Development of a new inhaled swellable microsphere system for the dual delivery of naringenin-loaded solid lipid nanoparticles and doxofylline for the treatment of asthma

This study developed a new dual delivery system of naringenin (NRG), a polyphenol, and doxofylline (DOX), a xanthine derivative, as an inhaled microsphere system. In this system, NRG has been first loaded into glyceryl tristearate-based solid lipid nanoparticles (NRG SLN), which were further loaded with DOX into swellable chitosan-tripolyphosphate-based microspheres (NRG SLN DOX sMS). The system was characterized based on particle size, PDI, zeta potential, surface morphology (SEM, AFM, and TEM), solid-state and chemical properties (XRD, IR, and NMR), aerodynamic parameters, drug loading, entrapment efficiency and in vitro drug release study. The optimized NRG SLN DOX sMS exhibited particle size, zeta potential, and PDI of 2.1 µm, 31.2 mV, and 0.310, respectively; a drug entrapment efficiency > 79 %; a drug loading efficiency > 13 %; cumulative drug releases of about 78 % for DOX and 72 % for NRG after 6 and 12 h, respectively; good swelling and desirable aerodynamic properties. In addition, in vivo studies conducted in mice, a murine model of asthma showed significant reductions in serum bicarbonate and eosinophil counts and improvement in respiratory flow rate, tidal volume, and bronchial wall lining compared with the asthmatic control group. Overall, this novel inhalable dual-delivery system may represent a good alternative for the effective treatment of asthma.

Effect of doxofylline on pulmonary inflammatory response and oxidative stress during mechanical ventilation in rats with COPD

OBJECTIVE

To evaluate the effects of doxofylline on inflammatory responses and oxidative stress during mechanical ventilation in rats with chronic obstructive pulmonary disease (COPD).

METHODS

Eight-week-old male Sprague Dawley rats were selected, and the COPD rat model was constructed. The rats were randomly divided into a model group (group M), a model + normal saline group (group N), a doxofylline group (group D), and a control group fed with conventional chow and given normal oxygen supply (group C) (n = 12 in each group). Tracheal intubation and mechanical ventilation were conducted in the rats in each group after anesthesia. A real-time intravenous infusion with 50 mg/kg of doxofylline was conducted in group D, and there was no drug intervention in groups C, N and M. Pathological manifestations of the pulmonary tissues were observed and compared among the groups. And some indicators were evaluated.

RESULTS

(1) The pulmonary tissues of the rats in groups M, N, and D exhibited typical pathological histological changes of COPD. (2) Groups M, N, and D showed increased Ppeak, PaCO2, total white blood cell count in BALF, and IL-8, TNF-α, and MDA levels in the pulmonary tissue and BALF, and decreased PaO2 and IL-10 and SOD levels, compared with group C. (3). Group D showed decreased Ppeak, PaCO2, total white blood cell count in BALF, and IL-8, TNF-α, and MDA levels in the pulmonary tissue, and increased PaO2 and IL-10 and SOD levels, compared with group N or M.

CONCLUSION

Doxofylline was shown to improve ventilation and air exchange during mechanical ventilation in rats with COPD, reduce the inflammatory response and oxidative stress, and mitigate the degree of pulmonary tissue injury.

The protective effect of doxofylline against lipopolysaccharides (LPS)-induced activation of NLRP3 inflammasome is mediated by SIRT1 in human pulmonary bronchial epithelial cells

