L, Li X, Gu X, et al. Health outcomes in people 2 years after surviving hospitalisation with COVID-19: a longitudinal cohort study. Lancet Respir Med. 2022;10(9):863–76. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Zhang H, Huang C, Gu X, et al. 3-year outcomes of discharged survivors of COVID-19 following the SARS-CoV-2 Omicron (B.1.1.529) wave in 2022 in china: a longitudinal cohort study. Lancet Respir Med. 2024;12(1):55–66. [DOI] [PubMed] [Google Scholar]
- 8.Zhao F, Ma Q, Yue Q, Chen H. SARS-CoV-2 infection and lung regeneration. Clin Microbiol Rev. 2022;35(2):e00188. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Han X, Chen L, Guo L, et al. Long-term radiological and pulmonary function abnormalities at 3 years after COVID-19 hospitalisation: a longitudinal cohort study. Eur Respir J. 2024;64(1):2301612. [DOI] [PMC free article] [PubMed]
- 10.Niknam Z, Jafari A, Golchin A, et al. Potential therapeutic options for COVID-19: an update on current evidence. Eur J Med Res. 2022;27(1):6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Yuan Y, Jiao B, Qu L, Yang D, Liu R. The development of COVID-19 treatment. Front Immunol. 2023;14:1125246. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Saha T, Quiñones-Mateu ME, Das SC. Inhaled therapy for COVID-19: considerations of drugs, formulations and devices. Int J Pharm. 2022;624:122042. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Cazzola M, Ora J, Bianco A, Rogliani P, Matera MG. Guidance on nebulization during the current COVID-19 pandemic. Respir Med. 2021;176:106236. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Wiersinga WJ, Rhodes A, Cheng AC, Peacock SJ, Prescott HC. Pathophysiology, transmission, diagnosis, and treatment of coronavirus disease 2019 (COVID-19): A review. JAMA. 2020;324(8):782–93. [DOI] [PubMed] [Google Scholar]
- 15.van Haren FMP, Page C, Laffey JG, et al. Nebulised heparin as a treatment for COVID-19: scientific rationale and a call for randomised evidence. Crit Care Lond Engl. 2020;24(1):454. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Erelel M, Kaskal M, Akbal-Dagistan O, et al. Early effects of low molecular weight heparin therapy with Soft-Mist inhaler for COVID-19-Induced hypoxemia: A phase IIb trial. Pharmaceutics. 2021;13(11):1768. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.DeNucci G, Wilkinson T, Sverdloff C, et al. Inhaled nebulised unfractionated heparin (UFH) for the treatment of hospitalised patients with COVID-19: A randomised controlled pilot study. Pulm Pharmacol Ther. 2023;80:102212. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.van Haren FMP, van Loon LM, Steins A, et al. Inhaled nebulised unfractionated heparin for the treatment of hospitalised patients with COVID-19: A multicentre case series of 98 patients. Br J Clin Pharmacol. 2022;88(6):2802–13. [DOI] [PubMed] [Google Scholar]
- 19.Ramos da Silva Grillo VT, Bertanha M, da Silva Rodrigues L, et al. Nebulized enriched heparin improves respiratory parameters in patients with COVID-19: a phase I/II randomized and triple-blind clinical trial. Sci Rep. 2024;14(1):19902. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Gupta B, Ahluwalia P, Gupta N, Gupta A. Role of nebulized heparin in clinical outcome of COVID-19 patients with respiratory symptoms: A systematic review. Indian J Crit Care Med Peer-Rev Off Publ Indian Soc Crit Care Med. 2023;27(8):572–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Panahi Y, Ghanei M, Rahimi M, et al. Evaluation the efficacy and safety of N-acetylcysteine inhalation spray in controlling the symptoms of patients with COVID‐19: an open‐label randomized controlled clinical trial. J Med Virol. 2023;95(1):e28393. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Izquierdo-Alonso JL, Pérez-Rial S, Rivera CG, Peces-Barba G. N-acetylcysteine for prevention and treatment of COVID-19: current state of evidence and future directions. J Infect Public Health. 2022;15(12):1477–83. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.N-acetylcysteine for. The treatment of COVID-19 among hospitalized patients. J Infect. 2022;84(1):94–118. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Ramakrishnan S, Nicolau DV, Langford B, et al. Inhaled Budesonide in the treatment of early COVID-19 (STOIC): a phase 2, open-label, randomised controlled trial. Lancet Respir Med. 2021;9(7):763–72. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Yu LM, Bafadhel M, Dorward J, et al. Inhaled Budesonide for COVID-19 in people at high risk of complications in the community in the UK (PRINCIPLE): a randomised, controlled, open-label, adaptive platform trial. Lancet Lond Engl. 2021;398(10303):843–55. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Agustí A, De Stefano G, Levi A, et al. Add-on inhaled Budesonide in the treatment of hospitalised patients with COVID-19: a randomised clinical trial. Eur Respir J. 2022;59(3):2103036. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.The National Heart, Randomized L. Placebo-controlled clinical trial of an aerosolized β2-Agonist for treatment of acute lung injury. Am J Respir Crit Care Med. 2011;184(5):561. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Villamañán E, Sobrino C, Carpio C, et al. Inhaled bronchodilators use and clinical course of adult inpatients with Covid-19 pneumonia in spain: A retrospective cohort study. Pulm Pharmacol Ther. 2021;69:102007. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Moustafa HAM, Elbery FH, Al Meslamani AZ, Okda SM, Alsfouk BA, Kassem AB. Evaluating the use of inhaled Budesonide and Ipratropium bromide combination in patients at high risk of acute respiratory distress syndrome development: A randomized controlled trial. Pharmaceuticals. 2025;18(3):412. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Sheridan RL. Fire-related inhalation injury. Ingelfinger JR, ed. N Engl J Med. 2016;375(5):464–9. [DOI] [PubMed] [Google Scholar]
- 31.Enkhbaatar P, Pruitt BA, Suman O, et al. Pathophysiology, research challenges, and clinical management of smoke inhalation injury. Lancet. 2016;388(10052):1437–46. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Jones SW, Williams FN, Cairns BA, Cartotto R. INHALATION INJURY: pathophysiology, diagnosis, and treatment. Clin Plast Surg. 2017;44(3):505–11. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Elsharnouby NM, Eid HEA, Abou Elezz NF, Aboelatta YA. Heparin/N-acetylcysteine: an adjuvant in the management of burn inhalation injury. J Crit Care. 2014;29(1):182.e1-182.e4. [DOI] [PubMed] [Google Scholar]
- 34.Francone M, Iafrate F, Masci GM, et al. Chest CT score in COVID-19 patients: correlation with disease severity and short-term prognosis. Eur Radiol. 2020;30(12):6808–17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Pan F, Ye T, Sun P, et al. Time Course of Lung Changes at Chest CT during Recovery from Coronavirus Disease 2019 (COVID-19). Radiology. 2020;295(3):715–21. [DOI] [PMC free article] [PubMed]
- 36.Yun Y, Wang Y, Hao Y, Xu L, Cai Q. The time course of chest CT lung changes in COVID-19 patients from onset to discharge. Eur J Radiol Open. 2021;8:100305. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Wang Y, Dong C, Hu Y, et al. Temporal changes of CT findings in 90 patients with COVID-19 pneumonia: A longitudinal study. Radiology Published Online March. 2020;19:200843. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Gupta B, Chandrakar S, Gupta N, Jain G. Nebulized heparin to reduce COVID-19-induced acute lung injury: A prospective observational study. Indian J Crit Care Med Peer-Rev Off Publ Indian Soc Crit Care Med. 2023;27(3):222–4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Lana JFSD, Lana AVSD, Rodrigues QS, et al. Nebulization of glutathione and N-Acetylcysteine as an adjuvant therapy for COVID-19 onset. Adv Redox Res. 2021;3:100015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 40.Yu SY, Choi M, Ryoo S, et al. Clinical efficacy of inhaled corticosteroids in patients with coronavirus disease 2019: A living review and meta-analysis. PLoS ONE. 2023;18(11):e0294872. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 41.Wang Y, Liu K, Chen C, Zhang C. Acetylcysteine and Budesonide for the treatment of refractory Mycoplasma pneumoniae pneumonia in children: a clinical observation. Ital J Pediatr. 2023;49(1):80. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 42.Chen J, Zhu Y, Zheng C, Zhao W, Liu Q. Clinical efficacy of Budesonide combined with acetylcysteine in the treatment of mycoplasma pneumonia infection. Immun Inflamm Dis. 2023;11(11):e1068. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 43.Wang C, Zhang X, Qian W, Liu X, Zhang W. Budesonide combined with Ipratropium bromide in the treatment of Bronchopneumonia and its efficacy on pulmonary function. Int J Clin Exp Med 2020;13(2):1092–7. [Google Scholar]
- 44.Zu ZY, Jiang MD, Xu PP, et al. Coronavirus disease 2019 (COVID-19): A perspective from China. Radiology. 2020;296(2):E15–25. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 45.O’Reilly S. Pulmonary fibrosis in COVID-19: mechanisms, consequences and targets. QJM. 2023;116(9):750–4. [DOI] [PubMed] [Google Scholar]
- 46.Vreeman ECA, Pillay J, Burgess JK. Post-COVID pulmonary sequelae: mechanisms and potential targets to reduce persistent fibrosis. Pharmacol Ther. 2025;272:108891. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets in this study are available from the corresponding author upon reasonable request.