Lung diseases are common health problems in many countries. The dysfunction of bronchial epithelial cells is important for the development of lung diseases. Recent progress reveals that inflammasome is the fundamental mechanism of epithelial activation. Here, we report the protective effect of doxofylline, a theophylline derivative agent, on lipopolysaccharides (LPS)-induced inflammatory response in bronchial epithelial cells. The presence of doxofylline reduces LPS-induced production of NO and PGE₂. Doxofylline also inhibits LPS-induced production of mitochondrial ROS. Mechanistically, we show that doxofylline suppresses the expression of NOX4 induced by LPS. Doxofylline inhibits LPS-induced NLRP3-TXNIP inflammasome activation as revealed by its inhibitive effect on NLRP3, caspase 1 (P10 unit), and TXNIP induction as well as weakened induction of IL-1β and IL-18. Furthermore, we show that doxofylline ameliorates LPS-induced Sirtuin 1 (SIRT1) reduction. The silencing of SIRT1 abolishes the inhibitory effect of doxofylline on NLRP3 inflammasome activation. Collectively, our study demonstrates that doxofylline mitigates epithelial inflammation via amelioration of multiple cellular pathways, including NLRP3-TXNIP inflammasome activation.

The effect of doxofylline in asthma and COPD

Theophylline is still one of the most widely prescribed drugs for the treatment of asthma and COPD in developing countries because the majority of asthma and COPD medicines are largely unavailable and also because it is a cheap option. In any case, its anti-inflammatory effects and capacity to reverse corticosteroid resistance deserve consideration, but it can induce numerous side effects and drug-drug interactions and frequently requires measurement of drug levels in plasma. In order to overcome the problems posed by theophylline, other xanthines have been developed. Doxofylline is a newer generation xanthine with both bronchodilating and anti-inflammatory activities and for this reason it has been called "novofylline". It differs substantially from theophylline at the pharmacological level. Clinical studies have shown substantial differences between doxofylline and theophylline. In particular, efficacy/safety profile of doxofylline is better than that of theophylline.

A long-term clinical trial on the efficacy and safety profile of doxofylline in Asthma: The LESDA study

Doxofylline, an oral methylxanthine with bronchodilator and anti-inflammatory activities, offers a promising alternative to theophylline due to its superior efficacy/safety profile. No long-term studies on the efficacy and safety of doxofylline are currently available in asthma. The aim of the Long-term clinical trial on the Efficacy and Safety profile of Doxofylline in Asthma (LESDA) study was to investigate the safety and efficacy profile of doxofylline administered for one year in asthmatic patients. LESDA was a multicenter, open-label, Phase III, clinical trial in which adult asthmatic patients received the same treatment (oral doxofylline 400 mg t.i.d.) for one year. Efficacy was assessed through periodic pulmonary function tests and by having the subjects keep monthly records of asthma events rates and use of salbutamol as rescue medication. The rate of adverse events (AEs) was recorded during the study. Three-hundred nine patients were screened and allocated in the study. Doxofylline significantly improved the change from baseline in forced expiratory volume in 1 s (FEV₁) (+16.90 ± 1.81%, P < 0.001 vs. baseline). Doxofylline also significantly improved the rate of asthma events (events/day: -0.57 ± 0.18, P < 0.05 vs. baseline) and the use of salbutamol as rescue medication (puffs/day: -1.48 ± 0.25, P < 0.01 vs. baseline). The most common AEs were nausea (14.56%), headache (14.24%), insomnia (10.68%), and dyspepsia (10.03%). There were neither serious AEs nor deaths during or shortly after the study. Concluding, doxofylline is effective and well tolerated when administered chronically in asthmatic patients.

Comparison of anti-inflammatory mechanisms between doxofylline and theophylline in human monocytes

BACKGROUND

Methylxanthines are important pharmacological agents in the treatment of asthma and of chronic obstructive pulmonary diseases. The present study was designed to compare the ability of doxofylline and theophylline to modulate inflammatory pathways in human monocytes.

METHODS

Monocytes isolated from healthy anonymous human buffy coats were treated with doxofylline or theophylline in the presence of phorbol 12-myristate 13-acetate (PMA) or lipopolysaccharide (LPS), and their phenotype, the oxidative burst, cytokine expression and release, cAMP production, and protein kinase C (PKC) activity were evaluated.

RESULTS

Doxofylline and theophylline did not have overlapping effects on human monocytes. While sharing some common characteristics, they differed significantly in their selectivity. Theophylline affected LPS- above PMA-induced cellular responsivity, while doxofylline behaved in the opposite manner. Furthermore, when testing PKC activity, we found an inhibitory effect of doxofylline but not of theophylline, at equimolar doses.

CONCLUSIONS

In conclusion, our data support the growing hypothesis that doxofylline does not have a superimposable mechanism of action compared to theophylline, and this may both explain some differences in the risk/benefit ratio and may direct studies to tailor therapy for patients.

Efficacy and safety profile of doxofylline compared to theophylline in asthma: a meta-analysis

Background

Oral methylxanthines are effective drugs for the treatment of chronic obstructive respiratory disorders. The novel methylxanthine doxofylline, that has bronchodilator and anti-inflammatory activities, is not affected by the major drawback of theophylline. Nowadays large-scale quantitative synthesis comparing the efficacy and safety profile of doxofylline vs. theophylline in the treatment of asthma is still lacking. Therefore, we performed a quantitative synthesis to compare the efficacy/safety profile of doxofylline and theophylline in asthma.

Methods

A pairwise and network meta-analyses were performed to assess the impact of doxofylline vs. theophylline and placebo on the change in asthma events, risk of adverse events (AEs), forced expiratory volume in 1 s (FEV₁), and salbutamol use.

Results

Data obtained from 696 asthmatic patients were extracted from 4 randomized controlled trials published between 2015 and 2018. Doxofylline was significantly (P < 0.05) more effective than theophylline in reducing the daily asthma events (mean difference − 0.14, 95%CI -0.27 – 0.00) and risk of AEs (relative risk 0.76, 95%CI 0.59–0.99). Doxofylline was as effective as theophylline in improving FEV₁, and a trend of superiority (P = 0.058) was detected for doxofylline over theophylline with respect to the reduction in the use of salbutamol as rescue medication. The rank of effectiveness was doxofylline>theophylline> > placebo, and the rank of safety was placebo>doxofylline> > theophylline.

Conclusions

Doxofylline is an effective and safe methylxanthine for the treatment of asthma, with an efficacy/safety profile greater than that of theophylline.

Trial registration

Meta-analysis registration: CRD42019119849.

Impact of doxofylline compared to theophylline in asthma: A pooled analysis of functional and clinical outcomes from two multicentre, double-blind, randomized studies (DOROTHEO 1 and DOROTHEO 2)

This pooled analysis of double-blind, randomized, placebo-controlled trials aimed to investigate the impact of DOxofylline compaRed tO THEOphylline (DOROTHEO 1 and DOROTHEO 2 studies) on functional and clinical outcomes in asthma. Asthmatic patients ≥16 years of age with forced expiratory volume in 1 s (FEV₁) ≥50% and <80% and with ≥15% post-bronchodilator increase in FEV₁ were randomized in a 1:1:1:1 ratio in DOROTHEO 1 to receive doxofylline 200 mg, doxofylline 400 mg, theophylline 250 mg, or placebo; in DOROTHEO 2 patients were randomized in a 1:1:1 ratio to receive doxofylline 400 mg, theophylline 250 mg, or placebo. All double-blind treatments were taken orally with immediate release formulations and three times daily. Data evaluating the effect of doxofylline 400 mg, theophylline 250 mg and placebo on FEV₁, asthma events rate, use of salbutamol as rescue medication and adverse events (AEs) were pooled from both studies. The pooled-analysis of 483 patients demonstrated that both doxofylline 400 mg and theophylline 250 mg significantly increased FEV₁, reduced the rate of asthma events and use of salbutamol to relieve asthma symptoms compared to placebo (p < 0.01). No significant differences were detected between doxofylline 400 mg and theophylline 250 mg. Doxofylline 400 mg did not significantly (p > 0.05) increase the risk of AEs compared to placebo, conversely in patients treated with theophylline 250 mg the risk of AEs was significantly (p < 0.05) greater than in those that received placebo. We conclude that doxofylline seems to offer a promising alternative to theophylline with a superior efficacy/safety profile in the management of patients with asthma.

Impact of doxofylline in COPD: A pairwise meta-analysis

Doxofylline is an effective bronchodilator for relieving airway obstruction in patients with asthma or chronic obstructive pulmonary disease (COPD), and displays a better safety profile with respect to theophylline. Herein, we performed a pairwise meta-analysis of the currently available data to provide consistent and homogeneous findings on the impact of this xanthine in COPD patients. Results obtained from 820 patients were selected from 20 clinical trials. Meta-regression was performed to examine the source of heterogeneity between-studies and identify potential confounder covariates. The quality of the evidence was assessed by the GRADE system. Doxofylline induced a significant (P < 0.001) increase in forced expiratory volume in 1 s (FEV₁) of 8.20% (95%CI 4.00-12.41; I² 93%) and 317 ml (95%CI 19-439; I² 87%) compared with baseline. The total administered dose of doxofylline significantly (P < 0.001) interacted with the size of the effect estimates detected for FEV₁. Doxofylline induced a significant (P < 0.001), although moderate, increase in adverse events (AEs) frequency (proportion 0.03, 95%CI 0.02-0.04; I² 88%), but only epigastralgia, nausea, dyspepsia and headache were statistically significant (P < 0.05). The GRADE analysis indicated high quality of evidence (++++) for the impact of doxofylline on FEV₁, and moderate quality of evidence (+++) for the safety profile in COPD patients. Doxofylline is an effective and safe medicine when administered to patients with COPD and can be considered as an alternative to theophylline.

Steroid sparing effects of doxofylline

Glucocorticosteroids are widely used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). However, there are growing concerns about the side effect profile of this class of drug, particularly an increased risk of pneumonia. Over the last two decades there have been many attempts to find drugs to allow a reduction of glucocorticosteroids, including xanthines such as theophylline. Use of xanthines has been shown to lead to a reduction in the requirement for glucocorticosteroids, although xanthines also have a narrow therapeutic window limiting their wider use. Doxofylline is another xanthine that has been shown to be of clinical benefit in patients with asthma or COPD, but to have a wider therapeutic window than theophylline. In the present study we have demonstrated that doxofylline produces a clear steroid sparing effect in both an allergic and a non-allergic model of lung inflammation. Thus, we have shown that concomitant treatment with a low dose of doxofylline and a low dose of the glucocorticosteroid dexamethasone (that alone had no effect) significantly reduced both allergen-induced eosinophil infiltration into the lungs of allergic mice, and lipopolysaccharide (LPS)-induced neutrophil infiltration into the lung, equivalent to a higher dose of each drug. Our results suggest that doxofylline demonstrates significant anti-inflammatory activity in the lung which can result in significant steroid sparing activity.

Xanthines and Phosphodiesterase Inhibitors

Theophylline is an orally acting xanthine that has been used since 1937 for the treatment of respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD). However, in most treatment guidelines, xanthines have now been consigned to third-line therapy because of their narrow therapeutic window and propensity for drug-drug interactions. However, lower than conventional doses of theophylline considered to be bronchodilator are now known to have anti-inflammatory actions of relevance to the treatment of respiratory disease. The molecular mechanism(s) of action of theophylline are not well understood, but several potential targets have been suggested including non-selective inhibition of phosphodiesterases (PDE), inhibition of phosphoinositide 3-kinase, adenosine receptor antagonism and increased activity of certain histone deacetylases. Although theophylline has a narrow therapeutic window, other xanthines are in clinical use that are claimed to have a better tolerability such as doxofylline and bamifylline. Nonetheless, xanthines still play an important role in the treatment of asthma and COPD as they can show clinical benefit in patients who are refractory to glucocorticosteroid therapy, and withdrawal of xanthines from patients causes worsening of disease, even in patients taking concomitant glucocorticosteroids.More recently the orally active selective PDE4 inhibitor, roflumilast, has been introduced into clinical practice for the treatment of severe COPD on top of gold standard treatment. This drug has been shown to improve lung function in patients with severe COPD and to reduce exacerbations, but is dose limited by a range side effect, particularly gastrointestinal side effects.

Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations

An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 μm column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively.